Ecology PDF

What is Ecology? Definition: the study of organisms of all shapes and sizes in a specific ecosystem through their patterns and processes in nature. Ecology : “relationships between organisms and the environment” - the process in which living organisms are thought to develop and diversify Indivi...

What is Ecology? Definition: the study of organisms of all shapes and sizes in a specific ecosystem through their patterns and processes in nature. Ecology : “relationships between organisms and the environment” - the process in which living organisms are thought to develop and diversify Individuals < populations < communities < ecosystem < landscape < region derived as a new way to classify the characteristics/ patterns of particular region dynamic and unifying viewpoint originates from Charles Darwin field of ecology started on a straightforward foundation Overtime other factors are added —> specifies interaction with each other and environment, abiotic and biotic processes, climate, time space, next generations Wide variety of disciplines: large/ small taxa or reactions abiotic interactions - communities Organisms - biomes Populations -earth Natural Selection: organisms adapt to their environment to survive, survived genes are passed on to the next generation. - Darwin’s finches : Galápagos Islands two types, turned into many types after their beaks started changing shapes overtime. Wolves: located in Yellowstone National Park -wolves were killed caused changes in the ecosystem and plant life (1926) -wolves were dropped off at National park after the changes were noticed (1996) more wolves = less elk, more aspen trees Ripple et al 2001 ( tracked wolves using radio collars ) following packs over the park - they associated habitat that wolves inhabit with habitats where elk avoid - trees grew taller in high wolf areas than in low wolf areas - 2010 = they enclosed areas from the elk: - unprotected would not grow for a long time - wolves did not provide protection for the aspen trees -more aspens eaten where wolves were present The wolves followed elk, elk follows the vegetation and avoid the wolves Beschta and Ripple et al. - elk populations decreased, bison population increased - over 20 years wolf/ elk reaction leveled out - willows grew fuller and taller, cottonwoods more established, aspens and alders did better, beavers loved it (when the wolves were present again ) Trophies Cascade: removal of top predators results in reciprocal changes in the reaction populations of predator and prey through the food chain - results in dramatic ecosystem changes and nutrient cycling Wolf/ Elk studies: predator/ prey interactions Animal behavior ( migration ) Biogeography: Biosphere: the combination of all ecosystems of the planet ( the earth) - where life is found and all life Biomes: the physical environment that determines which organisms live in a particular place. - temperature, water, sunlight, soil : all dictate the types of animals present -large regions that have similarities in the physical characteristic. -dictated by climate and soil —> dictates the animal and plant life Biota: the sum of all living things - heavy influence by: climate, soil, geography. ( physiographic features) Ecotone : boundary between the biomes ( transition zone of different regions) Climate : a region’s long term atmospheric conditions -Rotaion of the Earth - tilted earth axis = causes different seasons -causes movement of air that is predictable ~uplifts air and it is falling down —> affects precipitation patterns -water circulation ( ocean current ) that is predictable What dictates climate? - warm moist air rises. —— cools, condense, falls as rain -cooler dry air falls back to surface ~rainforests found near equator -major deserts found near the 30 * N/ S poles ocean currents — driven by the wind Coriolis effect: as earth rotates the tangential velocity at the equator is greater than the poles. -objects traveling from the equator n/s warm surface currents carry less dense water away from equator and towards poles ( wind, topography ) cold deep currents carry denser water away from the poles towards equator (density dependent, colder/ saltier = more dense) salinity differences causes the pulling of the water throughout the world Melting of the Greenland: - the cold ice cap water that is less dense, can water disrupt salinity gradient -the warm current that is usually going to Europe, Europe gets colder as the current is interrupted. - the fresh water is entering the conveyer belt and desalinizing the current Topography: study of the features/ characteristics of the region Elevation = higher up = colder, less diverse -partitioning can create a habitat on a single mountain Climate changes overtime -this should change the biomes as well, however it is changing way too quickly Ellis te al. 2010. Global Change Biology - quantifies different vegetation types across the globe -mapped vegetation and used/ un-used land across centuries -shows the conversion of natural biomes to used biomes -95% of the unused land in 1700 was converted into agricultural lands and urbanized land 61% in 2000 deserts remained deserts , woodland decline by cutting them down for building Grassland became main agricultural source Soil : Foundation of Biomes complex mixture of living and non living material - classified by vertical layering. ( soil horizons ) - constant state of flux Top