Campbell Biology, 12th Edition Unit 5 PDF

Campbell Biology, 12th Edition Esparza 1 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Table of Contents Chapter 26: Phylogeny and the Tree of Life 3 Concept 26...

Campbell Biology, 12th Edition Esparza 1 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Table of Contents Chapter 26: Phylogeny and the Tree of Life 3 Concept 26.1 Phylogenies show evolutionary relationships 3 Concept 26.2 Phylogenies are inferred from morphological and molecular data 5 Concept 26.3 Shared characters are used to construct phylogenetic tree 5 Concept 26.4 An organism’s evolutionary history is documented in its genome 6 Concept 26.5 Molecular clocks help track evolutionary time 7 Concept 26.6 Our understanding of the tree of life continues to changed based on new data 7 Chapter 27: Bacteria and Archaea 8 Concept 27.1 Structural and functional adaptations contribute to prokaryotic success 8 Concept 27.2 Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes 10 Concept 27.3 Diverse nutritional and metabolic adaptations have evolved in prokaryotes 11 Concept 27.4 Prokaryotes have radiated into a diverse set of lineages 12 Concept 27.5 Prokaryotes play crucial roles in the biosphere 15 Concept 27.6 Prokaryotes have both beneficial and harmful impacts on humans 16 Chapter 28: Protists 17 Concept 28.1 Most eukaryotes are single-celled organisms 17 Concept 28.2 Excavates include protists with modified mitochondria and protists with unique flagella 19 Concept 28.3 SAR is a highly diverse group of protists defined by DNA similarities 19 Concept 28.4 Red algae and green algae are the closest relatives of plants 20 Concept 28.5 Unikonts include protists that are closely related to fungi and animals 21 Concept 28.6 Protists play key roles in ecological communities 21 Chapter 29: Plant Diversity I: How Plants Colonized Land 23 Concept 29.1 Plants evolved from green algae 23 Concept 29.2 Mosses and other nonvascular plants have life cycles dominated by gametophytes 25 Concept 29.3 Ferns and other seedless vascular plants were the first plants to grow tall 26 Chapter 30: Plant Diversity II: The Evolution of Seed Plants 28 Concept 30.1 Seeds and pollen grains are key adaptations for life on land 28 Concept 30.2 Gymnosperms bear “naked” seeds, typically on cones 29 Concept 30.3 The reproductive adaptations of angiosperms include flowers and Fruits 30 Campbell Biology, 12th Edition Esparza 2 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Concept 30.4 Human welfare depends on seed plants 32 Chapter 31: Fungi 32 Concept 31.1 Fungi are heterotrophs that feed by absorption 32 Concept 31.2 Fungi produce spores through sexual or asexual life cycles 33 Concept 31.3 The ancestor of fungi was an aquatic, single-celled, flagellated protist 34 Concept 31.4 Fungi have radiated into a diverse set of lineages 35 Concept 31.5 Fungi play key roles in nutrient cycling, ecological interactions, and human welfare 37 Chapter 32: An Overview of Animal Diversity 38 Concept 32.1 Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers 38 Concept 32.2 The history of animals spans more than half a billion years 39 Concept 32.3 Animals can be characterized by body plans 40 Concept 32.4 Views of animal phylogeny continue to be shaped by new molecular and morphological data 43 Chapter 33: An Introduction to Invertebrates 44 Concept 33.1 Sponges are basal animals that lack tissues 44 Concept 33.2 Cnidarians are an ancient phylum of eumetazoans 44 Concept 33.3 Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms 45 Concept 33.4 Ecdysozoans are the most species-rich animal group 49 Concept 33.5 Echinoderms and chordates are deuterostomes 51 Chapter 34: The Origin and Evolution of Vertebrates 54 Concept 34.1 Chordates have a notochord and a dorsal, hollow nerve cord 54 Concept 34.2 Vertebrates are chordates that have a backbone 56 Concept 34.3 Gnathostomes are vertebrates that have jaws 57 Concept 34.4 Tetrapods are gnathostomes that have limbs 58 Concept 34.5 Amniotes are tetrapods that have a terrestrially adapted egg 59 Concept 34.6 Mammals are amniotes that have hair and produce milk 62 Concept 34.7 Humans are mammals that have a large brain and bipedal Locomotion 63 Campbell Biology, 12th Edition Esparza 3 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Chapter 26: Phylogeny and the Tree of Life Concept 26.1 Phylogenies show evolutionary relationships Phylogeny - evolutionary history of a species or group of species ○ Constructed using systematics, discipline focused on classifying & understanding relationships among organisms Binomial Nomenclature Binomial - two-part format of a scientific name ○ 1st part is the genus & 2nd part the epithet (species) ○ Ex: Homo sapiens Hierarchical Classification Linnaean system classifies organisms into groups, taxons: (general → specific) ○ Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species Linking Classification & Phylogeny Phylogenetic tree - branching diagram that shows evolutionary history & relationships Hierarchical classification represents the branching pattern of phylogeny ○ From left to right, classification gets more specific Characteristics of Phylogenetic Trees & Applications Evolutionary relationships depicted as dichotomies ○ Branch point = common ancestor of 2 diverging lineages ○ Horizontal branch = evolutionary lineage (new species, leads to next taxon) ○ Sister taxa - groups of organisms exclusively sharing a common ancestor Closest relatives (e.g. chimpanzees and humans) Can be represented vertically, diagonally, or in a rotation ○ Does not change the sequence of evolution (“leading to” a subsequent taxon) Campbell Biology, 12th Edition Esparza 4 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Rooted = branch point represents a common ancestor of all taxa involved; a basal taxon diverges from the group Does not represent phenotypic similarity, cannot infer ages of taxa/branch points, and should not assume taxa evolved from a close taxa Can be used to find beneficial alleles & infer species identities Concept 26.2 Phylogenies are inferred from morphological and molecular data Similar homologies arise from a common ancestor ○ Organisms with diff. morph, but sim. DNA sequences can still be closely related ○ Only homologies relate to evolutionary history Analogy - similarities due to convergent evolution ○ Since analogous structures are unrelated to descent, it is inapplicable In molecular homologies, DNA sequences are compared for similar bases ○ Differences accumulate over time due to deletions/insertions ○ Similar = recent common ancestor, different = distant common ancestor Concept 26.3 Shared characters are used to construct phylogenetic tree Cladistics - systematics approach in which common ancestry determines classification ○ Classified into groups called clades with ancestors & descendants Monophyletic - include a common ancestor & all descendants Paraphyletic - include a common ancestor & some descendants Polyphyletic - include no recent common ancestor & descendants Shared ancestral characters - originated from an ancestor (e.g. vertebrate backbone) Campbell Biology, 12th Edition Esparza 5 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Shared derived characters - unique to the clade (e.g. hair in mammals) ○ Can be used to determine evolutionary relationships in a clade ○ Outgroup is in an evolutionary lineage similar to, but not in the group of study (ingroup) Comparing outgroups & ingroups can help derive characters at specific branch points Phylogenetic trees may have branch lengths proportional to evolutionary change or chronological time With large amounts of DNA sequence data, tree must be constructed efficiently ○ Maximum parsimony (Ockham’s razor) states that the simplest explanation (with little evolutionary events) should be examined first ○ Maximum Likelihood identifies the tree that most likely produced a specific DNA set, based on probability Phylogenetic tree represent hypotheses supported by morphological & molecular data ○ Phylogenetic bracketing predicts that a shared trait between two groups is present in their common ancestor Ex: It was reasoned that dinosaurs built nests and cared for their eggs based on the common ancestor of crocodiles, dinosaurs, and birds, which was supported by the fossil remains Oviraptor and eggs Concept 26.4 An organism’s evolutionary history is documented in its genome Comparison of molecular data reveals evolutionary relatedness not seen morphologically ○ Analysis of slow-changing rRNA reveals fungi are more related to animals than plants ○ Inquiry of