Classification Scheme - Biology PDF

CLASSIFICATION CLASSIFICATION SCHEME: - People have given different life names - the binomial (two part) system for naming organisms -  generally referred to *Genus species* e.g. *Homo sapiens* - Carolus Linnaeus  (a.k.a. Carl von Linné) -- popularized this system...

CLASSIFICATION CLASSIFICATION SCHEME: - People have given different life names - the binomial (two part) system for naming organisms -  generally referred to *Genus species* e.g. *Homo sapiens* - Carolus Linnaeus  (a.k.a. Carl von Linné) -- popularized this system (mid 1700's)  - *Taxonomy* -- science of naming and classifying the diverse forms of Life We begin to group and organize living things based on how they are related.  - Originally this was accomplished on the **phenotype** (physical characteristics) - Now on the **genotype** (DNA sequence) contributes significantly to studies of relatedness Example: Human beings Domain: *Eukarya* -- you are composed of eukaryotic cells Kingdom: *Animalia* -- you are multicellular and don't photosynthesize Phylum: *Chrodata* -- during development you had a notochord (subphylum): *Vertebrata* -- your notochord developed into vertebrae Class: *Mammalia* -- warm blooded (not a reptile), no feathers and have teeth (not a bird), females can nurse their young (subclass): *Eutheria* -- you don't lay eggs, you don't develop in a pouch (marsupials, e.g. kangaroos), developed with a PLACENTA Order: *Primata* -- you have opposable thumbs (suborder): *Arthropoidea* -- eyes are on the front of your head, not on the sides like some monkeys There is a tremendous amount of **information** in this classification scheme.  Tells you about: Development, Physiology, Genetics, How you interact with your young KNOW the Hierarchy of classification:  Dumb (Domain)  King (Kingdom) Philip (Phylum)  Can (Class)  Only (Order) Find (Family) Green (Genus) Snakes (Species) **Kingdoms and Domains:** - Originally just two big classifications: plant and animal - Then 5 kingdoms: plant, animal, fungi, protista, monera (prokaryotes) - Now greater classification level 🡪 DOMAIN : Bacteria, Archaea, Eukarya **\ ** PROKARYOTES **PROKARYOTES: ** - Been around longer than any other life form known -- about 4 to 3.5 billion years. Consider the Earth is only about 4.5 billion years old, so prokaryotes have been around for almost 80% of the age of the Earth! - Microbes can live EVERYWHERE -- from water in temperatures above boiling, to ice, to high levels of radiation  (*Deinococcus radiodurans*)  - Prokaryotes constitute the most abundant form of life on earth -- by biomass - Possess much more genetic plasticity than multicellular eukaryotes - Prokaryotes  are essential to ALL life on this planet as primary decomposers -- recycling the elements of life Microbes are differentiated based on genotype and phenotype: - Genotype is very accurate but you can't sequence the entire genome very easily of everything you find to identify it -- yet Identify microbes based on the following characteristics:  - Shapes: - Spherical -- *cocci*, singular *coccus* (greek word for berries) - Rod-shaped -- *bacilli*, singular *bacillus* - Spiral-shaped - spirillum - Two major categories of prokaryotes:  - Gram Positive -- stain purple in the Gram stain test - Have thick cell wall of **peptidoglycan** (protein / carbohydrate mix)  - Gram Negative -- stain pink in the Gram stain test - Have thin cell wall and a second membrane creating the **periplasm**, also called the periplasmic space - Metabolism:   - Oxygen dependence: - Aerobic : need oxygen to live - Anaerobic : no need for oxygen - Facultative Anaerobe: can switch metabolism for either - Incredibly varied  - Essential to the health of an ecosystem as **decomposers and synthesizers** - - - - **Environments:** - Some bacteria have the ability, when the environment is hostile, to form endospores - often a small portion of the population will survive because they can form ENDOSPORES - form a hard "seed-like" coating - Endospores are bacteria in "hibernation" - Inert  - Highly resistant to: desiccation and temperature extremes  **Two major groups of prokaryotes: ** Domain Bacteria Domain Archaea Which Domain the prokaryote is from can only be determined on a molecular level - Archaea are more closely related to Eukaryotes than they are to Bacteria Archaea include the *EXTREMOPHILES:* "Love Extreme" environments - Temperature extremes, pH extremes, high salt, etc.  - All possess physiology that is adapted to their particular environment, but would not necessarily do very well under "normal" conditions KINGDOM PLANTAE **KINGDOM PLANTAE** Terrestrial Plants organized into 4 different groups:  - seedless nonvascular (bryphytes = mosses, liverworts) - seedless vascular (ferns) - nonflower seed (gymnosperms) - flowering seed (angiosperms) -- dominant vegetation  **LIFE CYCLE: ** *Alternation of generations*: when multicellular haploid and diploid forms of an organism alternate.  - - - - **Bryophytes:** seedless plants, non-vascular plants (hence no true stems, leaves or roots) - Bryophytes: mosses, hornworts, liverworts - Short plants, do not have true stems to grow tall  - Grow in moist environments - Gametophyte is DOMINANT - No true vascular tissue, most water is absorbed directly through surface - Dependent upon water to reproduce - Relevance: - Reduce flooding and erosion, act as moisture reservoirs - e.g. Peat moss if very important as soil conditioner -- 1 pound can absorb 25 pounds of water! Used as packing for shipping things as well.  **\ ** ferns and fossils **KINGDOM PLANTAE** Terrestrial Plants organized into 4 different groups:  - seedless nonvascular (bryphytes = mosses, liverworts) - seedless vascular (ferns) - nonflower seed (gymnosperms) - flowering seed (angiosperms) -- dominant vegetation  **Ferns:** Seedless, vascular plants  Advancement in land adapted traits for the seedless vascular plants:  - Seedless plants, produce spores - True leaves and vasculature; many have a underground stem (rhizome) - Sporophyte is dominant - Reproduction is still dependent upon water - Common house plant, some medicinal values - Where the dominant land vegetation during the Carboniferous Period (360-300 mya)  - - - - - [Fossil Fuels vs. Bio Fuels] Photosynthesis:   CO~2~ (*g)* + H~2~O + light energy 🡪 C~6~H~12~O~6~ (glucose) + O~2 ~ Carbon Fixation ("fixing carbon"): converting gaseous (atmospheric) carbon (CO~2~) into a "fixed" form such as starch or cellulose where it cannot act as a greenhouse gas.  Fossil Fuels: burning oil release CO~2~ that was fixed from the atmosphere millions of years ago, i.e. dumping a large amount of green house gas into the atmosphere very rapidly Biofuels: burning CO~2~ that was fixed recently and will be retrieved and fixed from the atmosphere again quickly  gymno and angio **KINGDOM PLANTAE** Terrestrial Plants organized into 4 different groups:  - seedless nonvascular (bryphytes = mosses, liverworts) - seedless vascular (ferns) - nonflower seed (gymnosperms) - flowering seed (angiosperms) -- dominant vegetation  **Gymnosperms: "naked seed"**; vascular, non-flowering seed plants - Division Coniferaphyta: 80% of all gymnosperms  - Several very important families (which you do NOT need to memorize!): Pinaceae (Pines, Firs, Spruces -- lumber); Cupressaceae (cypress and junipers); Taxodiaceae (redwoods); Taxaceae (yews, pacific yew) - True leaves and true roots - Still alternation of generations but gametophyte much reduced - Reproduction is independent of water - Introduce POLLEN as the male gametophyte! Wind driven - Female gametophytes are the ovules of the pine cones! - Introduce the SEED:  - Seed: mature ovule containing an embryo; bound by a protective seed coat which is resistant to desiccation and harsh conditions - Ovule: structure that contains the female gametophyte - Some seeds require special conditions prior to germination: fire, mechanical damage, acid, cold temperatures, etc.  - EVOLUTION!!  - Most species exhibit SECONDARY GROWTH -- lateral growth (thickening of stems) i.e. wood - Source of lumber, building materials, etc.  **Angiosperms**:  - Flowering seed plants - Dominants the land vegetation of the planet, 80% of all land plants - Most recent evolutionarily, but huge adaptive radiation event i.e. tremendous amount of diversity over a short period of time - Put their genitalia on display -- flowers to attract pollinators  - Pollinators -- organism that carries pollen between individual flowers  - Biological Vector -- carry the pollen from flower to flower - Co-evolution: two or more interdependent species, each adapting to changes in the other.   - Defining feature is the flower, containing the male and female reproductive organs - *Flower structure*: modified leaves and stem - Composed of 4 "whorls": sepals, petals, stamen (filament and anther), carpel (ovary, style, stigma) - Develop FRUIT: matured, ripened ovary, which aid the spread of seeds (matured ovules) LAND PLANTS -- SUMMARY **[LAND PLANTS -- SUMMARY ]** +-----------+-----------+-----------+-----------+-----------+-----------+ | **Group** | **Descrip | **Example | **Dominan | **Reprodu | **Notes** | | | tion** | (*Divisio | t | ction** | | | | | n)*** | in Life | | | | | | | Cycle** | | | +===========+===========+===========+===========+===========+===========+ | Bryophyte | seedless  | mosses | gametophy | dependent | reduce | | s | | (*Bryophy | te | on water | flood and | | | non-vascu | ta*) | | | erosion, | | | lar | liverwort | | | moisture | | | | s, | | | reservoir | | | | hornworts | | | s | +-----------+-----------+-----------+-----------+-----------+-----------+ | Ferns and | seedless | whisk | sporophyt | dependent | common | | Relatives | vascular  | ferns, | e | on water | house | | | | horsetail | | | plant, | | (Dominate | | s | | | medicinal | | d | | (*Equiset | | | , | | \~350 | | ophyta)*, | | | dominant | | mya) | | ferns | | | during | | | | (*Pterido | | | the | | | | phyta)* | | | Carbonife | | | | | | | rous | | | | | | | Period | +-----------+-----------+-----------+-----------+-----------+-----------+ | Gymnosper | non-flowe | conifers | sporophyt | independe | lumber, | | ms | ring | (*Conifer | e | nt | paper, | | | seed, | ophyta*), | | of water | medicinal | | (Dominate | vascular | Ginkgo | | because | | | d | | | | of pollen | | | \~200 | | | | | | | mya) | | | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ | Angiosper | flowering | oak, | sporophyt | independe | medicine, | | ms | seed, | corn, | e | nt | food, | | | vascular  | wheat, | | of water | clothing, | | (began | | rose, | | because | shelter  | | rise to | | daisy, | | of pollen | | | dominance | | (*Magnoli | | | | | \~100 | | ophyta*) | | | | | mya) | | | | | | +-----------+-----------+-----------+-----------+-----------+-----------+ Plant Structure **Plant Structure**:  The parts of a typical angiosperm: *shoot system*: stem, node, internode, leaf (petiole, blade), axillary bud, terminal bud (SAM)  *root system*: roots, tap root (RAM), root hairs. Variations on the theme: three organs = stems, roots, leaves -- all have variations:  Leaves: cactus needles, pea tendrils, spines Shoots: rhizome (underground shoot), bulbs (onion = leaves and shoot), tubers Roots: storage organs (carrots, sugar beets)  *Flower structure*: modified leaves and stem **Tissue Systems:** Body of the plant is composed of three tissue systems: 1) epidermis, 2 )Vascular tissue  3)Ground tissue  *Epidermis:* - \"Skin\" of the plant - first several layers of the cells on the exterior of the plant - secretes the cuticle -- water proof layer which is thin on some plants and thick on others - Punctuated by stomata for exchange of gases (oxygen and CO~2~)  - Stomata (singular Stoma) are flanked by GUARD CELLS - Guard cells swell and deflate like tires to open or close the stoma - found primarily on the underside of leaves and in some stems *Vascular Tissue:* - comprised of the XYLEM and the PHLOEM - Transport and provide STRUCTURAL support to the plant - XYLEM:  - dead cells that have been impregnated with lignin (waterproofs and adds strength) - connected create pipes that transport water and minerals from the roots to the shoots TRANSPIRATION: the process by which water evaporating from the leaves of plants draws water up through the xylem from the roots; mechanical process based on the cohesion and adhesion of water; moves water and minerals through the plant.  - PHLOEM: - living system for food transport - comprised of sieve-tube members and companion cells - sieve tube members are enucleate (no nuclease) and is dependent upon the companion cell for protein synthesis and major metabolites.  *Ground Tissue System*:  - makes up the bulk of the tissue in a seedling and young plants - fills the space between the epidermis and the vascular tissue - variety of purposes: storage, structural support, photosynthesis Consider the structure of a leaf: constructed for PHOTOSYNTHESIS; gradient of light and gases - *Chlorophyll* is the pigment in the chloroplast that is responsible for the capture of light energy and begins the conversion to biological forms of energy.  