Soil : O layer with A layer made over many many years Fertilizer : soil that is synthetically derived that is used to boost crops -nitrogen and phosphorous mixed with animal waste and minerals How is soil created?: Time : the age of soil is considered in thousands or millions of years Parent material : earthy materials, both mineral and organic that is getting worn down overtime Mississippi River flood plain allows the minerals of rocks to be floated down to Midwest and leaves nutrients in soil Climate : breaks down the parent material more Living Organisms. : plants and animals die and add to the matter of weathered material Topography: Hilliness, flatness, slope/ land Layers of Soil: -O layer : superficial layer that is freshly fallen organic materials, dead animals, waste, rocks, -A layer :mixture of minerals, clay, silt, and sand. ( broken down particles of O layer ) -B layer: more compacted material that reached from A layer, clay, humus(leaves bacteria) (contains the deep roots of plants) -C layer: weathered parent material. Often rock fragment/ bedrock /sand (The desert is mainly C layer) Biogeography - Water Peppermine Most of the fresh water is - glaciers/ polar ice caps Biosphere: 71% Ocean: 97% Polar ice: -2% Fresh water rivers lakes groundwater: 1% Why water movement? lakes : formed through natural geological forces ( glacier activity, volcanism) - Great Lakes were carved out through glacier ice sheet receding and moving - in the south the lakes are handmade. ( flooding a river dam = finger shaped lakes) -lentil system: stagnant water —Composition : - stagnant, not structure ( water is not flowing) -specified through the sunlight passing through -Littoral zone : where the water meets the shoreline -Limnetic zone : the open water —Layers - Epilimnion: sunlight penetrates water., plant and bacteria growth -Metalimnion: medium sunlight and temperature -Hypolimnion: no sunlight penetrates, cold, dark —Temperature: -Thermocline: a layer of water that divides temperature fluctuation in large water bodies - gradient of sunlight that passes through the water surface ~ - thermal stratification : segments the lake based o the temperature from top to bottom Lakes Turn over : mixes the nutrients and energy in the lake Oligotrophic. ( well oxygenated. More life ) ~ Eutrophic (oxygen depleted, less life -thermal stratification reverses, the warmest parts Travel to the bottom and vertically mixed -today: most water bodies have too many nutrients and are unable to turn over, top layer has way more nutrients, algae and biological activity. - kills off the system by the algae dying and taking the oxygen from the lake Too many nutrients for turn over? -Influence on biota: Lake Erie : crazy input of extra phosphorus, lead to an increase in Western fertilizers from the farms drained into Lake Erie studied number of fish species in areas of lake —> poor water quality, Low oxygen levels, dead organisms —> Clean water act was created to help the fish survival Productivity index: level of eutrophication ( how oxygen depleted ) -lower levels: oligotrophic -high levels: severely eutrophication -when Lake Erie would get to a level of eutrophication - hypoxia (death of all the organisms, loss of nutrient) would occur and less fish would be present -most fish have lower harvest with greater productivity index P value : the correlation between the statistic and the differences in data less than.05 : significant change overtime (increased/ decreased) Streams and Rivers adjacent landscape dictates he ecology Logic system : water that is flowing * - size is driven by the watershed —> categorized through order number (1-12) - Riparian Zone : transition near a body of water that contains a specific type of organism and the differences —Flowing system: - Riffle: shallow fast current, gravel rubble or boulder bottom “rapids” - Run/Glide: flat water deeper than riffle carves out the bank using large water force - Pool : deep slow moving water with flat surface bottom of sand/ gravel —Composition: - water column: where water is flowing - Benthic Zone: interface of water and land, most biological activity, where the water meet the ground -hyporheic Zone: ground water and surface water interaction, little biological act -Phreatic Zone: the ground level of the river, stream bedrock Differences in flowering system ( Stream/ River) River continuum concept: - logic systems processes change in a downstream direction - the orders will tell you the characteristics of the organisms that live near/ within the body of water Headwaters not necessarily most nutrient rich - nutrient spiral downstream and accumulate 1st order —> higher nutrient input in headwaters. ( allochthonous ) -widths depth, flow, temp -leaves that flow into he stream allows more diversity and abundance of species 2nd order —> smaller systems, clear, high alochthonous structure of the biological community is predictable. ( based on position within stream ) Consequences of Logic system: major farm land athat use phosphorus and nitrogen fertilizers —> created the eutrophic zone in the Gulf of Mexico by inputting too much nutrients into the water by dumping the Mississippi River in it shorelines vs. the rest: - shoreline: mot biologically diverse area of oceans -influenced by tides , intertidal zone ( same as shoreline/ littoral zone.) ocean water meets the land ( where the tides move in and out ) -species