fast-changing mtDNA show that the Pima of Arizona, Maya of Mexico, & Yanomami of Venezuela all descended from those that crossed the Bering Land Bridge Campbell Biology, 12th Edition Esparza 6 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Gene Duplications and Gene Families Gene duplications have produced homologous gene families, cluster of related genes ○ Orthologous genes - form between species as a result of speciation Used in phylogeny since their difference reflect speciation history ○ Paralogous genes - forms within a species from gene duplication and divergence (e.g. olfactory receptor genes) Genome Evolution Distant lineages share many orthologous genes ⬆️ ○ Explains metabolic pathways (e.g. glycolysis) common in disparate organisms Many duplicated genes does not necessarily phenotypic complexity Concept 26.5 Molecular clocks help track evolutionary time Molecular clock estimates absolute age of evolutionary changes by assuming some genes evolve at constant rates ○ Calibrated by plotting genetic differences against divergence time (based on fossils) Difference in clock speed stems from the fact that genes are selectively neutral ○ More harmful, less neutral = slow ○ Less harmful, more neutral - fast Irregularities result from natural selection, the gene in different taxa having having evolved at different rates When applied to HIV, the strain HIV-1 M likely spread to humans around 1910 - 1930 Campbell Biology, 12th Edition Esparza 7 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Concept 26.6 Our understanding of the tree of life continues to changed based on new data Classification went from two kingdoms (plants & animals) to three domains (eukarya, archaea, & bacteria) ○ Bacteria - prokaryotes, Archaea - diverse prokaryotes living in different environments, eukarya - those with a true nuclei Horizontal gene transfer - genes transferred from one genome to another ○ May explain why trees using different genes yield different branching patterns Some eukaryotic genes are more related to bacteria while others to archaea ○ Ex: alga Galdieria sulphuraria may have acquired its ability to withstand extreme habitats from prokaryotic genes Chapter 27: Bacteria and Archaea Concept 27.1 Structural and functional adaptations contribute to prokaryotic success Prokaryotes - relatively small, unicellular organisms in the bacteria & archaea domains ○ Variable shape (cocci (circular) bacilli (rod-shaped), spirilla (coil-shaped)) Cell-Surface Structures Cell wall provides rigidity & support for the cell ○ Composed of a polymer called peptidoglycan ○ Using a technique called gram stain, bacteria are grouped into: Gram-positive - thick wall of peptidoglycan, purple Gram-negative - thin peptidoglycan layer, lipopolysaccharide outer layer, pink likely to resist antibiotics that attack cell walls (e.g. penicillin) Campbell Biology, 12th Edition Esparza 8 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Capsule - sticky layer of polysaccharide/protein aiding in cell adherence and/or evasion of a host’s immune system Endospores - resistant cells that allow for survival in harsh conditions ○ Remain dormant until conditions improve where it can then revive Fimbriae - hairlike appendages that help attach to surfaces or other cells Pili - appendages that facilitate conjugation Motility Most prokaryotes are capable of moving in response to a stimulus (taxis) ○ In chemotaxis, they can move toward nutrient (+) or away from toxin (-) Move via a prokaryotic flagella (evolved analogously to eukaryotic flagella) ○ Evolved as proteins were added to an ancestral secretory system (exaptation) Internal Organization and DNA Simpler than eukaryotes as they lack membrane-bound organelles Circular chromosome packaged into a region called the nucleoid ○ May contain independently replicating circular DNA molecules (plasmids) Different ribosome structure allows for antibiotics to only attack bacteria Campbell Biology, 12th Edition Esparza 9 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Reproduction Can reproduce exponentially through binary fission; often have short generation times Concept 27.2 Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes Rapid Reproduction and Mutation ⬆️ With short generation times & large populations, rare mutations are common ○ genetic variation & rapid evolution in a new environment Genetic Recombination Combining of DNA from two sources (genetic recombination) occurs in: ○ Transformation - uptake of foreign DNA from the environment Produces a recombinant via homologous DNA exchange (crossing over) ○ Transduction - phage transfers prokaryotic DNA from one host (donor) to another (recipient) ○ Conjugation - DNA is transferred between prokaryotes via pili, forming a “mating bridge” In e.coli, F factor is transferred between cells as: F plasmid moves from donor (F+ cell) to recipient (F- cell) ○ F- cell becomes a recombinant F+ cell Chromosome carried from donor (Hfr cell) to recipient (F- cell) ○ F- cell become a recombinant F- cell R plasmids carry antibiotic resistance genes that can spread through a bacterial population, promoting adaptive evolution  Campbell Biology, 12th Edition Esparza 10 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Concept 27.3 Diverse nutritional and metabolic adaptations have evolved in prokaryotes Phototrophs = energy from light, Chemotrophs = energy from chemicals, Autotrophs = only needs CO2, Heterotrophs = need at least one organic source Table 27.1 Major Nutritional Modes Mode Energy Source Carbon Source Types of Organisms AUTOTROPH Photoautotroph Light CO2, HCO3-, or Photosynthetic related compound prokaryotes (e.g. cyanobacteria); plants; certain protists (e.g. algae) *Chemoautotroph Inorganic chemicals CO2, HCO3-, or Unique to certain (e.g. H2S, NH3, related compound prokaryotes (e.g. Fe2+) Sulfolobus) HETEROTROPH *Photoheterotroph Light Organic compounds Unique to certain aquatic and salt-loving prokaryotes (e.g. Rhofobacter, chloroflexus) Chemoheterotroph Organic compounds Organic compounds Many prokaryotes (e.g.  Campbell Biology, 12th Edition Esparza 11 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Clostridium) and protists; fungi; animals; some plants The Role of Oxygen in Metabolism Obligate aerobes - require O2 for cellular respiration Obligate anaerobes - poisoned by O2; fermentation or anaerobic respiration Facultative anaerobes - can choose which process depending on the environment Nitrogen Metabolism Nitrogen fixation - nitrogen (N2) → ammonia (NH3); fixed to organic molecules ○ Nitrogen-fixing prokaryotes (e.g. cyanobacteria) provide a nitrogen source to plants Metabolic Cooperation Cyanobacterium Anabaena cannot perform N2 fixation & photosynthesis concurrently ○ Forms filamentous chains (photosynthesis) with heterocysts (N2 fixation) ⬆️ ○ Corporate metabolically with other prokaryotes in surface-coating biofilm May have antibiotic resistance (e.g. Pseudomona aeruginosa) Concept 27.4 Prokaryotes have radiated into a diverse set of lineages Archaea are more related to eukaryotes than bacteria, earning them a separate domain Using PCR in genetic prospecting reveals immense prokaryotic diversity ○ Genomes obtain from environment using metagenomics Bacteria Figure 27.17 Exploring Bacterial Diversity Type of Characteristics Gram +/- Heterotrophy/Auto Examples Images Bacteria trophy  Campbell Biology, 12th Edition Esparza 12 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Proteoba Large and diverse Gram Photoautotrophs, Thiomargarita cteria clade that show negative Chemoautotrophs namibiensis evidence of Heterotrophs (contains sulfur modern wastes) endosymbiosis Neisseria with mitochondria gonorrhoeae Thiomargarita (alpha (gonorrhea) namibiensis contains proteobacteria) Vibrio cholerae sulfur wastes (LM) (cholera) and Helicobacter pylori (stomach ulcer) Chlamydi Obligate Gram N/A Chlamydia as intracellular negative trachomatis parasites that (blindness & depend on the nongonococcal host for ATP; lack urethritis) peptidoglycan in their gram (-) cell Chlamydia (arrows walls inside an animal cell) Spiroche Spiral through Gram Heterotrophs Treponema tes environment via negative pallidum rotation of (syphilis) flagella-like Borrelia filaments; burgdorferi free-living or (Lyme disease) pathogenic parasites Leptospira, a spirochete Cyanoba Only prokaryotes Gram Photoautotrophs Phytoplankton, cteria that perform negative small plant-like photosynthetic photosynthesis; organisms on the solitary & ocean’s surface filamentous; Cylindrospermum, a chloroplasts may filamentous have originated cyanobacterium from an