Ecology
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Created by:
trishabristow on February 15, 2012
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Exam 2
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119 terms
Terms | Definitions |
|---|---|
 Evolution | Change in gene pool from one generation to the next |
| 3 types of natural selection | stabilizing, directional, disruptive |
| stabilizing (natural selection) | extremes are being selected against and the mean is stable. |
| directional (natural selection) | one extreme is selected and mean changes. |
| disruptive (natural selection) | Selection that favors alleles towards the endpoints of a frequency distribution, but not alleles towards the middle. |
| Population | all the members of the same species that live and reproduce in the same place |
| gene pool | considering all of the alleles in a population collectively as a set |
| if a populations allele frequencies change... | phenotypes and genotypes change. |
| mutation | random change in a gene or chromosome that is passed down(heritable) |
| mutations are... | a source of new variation and are usually harmful. |
| gene flow | movement of genes into and out of a population via migration of individuals. |
| immigration | moving in. |
| emigration | moving out. |
| gene flow can... | increase variation and reduce differentiation amoung populations. |
| non-random mating | choosing mates in a non-random manor |
| assortive mating | mating w those of the same phenotype or those of the opposite phenotype. |
| assortive mating can | be more homozygous if the same and more heterozygous if opposite. |
| sexual selection | choosing mates based on phenotypes. |
| inbreeding | closely related individuals mate more often than by chance. |
| inbreeding can... | increase homozygous individuals for all of the genes and create a depression. |
| genetic drift | change in allele frequency due to random chance. |
| natural selection | environment favors some phenotypes. |
| natural selection is... | the only process that leads to adaptations. |
| Hardy-Weinberg Principal | under conditions of random mating the allele frequency of a population remains constant through time. |
| a population's allele frequencies will not change unless... | mutation occurs, gene flow occurs, non random mating occurs, genetic drift occurs, natural selection occurs, only one has to occur. |
| evolution | change in allele frequency over time. |
| sum of allele frequency must equal | one. (P+Q=1) (P+H+Q=1) (Psquared + 2PQ +Qsquared =1) |
| P | homozygous dominant. |
| H | hetero zygote. |
| Q | homo zygote recessive. |
| natural selection can... | result in genetic differentiation. |
| genetic differentiation | the genetic variation among sub-population of the same species. |
| greater distance between populations cause... | greater phenotypic differences. |
| geographic variation w/in a species can result in... | clines, ecotypes and geographic isolates. |
| cline | average phenotypic or genotypic trait changes in a measurable way over geographic region. |
| clines are... | usually associated with an environmental gradient. |
| ecotype | a population adapted to its unique (often abrupt) local environmental conditions. |
| geographic isolates | occur when gene flow among sub-populations is prevented. |
| 2 major roles of trade-offs and constraints in natural selection | Fitness of phenotype is a function of prevailing environmental condition. Individual phenotypic characteristics often involve multiple traits and loci. |
| adaptive radiation | 1 species gives rise to multiple species that exploit different features of an environment. |
| Organisms respond to environmental variation at... | The individual and population levels. |
| As environmental conditions change... | Selection favors certain phenotypes, causes shift in distribution of phenotypes in the population and increases avg fitness of individuals in population over time. |
| individuals can respond to temporal(time and spatial(space) changes in the environment... | by moving or by a direct influence of environmental or gene expression(phenotypic plasticity) |
| phenotypic plasticity | ability of a genotype to give rise to different phenotypes under different environmental conditions. |
| Differnt forms of phenotypic plasticity are... | developmental plasticity and acclimation. |
| developmental plasticity | change in phenotype during growth and development due to different environmental conditions. often irreversible. |
| acclimation | change in phenotype in an individual in respone to changing environmental conditions. can involve biochemical, morphological, and/or behavioral traits. reversible. |
| ecological issues | the ecology of antibiotic resistance. |
| antibiotics | compounds that destroy or inhibit growth of micro-organisms. |
| antibiotic resistance | outcome of evolution and an accelerated process of natural selection by widespread use of antibiotics by humans. |
| characteristics of population include... | density, prop of individuals of various ages and stages, spacing of indvls, birth death and movement (migrations) of individuals. |
| distribution of a population... | defines its spatial location. |
| geographic range | area that encompasses all individuals of a species. |
| what restricts population's geographic range? | environmental barriers, geographic barriers, competition and predation. |
| abundance | number of individuals in a population. measure of population size. |
| population density | number of individuals per unit area or per unit of volume(aquatic). |
| population distribution | area over which the population is distributed. |
| 3 distribution patterns | random, uniform, clumped. |
| Random distribution pattern | an individual's position is Independent of others. |