diverse, interconnected relationships Sea Otters study ( Wilmers et al. 2012) Oceans: shorelines = important for ocean vegetation Vegetation = carbon = net Primary productivity. ( how much plants are growing ) [MORE PLANTS MORE CARBON STORED IN PLANT TISSUE] kelp forest grew ad the sea urchins loved to eat the kelp, wiping out areas Otters love to eat sea urchins Relationship = looking at density of the kelp, otter, and sea urchins - deep ocean incorporated carbon into sediment -kelp carbon pool is being recycled in atmosphere - plants are using the atmospheric carbon pool to continue grow kelp forest -otters ate so many sea urchins allowing the kelp pool to grow -without otters the sea urchins overtook the kelp population Oceans. : - estuaries, salt marches, and mangrove forests Estuaries: where the river meets the sea, the mouth of a large river where the tide of the ocean is meeting the stream - fresh water desalinates the sea water and creates unique environment - forms transition zone between both environment = ecotone Magnusson and Hillsboro 2003 —Fish Stocking Coho and Chinook Smolts = baby salmon - eggs released into estuaries, allowed to grow in the ocean and then return to estuary to travel upstream through the stream/rivers survival rates of coho and fall chinook salmon studied based on : 1) size of estuary 2)the percentage of estuary that is in natural condition 3)presence of oyster culture in estuary Overall Results - more natural estuaries = more chinook salmon -chinook salmon are dependent on the habitat for growth and to be able to transition from fresh to saltwater - 0 natural habitat = 0.5% survival rate -total pristine habitat. = 1.7 % survival rate —> more than 3x higher - Recap: Most of the after on the planet is salty Evolutionary Biology Evolution: change overtime biological evolution = change that occur in organism characteristic through time mutation , migration , genetic drift , natural selection : natural selection : affects the population level - 4 observations of living things 1) Variation: there is differences in traits among organism Ex: One species of beetle can have totally different color/ body size -Phenotypic Plasticity: variation among individs as result of envirnmental influences. ( not caused by change in genes ) Ex. Variation within tadpoles to vary shape of tail based on survival -blue gill predator = thin tadpole tail // -beetle predator = thick tail Amphibian mating routine : climate is warming, summer is stronger, shorter winter - timing of breeding for species were changing, plasticity - fall = arrive late (in order to get more growth) // winter breeders = start arriving early (winter months are over faster now) - temperature and rainfall influenced breeding time 2) Inheritance: some traits can be passed to offspring Ex: Proportion of phenotypic variation is attributable to genetic variation - body size in beetles ( heritable trait ) -Evolutionary Fitness : when heritable trait is passed down 3) Population growth: over production of offspring 4) Differential reproduction/survival: better traits = more surv/reprod Inheritable Variation : individuals in population vary in genotype Heritability : proportion of phenotypic variation due to variation in genetic values h2 = Va/Vp Va = genetic variance Up : phenotypic variance alleles at the loci influence traits passed down now genotypes Effect of alleles on population allele frequency Organisms produce more offspring than able to survive 3) Population growth: over production of offspring 4) Differential reproduction/survival: better traits = more surv/reprod Non random mating Sexual selection : choosing a mate based on certain physical characteristics If non survival characteristic are used in mate selection then the frequency of preferred traits should increase over time Creates variation in mating Sexual Dimorphism : different appearances of males vs. females in organisms Ex: male peacock has the colorful feathers while females r neutral / camouflage -present in population for atleast hundred of years. What creates new variation? random mutation. = evolution of new traits occurs in sex cells. ( therefore heritable ) Mechanisms for new variation : Mutation: most harmful< SOME useful < a few are beneficial changes in the nucleotide sequence of DNA Migration : increase / decrease can isolate or grow genetic tool box evolution/ lack of evolution due to immigration/ emigration between different population allows genes from one population to mix with another the more gene flow the less change as a result of adaptation to a specific environment Ex: One species of snake with 6 subspecies of snake ( it just variation) ``- some snakes have been separated from each other to evolve to different phenotypes. Genetic Drift : the fluctuation of gene frequency by chance the effect is greater on small population (Bottle neck effect): drastic reduction of population, out of those surviving the next generation is built off that 8 · · Fl - new pop Neutral Theory : Versions of a gene in population are likely just frequencies drifting around majority of evolutionary changes at molecular is not cause by selection, rather random fixation of neutral mutants/ genetic drift Evolution = random change (bottom line) -human and sharks are phenotypically unlike shark -human and mice are evolutionary equidistant from sharks -phenotypic evolution is occurring at different rates but