Plant Growth **[Plant Growth:]** Consider how plants grow: they have a [repeating body plan] *Indeterminate growth*: continue to grow as long as you live, most plants show this type of growth Because plants are sessile (they can't move) this is helpful for them to GROW where they need to go!  *Determinate growth*: cease growth upon reaching a predetermined size, usually at maturity, animals and humans are like this! Not all plants live forever though: two major types *Annuals*: complete their life cycle and die in one year or growing season, i.e. peas, wheat, etc. *Perennials*: live and reproduce for many years  - Some Perennials live a very long time: Giant Sequoias -- thousands of years old - Bristlecone Pine -- latin *Pinus longavea* -- one specimen is known to be about 4300 yo!  Growth on a cellular level:  Plant cells have a cell wall -- they are locked into place and can't move like animal cells can, the SAM and the RAM are the main points where cell division occurs and new cells are added onto the plant. Meristem: packet of unspecialized cells that divide for plant growth PRIMARY GROWTH: All growth from the SAM and the RAM, generally lengthens roots and shoots, lays down the fundamental body plan SAM and RAM are considered: PRIMARY MERISTEMS - HERBACIOUS PLANTS: ONLY HAVE PRIMARY GROWTH Secondary GROWTH: all growth derived from secondary meristems, generally growth in girth or width of a plant; seen in WOODY plants (e.g. trees!)  What is the wood of woody plants?  - Secondary growth from the *vascular cambium* - Produces new xylem on the inside, and phloem on the outside every growing season - Spring wood -- light and large xylem - Summer wood -- dark and smaller xylem  - These are the rings of a tree's cross section!  Fungi **[Fungi]** - Most are Multicellular (yeast -- used in beer and wine making -- is an example of a single cellular fungus) - All heterotrophic -- like animals - secrete digestive solution and then absorb nutrients - very important ecologically as decomposers - Have cell wall made of chitin - majority of the body composed of filaments called **hyphae**, forming a mat called a **mycelium** - fruiting bodies, like mushrooms, are a small portion only! - Source of medicine, food 3 main groups to know:  1. Zygomycota 2. Ascomycota 3. Basidiomycota Zygomycetes:  - Fast growing molds - Bread mold e.g. *Rhizopus* Ascomycetes:  - Sac fungi, "baker's yeast" (*Saccharomyces cerevisiae*) - Sac like structures -- asci, for spore production Basidiomycetes:  - Club fungi -- mushrooms, puffballs, shelf fungi General Life Cycle:  - Asexual reproduction via spore forming structures and spore dispersal - Sexual reproduction includes: (Zygotic Life Cycle) - Plasmogamy -- cytoplasmic fusion - A heterokaryotic stage -- two different nuclei inhabit one cell -- follows - Karyogamy -- fusion of nuclei - Zygote which undergoes meiosis and produces spores for dispersal Important Fungi:  1\) Mycorrhizae:  greatly increase the absorptive surface area of roots  2\) Disease:  \~80% of plant diseases are caused by fungi 3\) Penicillin: antibiotic Animal intro Overview of Animal Diversity:  **What makes an animal an animal? ** 1. Eukaryotic 2. Multicellular 3. Heterotrophic 4. Lacking cell walls (we're not fungi) 5. Gametic Life Cycle -- not alternation of generations 6. Development of the Zygote 1. 1. Kingdom Animalia: 35 Phyla  - Let us consider 9 major animal phyla: covering very simple to very complex - Focus on body structure - Specialized structures/strategies The **nine phyla** that we are going to consider are:  *Porifera*: the sponges, simple body plan; radial symmetry *Nematoda*: round worms   *Mollusca*: snails, slugs, clams, octopi, and squids *Annelida*: segmented worms, earthworms, leeches *Arthropoda*: crayfish, lobsters, crabs, spiders, ticks, insects *Echinodermata*: seastars, sea urchins, radial symmetry *Chordata*: fish, amphibians, reptiles, birds, mammals, bilaterally symmetric  **Body type:** - The bodies of animals can be classified into two groups - *Radially symmetric*: symmetric around a central axis for any given diameter - Radial symmetry is seen: sponges, jelly fish, hydras, sea anemones, seastars, sea urchins - *Bilaterally symmetric*: two mirrored halves, symmetric around the central plane - Bilateral symmetry is seen: most other cases, from worms to humans **Cephalization** is seen in bilaterally symmetric animals \-- they have a head where sensory organs and usually nervous processing tissues are located.  *Cephalization makes sense because most bilaterally symmetric animals MOVE, traveling head first through their environment.  And putting sensory organs first allows for more immediate response to changing conditions. * Bilaterally symmetric organisms have orientation: each side has a name: *Anterior end*: end with the head *Posterior end*: end opposite the head, tail end *Dorsal surface*: back side or top side, think of the dorsal fin on a fish *Ventral surface*: bottom side *Lateral surfaces*: two sides **STUDY SUGGESTIONS: ** - **Think about the GENERAL characteristics of each kingdom (types of cells, heterotrophic/autotrophic/both, single cell celled/multicelled, etc.) ** - **What characteristics of fungi are like plants? like animals?** - **What are the different types cells wall made of? ** - **Take a blank piece of paper and list all the characteristics that make an animal an animal.  List all the animal phyla. Then do the same for the characteristics of what is alive (review). ** - ** What kinds of relationships do organisms have? ** Kingdom Animalia Kingdom Animalia: 35 Phyla  - Let us consider 9 major animal phyla: covering very simple to very complex - Focus on body structure - Specialized structures/strategies *[Porifera]* - The sponges (we'll see them in lab) very simple animals, radially symmetric - Do not have true tissue systems - Two cell layer (with "jelly" in between) system - Basic body plan of the sponge is a large tube with an opening on one end and perforated by  - Filter feeders, creating a flow of water through the tiny holes and out the large end - Consume bacteria mostly that they capture as water streams through their bodies - 5000 species, most are marine (salt water) *[Cnidaria]* - Hydras, Jelly-fish (not really fish), sea anemones and corals - Radially symmetric in two forms with a gastrovascular cavity:  - *Polyp form*: like the hydra (small creatures found in most fresh water ponds and lakes) composed of a cylindrical body with tentacles radiating from one end - *Medusa form*: like a marine jelly, shaped like an umbrella with tentacles hanging down from the edge - Some move through both forms in their life cycle - Carnivores: eat other animals, not plants, and have a digestive cavity - **Cnidocytes/Nematocyts**: specialized stinging cell on their tentacles to capture prey - Fine thread that is released upon touch - Stings and entangles the prey *[Platyhelminthes]* - "flatworms" Leaf or ribbon-like animals - "blind gut": incomplete digestive track, mouth but no anus - three groups of flatworm - Free-living Flatworms: - Example: planarian (see in lab) - Primitive nervous system - Mouth and feeding tube - Flukes - Parasites - Attach to the insides of blood vessels near the intestine  - Example: blood fluke (*Schistosoma*) which causes schistosomiasis - Tapeworms - Parasites - Inhabit the intestine and absorb partially digested food directly into their bodies - Anterior end has hooks and suckers to attach to the walls of the intestine - Segmented body grows behind the head and each possessing reproductive structures, which can break off and pass out of the hosts body - Larvae of tapeworms can be found in raw meat *[\ ]* Chordata **[Chordata]** - - - - - - - - **Type of vertebrates: ** Fishes:  - Class: Agnatha - Jawless fish the only vertebrates without a jaw  - lamprey  - Jawed fish : possess a lateral line system: sensory organs running along the length of the body to detect pressure changes in the water - cartilaginous fishes: sharks  - Class Chondrichthyes - poor eye sight - excellent sense of smell - no swim bladder -- must keep moving or will sink - no operculum -- must keep moving or will suffocate!  - bony fishes: have bones like we do -- reinforced with calcium salts - Class Osteichthyes - excellent eyesight - operculum -- flap that protects the gills and move to keep fresh water moving over the gills - swim bladder -- organ filled with gas, to help maintain the fishes buoyancy Amphibians: Class Amphibia - name means "double-life" - possess adaptations for both the land and water - tied to the water because they are dependent on it for reproduction Reptiles: Class Reptilia - First group of the amniotes - You develop in an aminotic egg - Fertilization is usually internal as apposed to "broadcast spawning" of things like porifera or molluska   - separates them from the water - eggs that are covered with a parchment like shell that retains water KINGDOM PROTISTA **KINGDOM PROTISTA:** - Kind of a "catch-all" kingdom for unusual, simple organisms but COMPLEX CELLS - Live just about everywhere - There are heterotrophic types and autotrophic types  - **The only common thing to say is they are all EUKARYOTIC** Break it down into 4 groups based on Lifestyle:  - - - - ***Protozoans: ("protos" Gr. "first", "zoion" Gr. "Animal") *** - Single celled organisms Protists that live mainly by ingesting food, heterotrophic - Four common types: 1. - - - - - 2. - - - 3. Apicomplexans (Phylum: Sporozoa) - - 4. - - - ***Slime Molds:*** - Plasmodial Slime Molds (Phylum Myxomycota) - one mass of multinucleated cytoplasm - Cellular Slime Mold (Phylum Acrasiomycota) - very unique organism, *Dictyostelium* with three life stages:  - unicellular organism -- amoeboid, living on bacteria - slug-like colony -- needs to move for food, cells congregate and crawl away - reproductive structure -- where spores are released that are resistant to adverse conditions. Single cells develop from the spores Algae: unicellular ***Algae: unicellular (one cell)*** - most are photosynthetic = autotrophic - Dinoflagellates - Phylum Pyrrhophyta  - Single celled, very common in marine and freshwater environments - Most are photosynthetic though some are not - Responsible for "red tides" -- proliferate and produce a neurotoxin that kills fish and marine life, dangerous to eat that marine life - Diatoms (Phylum Chrysophyta)  - Single celled - Unique glassy cell wall composed of silica (i.e. GLASS) - Form diatomaceous earth at the bottom of the ocean  - - - Believed to be the group that higher plants arose from - Contain the pigment CHLOROPHYLL - - - **Move to Multicellularity: new organizational levels** *Cell*: the fundamental structural unit of Life; a basic unit of living matter separated from its environment by a plasma membrane *Tissue*: a cooperative unit of many similar cells that perform a specific function (within a multicellular organism) *Organ*: a structure consisting of several tissues adapted as a group to perform a specific function *Organ Systems*: group of organs that function together to perform a vital bodily function *Organism*: an individual living thing (not always clear) ***Algae Multicellular: "Seaweeds"*** - Phyla: Chlorophyta (green algae) \[others include: Phaeophyta (brown algae), Rhodophyta (red algae, etc.\] - Often look like plants, but lack true plant organs (stem, leaves, roots) - Often display the higher organismal trait of **ALTERNATION of GENERATIONS** Tab 1 **Ecology:** The scientific study of the interaction of organisms with their environment   - - Course has looked at Life at many different levels: - - - Hierarchy of Biology:  *Atom*: the smallest unit of matter that retains the properties of an element *Molecule*: two or more atoms held together by covalent bonds \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- *Cell*: the fundamental structural unit of Life; a basic unit of living matter separated from its environment by a plasma membrane *Tissue*: a cooperative unit of many similar cells that perform a specific function (within a multicellular organism) *Organ*: a structure consisting of several tissues adapted as a group to perform a specific function *Organ Systems*: group of organs that function together to perform a vital bodily function *Organism*: an individual living thing (not always clear) *\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--* *Population*: interacting group of individuals of the same species *Community*: all the living components of a particular area; all the different *species* *Ecosystem*: all the living and non-living components of particular area - *Biotic factors*: all the living factors - *Abiotic factors*: all the non-living factors, e.g. Temperature, Water, Salinity, Sunlight, Rocks and Soil (substrate), etc. - *Biosphere*: global ecosystem, the portions of the planet where life exists EMPHASIS = INTERCONNECTEDNESS leads to COMPLEX SYSTEMS Tab 2 Challenges to Studying Ecology:  - COMPLEX modeling -- not just one species with its environment, rarely are populations isolated; macro and MICRO ecology - Biology in general is