endosymbiont cyanobacterium  Campbell Biology, 12th Edition Esparza 13 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Gram-Po Diverse; Gram N/A Actinomycetes sitive pathogenic or positive (tuberculosis and Bacteria decomposers leprosy) Streptomyces (source of antibiotics) Staphylococcus Streptomyces, the aureus, Bacillus source of many anthracis antibiotics (e.g. (anthrax) tetracycline) Clostridium botulinum (botulism) Table 27.2 A Comparison of the Three Domains of Life DOMAIN CHARACTERISTIC Bacteria Archaea Eukarya Nuclear envelope Absent Absent Present Membrane-enclosed Absent Absent Present organelles Peptidoglycan in cell wall Present Absent Absent Membrane lipids Unbranched Some branched Unbranched hydrocarbons hydrocarbons hydrocarbons RNA polymerase One kind Several kinds Several kinds Initiator amino acid for Formyl-methionine Methionine Methionine protein synthesis Introns in genes Very rare Present in some genes Present in many genes Response to the antibiotics Growth usually Growth not inhibited Growth not inhibited streptomycin & inhibited chloramphenicol Histones associated with Absent Present in some species Present  Campbell Biology, 12th Edition Esparza 14 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity DNA Circular chromosomes Present Present Absent Growth at temperature > No Some species No 100°C Archaea Share trait with bacteria and eukaryotes (more with eukaryotes) Live in extreme environments (extremophiles) ○ Extreme halophiles - live in highly saline environments (such as the Great Salt Lake, the Dead Sea, and the Spanish lake) Ex: Halobacterium, require salinity for proper function ○ Extreme thermophiles - thrive in very hot environments (hotsprings, hydrothermal vents, etc.) Ex: Pyrococcus furiosus (source of taq polymerase), Sulfolobus, “strain 121” that reproduce at 121° Methanogens - release methane as a by-product of a metabolic process; obligate anaerobes ○ Live in swamps, marshes, guts of hosts, etc. Clades include: Euryarchaeota and Crenarcheota TACK supergroup - Thaumarchaeota, Aigarchaeota, Crenarchaeota, Koraarcheaota ○ Highlighted by the discovery of lokiarchaeota, which may provide incite into how prokaryotes → eukaryotes Concept 27.5 Prokaryotes play crucial roles in the biosphere Chemical Recycling Decomposers - heterotrophic prokaryotes break down waste, releasing nutrients (N, P, K, and more) that can be used by other organisms ○ Affects soil nutrient availability for plants Can convert inorganic molecules (e.g. CO2) to usable forms for other organisms Ecological Interactions Symbiosis - ecological relationship in which two organisms live in close contact Campbell Biology, 12th Edition Esparza 15 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Prokaryotes (symbiont) usually form a symbiotic relationship with a larger organism (host) ○ Mutualism - both species benefit from the interaction ○ Commensalism - one species benefits and the other does not ○ Parasitism - one species (parasite) benefits and the other (host) is harmed Pathogens = disease-causing parasite Some ecosystems depend entirely on prokaryotes ○ Ex: In hydrothermal vents, energy is sourced from chemoautotrophic bacteria that convert hydrogen sulfide (H2S) into organic compounds Concept 27.6 Prokaryotes have both beneficial and harmful impacts on humans Mutualistic bacteria (e.g. gut bacteria, Bacteroides thetaiotaomicron) in our intestine help digest food and break down waste Pathogenic bacteria (e.g. Mycobacterium tuberculosis) cause many human diseases ○ Some transmitted by pests (e.g. ticks, Lyme disease) ○ Produce poisons classified as: Exotoxins - proteins secreted by certain bacteria Endotoxins - lipopolysaccharide components of a gram negative bacteria’s cell wall (e.g. Salmonella typhi, causing typhoid fever) Only secreted when the bacteria dies ○ Through horizontal gene transfer, harmless bacteria can become pathogenic (produces resistance to multiple antibiotics) ⬆️ Ex: O157:H7, virulent strain of E.coli, causes intestinal infection Antibiotic resistance is rapidly in bacteria, making disease incidence higher ○ Due to rapid reproduction & spread via horizontal gene transfer ○ New class of antibiotics, malacidins, may be able to kill resistant strains Produces fermented foods like cheese, yogurt (e.g. lactobacillus), & sourdough bread Utilized in biotechnology (e.g. E.coli in gene cloning) & genetic engineering Campbell Biology, 12th Edition Esparza 16 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ CRISPR-Cas9 system used to treat HIV infection through gene editing Used to create biodegradable natural plastics (from PHA (polyhydroxyalkanoate)), vitamins, antibiotics, and other products In bioremediation, bacteria can be used to remove pollutants from the environment Environmental challenge Prokaryotic feature enabling success Lack of water Capsule or slime layer Exposure to antibiotics Rapid reproduction (through binary fission) and spread of resistant genes (through horizontal gene transfer (transformation, conjugation, and transduction)) Lack of nutrients May form a symbiotic relationship (mutualism, commensalism, or parasitism) with a larger organism Harsh conditions Capsule or endospores; some archaea have biochemical adaptations for extremely hot or salty environments Chapter 28: Protists Concept 28.1 Most eukaryotes are single-celled organisms Protists - diverse, unicellular eukaryotes with membrane-bound organelles and a cytoskeleton allowing for variable shapes ○ Most eukaryotic lineages consist of protists Structural and Functional Diversity in Protists Unicellular with complex subcellular structures (e.g. ocelloid) Campbell Biology, 12th Edition Esparza 17 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Photoautotrophs, heterotrophs, or mixotrophs (photosynthesis + heterotrophs) Reproduce sexually, asexually, or both Endosymbiosis in Eukaryotic Evolution Diversity may originate in endosymbiosis ○ Ancestral archean cell (or related) engulfed an alpha proteobacterium (mitochondria) and then a cyanobacterium (plastids) Cyanobacterium engulfed by an ancestral heterotrophic eukaryote (primary endosymbiosis) evolved into plastids, giving rise to green/red algae ○ Became endosymbionts themselves (eaten by a heterotrophic eukaryote) in secondary endosymbiosis ○ Nucleomorph within a plastid of chlorarachniophyte indicate it was a green alga Four Supergroups of Eukaryotes Hypothesis that 1st lineage to diverge from eukaryotes was amitochondriate protists was disproven Excavata, SAR, archaeplastida, and unikonta ○ Relationships of haptophytes & cryptophytes are unresolved Concept 28.2 Excavates include protists with modified mitochondria and protists with unique flagella Excavata - supergroup including diplomonads, parabasalids, and euglenozoans Campbell Biology, 12th Edition Esparza 18 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Diplomonads & parabasalids have reduced mitochondria, no plastids Diplomonads have reduced mitochondria (mitosomes), get energy from anaerobic pathways, & some are parasitic (e.g. Guardia Intestinalis) Two equal-sized nuclei and many eukaryotic flagella Parabasalids have reduced mitochondria (hydrogenosomes) Ex: Trichomonas vaginalis, sexually transmitted parasite ○ Euglenozoans - diverse protist clade known for unique flagella (crystal rod) Kinetoplastids - protests with a single, large mitochondria (contains a mass of DNA called kinetoplast); known to be parasites Ex: Trypanosoma, carried by the African tsetse fly, causes African sleeping sickness Euglenoids - contain a pocket with a long and short flagella; mixotrophs Ex: Euglena, commonly found in pond water Concept 28.3 SAR is a highly diverse group of protists defined by DNA similarities SAR - supergroup consisting of three clades - stramenopiles, alveolate, & rhizarians ○ Stramenopiles - photosynthetic with hairy & smooth flagella Diatoms - unicellular algae with a two-part glass-like wall of silicon dioxide; photosynthetic producers Constituents of diatomaceous earth (its rigidity allows for it to be abundant in fossils) Component of phytoplankton After blooms, they sink to the bottom of the ocean & effectively pump CO2 out of the atmosphere Brown Algae - large, multicellular, marine algae Have rootlike holdfast, stemlike stipe, and leaflike blades Undergo Alternation of Generations - alternation of multicellular haploid and diploid forms ○ Sporophyte (2n) → zoospores (n) → gametophytes (n) → gametes (n) → sporophyte (2n) Heteromorphic = sporophyte & gametophyte look different Isomorphic = sporophyte & gametophyte look similar Campbell Biology, 12th