molecular is by chance - Tim Holine ( Ecology — aquatic ) Auroch ( wild animal ancestor of cow ) lived in Europe and Asia They were kept in communities to mate different types of aurochs ( -4000 yrs) From the aurochs we get different types of cows today Allele Frequency : relative abundance of allele;s in a population version of a gene ( cow hair color - has alleles that correspond) Evolution: a change in allele frequency of a population from one gen to the next acts on scale of populations not individuals Genetic Equilibrium : no change in allele frequency b/t generation. ( opposite of evolution ) Hardy- Weinberg Genetic Equilibrium Conditions Sinehappen 1) Large Population 2) No immigration/ emigration 3) No mutation 4) random mating 5) allele combinations all have equal fitness a 6) no genetic drift  Evolutionary Selection natural selection can act on distribution of traits in population · fred out come Natural Selec. - · - Bell curve can more the generations distribution distrib through. trait A) Directional Selection: one end of the distribution dies( is not fit) while the other end of the distribution is fit - next generation —> bell curve shift one way Ex: Pesticide / antibiotic resistance - few individuals that are less sensitive to the toxin —> growth of that resistant organism B) Stabilizing Selection: both ends of trait distribution is not fit for environment - next generation —> bell curve is more narrow in the middle Ex: Birthweight in humans and mortality -the most common is for average size babies while the premature and the extra large babies are more likely to death. C) Disruptive Selection: middle values in the trait distribution are not fit, extreme are best fit - next generation —> 2 peaks in trait distribution on either extreme end Ex: Butterfly colors - at each end the butterfly phenotype presents are poisonous so they survive while in the middle they look normal Speciation: some kind of isolation occurs with groups of a species —> groups reproduce within their group rather than across species —> allele freq. changes and you can end up with 2 different species from 1 Why does separation occurs ? Allopatric Speciation = Space: in different locations with a barrier ( ex. Islands. ) - geographic isolation , dispersal, climates Sympatric Speciation= Time: all indiv in same place but finds way to specialize some habitat/resources (ex. Nocturnal vs non nocturnal) What is a Species Vs 2 different populations of a species - exists as a gradient because evolution is occurring overtime Species - interbreeding populations connected by gene flows, and fundamental unit of evolutions Species Concepts ( classification of species ) 1) Biological = members of population that actually/potentially interbreed 2) Phylogenetic approach = piecing the historical pathway of reproduction of species contruct ‘family tree’ —> shared genetic materials = more related 3) Phenetic Species / Morphological =species are based on physical traits, characteristics ( fossils ) - problem : some species that look alike but different genetic history Island Biogeography - offers unique set of landscapes How are islands created? - movement of the earth’s tectonic plate movement leads to friction - up wells land area and also creates hotspots of lava. —> volcanic islands Islands species - become isolated by habitat type , eventual stop of interbreeding - salamanders in California all have different characteristic based on environment - they are connected to one another in a circle but not in-between species Ring species : interconnected species through gene flow that is circle - snakes that are present on sky islands Anthropogenic Change: human caused changes to environment - urbanization : around forests preserves = create island of habitat - Deer are restricted to these forest preserves -agriculture : transformation of land to farmable land -deforestation: patches of new and old forest -Remnant habitats : several areas that are highly urban —> prairies that exist in urban / agriculture areas Climate and Habitat Islands - areas that could become isolated in the future Kramer et al 2011 — Sky Islands in W North America ( gene flow ) - gene flow between plants from different pollination strategies -level of genetic distance vs level of geographic distance genetic distance varied, it was driven by type of pollinator As geographic distant increases: - Birds genetic distance = constant, less mixing of gene, less gene flow -Bees genetic distance = increase How do species arrive on island? - through air or sea ( overtime the plants/animals can colonize ) - driven by immigration from mainland — increase species until equilibrium Niche-Partitioning: -way for species to conserve limited resources —> Darwin Galapagos Island -separates based on what they eat = specializing = different beaks -overtime this separates the species into different types = speciate Island biogeography Theory — MacArthur and Wilson (equilibrium model) - examined the number of species that should be present = community behaviors and specified rules of prediction for islands -conservation of island ecosystem through prediction Prediction of Theory 1) Number of species on and island become constant with time - islands can only support so many species 2) Constant number should be a result of continual species turn over - some go extinct/ immigrat —> new ones can come 3) Larger island will be able to