Ecology

Test time :P

Population dynamics

Changes in population size and structure over time

Demography

Study of population dynamics

Growth Rate

number of new individuals produced in a given amount of time-number of individuals that die

Exponential growth model equation

Nt=N0e^RT

intrinsic growth rate®

highest possible per capita growth rate for a population

geometric growth model

models population growth that compares population sizes at regular time intervals(not continuous change)

density independent

factors that limit population size regardless of the population’s density

density dependent factors

factors that affect population size in relation to the population’s density

negative density dependence

when the rate of population growth decreases as populations density increases

positive density dependence aka inverse density dependence/allee effect

when the rate of population growth increases as population density increases

self-thinning curve(also known as the -3/2 rule)

a graphical relationship that shows how decreases in population density over time lead to increases in the mass of each individual in the population

carrying capacity

the maximum population size that can be supported by the environment

inflection point

the point of fastest growth after which growth begins to slow

Age structure

in a population, the proportion of individuals that occurs in different age classes

life tables

tables that contain age class-specific survival and fecundity data

Generation time(T)

the average time between the birth of an individuals and the birth of its offspring

Net reproductive rate

the total # of female offspring that we expect an average female to produce over the course of her life

Two types of life tables

cohort life table

static life table

Cohort life table

a life table that follows a group of individuals born at the same time from birth to death of the last individual

static life table

a life table that quantifies that survival and fecundity of all individuals in a population over a single time interval. Often uses proxy data

population overshoot

when a population grows beyond it carrying capacity

population die-off

a decline in density that typically goes well below the carrying capacity

population cycles

regular oscillation of population size over a long period of time

delayed density dependence

when density dependence is based on a population density at some time in the past rather than current densities

damped oscillation

a pattern of population growth in which the population size initially oscillates but the magnitude of the oscillations declines over time

stable limits cycles

a pattern of population growth in which the population size continues to exhibit large oscillation over time

habitat fragmentation

the process of breaking up larger habitats into a # of smaller habitats

deterministic model

a model that is designed to produce a result without accounting for random variation in population growth rate

stochastic model

probabilistic model that incorportates random variation in population growth rate

demographic stochasticity

variation in birth rates and death rates due to random difference among individuals

environmental stochasticity

variation in birth rates and death rates due to random changes in eenvironmental conditions

Assumption of basic model of metpopulation dynamics

pathces are equal quality, each patch has an equal subpopulation size, each subpopulation supplies the same number of dispersers

Rescue effect

The phenomenon of dispersers supplementing a declining subpopulation that is headed toward extinction

subpopulation

when a larger population is broken up into smaller groups of conspecifics that live in isolated patches

metapopulation

the collection of subpopulations that live in isolated patches are linked by dispersal

habitat fragmentation

the process of breaking up large habitates into a # of smaller habitats

basic metapopulation model

A model that describes a scenario in which there are patches of suitable habitat embedded within a matrix of unsuitable habitat

source-sink metapopulation model

builds in basic metapopulation mdoel and accounts for the fact htat not all patches of suitable habitat are of equal quality

Landscape metapopulation model

a population model that considers both difference sin the quality of the suitable patches and the quality of the aurrounding matrix

Life history traits

fecundity, parity, parent investment, onset of senescence, longevity

principle of allocation

limited amount of energy to invest in survival, maintenance, and reproduction

Fisher’s Principle

1:1 sex ratio is predicted as the evolutionary stable strategy, as rare sex has more mating opportunities—favors selection for production of rarer sex

offspring-offspring conflict

occurs when siblinds compete for parental care or limited resources

Trivers—Willard hypothesis

mothers alter sex ratio depending on condition

produce females when in poor condition; daughters will likely have some offspring even if in poor condition

produce males when in good condition; males likely to benefit more from being large and will more readily attract mates

parent-of-origin effect

an effect on the phenotype of an offspring caused by an allele inherited from a particular parent

genomic imprinting

when genes inherit from 1 or the other parent are silenced due to methylation. Expresses 1 parental copy in offspring

methylation

process by which methyl groups are added to certain nucleotides. Asosciated with altered gene expression

parental conflict

occurs when parents have an evolutionary conflict of interest over the optimal strategy for parental care

parent-offspring conflict

occurs when parents benefit from witholding parental care or resoures from some offspring and invest in other offspring. Conflict arises because the deprived offspinrg would beenfit more if they recieved the witheld care/reources

intralocus sexual conflict

a conflict between the fitness effects of alleles of a given locus on males and females

senescence

the deterioration in biolgoical functions of an organism as it ages

four theories explaining evolutuion of the onset of aging(scenescence)

high mortality, mutation—accumulation, pleiotropy, disposable soma

selection shadow

an evolutionary theory concept stating that natural selection pressure weakens as an organism ages and passes reproductive maturity

high mortality theory

high morality in the wild causes senescence-associated mortality to be rare and undermines idea that genes causing aging have evolved

mutation-accumulation

the selection shadow at older ages may permit an accumulation of late-acting deleterious mutations

pleiotropy

Genes benefiting organisms early in life will b e favored by selection even if they are detrimental at later ages

disposable-soma

selection for investment in somatic maintenance and repair is limited; all that is required is to keep the organism in sound condition for as long as it might survive to reproduce in the wild

