Population Ecology: Who, Where, How Many? PDF

not on exam purpose of system options/variety of body plan ↳ benefits + trade offs Population Ecology: Who, Where, How Many? S...

not on exam purpose of system options/variety of body plan ↳ benefits + trade offs Population Ecology: Who, Where, How Many? S neurons neuroglia · PNS division · HOW Act. Pot works  calculation x heavy low populations ↑ due to - more lions/unit of space higher density of prey Introduction ecology : interactions between organisms Population ecology: study of populations in relation to their environment Populations = groups of individuals of the same species in the same area Contain various ages, sizes, sexes, locations “Area” depends on specifics (from a single fruit to the entire planet) - be big can small dependent or behavior ; organisms on of Population dynamics = patterns and changes in populations, studied in field of demography looking changes - at in population all factors Population structure (actual + potential): growth (births), decline affect growth E (deaths), movement (immigration/ emigration) rates Population density: measure of individuals per unit space ↳ # of individuals D = Area (units) ⑭ How to Measure Populations Method depends on features of population of interest: Do they move? How far? Are individuals easily identifiable? tigers easily distinguishable ex. not deer but Hard count: most accurate, but most labor-intense Count every individual in a specific region (tree counts, human census) Sampling method (estimate): less accurate, but less labor-intense given extrapolate pop, in a area Count small proportion of population and calculate total ( size Quadrants, line-transects, mark-recapture can be highly variable , works in specific conditions  methods * estimate recapture in short amt of time · mark > - - compare marked #v. recapt line population challenging to walk in a straight to make rough estimate of ↑ ex mangrove swamp - · Mark-recapture: useful for highly Line-transect: useful for mobile animals, longer-term larger, less evenly studies (ex: many marine animals, distributed organisms birds) (ex: some plants, marine mammals, squirrels) uniform envir. -good for be inaccurate w/short - can distances · for smaller organisms - > not much movement can accurately count organisms Quadrant: useful for small, sedentary organisms (ex: some plants, tidepool animals) > ↳ very specific ; must be able to capture organism again ↳ marking can decrease survival rates of organism  clumped hard count Not Just Density mark/recapture · uniform same as dispersal not Dispersion: distribution of individuals in space ① ② random ⑤ Clumped, uniform, random Age structure: distribution of individuals in age less individualsesputation Not all individuals contribute equally to ↑ populations Potentially influential on demographic potential Survivorship: odds of surviving to a specific age/stage; estimated from life tables C ↑ rapid growth 1 ~ same width few - young people : decline in population growth Life Table Summary of survival and reproductive rates based on age or life stage In humans called actuarial tables; highly valued by insurance companies) ↳ if you die early > - less $ from insurance · shows why/when people die  Life Table Summary of survival and reproductive rates based on age or life stage Cohort (horizontal table) follows a group of individuals from birth to death Vertical tables take a measure of each age/stage at a single moment in time (snapshot) less - required time Life tables show: birth- later Survivorship: proportion of original cohort that not life stagesurvive to a certain age/stage inverses Mortality: proportion of individuals in an age/stage that do not survive to next age/stage Gavesn't (die) Cumbers make it show environment restraints  Fecundity - measure of fertility only counting - females Organisms of different ages/sexes contribute to population growth differently Generally, females only counted toward producing offspring Fecundity: measure of number of offspring produced by cohort at each age/stage Very young, old have low fecundity Fecundity may be influenced by environment S snow what happens - can win pop (environmental conditions  to draw this graph be able Survivorship Curves j Life table data in graph form! Type I survivorship: I Y low juvenile, adult ex birds inverse -. mortality humans ex. · some chicks survive due to parental birds Type II survivorship: · adult care killed by moderate juvenile predators and adult mortality Type III survivorship: S high juvenile, low adult mortality - few natural causes to ↳ ex. turtles kill adults X IRL doesn't always match theories ↳ besure to recognize general trends (mas sire decline in babies  Population Dynamics Populations grow, are stable, or decline largely based on: Survivorship + reproductive rates Basically: more births (&/or immigrants) than deaths (&/or emigrants) = grow; more deaths (&/or emigrants) than births (&/or immigrants) = decline; same values = stable Reference site -n = (B + 1) - (D + E) I 4 B + I > D + E => pop. growth guys have chance of mortality - X-linked diseases = pop dec B1 <. De. - juvenile risky behavior => Stable intensive jobs B+ I = D + - more labor  n = 5 snape cexp , growth) ------- carrying capacity ---X 8 Population Growth S-shape curve A - - time > - Populations/species have varied intrinsic rates of increase (r) r = b – d (births – deaths) If r = 0 population is stable If r > 0 population is growing (larger value = more rapid growth) If r < 0 population is declining (smaller value = more rapid decline) When growing, populations can either go through exponential (geometric) or logistic (sigmoidal) growth The carrying capacity (K) of a system is the maximum number of individuals that the environment can support indefinitely ↳ limits growth of a population  · ex fisheries collapse due to. delays in population's overfishing Limiting Growth does not need inverse relationship ~ to be Density-dependent factors: regulatory mechanisms based on population density Food, shelter, available territory all decrease as density increases Predation can increase as density increases Disease increases as density increases Density-independent factors: events that impact populations but are not influenced by density still impacts pop. growth Abiotic factors: drought, flood, fire, natural disasters (unpredictable events) X at carrying capacity carrying capacity affected = by => pop. Struggling can change over time density indep. factors - low amount of food population responds to changing carrying capacity  allocate resources Life-History Strategies to - How or utilize energy - > invest in self ↳ invest into offspring Traits that affect reproduction and survival are influenced by environment via natural selection, forming somewhat predictable patterns of how to invest resources Organisms have to ‘decide’ when to start reproducing, how often to reproduce, and how many offspring to have per reproductive event = can organisms Combined, this is their life history strategy (how to maximize fitness) reproduce than once more ? How fast pop grows -> r-selected organisms tend to have high r values, be found in unpredictable environments, and have shorter life expectancies; they also are more likely to be semelparous (only reproducing once in a lifetime). I will > - rep energy put offspring into chasing carrying > - K-selected organisms tend to be in fairly stable environments, existing at their K value, capacity and have longer life expectancies; they are more likely to be iteroparous (have multiple reproductive attempts in a lifetime) ↳ invest in self  environmenis development ranabe large pop. ·get · & common fluctuations reprvan a. care not parental & will abandon offspring to ensure self survival N T opposites  Life History Strategies Con’t Each strategy has pros and cons, and is largely dependent on the constraints of the organism and environment Most organisms are not entirely r- or K-selected intermediates gradient = - most organisms madagascar giant rat: K-selected elephants · : J r selected : Wild flowers I baby per reproductive event - - mate for life ; K -large body size , parental care parentwoffspringhasincreasedmortaly X it i -variable environment required for reproduction R-Short lifespan