11: Lecture Who are we? 4 types(polyphyletic): monotremes (egg-laying, no teats), marsupials (immature offspring reared in pouch "bun in oven" advantage), placentals (fullydeveloped young b/c placenta 1st= shrewlike to primates) Greatest diversity of vertebrate lifestyles (abilities) next insects (no saltwater) 2.5 myo: ice age (land bridge b/c water frozen in ice, sea drops new species) Humans: part of tree of life (ardipithecine ancestor) o Af (200 K yrs), last= Aus, N/S Am Bering Straight (Ice Age: 14K yrs)
Lived w/ Neanderthals: massive, rugged (both "humans")- could talk, but no higher thinking o Theories: killed, bred out, out-competed Walking upright (see predators above grass)- frees hands, large brain:body mass ratio, tools (birds use thorns, BUT we engineer tools/ more specialized), speech/ complex social org (transmit thoughts, hyoid bone in throat), abstract thought- art, burial (34K yrs) o Races: (20-14K yrs) less sun= less Vitamin D synthesization, lighter skin Not good for biodiversity: cause for demise of large-bodied (>10 kg) mammals o Hunting/gathering: vegetables, fruit, animals o Herding (10K yrs- raising own food): habitat destruction
Lecture 12: Behavioral ecology- how to get resources/ live in groups 1973 Nobel prizes: Lorenz- Imprinting (baby ducks- pt in life to learn: who is mom?), Tinbergen- Stimulus/ Response (seagulls-babies beg b/c mom or dad?) von Frisch- Communication (bees-food location) o WWII: Lorenz (Ger) saved Tinbergen (Holl) from SS, Frisch (Ger) smuggled gold (crushed like pollen, gathered hives) Behavior studies 1930s: descriptive/ proximate (Ethology)HOW behavior occurs (purpose)/ ultimate explanation (early Behavioral ecology) WHY o Why would natural selection favor one behavior over another? o Led to Physiology, Endocrinology, Genetics (i.e. slob/clean bees); nature v. nurture (are behaviors learned?) o Ev. fitness= lifetm survival x lifetm reproduction (expected # offspring) WHY not HOW things happen to get greater fitness o Foraging ecology: more energy/ nutrients(=better survival, more resources for reproduction) in least time: less exposed to predators, more time for reproduction o Bluegills: select to eat what gives greatest amount of food (both by size and abundance) to maximize rate of energy intake o Plants: "forage" for photons, nutrients, and water change leaves/roots for better fitness (photosynthesis production) Leaf size/ shape effects photosynthesis/ water loss Root structure/ depth volume determine nutrient/ water intake o Waggle dance: not to communicate which flower to go to, but WHY flowers are selected (provide greater fitness provide nutrients to ^ fitness, getting food from one takes less time?) Fitness: natural selection favors relative (not absolute) reproduction, reproductive success (not reproduction) o Mouse A: 10 babies Mouse B: 5 babies A's babies produce 2, B (more productive)'s babies produce 5 B kills 5 of A (wasted energy)'s babies B (perpetuates genes) helps raise siblings' babies, A does not Social Groups: living in group you are social resource aggregation (easier, more efficient, gain more); protection from predators (more eyes/ears on watchsee attacker sooner i.e. pigeons flocking vs. hawks BUT costly for lone males waiting for females) o Territorial behavior: tolerating others has a cost- sharing food (you get less), males w/ more testosterone= more territorial i.e. lizards not territorial in the summer (will die) o Kin selection (cooperation/ altruistic behavior): who are you willing to aid? confusing til 70s (saw interrelatedness) i.e. bees/ants protect queen Tit-for-tat: i.e. prisoners shared cigs/candy, bats regurgitate blood in stomach after hunting (expecting in return) Evol Psych: can "smell" good genes link b/w feeling good/ gene perpetuation o child abuse 20x more likely in single parent households like infanticide in lions/langurs when male of group is replaced doesn't make acceptable o genocide= not entirely learned tendency? ducks kill painted sibling
