Biodiversity PDF

Diversity of Life Reading, Bio 2e, Chps 21-29 Optional, Freeman Chapters 26-33  Learning Goal Students should have a basic understanding of the major branches of the tree of life, to the extent that they can: 1) name attributes of major animal phyla and plant divisions...

Diversity of Life Reading, Bio 2e, Chps 21-29 Optional, Freeman Chapters 26-33  Learning Goal Students should have a basic understanding of the major branches of the tree of life, to the extent that they can: 1) name attributes of major animal phyla and plant divisions 2) identify key groups of non-animal eukaryotes, and 3) identify some major features of the groupings on the tree of life.  Tree of Life/Phylogenetic Tree/Taxonomic Groups a.k.a. eukaryotes (like you!) Node Common ancestor Bacteria, Archaea, Eucaryot a= domains  LUCA The last universal common ancestor, LUCA, was not the first form of life (because many forms went extinct early on and LUCA descended from a survivor) We have been able to infer a great deal about this organism from comparing DNA from existing organisms. It was a unicellular prokaryote It existed 3.5-3.8 billion years ago (how do we know? The molecular clock!) It had genes and a genetic code (the RNA world was over by then) It was capable of ion transport, carbon fixation, and maybe methanogenesis. https://www.newscientist.com/article/2098564-universal-ancestor-of- all-life-on-earth-was-only-half-alive/ It was likely thermophilic.  Prokaryotes “Prokaryotes” are the most ancient, most abundant, and most metabolically diverse organisms. – This term describes a state of organization (no nucleus) rather than a taxonomic group. Prokaryotes include the: – Bacteria – Archaea  Bacteria Some major groups of bacterica include: Proteobacteria Cyanobacteria Gram-Positive Bacteria Chlamydias Spirochetes  Proteobacteria The proteobacteria are a large and diverse group that includes photoautotrophs, chemoautotrophs, and heterotrophs. – There is no taxonomic divide between “good” bacteria, those that are essential to the functioning of the biosphere, and “bad” bacteria, those that can kill us. Pathogenic bacteria occur within many different groups. www.biology.ed.ac.uk/.../microbes/myxococc.htm Among the proteobacteria are the myxobacteria, interesting gliding bacteria that produce “fruiting bodies” under conditions of starvation. Myxobacteria live in the soil, and “glide” along solid surfaces via a polysaccharide slime.  Among the proteobacteria are the ancestors of mitochondria. Also included are Rhizobium species that live in the roots of plants, and the rickettsias, tiny pathogens that live within the bioinfo.bact.wisc.edu/.../Effects.html  These are among the most Spirochetes distinctive bacteria they move by a spiraling corkscrew motion. They can be free living or parasitic. Syphilis and Lyme’s disease are caused by  Bacterial Photosynthesis Photosynthesis has evolved repeatedly in the bacteria. Cyanobacteria are the group best know for it, and their ecological importance is overwhelming. Other groups include purple sulfur bacteria, green sulfur bacteria, and certain heliobacteria. These groups can perform anoxogenic photosynthesis-they use molecules other than wate as an electron donor. For instance, H2S can be oxidized by purple sulfur bacteria, to granules of S  Chromantium sp, from a salt marsh near Woods Hole MA.  Archaea Although we know very little about them, the archaea are some of the most abundant, and important, organisms on the planet. – The group is very ancient-some bear a striking resemblance to fossils dated at more than two billion years old and many exploit ecological niches that were probably more important billions of years ago. – Though the majority live in ordinary habitats, the group includes many extremophiles. – These include, but are not limited to; methanogens-live in anerobic conditions and break down methane extreme thermophiles-live in incredibly hot Unlike Bacteria, Archaea often have genetic sequences called introns. They have this in common with Eukarya. Also, like Eukarya, Archaea have histones,-proteins that wind DNA strands to manage their configuration. Like bacteria, they lack nuclei and membrane bound organelles. Unlike either-they have ether linked, rather than esther linked lipids in their cell membranes  Archaea Bacteria What’s an Intron? Below: A gene segment intro exon Have No nucleus or n introns & membrane intron histones bound organelles DOES DOES code for NOT code amino for amino acids/pr acids/protei otein n product product Image credit: -https://images.search.yahoo.com/search/ images;_ylt=AwrhexOfqrpk09IIULZXNyoA;_ylu=Y29sbwNiZjEEcG9zAzE EdnRpZAMyQURTQ0FURUdPUllfMQRzZWMDcGl2cw--? p=what+is+a+histone&fr2=piv- web&type=E210US739G0&fr=mcafee#id=4&iurl=http%3A%2F %2Fvignette3.wikia.nocookie.net%2Fmmg-233-2014-genetics-genomics Histone= %2Fimages%2F6%2F60%2FFigure-1-Histones-1024x1022.jpg%2Frevision %2Flatest%3Fcb%3D20141020193149&action=click -https://images.search.yahoo.com/search/ images;_ylt=AwrEt09HpLpkJIsIWchXNyoA;_ylu=Y29sbwNiZjEEcG9zAzE “spool” for EdnRpZAMyQURTQ0FURUdPUllfMQRzZWMDcGl2cw--? p=taxonomic+ranking+system&fr2=piv- web&type=E210US739G0&fr=mcafee#id=2&iurl=http%3A%2F %2Fthevenominterviews.com%2Fwp-content%2Fuploads %2F2019%2F06%2FTaxonomic_Rank_Graph.png&action=click -https://www.researchgate.net/profile/Sara-Heap-2/publication/241247131/ figure/fig2/AS:718645441351682@1548349833366/Tree-of-Life-showing- the-three-domains-bacteria-archaea-and-eucaryota-The.png DNA  Eukaryotes Eukaryotes, organisms with nuclei and nearly always possessing membrane- bound organelles, are a single branch on the tree of life. It is likely that the original eukaryote was an amalgam of prokaryote species, and possibly a viral component as well. – Modern studies of eukaryote taxonomy indicate there are probably between 11 and 20 eukaryote kingdoms. These kingdoms include many groups formerly classed simply as “protists”, such as  Endosymbiosis In 1966, Lynn Marguils developed an old hypothesis that the mitochondrial of eukaryotes evolved from bacteria that had lived, billions of years ago, as a mutualistic endosymbiosis with early eukaryotes. – These particular organelles are surrounded by a double cell membrane, suggesting a bacterium embedded in a membrane that encapsulated it. – These organelles also have DNA, and ribosomes that resemble those of bacteria Similarly, chloroplasts likely have analogous origins from cyanobacteria. At the time it was not accepted, and was considered a testable hypothesis. The invention of DNA sequencing and modern systematic analyses have provided overwhelming support.  In both cases, a prokaryote was an endosymbiont in an ancestral archaea (bacteria-probably a Rikketsia), or eukarya (cyanobacteria). Lateral gene transfer over hundreds of millions of years has moved much of the original genetic material to the nucleus. – It is possible that other such events have occurred, influencing the evolution of the nucleus and the flagella.  Viruses Whether a virus is “alive” or not is no great mystery-it simply depends on how life is defined. – Most viruses have DNA, some have RNA. – Viral genomes are typically small, they hijack the transcription and translation mechanisms of a host cell to produce more viruses. – Isolated, a virus has no metabolism, no need for an energy source. – All the living processes of a virus require a host. – Viruses require energy when infecting hosts, reproduce, and evolve.  Typically, a virus has a core of genetic material, – linear or circular, single or double stranded, sense or antisense, protected by a protein coat. – There may be a lipid envelope, and proteins that encourage a host cell to engage it by phagocytosis. – Once engulfed, the viral genes are translated by the host cell, “early expression” enabling the virus to replicate and take over, “late expression” Right-Ebola, a “stripped down” virus with only the essentials.  Viruses have no specific place on the tree of life because they have multiple origins. – Some are probably degenerate bacteria. – Others likely descend from plasmids or “selfish DNA. – There are many groups of viruses, classified by whether they have DNA or RNA, whether they have “sense” or “antisense” genetic material, Sputnik virophage-a whether the genetic material is virus that attacks viruses single or double stranded, etc.  Compared to prokaryotes, Eukaryotes have Domain 1) a nucleus, and usually a larger genome Eukarya 2) linear chromosomes 2) a much more sophisticated cytoskeleton 3) potential for sex in most Domain Eukarya consists of several “kingdoms”. Of these, the “protista” are not a natural biological grouping… – Protista - single celled (several kingdoms lumped for our convenience) – Plantae – multicellular – Fungi - multicellular – Animalia - multicellular You are here  “Protists” “Protists” are simply eukaryotes, most of which are are unicellular for most of their life cycle. – There are many groups of distantly related protists, which are now thought of as “kingdoms” in their own right. – Several groups have independently acquired photosynthesis, and become “algae”, others have evolved multicellularity. One group of multicellular protists evolved into animals. Another lineage evolved into fungi.  Euglenozoa The Euglenozoa are a large and important group of flagellate protists (having flagella as opposed to cillia). – They branch off early in the eukaryote tree. – Many are free living, some are parasites. – Some are photosynthetic Trypanosoma brucei, mixotrophs, such as the well- the cause of African known Euglena gracilis. sleeping sickness  Alveolates This clade all have sacklike structures on the inner surface of their plasma membrane, and many common DNA sequences. The include Cilliates, Sporozoans, and Dinoflagellates – Stentor-a ciliate  Ciliates This group of unicellular eukaryotes moves by means of many small cillia, as opposed to one or more flagella. – Cillia are often used in feeding as well. They have a small diploid micronucleus for reproduction, and polyploid macronuclei for gene regulation. – Many are large, sophisticated organisms, rivaling small animals in their behavioral complexity and filling some of the same niches. Many are free living, many are parasites or commensals – Many can be seen with the naked eye  Dinoflagellates Dinoflagellates are a large group of unicellular eukaryotes that are very important producers, especially in marine environments. They have a distinctive arrangement of two flagellae, one lateral, one longitudinal, producing forward motion and turning force. Most are mixotrophic, combining photosynthesis with the ingestion of prey.  