comprised of systems more complex than we can currently understand -- do not let current paradigms limit your ability to explore - Generally looking at populations -- significant statistical analysis b/c you can only sample; sampling can be difficult (access, and trying to avoid perturbing the system)  - Huge breadth of tools -- from molecular biology, computers, to planes and satellites - Time frame: often large; migrations sometime take decades; introduce a variable and sometimes it is years before an effect is seen **[Population Ecology]** Populations:  evolve through fitness of the individuals of which they are comprised  - Reproductive success is limited by physiology as white-footed mice population density increases (even if food and shelter are not limiting) - High population density induces stress hormones -- delay sexual maturation, reproductive organs shrink, immune systems are depressed  **[Population Ecology: ]** How do you study a population?  Parameters you can assess:  - WHERE ARE INDIVIDUALS: Density and Dispersion (clumped, random, uniform) - KEY:  numbers alive at a given time - Survivorship curves -- modeling with "Idealized Curve" types - Type I Curve: e.g. humans -- low infant mortality - Type II Curve: e.g. ground squirrels -- constant death rate over life span - Type III Curve: e.g. marine invertebrates -- high infant mortality then stabilization of death rate at a "threshold" age. - Population Growth Models  - Exponential - Logistic -- plateau's when "carrying capacity" is reached - K: carrying capacity;  the number of individuals in a population an environment can just maintain, or "carry", with no net increase or decrease i.e. rate of growth (symbolized with "r") is zero Population Dynamics = Complex Studies - Many populations experience cyclic fluctuations e.g. snowshoe hare and lynx (Boom -- Bust) - 90% of hares are killed by predators -- suggests predation contributes **[\ ]** Tab 3 **[COMMUNITY ECOLOGY: ]** Community: all the populations of species in an area - Niche:  the "role" of a species in its community - Resources it utilizes and produces - Competition: individuals of different species compete for finite resources that limit growth/survival/reproductive success e.g. food, water, space, etc.  - Competitive Exclusion = increased reproductive advantage conferred by more efficient resource utilization results in elimination of less efficient species.  Community Structure -   Trophic Structure: pattern of feeding relationships, consisting of several different levels - "Food chains" are created as we move from: - producers -- generally photosynthetic organisms - primary consumers -- herbivores - secondary consumers -- eat primary consumers - mice -- may eat herbivorous insects - spiders -- may eat herbivorous insects - lion -- eats grazing animals - tertiary consumers -- eat secondary consumers - snakes -- may eat mice - quaternary consumers -- eat tertiary consumers - killer whales, hawks  - Detritivores -- derive their energy from dead material (detritus)  - Decomposers Food Webs - A "chain" and even a "web" are representations that are far too simple - consider the interconnectedness of all  Tab 4 Limits of Energy Supply: Trophic Levels - Tremendous amount of energy comes into the planet from the sun - But only 1% of it is fixed by photosynthesis i.e. enters the food web - Idealized about 10% of the energy that an organism is composed of can be passed on to the next trophic level -- Rule of 10 - Consider the numbers of secondary, tertiary, and quaternary consumers in a ecosystem - it MUST be in a pyramid format otherwise it could not sustain itself - Generally no more than 5 links in any chain - Species influence - Dominant Species: a species with substantially higher abundance or biomass than other species in a community.  - Pines and Firs in northern coniferous forests.  - [Keystone species] : not the necessarily the most abundant, but play a pivotal role in ecosystem;  occupy a vital niche - Every population has a *niche* in the ecosystem:  population's role in its community; the sum total of its use of the biotic and abiotic resources - E.g. sea otter in the North Pacific -- control urchin populations which feed on kelp forests - [Foundation species:] "engineers" - Influence ecosystem not by their trophic interactions but their influence on the physical environment  - E.g. beavers