Lecture 13: Behavioral ecology- how to reproduce (reprod iso: mate w/ own species) *why/ how natural selection favors diverse modes of reproductive behaviors *"battle b/w the sexes" what is best for female may not be best for male Praying mantis: female bites off male's head before copulation (>80 species) o Food for female (male= investment, nutrients) make more young o "Spite" (remove males for female competitors) only if few males o Better male section escapees= more fit Burying beetle: male helps find chipmunk carcass for young BUT headstand expose abdomen (scent) o Male wants > females, female will have less resources to support young Lion: female "sex mania" (many mammals, very costly to male) o Stimulation for females become pregnant (sexually active) o Prevent multiple paternity males keep others from copulating female o Shows male strength supported by female- new male would kill young Fruit fly: faulty Bateman model- "sperm are cheap" limiting factor (females: eggs, males: mates) o Mating= cost to male not just in amount of sperm produced, but all other activities (energy, time exerted) sperm NOT unlimited Marine iguana: reproductive tactics o "The Hunk" many mates, inadequate (insecure) o "The Runt" pushy, very adequate Manatee: homosexual- must be genetic, exclusive (always bachelor/ spinster), common behavior (10-15% population), ^ reproductive success of heterosexual kin (their genes will still increase in abundance) Vultures: monogamy may stabilize social grouping BUT not equivalent to reproductive fitness o Mutual benefit (RARE deviant): females can't raise young alone/ females hard to come by Humans: males bigger, have more females (2.5) in harem polygamous Criticism: suggestive wording (i.e. sexual mores, predilections) nat sel provides outcome, does not have to do with morals o Sexual behavior is not genetic, but choice o Nat sel not important to humans book (doesn't pass judgment on human behavior)= explanation of behavior that can be provided by nat sel, understand how behaviors shaped to reduce in societies
Lecture 14: Population ecology- can you ever avoid others? Birth (deposits) rate- death (withdrawals) rate= population growth rate (bank acct) try to figure out what cases changes in birth/death rates Survivorship curves: inform us about environmental rigors
Survivorship: a. due to senescence (old age) b. constant over time (no young/ old age advantage) c. not good to be young, but will live for a long time after certain age
Exponential (density ind) growth: populations growing w/o limits o J-shaped, doesn't usually happen i.e rabbits in Aus o Malthus: worried about exponential growth for humans ("cannon fodder") b/c resources: either constant of increase linearly 4 Horsemen of the Apocalypse (pestilence, disease, famine, war): only thing keeping us alive Logistic (density dep high density inhibits) growth: carrying capacity of environment (K) o set by internal competition w/in population for resources (b4 horsemen factor in) i.e. bacteria (self poison w/ metabolic waste), Tasmanian sheep (environment varies from yr to yr) o i.e. sparrows: ^ males ^ floaters (don't reproduce/mate) ^ population, decrease survival of fledglings rate (chance of survival/ reproduction) DOWN, as population goes UP Neo-Matlthusian Concern: what about demands on the environment? o ^ difference b/w birth and death rates death rate decreased b/c medicine; birth rate hasn't decreased correspondingly o humans= only animals in world w/ exponential growth (black plague= only known instance of killing of human pops) BUT growth rates slowing o ^ human pop, ^ demands of the sea (overfishing) Whale hunting: declines in catchable stock shift to smaller species (since 50s: new whale harvested to compensate after peak) If you keep harvesting to max sustained yield, pop will rapidly grow to carrying capacity again (Tragedy of the Commons)
Lecture 15: Community ecology-competition, predation, disease, mutualism
i.e. giraffe eats top of trees, rodents underneath the trees that were hidden are now exposed to predators (ammensalism) *cow's stomach bacteria for grass/vegetation digestion (mutualism) *ants eat fungus that grows on plant, fungus digests plant for them (mutualism) *egrets live near ox (commensalism) Competition: (of two species) how do their niches compare with one another? how similar can they be and still be able to co-exist? o No two species can occupy same niche or one will competitively exclude *Realized niches specialize to live in a specific climate/ region (A) (Fundamental) niche with absence of other niches (B) if another species is present, specialize to form realized niches to limit competition and allow them to competitively co-exist together *niche partitioning: i.e. all bird species eat same type of insect, but specialize on what part of the tree they eat in able to coexist Predation: scientists can't agree on how important (Darwin: competition more important for nat sel) depends on system o Individual vs. w/in community o Mimicry: mimic must be less abundant than norm (or it won't work) Nonpoisonous species mimics appearance of poisonous species o Enough predators habitat be can't used by prey i.e. dragonflies/tadpoles o Population effect: i.e. hare pop cycles affected by food supply/ predators (lynx peak follows after the hares) World shaped by competition b/w predators and their environments Abiotic (environmental) vs. biotic (organismal) factors o i.e. ^ mice, ^ Lyme disease in humans ^ West Nile, decrease gypsy moths we know little about how bacteria/ protists affect ecosystem (hard to visually id)