Edition Esparza 19 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Oomycetes - include water molds and their relative Morphologically similar to fungi with filamentous hyphae, but have cellulose cell walls and no plastids (no photosynthesis) ○ Alveolates - subgroup of SAR with membrane-enclosed sacs (alveoli) Dinoflagellates have two flagella, and each cell is reinforced by cellulose plates Produce“red tides” that kill fish and invertebrates Apicomplexans - parasites of animals; modified plastid (apicoplast) originating from red alga in secondary endosymbiosis Infect via sporozoites, which invade liver cells & RBCs Ex: Plasmodium, carried by anopheles mosquito, causes malaria Ciliates - known to move & feed via cilia; multinucleate Contain a small micronuclei & a large macronuclei Genetic variation result from conjugation Ex: Paramecium caudatum expel excess water from its hypotonic environment using contractile vacuoles ○ Rhizarians - amoebas (protists that use cytoplasmic extensions called pseudopodia for movement) Radiolarians contain symmetrical siliceous skeletons Move via cytoplasmic streaming Accumulate as oozes after dying Foraminiferans (forams) have porous shells called tests Most are known from fossils (due to hardening with CaCO3) Thread-like pseudopodia Cercozoans - amoeboid & flagellated protists with thread-like flagella Important predators of bacteria and other organisms Ex: Paulinella chromatophora may have consumed a cyanobacterium, a chromatophore (primary endosymbiosis) Concept 28.4 Red algae and green algae are the closest relatives of plants Heterotrophic protists acquired a cyanobacterial endosymbiont, evolving into red & green algae; green algae → plants ○ Archaeplastida - supergroup composed of red algae, green algae, and plants Red algae (rhodophytes) owe their red pigmentation to phycoerythrin ○ Multicellular, reproduce sexually, non flagellated gametes Green algae - closely related to plants; plant-like chloroplasts ○ Charophytes - most closely related to plants ○ Chlorophyta - unicellular, sexually reproducing (e.g. Chlamydomonas) ○ Larger size and great complexity evolved by:  Campbell Biology, 12th Edition Esparza 20 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Formation of colonies of individual cells, forming pond scum Formation of multicellular bodies by cell division & differentiation Nucleic division without cytoplasmic division Concept 28.5 Unikonts include protists that are closely related to fungi and animals Unikonta (Amorphea) - eukaryotic supergroup hypothesized to be the first to diverge from eukaryotes ○ Amoebozoans - clade with lobe/tube shaped pseudopodia Tubulinids - unicellular protists, ubiquitous in soil Slime molds (mycetozoa) - convergently similar to fungi Plasmodial slime molds contain a unicellular plasmodium “supercell” that feeds via phagocytosis Cellular slime molds form multicellular aggregates in which cells are separated in their membranes ○ Cells feed individually but can aggregate to migrate and form a fruiting body Entamoebas - symbiotic parasites that infect all vertebrate animals Ex: pathogenic E. histolytica ○ Opisthokonts include nucleariids (closely related to fungi) & choanoflagellates (closely related to animals) Concept 28.6 Protists play key roles in ecological communities Form mutualistic (dinoflagellates & coral polyps, parabasalids & termites) or parasitic (Phytophthora ramorum with oak tree) symbiotic relationships with other organisms Function as the base of aquatic food webs (producers) with consumers depending on them for food ○ Limited by nutrients; population proliferate when limiting nutrients are added ○ Biomass of photosynthetic protists have declined as sea surface temperatures rise Key Concept/Eukaryote Major Groups Key Morphological Specific Examples Supergroup Characteristics Excavates Diplomonads and Modified mitochondria Giardia, Trichomonas parabasalids Euglenozoans Spiral or crystalline rod Kinetoplastids inside flagella Euglenids Trypanosoma, Euglena  Campbell Biology, 12th Edition Esparza 21 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity SAR Stramenopiles Hairy and smooth Phytophthora, Diatoms flagella Laminaria Oomycetes Brown algae Membrane-enclosed Alveolates sacs (alveoli) beneath Dinoflagellates plasma membrane Apicomplexans Amoebas with Ciliates threadlike pseudopodia Pfiesteria, Plasmodium, Rhizarians Paramecium Radiolarians Forams Cercozoans Globigerina Red algae, Green algae, Red algae Phycoerythrin Porphyridium, Palmaria Plants (photosynthetic pigment) Green algae Plant-type chloroplasts (See Chapters 29 and 30.) Plants Chlamydomonas, Ulva Mosses, ferns, conifers, flowering plants Unikonts Amoebozoans Amoebas with lobe- Amoeba, Dictyostelium Tubulinids shaped or tube-shaped Slime molds pseudopodia Entamoebas (Highly variable; see Opisthokonts Chapters 31–34.) Campbell Biology, 12th Edition Esparza 22 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Choanoflagellates, nucleariids, animals, Fungi Chapter 29: Plant Diversity I: How Plants Colonized Land Concept 29.1 Plants evolved from green algae Evidence of Algal Ancestry Plants & algae are multicellular, eukaryotic, photosynthetic autotrophs ○ Have cellulose cell walls and similar pigments (chlorophyll a/b) Charophytes & plants have rings of cellulose-synthesizing proteins, flagellated sperm, formation of a phragmoplast, & similar DNA sequences (nuclear/non-nuclear) Adaptations Enabling the Move to Land Durable polymer called sporopollenin toughened spore walls, protecting zygotes from drying out Advantages: unfiltered sunlight, plenty of CO2 from the atmosphere, nutrient-rich soil Disadvantages: water scarcity, lack of structural support against gravity Derived Traits of Plants Traits found in plants, but not charophyte algae include: ○ Alternation of generations between multicellular diploid & haploid forms Gametophyte (“gamete-producing plant”, n) → Gametes (n) → Sporophyte (“spore-producing plant”, 2n) → Spores (n) → Gametophyte (n) Campbell Biology, 12th Edition Esparza 23 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Walled spores produced in sporangia (organs of a sporophyte) Spores can be dispersed through dry air without harm ○ Apical meristems (concentrated regions of cell division at ⬆️ roots/shoots) Elongation exposure to environmental resources ○ Multicellular dependent embryos protected/nourished by placental transfer cells Plant are known as embryophytes because of this Cuticle - waxy epidermal covering that prevents desiccation (drying out) Stomata - specialized pores that control gas exchange and prevent water loss Without roots, they formed symbiotic relationships with fungi (mycorrhizae) to absorb nutrients from the soil The Origin and Diversification of Plants Fossilized spore tissue from 450 mya match those of plants today, not algae Distinguished by presence/absence of vascular tissue (transports H2O & nutrients) ○ Vascular tissue = vascular plants Seedless vascular plants Lycophytes - club mosses and their relatives Monilophytes - ferns and their relatives Seed vascular plants Gymnosperms - seeds not enclosed in chambers Campbell Biology, 12th Edition Esparza 24 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Angiosperms - seeds enclosed in chambers; flowering plants ○ No vascular tissue = nonvascular plants (bryophytes) Concept 29.2 Mosses and other nonvascular plants have life cycles dominated by gametophytes Bryophytes are broken down into phyla - ○ Liverworts (phylum hepatophyta) ○ Mosses (phylum bryophyta) ○ Hornworts (phylum anthocerophyta) NOT a clade Bryophyte Gametophytes Dominant stage of the life cycle Bryophyte spores may form haploid protonemata, which produce “buds” that form gametophores Rhizoids - long tubular single cells that anchor the gametophyte to substrate Form gamete-producing structures called gametangia Campbell Biology, 12th Edition Esparza 25 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Archegonia - female gametangia producing 1 egg; where fertilization occurs ○ Antheridia - male gametangia producing many flagellated sperm Sperm must swim through a film of moisture to reach egg Disadvantage in arid regions with little moisture Some mosses reproduce asexually by forming brood bodies Bryophyte Sporophytes Developing sporophyte embryo depends on the gametophyte for nourishment ○ Sporophyte consists of a: Foot (absorbs nutrients from gametophyte) Seta (conducts nutrients to sporangium) Capsule (produces spores by meiosis) Release spores with a peristome Mosses & hornworts larger & more complex ⬆️ Ecological and Economic Importance of Mosses