support more species than small island 4) Species number should decline with increasing remoteness - more secluded the island, the species number would decline i rate of colonization Simberloff and Wilson 1969 — Florida Keys. (Mangrove islands) - fumigated the islands and then examine the new colonized species -document the number of species that returned Island Apocalypse: Krakatoa loudest explosion of volcano —> wipes out all life -> ideal study Dutch nationalist : kept track of returning species to island —> almost exactly the same number of species repopulated island - ecosystems naturally found their equilibrium Russell et all 2006 quantified number of terrestrial birds on island. ( they couldn’t go to other islands ) - similar to Simberloff and MacArthur : the rates went along with the island biogeography theory , small island = less species and colonization Godefroid and Koedam 2003 island that are natural throughout urban populations - larger more connected island. = more habitat - similar relationships with urban and fragmented landscapes - % of ancient forest combined with the size of forest had biggest impact on species richness (bigger area + old forest = more biodiversity of plants) Island Size Vs Biota Characteristic Tricolored squirrel - smaller island = smaller animal -more distant = smaller animal Species Richness: the number of species within a community Species Eveness: The relative abundance of rare and common species in a community. · better for · uneven environment b/ 1specy ·maximizes is dominat not enough group of species ~ survival resources ↑ same richness R higher eveness &, same #. , sample diversity Species Diversity: A communities species richness and evenness combined — more diversity near the equator , near tropical biomes  Simpson’s Index : N(N-1) Ds = [n ; (ni 1) - N = total number of individuals of all species ni = the number of individuals of species i Randomly sample community twice = contain different species. (Depending on density Shannon’s Weiner Index H = dust and debri blocked the sun = die off of plants and then dinosaurs turtles, crocodiles, amphibians, snakes all survived from that event Led to the origination of mammals once dinosaurs gone Reset of the biodiversity Holocene ( human driven 6th mass extinction ) background extinction rate is 1000-10000 times greater than expected Every second several species go extinct on earth Occurred in the past 100 years The expected extinction was 9 but about 468 have occurred Causes: - loss of habitats ( deforestation, urbanization) -introducing exotic species -pollution -overexploitation -global climate change ( future impact about extinction ) How do we stop this ? stop burning fossil fuels Try to preserve 1/2 of earth’s land End public subsidies that damage nature (polluting oceans) Slow human population growth Communities community: interacting species that inhabit an area Metrics- —> Structure : number of species, relative abundance, the different kinds of species —> Guilds: groups of organisms that exploit the same resource in similar ways (ex, fish species in a community that consume leaf litter) ( mostly through eating) Factors that influence structure: - Physical: habitat ( soil/ climate), adjacent landscapes -Biological: relative abundance, species richness, species interactions —> Feeding Relationship — Food Chain (chain of command of energy) Diatom < Krill < fish/birds < seals < Killer Whales [Arctic food web] species interactions = predation, paradise, competition, mutualism — web describes species interaction and is important part of structure Types of Species Dominant/ Foundation species = species with substantial influence on structure - due to high biomass or high density of species (ex. Coral reef, creates habitats for other species) Mols and Visser 2002. : Great tit bird consumes a lot of insect larvae - either excluded bird or welcomed to apple orchard to test of they would reduce pests —-> when they were present, there was less damage from caterpillars —-> tested removal of caterpillars, there was less destroyed plants - Bird would reduce the pests and apple orchards survived better ( they ate so much pest) More birds = increased yield of apples, less pests Keystone Species = a species that had a disproportionate impact on community relative to its abundance. [ if removed = significant changes ] - can influence the habitat, and interactions of other species - species can be dominant despite low biomass or density —> low density but has a large impact on the community structure —> Removal of keystone = alter community structure, diversity loss African Elephants : they would damage the habitat to get their food - more damage to trees. = more arboreal geckos = more habitat for geckos in trees Yellow Stone National Park Food web coyotes Abstrat / Tropic Levels feeding grounds of organisms partitioned by where the energy is derived - energy as sunlight or other organisms 1) Primary producer: plants, phytoplankton [ energy comes from sun ] 2) Primary consumer: solely feed on primary producer —> herbivore, zooplankton 3) Secondary consumer: carnivores that consume primary consumers (rat) 4) Tertiary consumer: eats organisms that move of secondary (snake, hawk) 5) Quaternary consumer: eats organisms from last group Top down Control => Productivity controlled by highest trophies level carnivores depress herbivore populations that would otherwise