| uniform distribution pattern | results from negative interaction among individuals. |
| clumped distribution pattern | results from patchy resources, social groupings, etc. most common distribution of organisms. |
| population size = | density x area |
| how do you calculate density? | count individuals in a small area or take a sample. |
| How to determine density for plants and sessile organism | Divide area into quadrants, count organisms within area. Average this bunch |
| How to determine density for mobile organisms | Mark-recapture or indices of abundance (Counts of vocalization, scat, tracks, or some other sign) |
| Lincoln-Peterson Index of Population | N= (MS)/R |
| In Lincoln Peterson Index, What does the N represent? | Population size estimate |
| In lincoln-peterson index, what does the M represent? | Marked individucals released |
| In lincoln-peterson index, what does the S represent? | Size of second sample |
| In lincoln-peterson index, what does the R represent? | Marked animals recaptured |
| Age structure in population | Influenced by reproduction and mortality, and affects rate of population growth. |
| What are the 3 ecologically important age stages? | Prereproduction, Reproduction, and Postreproduction |
| Life history | Time individuals spend in each stage depends on? |
| Techniques used for aging animal populations | Mark young (follow survivors), study rep. sample, tooth wear, plumage changes, and growth rings in teeth. |
| Techniques used for aging plant populations | Mark individuals, follow through time, diameter at breast (DBH), or count annual rings |
| Age Pyramid | A snapshot of populations age structre at a given period of time. |
| Skewed | Plant populations often have what kind of age class distributions |
| Homozygous | two copies of the same allele |
| heterozygous | different alleles on each chromosome |
| phenotype | outward appearance of organism for a given characteristic |
| adaptive radiation | 1 species gives rise to multiple species that exploit diff features of an environment (food, habitat) |
| phenotypic plasticity | ability of a genotype to give rise to diff phenotypes under diff env conditions. |
| norm of reaction | set of phenotypes expressed by a single genotype across a range of environmental conditions |
| primary sex ratio (at conception) | tends to be 1:1 |
| secondary sex ratio (at birth) | in most mammals tends to be males > females |
| dispersal | movement of individuals in space. |
| different catagories of dispersal are | passive and active |
| passive dispersal | something else moves it (gravity wind water) |
| active dispersal | mobile organisms move around on their own. |
| one way movement | Emigration(out) immigration(in) |
| migration | round trip movement made by an animal |
| dispersal | changes the spatial distribution of individuals and changes local patterns of population density |
| range expansion | can happen when a population has been introduced to a region where they did not previously exist |
| population growth | how number of individuals in a population increase or decrease w time. |
| open population | population where immigration and emigration occur |
| closed population | no migration. |
| budding | intrinsic form of asexual reproduction |
| intrinsic rate of population increase (r) | population birth rate - population death rate = r |
| birth rate | number of newborns per unit of time/ total population size |
| death rate | number of deaths per unit of time/ total population size |
| increases exponentially if | births > deaths -> r = > 0 (population rises) |
| decreases exponentially if | births < deaths -> r = < 0 (population lowers) |
| no population change if | births = deaths -> r = 0 (population change 0) |
| exponential growth | growth that is continuously accelerated (j curve) |
| If known (r) can predict next years population size= | exponential growth equation: Nto the t = 1= Nto the t + Nto the t (r)... |
| exponential growth equation: Nto the t(Nt) = 1= Nto the t(Nt) + Nto the t(Nt) (r)... | Nt+1= pop size at next time interval Nt = pop size at current time r = intrinsic rate of pop increse Ex: r=0.06; Nt=49,000; Nt+1=? (49,000x0.06=2,940+49,000=51940) (Nt x r = ? + Nt = (Nt+1)) |
| Exponential growth equation discrete form | Nt+1=Nt=Nt(r) change in N/ change in t=(birth-death)N(t) dN/dt=r=(b-d)N(t) |
| Exponential growth equation continuous form | Nt=Nto the0 (e^rt) Nt=pop size at any time in question Nto the0= pop size at the beginning e= bas nat log (~2.718) r= intrinsic rate of pop increase t= time |
| Exponential growth equation straight line form | ln N= ln Nto the0 + rt ln= nat log Nt= pop size at any time in question Nto the0= pop size at the beginning r= intrinsic rate of pop increase t= time |
| slope = | change in y/ change in x |
| Exponential growth rate | characteristic of pops that inhabit favorable conditions at low pop densities. i.e. have access to unlimited resources. |
| If population exceeds its resources | pop crashes and pop growth slows as near resource limitations |
| reproductive success is... | density dependent(sensitive to how many individuals per unit area) |
| logistic growth | growth is eventually limited and reaches stable size. S-shaped growth curve |
| carrying capacity (k) | the max pop size supported by the resources. |
| logistic growth equation | proportion of habitat space available for new members of a pop. = (K-N)/K |
| For equation on pop growth that considers resource availabilty, use exponential growth equ + logistic equ | Nto the(t+1)= Nt+Nt(r)*((K-Nt)/k) |
| When K is treated as a constant | stable ecosystem. not always true bc K can change. |
| acclimation | Change in physiology or form of an organism in response to changes in environmental conditions |
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