the availability of N in the soil with the help of cyanobacteria Can withstand large amounts of dessication & UV radiation Sphagnum, peat moss, component of peat (decayed organic material) used to coal ○ These peatlands create a environment for preservation of animals ○ Harvesting of peat release CO2 into the atmosphere, promoting global warming Concept 29.3 Ferns and other seedless vascular plants were the first plants to grow tall Origins and Traits of Vascular Plants Dominant sporophytes, vascular tissues, well-developed roots/leaves, and sporophylls ○ Similar to bryophytes except the sporophyte is larger & more complex than the gametophyte and the two live independently of each other ○ Vascular tissue include: Xylem - conducts water & minerals up with the help of tracheids (water-conducting cells) Water-conducting cells eventually die and become lignified (cell wall strengthened by lignin) Lignified well-defined vascular tissue helped the plants grow taller as they provided support against gravity ○ Advantageous since taller plants could outcompete short plants for light & had a higher range of spore dispersal, allowing them to colonize a larger area Phloem - tissue arranged into tubes that transport organic products downward Campbell Biology, 12th Edition Esparza 26 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Roots - organs that absorb water/nutrients & anchor vascular plants Provided structural support for taller plants ○ Leaves - structures that increase SA for photosynthesis Microphylls - unbranched leaves exclusive to lycophytes Megaphylls - large, branched leaves that are more photosynthetically productive than microphylls; found in ferns and seed plants Sporophylls - modified leaves with sporangia Can produce sporangia clusters called sori or cone-like structures of sporophylls called strobili May be: ○ Homosporous - one type of sporophyll Sporangium on sporophyll → single type of spore → bisexual gametophyte → eggs + sperm ○ Heterosporous - two types of sporophylls Megasporangium (on megasporophyll) → megaspore → female gametophyte → eggs Microsporangium (on microsporphyll) → microspore → microspore → male gametophyte → sperm  Campbell Biology, 12th Edition Esparza 27 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Classification of Seedless Vascular Plants Lycophytes (phylum lycophyta) includes club mosses, spikemosses, and quillworts ○ Small herbaceous plants that used to be giant trees Monilophytes (phylum monilophyta) includes ferns, horsetails, and whisk ferns ○ More related to seed plants with megaphyll leaves & multi branching roots ○ Horsetails only exist as genus Equisetum ○ Include a clade of “living fossils” - Psilotum & Tmesipteris Significance of Seedless Vascular Plants ⬇️ ⬆️ Formed large forests during the Devonian and Carboniferous periods ⬇️ ○ CO2, which caused global cooling and glaciation ○ Decaying remnants eventually formed coal, which CO2 even more Adaptation Description How it facilitates life on land Cuticle Wavy covering on outer body Reduces desiccation surface Stomata Regulates gas exchange Reduces desiccation (CO2/O2) and minimizes water loss Walled spores produced in Sporangia release millions of Spores can be dispersed through sporangia spores into its surroundings dry air without harm Apical meristems Concentrations of cell divisions at Increased exposure to the roots or shoots environmental resources Chapter 30: Plant Diversity II: The Evolution of Seed Plants Concept 30.1 Seeds and pollen grains are key adaptations for life on land Reduced gametophytes of seed plants depend on parental sporophytes for nutrition ○ Shields them from environmental stresses (e.g. desiccation, UV radiation) Campbell Biology, 12th Edition Esparza 28 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Heterospory involves megasporangia producing megaspores (forms female gametophytes) & microsporangia making microspores (forms male gametophytes) Ovule = megasporangium + megaspore + integument (protective sporophyte tissue) ○ Retains megasporangium within parent sporophyte Pollen grain consists of a male gametophyte enclosed within the pollen wall ○ Transported by wind or animals; eliminates dependence on water for transport ○ Pollen discharges sperm into the egg in a pollen tube (pollination) Eliminates necessity for mobility After pollination, the egg develops into a sporophyte embryo with food supply and a protective coast (seed) ○ Multicellular, protected by a seed coat, large lifespan, and food supply makes it an evolutionary novelty in comparison to spores Concept 30.2 Gymnosperms bear “naked” seeds, typically on cones Most gymnosperms are cone-bearing plants called conifers ○ They don't have ovaries; angiosperms do Life cycle of a pine Smaller pollen cone contains microsporocytes (in microsporangia) that undergo meiosis to produce haploid microspores, which develop into pollen Larger ovulate cone contains megasporocytes (in megasporangia) that undergo meiosis to produce haploid megaspores in the ovule (located inside cone scales) Campbell Biology, 12th Edition Esparza 29 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Pollination occurs when the pollen reaches the ovule ○ After the ovule is fertilized, its scales separate and release the seeds ○ Seeds germinate and give rise to pine seedlings Early Seed Plants and the Rise of Gymnosperms Early seed plant fossils come from Elkinsia, which lived 360 mya Drier climate of the Permian allowed gymnosperms living in Carboniferous ecosystems to dominate over seedless vascular plants ○ Dominated the mesozoic terrestrial ecosystems Gymnosperm Diversity Phylum Cycadophyta - large cones, palm like leaves, flagellated sperm Phylum Ginkgophyta - flagellated sperm, deciduous fanlike leaves Phylum Gnetophyta - include Gnetum, Ephedra, and Welwitschia Phylum Coniferophyta - largest gymnosperm phyla Concept 30.3 The reproductive adaptations of angiosperms include flowers and Fruits All angiosperms are grouped into a phylum called Anthophyta, in which they all have: ○ Flower - reproductive structure facilitating pollination Sepals - sterile floral organs that protect the flower prior to opening and are often photosynthetic Petals - sterile floral organs attracting pollinators Stamens - fertile floral organs (microsporophylls) that produce microspores, which develop into pollen Filament - stalk Anther - terminal sac where pollen is made Carpels (simple pistil) - fertile floral organs (megasporophylls) that produce megaspores, which develop into female gametophytes The “container” of seeds (ovules) Contains a sticky stigma that receive pollen and a style that leads into the ovary (has ovules) May aggregate to form a compound pistil Vary in shape, size, color, and odor Campbell Biology, 12th Edition Esparza 30 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Radial symmetry vs bilateral symmetry ○ Fruit - formed when the ovary wall thickens and matures (ovules → seeds) Protect seeds and aid in their dispersal May be fleshy (distributed by animals) or dry (dispersed by wind) Can also be distributed by water in coconuts Angiosperm life cycle ○ The flower of a mature sporophyte produces: Four megaspores (in the ovule) in which one forms a female gametophyte (embryo sac) containing the egg Four microspores (from anthers of a stamen) that develop into pollen Pollen contains two haploid cells - a generative and tube cell - that divide into two sperm & create the pollen tube, respectively Pollen reaches the stigma of the other flower (cross pollination) Enhances genetic variability Pollen tube penetrates the micropyle; two sperm are discharged into the ovule where double fertilization occurs One sperm fertilizes the egg (2n) & the other the central cell (3n) Zygote → Seed → Sporophyte with cotyledons (seed leaves) 3n central cell → endosperm (embryo-nourishing tissue) Originated in the early Cretaceous period (140 mya) & dominated by the mid-Cretaceous (100 mya) ○ Based on fossils of distinctive angiosperm features (e.g. Archaefructus) ○ Closely related to woody seed plants (e.g. Amborella trichopoda) Animals and plants coevolve (e.g. plant-pollinator interactions) ○ Animal herbivory selects for plant defense Campbell Biology, 12th Edition Esparza 31 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Interactions between pollinators and flowering plants for mutually beneficial adaptations ○ Flowers with bilateral symmetry restrict the movement of pollinators Angiosperm diversity is based on the number of cotyledons and other features ○ Monocots - species with one cotyledon ○ Dicots - species with two cotyledons