Lecture 16: Communities and ecosystems- food webs (main driving factor), nutrients (most E located at bottom of food pyramid), succession * large scale b/c we don't know enough about specific landscapes
*trophic levels= categories of consumers in food web *photosynhtesizers convert solar E to usable E (oxygen, sugar, starches) for other animals Energy/ biomass rel: graphs rep biomass of trophic levels always pyramidal o open ocean: inverted pyramid b/c efficient algae (producers reduced by herbivores) Detritivores: (neglected b/c very small) consume excrement, dead bodies *respiration: lose E while consuming (excrement, heat off body) *some detritivores eaten by/ converted back to detritivores *nutrients (unlike energy) are recyclable *macrodecomps break up dead matter for use by microdecomps (i.e. bacteria, protists, fungi) release nutrients back into soil (i.e. N fixation) Nitrogen cycle: nitrogen fixers "fix" N in soil taken up by plants, consumed by herbivores...omnivores, die... consumed by detritivores o some washed out by water in soil to ocean, returns to atmosphere Calcium cycle: from weathering of rocks (bedrocks) Carbon cycle: fixed by plants in atmosphere o global climate change: ^ CO2 in atmosphere more photosynthesis by plants- most cycled by animals (respiration), some washed away to ocean back to atmosphere ^ precip (expon)/ temp (log)- applies to deserts/ nutrient availability, ^ (terrestrial) primary production
Species matter species not replaceable/ dependent on each other o Fewer inds of large species (need more E, space) Ecosystems function to support balance o Biodiversity rises/falls at low/high ends of primary production i.e. plots w/ more species > production, varied less in annual net primary production of biomass primary succession: development of ecosystem in area w/o topsoil o after volcano/glaciation: Nitrogen in deep soil never reaches as high a level as topsoil secondary succession: recovery of ecosystem after disturbance o don't have to replace soil b/c: forest: tree falls competing seedlings grow towards sun water to land: mud accumulates @ mouth of river; w/ each new tide, plants grow higher and higher
Lecture 18: Global change- environmental legacy and future Tool-making, agricultural, industrial- scientific revolutions stabilize/ crash? ^ human demands on natural resources o Unsustainable use of forests (in US), water (20 yrs- D will exceed S) o Declining marine fisheries (overexploited) o ^ E use/ person exponentially (US: 2x/ person vs. rest of industrial world) ^ Nitrogen: (fertilizer, N-fixing crops, fossil fuels) ^ productivity of terrestrial environs, can create acid environ (acid rain, decrease pH in lakes) ^ CO2: (fossil fuels) ^ agricultural productivity affects photosynthesis Climate change: ^CO2, ^ Temp (Greenhouse effect) o Troughs: summer in N hemis b/c plants using up CO2 o Peaks: sinter in N hemis b/c plants are dead More land mass in N vs S hemis HUGE effect! o Fagan (archeologist- civilizations i.e. Egyptians/Nile collapse b/c climate change, Diamond Precip change: N At oscillation slows b/c less warm water colder temp in Eur/ cold summer "mini ice age" o S oscillation: El Nino slows no nutrients- no fish- no food- starvation o S oscillation: Aus move N Afr/ Egy precip o i.e. Roman Emp expanded (wheat, rye, barley) N w/ climate warming Huns threatened N border of empire w/ climate cooling ^ human demand for land lost habitat, creation of "islands" o Decrease # of animals migration/ extinction o Island biogeography: US has best sys of nat parks creates more islands Smaller park= higher levels of (natural) extinction Natural rate of extinction= actively killed rate Introduce diseases: i.e. bleach coral reefs, avian malaria (HA) Loss of biodiversity= our fault ( 70% success since 1900 when we try to save species we rarely try) Ripple effect
Lecture 17: Biomes- abundance, primary productivity, contribution to earth's primary productivity Open ocean: 65% (most common), v. low productivity Upwelling nutrient zones: least common BUT important fisheries Rainforest: v. productive (not important to humans: productivity in canopy cows don't graze there) Savannas/ temp grasslands: most important to humans (farming, cattle prod)