Dinoflagellates are known for the potent toxins produced by some species, and by their endosymbiotic associations. The “red tide’, seasonal blooms of phytoplankton that make seafood potentially deadly to ingest, are due to certain dinoflagellates, such as Pfiestieria. Dinoflagellate endosymbionts form associations with reef building corals, jellyfish, giant clams, and others.  Malaria-a Eukaryote Pathogen Plasmodium is a large genus of parasitic protozoa that parasitize birds, reptiles, and mammals, including humans. There is always a dipteran (Fly) vector which also hosts the parasite. – Sexual reproduction occurs in the insect host. – Many rounds of asexual reproduction occur in the vertebrate host. Plasmodium is a member of the Apicomplexa, a group derived from parasitic Dinoflagellates, thus, an Aveolate.  Malaria life history is complex. – A mosquito ingests blood containing malarial gametocytes. – These gametocytes unite in the mosquito midgut to form a zygote within the mosquito. – The zygote transforms into a mobile stage, moves, and releases sporozoites that migrate into the salivary glands. These Sporozoites are transferred during feeding, and enter the vertebrate bloodstream, where they move to the liver and invade, where they multiply, bud off from liver cells, and lodge in the lungs, where they have an opportunity to invade red blood cells. Once encysted in a red blood cell, the parasites transform several times, multiply, and explode the cell, releasing asexual progeny to invade other cells, or sexuals, to be picked up by mosquitoes.  Interestingly, the malaria parasite does not seem to harm the mosquito (it is more commensal rather than parasitic), but like nearly every parasite, it manipulates the behavior of its host. Female mosquitoes carrying malaria bite more often than mosquitoes not carrying malaria.  Stamenopiles This clade has certain pigments in common. – a yellow-brown pigment (which gives them their color). It is a carotenoid called fucoxanthin, and chlorophylls a and c It includes several important groups of producers, including; – Diatoms, Brown Algae, Red Algae – Some are multicellular, and called “seaweeds”, but not plants. – Macrocystis, on left, a brown alga  Diatoms Diatoms are a diverse and ecologically important group of unicellular eukaryotes. Most are non motile, and pelagic ones rely on turbulence to stay afloat. Common in fresh and salt water they are very important producers – (though there are hetrotrophic diatoms) – Their plastids have distinctive quadruple membranes encasing them, suggesting serial endosymbiosis.  Diatoms have distinctive silica cell walls, called frustrules, that encase them. – With each asexual division one daughter cell keeps each half of the box. Since the halves fit together, each daughter cell grows the new inside half, leading to a decline in size over time. – This decline in size is reversed by the formation of a sexual auoxspore, which gives rise to a much larger cell. Their use of silica means gives them a certain amount of character displacement from other unicellular algae, a possible key to their success.  Amebozoa This is a major taxonomic unit encompassing unicellular, or aggregate-multicellular eukaryotes often containing lobose pseudopods. These appendages serve many functions They contain slime molds, amebas, and foraminifera. They are a sister group to the Ophistokonts, which contains  Cellular Slime Molds As the sister group to Ophistokonts, the amebozoa are interesting because the cellular slime molds have the capacity to organize themselves into multicellular structures. – Typically, these organisms are free living ameboids, till the food runs out. – Then they signal each other to organize into a multicellular structure for dispersal. Dog vomit slime mold common at UIC  Fungi Fungi are a kingdom of organisms that includes decomposers, parasites, and mutualisms. There are four major groups; Chytridomycots Zygomycots Ascomycots Basidiomycots  Characteristics of Fungi Fungi are a major clade (branch) or organisms on the tree of life. – They have cell walls containing chitin, a long chain polymer polysaccharide. – Fungi are heterotrophs-they typically digest food extracellularly, and absorb it, as opposed to animals, which typically ingest food. – Most are multicellular but many have reverted to unicellular forms called “yeasts”. Many ecological associations, including decomposers, parasites, mutualists, and commensals. Many fungi alternate between haploid and diploid multicellular phases.  Chytrids are usually aquatic and saprobes or parasites. – At least some of their cells have flagella, a primitive trait for fungi. Zygomycots usually live in the soil or decaying material. We encounter many of them as “molds” – Many live in a mycorryzal mutualistic symbiosis with terrestrial plants. – Zygosporangia are resistant to freezing and dessiccation. Ascomycots are usuallycomplex multicellular fungi that often produce spectacular fruiting bodies. – Their spores are held in saclike “asci” – About half live in mutualistic symbiotic associations called “lichens”, some are mycorryzal fungi. Basidiomycots are usually complex multicellular fungi, that often produce spectacular fruiting bodies called “mushrooms”. – Spores are arranged on a structure called a “basidium” – These fungi are often important decomposers of wood, others live in mycorrhyzal associations. EO Wilson’s Biodiversity again  Polling Question Which of the following organisms is a prokaryote? A) a mouse B) a yeast C) E. coli bacteria D) B and C E) None of the above  Some fungal diseases of humans. “Athletes foot” is a very common fungal infection caused by ascomycots in the genera Epidermophyton, Trichophyton and Microsporum. These are dermatophytes-fungi that prefer to live in layers of dead human skin, as parasites in the mold growth form. – “Ringworm” is usually caused by dermatophytes in the genera Trichophyton and Microsporum. – Candidiasis is caused by the over growth of an organism that is usually commensal, Candidia albicans, a unicellular ascomycot yeast.  