Regrouped into a larger clade called eudicots Subdivided into four lineages - basal angiosperms (¾ lineages) and magnoliids Concept 30.4 Human welfare depends on seed plants Crucial for food, wood, and many medicines (e.g. willow leaves, traced to salicin) Destruction of habitats threatens plant diversity and animals that depend on them Chapter 31: Fungi Concept 31.1 Fungi are heterotrophs that feed by absorption Heterotrophs absorbs nutrients in surroundings using hydrolytic enzymes ○ Diverse food sources; ecological role as decomposers, parasites, mutualists Body Structure Grow as multicellular filaments (mycelia) or single cells (yeasts) Campbell Biology, 12th Edition Esparza 32 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Morphology of multicellular fungi enhances its absorption capabilities ○ Hyphae - network of tiny filaments consisting of strong chitin cell walls Enhances feeding as it prevents cells from lysing during absorption Subdivided into cells by cross-walls (Septa) that facilitate transport between cells Coenocytic fungi lack septa; continuous cytoplasmic mass Septate hypha have septa ○ Mycelium - interwoven mass that increases absorptive surface area Specialized Hyphae in Mycorrhizal Fungi May feed on animals or plants (using modified hyphae called haustoria) Exchange nutrients with plant hosts (using hyphae called arbuscles) ○ Mycorrhizae - mutualistic relationship between plants and fungi Mycorrhizal fungi provide minerals to plants & plant yield organic nutrients ○ Ectomycorrhizal fungi - form hyphae on the root surface & extracellularly of the root cortex ○ Arbuscular mycorrhizal fungi - form arbuscles through the plant’s cell wall & plasma membrane Disperse its fungal haploid spores to reproduce and spread to new areas Concept 31.2 Fungi produce spores through sexual or asexual life cycles Majority of the life cycle is spent in the haploid stage; in humans, it is the diploid stage Sexual Reproduction Initiated by hyphae from two mycelia secreting signaling molecules (pheromones) ○ If different mating types, hyphaes will fuse together Plasmogamy - union of cytoplasms of two parent mycelia ○ Heterokaryon - fused mycelium have genetically different haploid nuclei Campbell Biology, 12th Edition Esparza 33 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Dikaryotic - fused mycelium are separate haploid nuclei Karyogamy - haploid nuclei fuse to produce a diploid zygote (2n) ○ Zygote undergoes meiosis to produce haploid spores, which germinate into mycelia ○ Karyogamy + meiosis = genetic variation Asexual Reproduction Filamentous fungi (molds) produce spores (n) by mitosis, using conidia Yeasts may pinch off “budding cells” from the parent cell Deuteromycetes - fungi that lack sexual reproduction Concept 31.3 The ancestor of fungi was an aquatic, single-celled, flagellated protist Fungi and animals are more closely related to each other than most eukaryotes Basal lineages of fungi had flagellated sperm Opisthokonts - monophyletic clade consisting of fungi, animals, & protistan relatives ○ Nucleariids - group of unicellular protists closely related to fungi (suggesting fungi’s ancestor was unicellular) ○ More related to choanoflagellates Campbell Biology, 12th Edition Esparza 34 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Multicellularity likely evolved independently in animals & fungi Fungi likely originated from aquatic environments, but more evidence is needed May have colonized land earlier than plants, forming early mycorrhizae with plants that lacked roots (mycorhizzae form via expression of sym genes) ○ Expression of sym genes facilitates the formation of mycorrhizae Concept 31.4 Fungi have radiated into a diverse set of lineages Cryptomycetes and Microsporidians Cryptoyctes and Microsporidians form a sister group and a basal fungal lineage Crytomyctes (phylum Cryptomycota) - parasites with flagellated spores ○ Ex: Rozella Allomycis Microsporidians (phylum Microsporidia) - parasitic cells that form resistant spores ○ Ex: Nosema ceranae, parasite of honeybees; causes Colony Collapse Disorder Chytrids (phylum Chytridiomycota) - flagellated spores (zoospores) ○ Belong to lineages that diverged from fungi early in the group’s history Zoopagomycetes Zoopagomycetes (phylum Zygomycota) - resistant cygosporanfium as sexual stage ○ Sexual reproduction involves the formation of a resistant zygosporangium ○ Non Flagellated spores correlated with land colonization Non Flagellated = dispersed by wind Flagellated = dispersed by water Mucoromycetes Mucromycetes (phylum Mucoromycotina) - fungi that form arbuscular mycorrhizae with plants Campbell Biology, 12th Edition Esparza 35 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Life cycle involves two different mating types forming hyphal connections (gametangia), creating a thick-walled zygosporangium (heterokaryotic) via plasmogamy ○ Sexual phase Karyogamy and then meiosis occur in favorable conditions Zygosporangium germinates into a sporangium, which releases genetically diverse haploid spores that produce new mycelia ○ Asexual phase Sporangia form and disperse genetically identical haploid spores, which may germinate and produce new mycelia Include arbuscular mycorrhizae fungi (Glomeromycetes) Ascomycetes Ascomycetes (phylum Ascomycota) - produce sexual spores (ascospores) in sacs called asci ○ Sac fungus ○ During sexual reproduction, they develop fruiting bodies called ascocarps Can fuse with conidia of opposite mating type in plasmogamy Resulting dikaryotic hyphae produce dikaryotic asci (where a diploid nucleus forms (karyogamy)) Extension of the dikaryotic stage promotes genetic variation Diploid nucleus produces four haploid nuclei, which form eight ascospores (give rise to mycelia after germination) ○ During asexual reproduction, they produce numerous asexual spores (conidia) in external conidiophores (not in sporangia like mucormycetes) ○ Plant pathogens & decomposers; form lichens with green algae/cyanobacteria Basidiomycetes Basidiomycetes (phylum basidiomycota) Campbell Biology, 12th Edition Esparza 36 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Name derived from basidium, a cell where karyogamy occurs ○ Life cycle involves formation of dikaryotic mycelium (plasmogamy), which may form fruiting bodies (basidiocarps) after being induced by environmental cues ○ Basidiocarp gills lined with basidia that undergo karyogamy to produce a diploid nucleus, which yields four haploid nuclei (forms a basidiospore) ○ Basidiospores are dispersed by wind, germinating to produce mycelia Basidiomycete mycelium can produce fruiting structures (mushrooms) Concept 31.5 Fungi play key roles in nutrient cycling, ecological interactions, and human welfare Efficient decomposers of organic materials including cellulose and lignin ○ Perform recycling of chemical elements between living & nonliving world Mutualistic fungi absorb nutrients from the host, but also reciprocate benefits ○ Fungus-plant mutualisms - mycorrhizae; plants harbor symbiotic fungi (endophytes) that deter herbivores with toxins ○ Fungus-animal mutualisms - fungus plays a role in breaking down organic products in digestive tracts and yielding nutrient-rich tips to ants ○ Lichen - symbiotic relationship between a photosynthetic organism (green algae or cyanobacteria) & a fungus (often an ascomycete) Asexually reproduce by fragmentation or formation of soredia (clusters of hyphae) Photosynthetic organisms provides C compounds and/or N2 fixation Fungi provides a suitable environment for growth, gas exchange, retention of water & minerals, protection from intense sunlight, etc. Acts as parasites that harm plants (e.g. Cryphonectria parasitica) and animals (e.g. chytrids Batrachochytrium dendrobatidis & B. salamndrivorans) Campbell Biology, 12th Edition Esparza 37 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Mycosis = fungal infection in animals (e.g. ringworm, coccidioidomycosis) Practical uses include ○ Production of alcohol, bread, and cheese ○ Medicines (e.g. ascomycota Penicillium) ○ Genetic research Saccharomyces used to study Parkinson’s and Huntington’s diseases Insulin-like growth factor produced in Saccharomyces cerevisiae Gliocladium roseum used to make biofuels Chapter 32: An Overview of Animal Diversity Concept 32.1 Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers Animals are heterotrophs that ingest their food, processing it with enzymes Eukaryotic, multicellular organisms with structural support in animal cells from collagen Similar cells act as a functional unit, organized into tissue (e.g. muscle & nerve