Algael bed/reefs: most productive biome o open ocean/ rainforests contribute most to total production Temp, precip: determine where we see biomes (just temp for aquatic environs) Antarctic (N pole): just ice/ snow Arctic regions: upwelling area, high in nutrients lots of life o Life takes place at slower rates (i.e. insects live years, not months) Grasslands: grass grows from the base (not the tip) continual source of food o Required for agriculture/ herding o Concern: area diminishing into desert Desert: so hot little moisture o Plants change leaves: show whole leaf in morning, only edges in day o Blooming after infrequent rains Rainforest: wind can take away moisture in upper canopy, so small leaves diminish surface area o Angiosperms require insects to pollinate o Very few creatures live in area b/w floor (carpet of vegetation) and canopy no leaves, no animals o Floor not very fertile b/c no light from sun, minerals washed away by rain; very humid on ground promotes decay Coral reef: water equivalent of rainforest o Located in tropics, mostly around small lands o Immense variety
Polar Ice Cap (Tundra) Rays from sun strike equator perpendicularly (not at poles) Polar seas have become more enclosed ocean currents can't keep poles warm Algae reflects light give off color (in spring when uncovered on surface) only need light and minerals dissolved in water Only 2 flowering plants can survive lichens, mosses (eaten by long living insects) Boreal Forest (Taiga) Permafrost (frozen soil about a foot deep) several ponds Small flowering plants keep low little wind, warm sun rays (i.e. flat arctic willow) Burrowers, caribou: keep traveling to find food to sustain, goslings- mosquitoes Temperate evergreen (temperate rainforest, coniferous forest) Branches slope down to shed snow Threatens to freeze water in trees/ deprive trees of water need to conserve like cacti; needles/ lined pores w/ rinds prevent water loss Temperate deciduous Branches spread widely to capture solar energy Thin, delicate leaves; evaporate water to keep cool (in summer) Green chlorophyll broken down, withdrawn into tree (red/ brown waste products) b/c overabundant pores would lose too much water in winter Birds migrate south, small mammals hibernate Spring plants close to ground= lots of color (hurry to beat trees at soaking up light) Top of pines unharmed by natural (lightning induced) forest fires rejuvenates Ash of pines releases nutrients into soil, more flowering than any other time Grasslands Most successful/widespread/commonest plants (~10,000 species, 52% all vegetation) Wind for pollination, require less water than trees, can survive burning/ freezing/ grazing (of small i.e. termites and big creatures) grow from base Few trees too little rain (located in middle of continent, surrounded by mountains) Clay/ snow (N Am prairies- bison reach deepfrozen nutrients) on ground holds water flooding Domesticated grass= wheat Tropical grassland- Africa More trees- threatened by drought, fire keeps land open for grass (regrow quickly b/c buds close to ground) Animals not as big as in past (8 million yrs) evolution= greatest variety/ concentration of grass-rooting creatures Desert (Sahara= 3.5 million mi. in Africa) Insufficient vegetation to sustain animals Connected to climate changes of last Ice Age (rains moved N to Eur) recent environs Very cold at night, hot during day; lie in 2 broad zones across equator
Cacti only in Americas: thorny leaves reduce SA to lose moisture, green stem photosynthesizes Rainfall: dead plants come to life (opening= reaction to water) blooming, color Tropical Rainforest Greatest bulk/diversity of life warm and wetness, band around the equator (broken by rivers)f More sunlight, wind (can rob moisture, but distribute seeds) in canopy Canopy= still moisture, little sun; most densely populated, varying flowering patterns among species depend on insects, birds, bats (eat fruit) for pollination Infertile forest floor little light, rains wash away nutrients Shallow roots find nutrients in fallen dead leaves (fast decay b/c warm moisture) Ancient, stable environment
Freshwater Streams (Rivers): largest= Amazon Oldest mosses: provide shelter for insects Lakes/ streams: Very fertile, no current; species can proliferate Estuaries, mangroves: Muddy, mixed fresh/rain water lots of nutrients/ organic matter Slow decomposition produces hydrogen sulfide (poisonous, smelly) Fine, shallow roots (nutrients on surface) Coral reefs: Need light, clear (unpolluted) water, warmth Wide, shallow lagoons Most corals= stony (only outer parts alive)