Beer, wine, and bread use of the metabolic activity of domesticated yeasts, the ascomycots Saccharomyces cerevisiae and S. ovatus. – These species exist in the wild on the skins of ripe fruits. They require an insect vector, usually wasps, to move to new habitats. – In domestication, many strains have been selectively bred to ferment particular beverages. Ale yeasts-brew well at higher temperatures, their cells tend to sink. Lager yeasts-brew at lower temperatures, their cells tend to float.  Viridiplantae This group includes the green plants and the basal “bush” from which they originated. They have chlorophyls a and b, as well as certain other distinguishing characteristics. Green Algae-Chlorophytes Charophytes Plants  Green Algae The green algae are an informal grouping that includes the Chlorophyte and the Charophyte algae. – Land plants evolved from Chrophytes. Like land plants, they have chlorophylls a and b, giving them a green color. They move about with paired flagella (only present in charophyte gametes. – They include multicellular forms  True Plants These include several groups of multicellular, terrestrial photosynthesizers, including – Bryophytes-mosses, etc. – Pteridophytes-ferns. – Gymnosperms – Angiosperms- flowering plants  Adaptations to Life on Land Roots – intake water and minerals in soil Leaves – produce energy/sugar through photosynthesis Vascular tissue Xylem –transports water & minerals from roots to rest of plant (via evaporation from leaves, and adhesion of water in the column behind evaporating water). Phloem – pumps sugar/food/energy from leaves to rest of plant Cuticle Water and gas-tight; reduces water loss Stomata – pores in leaf cuticle; open to allow gas flow and close to reduces water loss  Plants Alternate Generations Reproductive cycle: alternation of generations. Sporophytes (2n) produce spores (n) by meiosis. Spores grow into gametophytes (n). Gametophytes make gametes (n) by mitosis, which fuse to become a fertilized zygote (2n). Zygotes grow into sporophytes. Fig. 29-5a Gametophyte Gamete from (n) another plant Mitosis Mitosis n n n n Spore Gamete MEIOSIS FERTILIZATION 2n Zygote Mitosis Sporophyte (2n) Table 29-1 * *  Nonvascular Plants Land plants evolved some time in the Silurian period, around 440 million years ago. By the early Devonian period, 415 mya, communities of plants had colonized the wet areas on land. The dry areas were still essentially barren.  Two early land plants, Rhynia and Psilophyton They grew in wet areas. The vascular tissue of Rhynia is primitive-thus, they are short. The sporophytes are shown. Psilophyton had vascular tissue and was a tracheophyte. Note the lack of true leaves, but the sporangium bearing structures.  Plants without sophisticated vascular tissue dominated terrestrial communities for 100 million years. As they proliferated, they altered terrestrial microenvironments, and created ecological niches for terrestrial animals, notably, arthropods. Animals did not colonize land out of manifest destiny-without food, in a punishing microenvironment, there was nothing there for them.  BUT they needed moist environments: No vascular system to take water up from soil! Sperm have to SWIM to egg So later, vascular plants gradually spread and became the dominant terrestrial producers Vascular tissue pumped water up from soil AND allowed them to grow TALL! The tree growth form had far-reaching effects on ecosystems. Many ecological niches opened up. Likely, the carbon pulled out of the atmosphere, and decomposing material from land sinking in oceans, caused a mass extinction.  Ferns vascular tissue spores, not seeds spores are sexual and haploid: not yet fertilized! Dominant sporophyte. Diverse - more than 12,000 species. Mostly tropical, some temperate Fig. 29-15d Seedless vascular plants Isoetes gunnii, a club “moss” a quillwort  Seed Plants A seed is an embryo and nutrients surrounded by a protective coat Their ecological importance cannot be overstated. – Gymnosperms, the “naked seed” plants, including the conifers, an informal grouping. – Angiosperms, the flowering plants  Gymnosperms Not a single lineage. Have vascular tissue, seeds, dominant sporophytes Gymnosperm means “naked seed” Conifer cone bearing trees: pine, fir, spruce. Most diverse and ecologically important group. – Cone - scaly structure produced by some seed plants; support either male or female reproductive structures; site of seed-production/ Cycads formerly very diverse. Others..such as Ginko bioloba (right)  Angiosperms Currently, the ecologically dominant group in most terrestrial environments. Produce flowers Seeds are enclosed in fruits Monocots are a distinct clade, the branch off early from within the” Dicots”.  Monocots vs. Eudicots Within the “Dicots”, the Eudicots are a true lineage.  