population ecology Flashcards
macroevolution
evolution on a large scale, phenotypic changes large enough new genera/higher taxa formed(Dinos to birds)
how are organisms influenced by genetic variation
- some species are negatively impacted by lack of genetic variation(low fertility, deformed sperm, low survivorship). EX. cheetahs
- other pops unaffected by lack of genetic diversity
Ex. elephant seals thrived after almost extinct
Irruptive(Malthusian growth)
Oscillation pattern of a population characterized by explosion(overshoot) followed by pop crash(dieback)
oscillation amplitude lower as time passes, pop settles around carrying capacity, but cc moving line because resources change
Founder effect
the loss of genetic variation when a new isolated opo formed by a very small number of indivs form a larger population
factors influencing carrying capacity
- Types of organism (simple vs complex), simple higher population
- available resources(environmental resistance). water, food, habitat, predatory, etc
logistic growth
form of pop growth, per capita rate of growth decreases linearly w/ increasing pop density, also called sigmoid growth curve
takes place when pop’s per capita growth rate decreases as pop size approaches carrying capacity(K)
rate of growth constant changing as result of environ resistance approaches varying capacity
ammensalism
interaction between two organisms/species, - / 0
sink habitats
regions where mortality higher than birth rates usually due to unfavorable conditions
w/o immigration of individuals from other source habitats, pop would cease to exist
microevolution
small evolutionary changes within pop or species
Ex. mosquitos resistance to DDT
Density Dependence
Tendency for growth rate of pop to be affected by pop density
death rate of pop increase or birth rates decrease as density of pop increases
Interference population
access to resources negatively affected by presence of other indivs
Life history
pattern of survival and reproduction events during life of organism, traits include max body size, longevity, age at maturity, fertility etc
Absolute population
actual total number of individuals of same species
Stabilizing selection
indivs with alleles for intermediate traits are favored to survive and breed , occurs when environment unchanging reduces Ange of possible phenotypes
Disruptive selection
India for extreme phenotypes at either end favored, occurs when environs favors more than one phenotype , more extremes allow range in population more chance to survive
Gene Flow
Movement of allele into the gene pool of a population from one or more other population from one or more other populations
for this to happen, must be immigration of individuals from other populations and must breed with resident populations
Random genetic drift
gradual changes in gene frequency of a population due to random events
Inbreeding Depression
reduced biological fitness from inbreeding, often result of population bottleneck, reduces survival and fertility
Fitness
avg repro success of entity from one gen to the next
fitness expressed as relative fitness where avg contribution of allele or genotype to the next gen compared w/ that of another allele or genotype(normally superior type)
Ie, How successful at passing on genes, longer able to survive and produce offspring
Genetic Diversity
total # of genetic characteristics in the genetic makeup of a species
ranges widely from # of species, diffs withins species
the range of different inherited traits within a species. In a species with high genetic diversity, there would be many individuals with a wide variety of different traits.
Ex. diff dog breeds
Speciation
A group of indivs that can share similar genes, can breed to produce offspring
3 types: directional selection, disruptive selection, stabilizing selection
Ecosystem diversity
variations in environment within a geographical location and its overall impact on human existence and environment,
Ie, the variety of habitats, communities, ecological processes
Types of diversity
Species, Habitat, Resource, Ecosystem
Environmental DNA (eDNA)
shed cellular DNA from organisms found in the environment, scales, skin, feces, etc
Mark-Recapture
Method used in ecology to estimate pop size when impractical to catch entire population
capture # of indivs, tag, release, capture again, count how many marked
(# initially caught - #captured second time) / #marked recaptured
Metapopulation
collection of pops that have regular/intermittent gene flow between geographically separate units
requires suitable corridors or migration routes to exist between pops for gene exchange
Directional selection
indivs w/ alleles for single extreme genotype more likely to survive and reproduce due to a response to an environmental change
Ex. giraffe neck lengths, humans killing bigger game so evolving to small only
Molecular Clock
Technique using mutation rate of biomolecules to deduce time in prehistory when 2+ life forms diverged
DNA/protein seq./ RNA evolve at constant rate among most organisms
measures # of changes/mutations accumulated in gene sequences of diff species over time
Ecological Niche
Where and how indivs of species live, defined by location of habitat, where the species lives, what where how resources are obtained
Extinction Vortex
A downward population spiral leading toward extinction where inbreeding and genetic drift cause small populations to shrink in size, leading to a loss in genetic variation which prevents adaptation to changes
Biodiversity
variety of living things and interactions, changes over time as extinction occurs and new species evolve
3 lvls of diversity: species, genetic, ecosystem
Hardy-Weinberg Equilibrium
The state of equilibrium in Hardy - Weinberg where the genetic variability of a population is preserved from generation to generation and remains constant in the absence of other evolutionary influences
No mutation, large population, No immigration or emigration, random mating, no selection. (p+q) = 1 p^2 + 2pq q^2 = 1
K selection
selection of life history traits that favor populations that stay close to carrying capacity in a stable environment
Traits: Large size, delayed repro, long lifespan, multiple young in lifetime, few offspring, much parental care, strong competitive ability
Neutral/Balance Theory
Theory that most genetic variation is neutral with respect to fitness w/ the result that most evolution at the molecular lvl occurs by genetic drift
most genetic variation maintained by balance of selective forces
R selection
selection of life history traits that favor populations that result in the ability to rapidly increase in numbers
traits: small size, early reproduction, large # of offspring, short lifespan
Statistically defined communities
set of species whose abundances are significantly correlated, positively or negatively, over time
Ecosystem engineers
Organisms that physically change the environment around them through presence or behavior(beavers, trees blocking out sun, changes in humidity, etc)
adaptive radiation
process in which organisms rapidly diversify from an ancestral species into a multitude of new forms particularly when a change in the environment makes new resources available
Guild
grouped by behavior, a guild contains any species or organisms that exploit the same resources in similar ways
Ex. birds, rodents insects eating seeds
Functional group
collection of species that are all engaged in some similar ecological process
perennial grasses, nitrogen fixing legumes, etc
Intrinsic rate of natural increase (r)/Malthusian parameter
per capita rate of increase of pop with a stable age distribution when there is no inhibition of growth by infraspecific competition(r)
used to estimate pop growth
of births - # of deaths per gen
(BR/1000) - (DR/1000) = X%
(20-5)/1000 = 0.015%
Taxocene
set of taxonomically related species within a community