Population and Community Dynamics Flashcards
Population:
Consists of all the members of a species that occupy a particular area at the same time.
Species:
A group of organisms that has the potential to interbreed in nature to produce viable, fertile offspring.
Evolution:
The change in the frequency of genes in a population’s gene pool from generation to generation.
Gene pool:
The total of all the genes in all the population members simultaneously.
The Hardy-Weinberg Principle:
Used to quantify an unchanging gene pool. The law states that the frequencies of alleles in a population’s gene pool remain constant over generations if all other factors remain constant.
Genetic equilibrium:
Stability of a population’s gene pool.
How does a population evolve?
If equilibrium is upset.
Conditions of the Hardy-Weinberg Principle:
The population is large, mating is random, no mutations occur, no migration occurs, and no natural selection occurs.
Microevolution:
A change in the gene pool of a population over successive generations.
Gene flow:
Movement of alleles from one population to another through the movement of individuals or gametes.
Genetic Drift:
Change in the gene pool of a population resulting from chance.
Founder Effect:
Genetic drift that results when a small number of individuals separate from their original population and find a new population.
Bottleneck effect:
A dramatic temporary event which leads to a reduction in population size, usually resulting in a significant genetic drift.
Factors that increase population size:
Natality and immigration.
Factors that decrease population size:
Mortality and emigration.
Exponential growth:
Population size increases by a fixed rate per unit of time with unlimited resources. The closes population’s only limit is biotic potential. J-curve.
Logistic growth:
Growth will level off as the population size reaches a carrying capacity. These are characteristics of an open population.
Density-Dependent Factors:
Factors that influence a population at a certain density.
Density-Independent Factors:
Factors that have the same influence on a population at any density.
What examples are there of density-dependent factors?
Intraspecific competition, predation, disease, and interbreeding.
Intraspecific competition:
Competition between the same species; within a population.
What examples are there of density-independent factors?
Weather and insecticides.
K-selected organisms:
S-curve associated, larger organisms, adapted to living at a population at or near carrying capacity.
r-selected organisms:
J-curve associated, small organisms, adapted to increase population size rapidly.
Estrous Cycle:
The shorter the time between cycles of sexual receptivity, the greater the biotic potential.
Mate availability:
The more readily available mates in a population, the greater the biotic potential.
Litter/clutch size:
The larger the litter/clutch size, the greater the biotic potential.
Fecundity:
The average number of offspring produced per female. The greater the fecundity of a species, the greater the biotic potential.
Age of onset of sexual maturity:
The earlier that sexual maturation occurs, the greater the biotic potential.
Gender ratio:
The more females there are, the greater the biotic potential.
Interspecies:
What occurs in a community (between species).
Symbiosis:
A close relationship between members of different species.
Mutualism:
Both species benefit from the association. I.e. Bees and pollinated flowers.
Commensalism:
One species benefits while the other neither benefits nor is harmed. Ie. Barnacles on a whale.
Parasitism:
One species, the parasite, benefits at the expense of the host. Ie. Tapeworms in the human body.
Plant defences against herbivores:
Thorns, microscopic crystals in their tissues, spines or hooks on leaves, and harmful chemicals.
Animal defences against predation:
Camouflage, deceptive coloration, mechanical or chemical defence mechanisms, and mimicry.
Succession:
The sequence of identifiable ecological stages or communities occurring over time in progress from bare rock to a climax community.
Primary Succession:
The initial colonization of a barren habitat by pioneer species. Soil is produced during this stage.
Secondary Succession:
Re-building of an area that once supported many organisms.
Climax Community:
The stage in ecological succession that is stable and self-supporting. There is more production of organic material than use.