Grasses One ecologically important group of monocots are grasses (family Poaceae) – They diversify and become widespread at the end of the Cretaceous period, eventually replacing ferns as the most important early-successional plants  In one way or another, most of our food calories come from grasses. Either domesticated edible grasses, called cereals,or up the food chain from grazing. – Their leaves grow from the base, making them tolerant of grazing. – Their leaves have parallel veins, and are alternate. – They are nearly always wind pollinated.  Animals Animals are a true lineage of multicellular organisms evolved from one line of protists (probably resembling a group called the choanocytes). Animals share a common ancestor with fungi, choanoflagellates, and some enigmatic groups to form a clade called the ophistokonts. – They have evolved many different body plans, each of which represents a phylum. There are about 35 present-day animal phyla, there were probably more in the  Choanoflagellaes A group very similar to the common ancestor of all animals are the choanoflagellates. – They are free living or multicelular ophistokont protozoa with a distinctive feeding apparatus that resembles the collar cells of sponges. – Sponges, the most primitive animals, evolved form organisms like this.  Sponges Until recently Phylum sponges Porifera were thought to be the most basal animals. DNA analysis suggests that nearly all other animal life evolved from a dermosponge ancestor. Sponge fossils first appear in the Cambrian, but molecular fossils suggest they arose 600mya or earlier  Sponges (Porifera) Are multicellular, with tissues, but no true organs, nor organ systems like digestive, circulatory, nervous, and muscular. They are composed of a gel-like mesohyl sandwiched between two layers of cells. They lack symmetry Produce sperm  Sponges are filter feeders, that use flagellated collar cells to create a water current. Spicules in the mesohyl for an endoskeleton. – Some use silica, some calcium carbonate, some use spongin fibers. Their cells are undifferentiated and the entire animal can regenerate. The Ediacaran Fauna The first creatures resembling animals appear in the fossil record approximately 600 million years ago. – The Earth was recovering from massive glaciation. – This fauna is found worldwide, some forms having very large geographic ranges.  The Ediacaran fauna form distinct assemblages in deep water and shallow water. – Some were quite large. – Many have a “quilted” body plan. – Their existence seems to be tied to the presence of microbial mats, which were much more pervasive before the evolution of multicellular animals, and the bioturbation associated with them. – Their phylogenetic affinities, physiology, and natural history are currently a scientific mystery.  The Cambrian Explosion The Cambrian explosion was a relatively short lived adaptive radiation that happened at the beginning of the Cambrian period, 530 million years ago, and lasted appx 20 million years. Nearly all of the present-day animal phyla, and many extinct groups, originated during this time.  The Ediacaran fauna disappear completely at this time. – Bioturbation becomes widespread, and as the radiation progresses, food webs with multiple trophic levels evolve. – Many forms of life evolve complex features and become fairly common, but go extinct soon afterwards. Sequencing of the genes that code for 18s ribosomal RNA has enabled us to come up with a good phylogeny of animals. 18s ribosomal RNA is very evolutionarily conservative, and preserves info on deep branches. This one was our view in about 2001 Here is the current consensus. As genomic sequencing Techniques improved, note some surprises. This is science- incorrect hypotheses are rejected as new evidence comes in.  Ctenophores The “comb jellies” resemble cnidarians in several ways, This group was, until recently, thought to be close to the common ancestor of the bilateral metazoan animals. Recent evidence (Dunn, et al, 2014) has suggested that it is the outgroup to all other animals, including Porifera. Move by rows of cillia. – Tissues? – a “nerve net” – Most waste is regurgitated, but some come out anal pore.  Eumetozoa This group contains all animal life except sponges and placozoa. Tissue is organized into 2, or 3 germ layers. Neurons present. Embryo goes through a gastrula stage. Originated in the Ediacaran, Dickinsonia might have been eumetazoan…  It is tempting to consider that our embryology reflects our evolution here. All animals begin as a zygote that divides rapidly into a ball of cells. This ball of cells organizes to be a blastula, a hollow structure, with an interior blastocoel. – Human blastula (right)  Sponges develop directly from the blastula stage. In eumetazoa, the blastula invaginates to form a gastrula. The gastrula has a blastopore, and two layers of cells. It is configured much like a hydrazoan.  The interior arechenteron gives rise to the gut. The blastocoel is now sandwiched, and the blastopore can serve as a mouth/anus.  Hox genes Hox genes are a group of related homeotic genes common to nearly all animals (sponges and ctenophores lack them) In segmented animals, they confer the identity of each segment along a head to tail axis. – Their produce a transcription factor – They contain a Homeobox DNA sequence. – In many animals, the organization of the Hox genes in the chromosome is the same as their orientation on the anterior axis – The fact that all animals have such similar Hox genes strongly suggests that the last common ancestor of all bilaterians had similar Hox genes. – Evolution of Hox genes may have paved the way for the development of complex body forms.  