consume most of vegetation. Ex. wolves kill off the primary consumer—> less pressure on on primary producers Bottom up - changes in trophic levels lead to increase in trophic levels above — increase primary producers = increase trophic levels abundance of organisms at a trophic level is determined by the rate of food production for them to eat Trophic Cascade : change in abundances of organism at one trophic level that influences energy flow at multiple levels Life History Evolution Life history = traits that determine the timing and details of reproduction and death - size at birth, growth rate, age of maturity, mortality rate, reproductive investment. - (population specific, not species specific) - each population has its own needs and characteristics that determines the best traits for survival Diversity In Babies blue whale : 12- 60 ton baby small baby size compared to mom Bat : twin bats are large in body size compared to mom Dung Beetle: 4-5 babies per lifetime Orchard: millions of offspring at one time Ideal Organism: IMPOSSIBLE lives forever, reproduces right after birth, has many offspring and protects them Out competes other species, avoids predators Trade Offs: allows organism to have specialized characteristics Balanced Energy Budget C =(R+A)+(F+U)+(B+G) Consumption = metabolic needs+waste+gain R= respiration B= Biomass G=Gonads A= activity F=egestion U=excretion Principle of Allocation: factors of the budget must “lose out” cancel ea other Allocation of Energy = allow life history to evolve - energy needed to live and reproduce —> organisms allocate accordingly -results of extrinsic (outside) and intrinsic (inside ) factors Extrinsic : how environmental factors affect survival/ reproduction - when you breed and die - Ecology of environment Intrinsic : interal trade off among traits -genetics, phylogeny, what dictates time of birth/death -reproduce early because you’re likely to die young Age and Size of Organisms Age at Maturity : produce young quickly or let them gestate a while — natural election favors the age or maturity that can lead to the most offspring to be produced over a lifetime Mature at age and size where reproductive payoff (fitness ) is greatest —perennial plants, harsh winters reproduce quickly 4 Assumptions of best trade off 1) older first time parted have offspring with better survival rates. (Elephants) — generally larger size parents = many small // fewer big offspring 2) older first time parents are generally larger (Fish and Plants — can either have more or fewer but larger offspring 3) Advantages of later maturity are counterbalanced with faster maturity —mature fast = short generation time , picks up environmental changes (rats) —mature slow = offspring better suited for immediate survival (elephants) 4) population are trying to reach evolutionary equilibrium — advantages/ disadvantages of maturing at an age come into balance fecundity grows · - strong selection for · more offspring therefore females must have larger sizes. semelparity : reproducing once then dying Salmon in freshwater die after lay breeding - -very few species like this times before dying iteroparity reproducing : several - most species Trade offs number offspring size us - few, large offspring many intermediate sized - thousand/millions of tiny offspring -  Lack's Hypothesis · too less resources spread many : to Boss 1 garnsze die too little they would easily · : · moderate : best version for survival Larger female = larger/more eggs size in in Larger eggs = large offspring Larger or more offspring = more survival per offspring (smaller) Jetz te al 2008 5290 bird species Large influence of where birds nest. ( habitat and region ) Birds would mostly lay eggs in the cold Arctic and northern regions - they are up north and winter is approaching temperature effects -therefore birds would lay the most eggs to make sure survival of some Aubret eat al 2002 - Pythons - parental care for eggs, manipulated how many eggs to a clutch - average of 7/8 clutch size - larger clutches dies out = mother cannot care for them = dried out - small clutch = some can not be viable Under Conditions - good. = grow fast and reproduce // -bad= grow slowly and wait to reproduce Parental care: if it has significant parental care. (More energy needed) - smaller offspring compared to mom and fewer in number - therefore less energy in reproductive measures Parental care Vs Number of Offspring Altricial : offspring are born helpless (humans) - humans release babies smaller and earlier investing more energy to keep it alive Precocial : born advanced. ( horses ) - horses pregnant longer more energy upfront in order to have fewer or bigger offspring = less energy from parents after birth Life history strategies organized in continuum from fast to slow r-selected species : life history dominated by intrinsic rate of increase:reach maturity quickly, high fecundity —> many, small offspring - short parental care if any - Ex: Rats -Characteristics = - many small offspring, reaches reproduction age rapidly, short generations -short lived, little to no parental care k-selected species : life history affected more by resources and competitive advantages: matures later/ at larger sizes, produce few larger offspring - long term parental care -Characteristics = Ex. Red Wood Trees, Swans, Giraffe - reproduce late in life, longer generation times, most energy in parental care