KNOW THIS!

genes involved in repair are switched on under stress—can slow aging

Adaptive explanations for menopause

mother hypothesis: risk of reproduction at older age selects for reduced fertility

Grandmother hypothesis

loss of fertility associated with shift in investment to grandchildren

principal driver of evolution of longevity=

level of mortality

introduced species(aka exotic species/non-native species)

a species that is introduced to a region of the world where it has not historically existed

invasive species

an introduced species that spreads rapidly and has negative effects on other species, human recreation, or human economies

Lotka-Volterra Predator-Prey Model

a model of predators-prey interactions that incorporates oscillations in the abudnacnes of preadators and prety populations and show predators #s lagging those of their prey

equilibruim isocline(or zero growth isocline)

the population size of one species that causes tat population of another species to be stable

Joint equilibruim point

the point at which the equilibrium isoclines for predators and prety populations cross

Joint population trajectory

the simultaneous trajectory of predator and prety population

Simplifying assumption of the Lotka-Volterra predator-prey model

No variatiion amongst individuals

closed system(no immigraiton or emigration)

no time lags

no refuges for prety

no density dependence in prey

no prey switching in predators

no satiation of consumption by predators

Biological control

introductions of 1 species to help control the abundance of another species

mesopredators

relatively small carnivores that consume herbivores

top predators

predators that typically consume both herbivores and mesopredators

Functional response

the relationship between the density of prey and an individual predator’s rate of food consumption

type I functional response

a functional response in which a predator’s rate of prey consumption increases in a linear fashion with an increase in prey density until satiation occurs

Type II functional reponse

a functional response in which a predator’s rate of prey consumption begins to slow down as prey densiity increases then pleataus when satiation occur

Type III function response

a functional response in which a predator exhibits low prey consumption under low prey densities, rapid consumption under moderate prey densities and slowing prey consumption under high prey densities

search image

a learned mental image that helps the predator located and capture food

3 biological mechanism for Type III response

1) limited # of prey refuges

2)development of search image by predators

3) prey switching by predators abrupt transition in predatory preferences for prey driven by proportional abundance relative to alternative prey species

Numerical response

a change in the number of the predators through population growth or population movement due to immigration or emigration(occur when the # of predators in a populatikon changes as a result of an increase or decrease in the prey population)—describes how the predator population changes(reproduction/migration) based on prey density

Crypsis-Camouflage

that either allows an individual to match its environment or breaks up the outline of an individual to blends in better with the background environment.

warning coloration(aka aposematism)

a strategy in which distastefulness of weaponry evolves in association with very conspicuous colors/patterns

batesian mimicry

when palatable species evolve warning coloration that resembles unpalatable or otherwise protected species

mullerian mimicry

when several unpalatable or otherwise protected species evolve a similar pattern of warning coloration

coevolution

when 2 or more species affect each other’s evolution

intraspecific competition

competition among indviduals of the same species

interspecific competition

competition among individuals of different species

resource

anything an organism consume or uses that causes an increase in the growth rate of population when its availability is increased

renewable resources

resources that are constantly regenerated

nonrenewable resources

resources that are not regenerated

liebig’s law of the minimum

law stating that a population increases until the supply of the most limiting resource prevents it from increasing further(overly simplistic—works for abiotic resources, NOT biotic factors)

competitive exclusion principle

2 species cannot cocexist indefinitely when they are both limited by the same resource

species can coexist when:

there are multiple reources and each species is limited by a different resource

Types of competition

explotative competition, intereference competition, allelopathy, apparent competition

exploitative competition

competition in which individuals consume and dirve down the abudnacne of a resource to the piont that other individuals cannot persist

interference competition

when competitiors do not immediately consume resources but defend them

allelopathy

a type of interference that occurs when organisms use chemicals to harm their competitors

apparent competition

appears to be competition, but it’s not! occurs when 2 species have a negative effect on each other through a shared enemy

Species can coexist when:

intraspecific competition is stronger than interspecific competition

Assumptions of the L-V Competition model

closed system(no migration)

is ir a constant

K ins a constant

A and B are constants

All individuals within species are equivalent

no time lags

chi square test

a stastical test that determines whether the # of observed events in different categories differs from an expected # of events, which is based on a particular hypothesis

degrees of freedom

(# of observed categories-1)