Ground Plan Each phylum has a ground plan, deeply ingrained in its developmental biology, that determines the general layout of its body cavities and organ systems. These body plans are very evolutionarily conservative, though in some organisms, they have been progressively modified by natural selection so many times that the original layout is hard to see. – Examine your own body for a tail-a key feature of the chrodate body plan. Ground plan for Phylum Arthropoda (example): segmented body, chitinous exoskeleton, periodic molts, and jointed appendages  Cnidaria This group is radially symmetric, even as embryos. Only two layers of tissue, surrounding a jelly like inner layer.  Phylum cnidaria…Jellyfish, Anemones, hydras, gorgonians, and corals. This is a major animal phylum, with over 10,000 species. Exclusively aquatic. Portuguese Man O’ War  Cnidarian Body Plan Cnidarian bodies consist of a jellylike, nonliving mesoglea, sandwiched between two layers of epithelium, one cell thick. Interior body cavity used as a gut and for respiration Lose nerve net Radially symmertic  The Cnidaria include: – 1) Hydrozoa – 2) Anthozoa-corals and sea anemones – 3) Scaphyzoa- jellyfish – 4) Cubozoa-box Cnidarians have jellyfish specialized Many groups cells, alternate between cnidocytes, that polyp and entangle or medusoid forms. harpoon prety.  The Bilatera Includes eumetazoa other than radiata=ctenophores+cnidaria Have 3 tissue layers. – Ectoderm, endoderm, mesoderm=triploblastic Differences in how tissue layers form: – Protostome-mouth forms first, sprial cleavage, determinate development, coelom forms from splitting of mesoderm. – Deuterostome-anus forms first, radial cleavage, coelom forms from inpocketing of mesoderm.  A coelom is an interior body cavity that is an Coeloms essential to the body plan of most animal phyla. – Lined with mesoderm – This fluid filled space separates the gut from the rest of the animal, allowing specialization of the gut. Gametes storage – It can also serve as hydrostatic skeleton  Lophotrochozoa The lophotrochozoa are group of animal phyla that share a very ancient common ancestor. – Members have a lophophore (a feeding structure), trochophore larvae, or 18s RNA sequences suggesting they are related to the others.  Phylum Platyhelminthes Flatworms – Unsegmented – No body cavity-aceolomate – Three tissue layers – Digestive cavity has only one opening – Nutrients and gasses move via diffusion-thus, flat shapes-no respiratory or circulatory system Ladderlike nervous system – Free living and parasitic Eye spots in some species members.  Ribbon Worms – Marine, freshwater, some Phylum terrestrial. Nemertea important marine predators and scavengers – Coelom serves to store proboscis, which can be everted for prey capture. Mouth and anus – Vessels for circulation – Flame cells for excretion – Brain + paired ventral nerve cords “pigment cup” ocelli chemosensory organs  Phylum Mollusca Chitons, Clams, Snails, Slugs, Squids, and Octopi A major animal phylum-85,000 extant species, about 23% of named marine species Freshwater, Banana Slug marine, terrestrial  “Typical” mollusk features: – A coelom that may function as a hydrostatic skeleton – A mostly open circulatory system with a heart – An excretory system with nephridia – A muscular “foot” on underside of animal – A shell – A mantle cavity – A radula – Paired nerve cords with ganglia – Metamorphosis from planktonic trochophore larvae.  Major mollusk groups: – Cephalopoda-foot modified into arms, closed circulatory system, cell lost in most contemporary species. – Gastropoda-torision, the visceral mass twisted – Bivalva-two valves (left and right, not top and bottom, to shell.  Segmented Worms Marine, freshwater, Phylum Annelida terrestrial species. Coelom forms hydrostatic skeleton Closed circulatory system. – Polychetes-marine – Oligochetes-mostly terrestrial burrowers – Hirudinea-leeches – Others..including pogonophores…  Phylum Brachiopoda Lamp shells, another lophophorate  Phylum Bryozoa Bryozoans, the largest phylum in the superphylum Lophophorata  Phylum Rotifera Wheel bearers. A very abundant group. Many asexual lineages. Uncertain affinities Many acellular forms.  Ecdyzoa Another large group of protostomes, discovered by 18s RNA analysis. – All members, in one way or another, shed their cuticles or exoskeletons.  Phylum Nematoda Roundworms. An abundant and ecologically important group of ecdyzoans. Pseudocoelomate Caenorhabditis elegans Ascaris lumbricoides  Phylum Tardigrada Water Bears. Amazingly tough cryptobiota  Phylum Arthropoda Horseshoe Crabs, Arachnids, Crustaceans, Myriapods, and Insects. – More species than all the other groups combined  Arthropods have a segmented body plan with jointed appendages and a cuticle made of chitin. – This confers ecological advantages and limitations. – They may be a sister Arthropoda originate group to the during the Cambrian onychophora, which explosion and quickly are specialized become numerous and segmented creatures ecologically important. that lack an Marella, above, a exoskeleton Cambrian arthropod.  Arthropods have a segmented body plan that allows the evolutionary specialization of certain segments – Ventral nerve cord – Dorsal gut – Open circulatory system. – Tagmosis-the progressive specialization and fusion of segments.  