tissue) Sexual reproduction involves haploid gametes (sperm & egg) forming through meiosis ○ In fertilization, the sperm and egg fuse to form a diploid zygote ○ Zygote undergoes cleavage - a succession of mitotic divisions - and reaches a multicellular embryonic stage called a blastula ○ Gastrulation - development of layers of embryonic tissues, forming a gastrula ○ Larva - sexually immature animal form different from the adult from Eventually transforms into a juvenile resembling the adult form (metamorphosis) ○ Hox genes control animal embryo development & morphology Campbell Biology, 12th Edition Esparza 38 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Concept 32.2 The history of animals spans more than half a billion years Choanoflagellates are the closest living relatives to animals ○ Evidence includes: (1) Morphological similarities between choanoflagellate cells and collar cells of sponges (2) Collar cells found only in other animals (3) DNA sequence data reveals they are sister groups; genes for signaling & adhesion (e.g. cadherin) proteins thought to be exclusive to animals were found in choanoflagellates Exception: CCD domain is not found in choanoflagellates Neoproterozoic Era (1 bya-541 mya) Macroscopic fossils of soft-bodied multicellular eukaryotes (Ediacaran biota) are linked to animal ancestry about 560 mya ○ Ex: Cloudina, bore holes linked to early predation Neoproterozoic rocks with microfossils have the basic structure of an animal Campbell Biology, 12th Edition Esparza 39 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Paleozoic Era (541-252 mya) Fossils found during the Cambrian explosion (535-525 mya) contain the ancestors of modern-day phyla of animals ○ Most were bilaterians - clade of animals w/ bilateral symmetry, complete digestive tract, and efficient digestive system ○ Ediacaran decline linked to new predator-prey relationships, increased atmospheric oxygen, and development of new life forms due to development of hox genes and other genetic changes Ordovician, Silurian, and Devonian periods experienced increased animal diversity ○ Cambrian animals (e.g. arthropods) colonized the land Diversified into animals here today (amphibians and amniotes) Mesozoic Era (252–66 Million Years Ago) Animal Phyla from the Paleozoic continued to diversify into new habitats and traits ○ Dinosaurs and eventually mammals emerged ○ Flight evolved in pterosaurs and birds Cenozoic Era (66 Million Years Ago to the Present) Characterized by mass extinctions of dinosaurs and marine reptiles ○ Mammals occupied the available ecological niches Concept 32.3 Animals can be characterized by body plans Body plan - set of morphological & developmental traits organized into one whole - the living animal Symmetry May have symmetry - bilateral or radial - or no symmetry at all (e.g. sponges) Symmetry fits lifestyle ○ Radial animals are sessile or planktonic; equipped to respond to the environment from all sides Campbell Biology, 12th Edition Esparza 40 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Bilateral animals freely move & coordinate with almost all animals having a central nervous system concentrated at the head Have dorsal (top) & ventral (bottom) sides; head & tail ends Tissues As gastrulation progresses, germ layers form tissues & organs of the body ○ Ectoderm - germ layer covering the surface of an embryo ○ Endoderm - innermost germ layer giving rise to the digestive tract & the lining of organs (e.g. liver & lungs) Diploblastic - animals with two germ layers Triploblastic - animals with three germ layers ○ Includes the mesoderm - middle layer - that forms the muscles & organs between the outer covering and digestive tract ○ Exhibited in all bilaterally symmetrical animals Body Cavities Body cavity - fluid- or air-filled space between the endoderm & ectoderm ○ Provides structural support & internal transport of substances Coelom - body cavity derived from the mesoderm ○ Cushions internal organs (allows the to grow & move independently) ○ Found in many triploblastic animals - coelomates Hemocoel (pseudocoelom) - body cavity formed between the mesoderm & endoderm ○ Contain nutrient-transporting fluid called hemolymph Campbell Biology, 12th Edition Esparza 41 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Acoelomates (lack a body cavity) don’t need an internal transport system due to a thin, flat body Protostome and Deuterostome Development Protostome development & deuterostome development distinguished by: ○ Cleavage Spiral (determinant) cleavage - planes of cell division diagonal to vertical axis of embryo; development fate of each embryonic cell determined early on; common in protostomes Radial (indeterminant) cleavage - planes of cell division parallel/perpendicular to vertical axis of embryo; retain the capacity to form a complete embryo; common in deuterostomes ○ Coelom formation Archenteron - blind pouch that becomes the gut In protostomes, mesoderm splits to form the coelom In deuterostomes, mesoderm buds from the archenteron to form the coelom ○ Fate of the blastopore Blastopore - indentation leading to archenteron formation In protostomes, it becomes the mouth In deuterostomes, it becomes the anus Campbell Biology, 12th Edition Esparza 42 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Concept 32.4 Views of animal phylogeny continue to be shaped by new molecular and morphological data The Diversification of Animals Evolutionary relationships between phyla determined by genomic & morph. data ○ All animals share a common ancestor Animals are monophyletic and share a clade (Metazoa) ○ Sponges (phylum Porifera) are the sister group to all other animals ○ Eumetazoa is a clade of animals with tissues ○ Most animal phyla belong to the clade Bilateria Defined by bilateral symmetry & three germ layers ○ There are three major clades of bilaterian animals Deuterostomia, Lophotrochozoa, and Ecdysozoa Phyla in these lineages are almost all invertebrates (lack a backbone), except chordates with vertebrates (backbone) Clade Deuterostomia include hemichordates, echinoderms, & chordates Clade Lophotrochozoa refers to a lophophore (ciliated tentacles used for feeding) & trochophore larva Clade Ecdysozoa contain an exoskeleton (ecdysis = shedding) Future Directions in Animal Systematics Questions of ongoing research involving animal phylogeny ○ Are ctenophores basal metazoans? Several studies put Ctenophores at the base of the animal tree, but they have tissues & do not have choanoflagellate-like cells ○ Are the Acoela basal bilaterians? Studies show flatworms in phylum Acoela as basal bilaterians while others place them within Deuterostomia Campbell Biology, 12th Edition Esparza 43 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Chapter 33: An Introduction to Invertebrates Concept 33.1 Sponges are basal animals that lack tissues Invertebrates - animals without a backbone Phylum Porifera (sponges) have no tissue ○ Filter feeders that filter out food particles in the water ○ Water flows through a central cavity (spongocoel) & out of a larger opening (osculum) Represent an early lineage that diverged from other animals (known as basal animals) Flagellated choanocytes draw in water through the pores, trap food particles, & engulf them by phagocytosis Diffuse gas/waste through 2 layers of cells, separated by a gelatinous layer (mesophyl) Amoebocytes carry nutrients throughout the body, produce material for skeletal fibers (spicules), & can differentiate into other cell types (totipotent) ○ Provides flexibility as it enables shape changes in response to the environment Hermaphrodites that can function as males and females Concept 33.2 Cnidarians are an ancient phylum of eumetazoans Phylum Cnidaria include hydras, corals, and jellies with simple, diploblastic, radial body plans ○ Contains a sac with a central digestive compartment (gastrovascular cavity) that functions as a mouth & an anus Polyps - sessile cylindrical form adhering to its substrate (e.g. hydras) Medusa - motile flattened, mouth-down form of the polyp (e.g. jellies) Campbell Biology, 12th Edition Esparza 44 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Use tentacles to capture prey, digest them using enzymes, absorbed, and remains expelled through the mouth/anus Armed with cnidocytes that defend & capture prey with cnidae Specialized cnidae (nematocysts) sting prey ○ Lined with a gastrodermis (inner layer) and epidermis (outer layer) ○ They have a non centralized nerve net to coordinate movement Medusozoans Clade Medusozoa produce a medusa ○ Scyphozoans (jellies) & Cubozoans (box jellies) retain