Crustacea – Biramous appendages Most have gills as one ramet of leg. – Marine, freshwater, terrestrial. – Antennae+antennules  Insecta – Terrestrial. – Uniramous appendages – Three segmented body plan. – Six legs, two antennae. – Evolved from crustacean ancestor – Trachae as respiratory structures. – Many winged forms. – Many undergo metamorphosis. – Mantispid lacewing, a neuropteran insect. Deuterostomes Obvious developmental differences from other animal phyla. Includes Chordates, Hemichordates, Echinoderms  Phylum Echinodermata Starfish, Brittle Stars, Urchins, and Sea Cucumbers Major deuterostome phylum Secondary radial symmetry Water vascular system  Phylum Chordata Phylum Chordata is the only phylum containing vertebrate animals, however, there are some invertebrate chordates  Chordates At at least some point in their life, all have a skeletal structure called a notochord. – a flexible rod located between the digestive tube and nerve chord. – Provides skeletal support. – In most vertebrates, it’s replaced by a jointed skeleton. Remains of the notochord exist as disks between the vertebrae. At least some development of a dorsal hollow nerve cord In some, like humans, it into the brain and spinal cord of the adult. Pharyngeal slits – At least some point in development, these appear. Water enters through the mouth and passes out through the slits in the pharynx, without going through the digestive system. Slits function as suspension-feeding devices in many invertebrate chordates – In most vertebrates, these slits have been exapted for: Gas exchange Hearing Jaw support Postanal tail – Provides propulsion for swimming  Subphylum Subphylum Cephalochordata Urochordata Adult form shows chordate features. Adult is sessile and feeds via pharyngeal Adults feed and slits swim. Marine fiolter feeders Lancet-below Tunicate-below Four anatomical features that characterize the phylum Chordata Subphylum Urochordata: a tunicate Subphylum Cephalochordata: the lancelet Branchiostoma More recent data suggest that urchordates are a little closer to us. This seems a little less bizarre if you consider that some urchordates have neotenic larvae that never settle and lose their tails. Polling Question Which of the following organisms is a deuterostome? A) A human B) A coral C) A sea star D)A and C E) All of the above  Vertebrates- subphylum vertebrata Vertebrate features Neural cresthttps://dos.uic.edu/student-legal/ Enhanced cephalization Vertebral column A closed circulatory system  Neural Crest Embryonic feature that allows for many unique vertebrate characteristics, e.g. bones and cartilage are formed from the neural crest cells throughout the body. Forms along the dorsal side of the embryo  Skeletal elements, such as the cranium (braincase), allow for the big evolutionary feature of vertebrates, cephalization. This gives us the term “Craniates” – Hagfish are probably craniates, but not vertebrates. – Likely, so were conodonts Vertebral column is the main support for the body axis. It allows for large size, fast movement, and protection of the nerve cord. The closed circulatory system pumps oxygenated blood to cells and allows rapid metabolism, rapid movement to search for food, escape predators.  Jawless Vertebrates First radiation of vertebrates was jawless Surviving groups include hagfish (no skeleton, no notochord in adult) Lamprey (early Early fish, a version of a cephalaspidomorph vertebral column).  Gnathostomes Gnathostomes have jaws – Vertebrate jaws evolved from skeletal supports of pharyngeal slit. – Members of group have two pairs of fins (or limbs) – Jaws and fins allowed fish to diversify ecologically Acanthodians and placoderms-early gnathostomes Hypothesis for the evolution of vertebrate jaws  Three groups of gnathostomes make up what we collectively call “fish” Chondricthyes: Sharks and rays have cartilaginous skeletons Osteichthes-bony fish. The most diverse group of vertebrates. 28,000 species in 435 families Sarcopterygii-lobe finned fish. Tetrapod relatives  Tetrapods Evolved from lobe finned fish. Early tetrapods were mostly aquatic air breathers. An assemblage of “amphibians” radiate in the Carboniferous period. Many groups, probably tied to water for reproduction  Bony fish have undergone multiple, spectacular adaptive radiations. The teleosts account for 98% of bony fish. Suzuki, D., Brandley, M.C. & Tokita, M. The mitochondrial phylogeny of an ancient lineage of ray-finned fishes (Polypteridae) with implications for the evolution of body elongation, pelvic fin loss, and craniofacial morphology in Osteichthyes. BMC Evol Biol 10, 21 (2010). https://doi.org/10.1186/1471- 2148-10-21  Tetrapods Evolved from lobe finned fish. –Early tetrapods were mostly aquatic air breathers. –An assemblage of “amphibians” radiate in the Carboniferous period. –There were many groups, including lepospondyls, stereospondyls, etc. –Most were probably tied to water for reproduction. –Contemporary amphibians and amniotes evolved from two separate groups. Acathoseega, an early tetrapod, aquatic and air breathing, prob not an ancestor to terrrestrial tetrapods. Early tetrapods diversify into a bewildering variety of groups. Amniotes and amphibians arise from two separate surviving branches Amemiya, C., Alföldi, J., Lee, A. et al. The African coelacanth genome provides insights into tetrapod evolution. Nature 496, 311–316 (2013). https://doi.org/10.1038/nature12027 A simplified tetrapod phylogenetic tree Surviving amphibians fall within a monophyletic group called the lissamphibia. They are in NO WAY ancestral to amniotes, but rather, originated during the Mesozoic Skin a major gas exchange Gerobatrachus, above. organ Nearly all amphibians Order Urodela – need to return to water Salamanders. to lay eggs and for Order Anura – Frogs development of larvae. Order Apoda – Caecilians.  Amniotes Includes reptiles, mammals, and birds) – The amniotic egg is a key adaptation to life in arid terrestrial environments.  Specialized extra- embryonic membranes that function in gas exchange, waste storage, and transfer of nutrients. Membranes develop from tissues derived from the embryo. Amnion Chorion Allantois Amniotic eggs require internal fertilization. Shell forms around fertilized egg in the reproductive tract.  Gastrulation in Amniotes Amniotes, often having a large amount of yolk, have evolved modifications of the gastrulation process to cope with the huge amount of yolk sitting over a tiny embryo, and to create the amniotic membranes. (other high-yolk vertebrates have analogous adaptations) The embryonic cleavages do not penetrate the mass of egg. What had formerly been a hollow ball is now a disk, with endoderm pressed against a huge mass of yolk. Embryonic membranes Note that the grow over the embryo, blastopore is incorporating multiple more of a groove, called germ layers. the “primitive streak” Amniotes split into several groups early on. A few stem groups retained the anapsid condition. One group, the synapsids (whose descendants include mammals) split off early. Another group, the sauropsids (whose Limnoscelis was originally described descendants include birds as an amphibian, but likely was a and reptiles) split off very early amniote. Whether it laid slightly later. amniotic eggs, we do not know. TY - JOURAU - Martin, AnthonyPY - 2023/08/18SP - T1 - Dinosaur Evolution: From Where Did They Come and Where Did They Go?  Reptiles “Reptiles” are a paraphyletic assemblage of sauropsid amniotes. Scales of keratin, waterproof skin - prevent water loss. Lepidosaura, – Unlike amphibians, (monophyletic) which reptiles cannot breathe includes lizards and through skin, so all snakes, has overlapping gas exchange occurs scales. via lungs. All surviving reptiles descend from diapsids- turtles have secondarily lost these openings and have restored the anapsid condition.  Nearly all “reptiles” are ectothermic, using behavior and external sources of heat to regulate their body temperature. Reptiles are able to survive on about 10% of calories required by mammals.  Archosaurs Archosaurs are a major group of saurposids. Archosaurs include crocodilians, birds, and nonavian dinosaurs, and some other extinct groups. They diversified during the Triassic Early archosaurs Birds, class Aves, are the sole surviving dinosaur lineage. Porous skeletons with air spaces are light and strong. Unidirectional air flow in lungs. Avian wing and feather- unlike dinosaur Dinosaur feathers, feathers, good for flight. above, lack the vanes All contemporary birds needed to support are toothless flight  All contemporary birds are endotherms and egg layers. Feathers provide insulation. Efficient circulatory system supports high rate of metabolism necessary for flying. – Flight was a key evolutionary adaptation during the Jurassic-enabled birds to colonize many ecological niches alongside the pterosaurs (who also flew) Toothed birds were once fairly common. Mass extinction took them out.  Synapsids Synapsids originate very early, soon after the origin of amniotes. – They diversify as “mammal-like reptiles” and become ecologically dominant in the Permian, before the age of dinosaurs – Early synapsids had differentiated teeth and were likely homeothermic.  Mammals originate in the early Jurassic. They were actually quite abundant during the Mesozoic. They diversified into new ecological niches following the KT extinction. – Mammary glands – Large brains – Hair and subcutaneous fat – Endothermic – Dentary bone Morganucodon, early mammal  Three surviving groups of mammals. – Monotremes – lay eggs and produce milk, but have no nipples. Survivors of a very ancient, Southern, group. – Marsupials – born early in embryonic development; climb to mother’s pouch and attach to a nipple. Platypus- an Very diverse in Cretaceous, lost ground due to mass egg laying extinction. mammal with – Eutherians – long pregnancy with many unique embryonic attachment to mother adaptations in uterus via placenta. Two ossicles in the mammalian inner ear are an excellent example of exaptation. They arise from jaw bones. They probably confer a greater range of pitches to our hearing The adaptive radiation of mammals produced our own group, the primates. The early branching of the tree follows continental breakup of the Mesozoic continents, but dispersal has moved species around.  You are: a homonoid, a primate a placental mammal a synapsid tetrapod a gnathastome a vertebrate a deuterostome a bilaterian a eumetazoan Primates diversify in the Eocene, an animal about 50 million years ago. an ophistocont One group gave rise to the apes, a eukaryote which include humans. Polling question Which of the following is an amniote? a). A trout b) A fly c) A human d) An ostritch e) C and D