a medusa shape ○ Hydrozoans alternate between the polyp & medusa forms Anthozoans Clade Anthozoa produce polyps ○ Many secrete an exoskeleton of calcium carbonate ○ Produce coral reefs (currently under environmental stresses) Concept 33.3 Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms Bilaterian Clade Lophotrochozoans name is based on lophophores & trochophore larva of its members (18 phyla) Flatworms Flatworms (phylum Platyhelminthes) are free-living & parasitic with thin bodies ○ Triploblastic, but acoelomates (gas exchange/waste removal through diffusion) ○ Protonephridia - simple excretory apparatus with networks of flame bulbs Pushes fluid through branched ducts outside ○ Gastrovascular cavity digests food Separated into two lineages ○ Catenulida - small asexually reproducing (through budding) clade Campbell Biology, 12th Edition Esparza 45 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Rhabditophora - diverse clade of free-living & parasitic species Planarians (genus Dugesia) - free-living predators that move via cilia Head features a pair of light-sensitive eyespots & ganglia Hermaphrodites Trematodes - parasitic with intermediate hosts & complex life cycles Ex: blood flukes (Schistosoma) causes schistosomiasis Tapeworms - parasites that depend on their hosts for nutrition Anterior end (scolex) attaches to the intestinal lining of its host & absorbs its nutrients Posterior end (proglottids, sacs of sex organs) releases fertilized eggs into the host & leaves through the feces Rotifers and Acanthocephalans Phylogenetic analysis reveals they should be put into one phylum, Syndermata ○ Rotifers - tiny, multicellular organisms w/ specialized organ systems Alimentary canal - digestive tube with a mouth and an anus Campbell Biology, 12th Edition Esparza 46 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Hemocoel, surrounding the organs, acts as a hydrostatic skeleton Fluidity moves nutrients throughout the body Have jaws (trophi) that grind up food; processed by the alimentary canal Parthenogenesis - females produce females from unfertilized eggs Sexual reproduction occurs under specific conditions ○ Acanthocephalans - sexually reproducing parasites of vertebrates No complete digestive tract, triploblastic, complex life cycles Have a curved hook; nicknamed spiny-headed worms Ectoprocts and Brachiopods These phyla have a lophophore, coelom, no distinct head, and are sessile ○ Ectoprocts (Bryozoans) - colonial moss-like animals Build reefs and have lophophores extending from the exoskeleton ○ Brachiopods (Lampshells) - marine animals with a hinged shell Molluscs Phylum mollusca Includes snails, slugs, oysters, clams, octopuses, and squids ○ Body plan consists of foot (movement), a visceral mass (contains internal organs), and a mantle (secretes a shell) Mantle produces a water-filled chamber (mantle cavity) ○ Radula - straplike organ used for feeding ○ Most have separate sexes with gonads in visceral mass, but others are hermaphrodites Life cycle includes a ciliated larval stage, trochophore Polyplacophora (chitons) have an eight-plated shell Gastropoda (snails and slugs) are marine, freshwater, and terrestrial ○ Mantle secretes a spiral shell that protects its soft body from predators ○ Move via a ciliated foot & perform gas exchange with their mantle cavity Bivalvia (clams, oysters, mussels, and scallops) have a hinged shell studded with eyes ○ Gills used for feeding & gas exchange; suspension feeders; sedentary Cephalopoda (squids, octopuses, cuttlefish, chambered nautiluses) Campbell Biology, 12th Edition Esparza 47 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Marine predators that grasp prey with tentacles, bite via beak-like jaws, and immobilize with poisonous saliva ○ Move via a modified excurrent siphon & tentacles ○ Closed circulatory system, well-developed sense organs, & a complex brain ○ Most have no shells (shelled cephalopods = ammonites) except chambered nautiluses High extinction rates due to habitat loss & overharvesting ○ Ex: Pearl mussels & Pacific island land snail, Partula suturalis Annelids Phylum annelida are segmented worms with coeloms ○ Traditionally subdivided into Polychaeta, Oligochaeta, and Hirudinea ○ Now subdivided into Errantia and Sedentaria Errantians - mobile (some immobile, e.g. Platuneresis) & marine Ridge-like parapodia function in locomotion; studded with bristles of chitin called chatae Well-developed jaws and sensory organs Sedentarians - mostly immobile, filter feeders Leeches can be parasitic or predatory ○ Use hirudin, an anticoagulant, to keep the host bleeding Earthworms extract nutrients from the soil & leave fecal castings ○ Hermaphrodites “Tube within a tube” structure with an inner alimentary canal and outer body wall ○ Separated by a coelom Campbell Biology, 12th Edition Esparza 48 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Concept 33.4 Ecdysozoans are the most species-rich animal group Clade Ecdysozoa includes those that shed a cuticle through ecdysis (molting) Nematodes Phylum Nematoda (roundworms) have cylindrical bodies with a tough cuticle (exoskeleton) ○ Lack segmentation and a true coelom (unlike annelids) ○ Nutrients transported through a hemocoel; most free-living (e.g. C. elegans) ○ Parasites of plants and animals (e.g. pinworms and hookworms) Ex: Trichenlla spiralis causes trichinosis Modify cellular functions of their hosts to provide a suitable environment Arthropods Phylum arthropoda (arthropods) are considered the most diverse & successful phyla ○ Body plan includes: segmented body, exoskeleton, and jointed appendages ○ Originated from the Cambrian explosion (e.g. lobopods, trilobites) Eventually developed groups of segment for specific functions Driven by a change in the expression of existing Hox genes Appendages have diversified into many functions - walking, feeding, sensory, defense Hard, chitin exoskeleton retains water and supports their body on land Complex sensory organs (e.g. antenna) & an open circulatory system with hemocoel Tracheal system allows for efficient gas exchange despite the presence of an exoskeleton Consists of three major lineages: ○ Chelicerates (sea spiders, horseshoe crabs, scorpions, ticks, mites, spiders) Have claw-like feeding appendages called chelicerae Eurypterids (water scorpions) - earliest chelicerates Most are arachnids with six pairs of appendages: chelicerae, pedipalps, and four pairs of legs Book lungs - stacked, platelike structures for gas exchange Construct webs of silk using organs called spinnerets Campbell Biology, 12th Edition Esparza 49 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Used to catch insects, transportation (“ballooning”), etc. ○ Myriapods (centipedes, millipedes) have antenna & modified appendages Millipedes - herbivorous, each segment has two pairs of legs Centipedes - carnivores, each segment contains one pairs of legs ○ Pancrustaceans (insects and crustaceans) Crustaceans - have specialized appendages (antenna, mandibles, legs) Gas exchange through a cuticle or gills Include small crustaceans (isopods) and larger ones (decapods) May be planktonic (copepods, e.g. krill) or sessile (e.g.barnacles) Insects (clade Hexapoda) has a head, thorax, and post-gential region Development of wings allowed them to disperse to new habitats and find food and mates Campbell Biology, 12th Edition Esparza 50 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity Incomplete metamorphosis - the young (nymphs) undergo rounds of molting, each time increasing in resemblance to the adult Complete metamorphosis - have larval stages completely different from the adult form, but eventually reach sexual maturity during the pupal stage Most reproduce sexually, finding mates through vibrant coloration, sound, and odor Concept 33.5 Echinoderms and chordates are deuterostomes Echinoderms and chordates are closely related yet have evolved independently for over 500 mya Echinoderms Echinoderms - slow-moving marine animals with a coelom ○ Water vascular system - network of hydraulic canals branched into locomotive extensions called tube feet Function in locomotion and feeding ○ Sexually reproducing, bilaterally symmetrical larvae Dividing into five clades  Campbell Biology, 12th Edition Esparza 51 Neil A. Campbell, et.al Unit 5: The Evolutionary History of Biological Diversity ○ Asteroidea (sea stars and sea daisies) - arms (with tube feet for movement) radiate from a central disk Slowly digests prey outside the body & then consumes the rest using digestive glands High regenerative abilities; sea daisies are armless sea stars ○ Ophiuroidea (brit