1D - Ecology Flashcards
(47 cards)
Gene pool
A gene pool is the complete set of different genes and their alleles in a population.
Why is the gene pool important in a population?
It represents genetic diversity, which helps populations adapt and survive changes in the environment.
If an organisms is diploid (2n), it’s genotype with have ____ alleles for a trait
Two
Phenotypic frequency
Rate of occurrence of a particular phenotype in a population/gene pool
Genotype frequency
Genotypic frequency is the proportion of a specific genotype (like AA, Aa, or aa) in a population.
How do you calculate genotypic frequency?
Genotypic frequency = (Number of individuals with a genotype) ÷ (Total number of individuals in the population).
What is the Hardy-Weinberg principle (genetic equilibrium)?
It’s a principle that states allele and genotype frequencies in a population remain constant over generations if certain conditions are met.
What are the five conditions for Hardy-Weinberg equilibrium?
- No mutations
- No natural selection
- Random mating
- No gene flow (no migration)
- Large population size (no genetic drift)
Why is Hardy-Weinberg important?
It provides a baseline to detect if evolution is occurring in a population by comparing expected and observed genotype frequencies.
gene flow
net flow of alleles (copy of your genes) from one population to another due to migration. Both populations are maintaines (one doesnt collapse) with increased genetic diversity in one of them
what is genetic drift
Random changes in allele frequencies in a population, especially small ones.
Happens by chance, not due to survival advantage
Can lead to loss of genetic variation
Stronger effect in small populations
Example:
A rare allele disappears after a natural disaster randomly kills some individuals.
genetic drift
a non selective (entirely random) process occurring in small populations.
Alleles (p&q) change over time die to random or chance events (rather than natural selection
the founder effect
when a new colony is started by a few members of the original population. This small population size means that the colony may have;
reduced genetic variation from the og population
a non-random sample of the genes in the original population
happens during a population crash, think natural disaster
think of darwins finches on the galapagos islands and adaptie ratiation
the bottleneck effect
genetic drigt resulting from the reduction of a population due to a natural disaster/human activity. the new population is not representative of the original population.
-decrease in genetic variation withing a given population
-this dicrease in variation can increase the differences BETWEEN popilations of the same species (think speciation)
-small populations can be more susceptible to random environmental impacts
-less able to adapt than larger populations with more genetic diversity
What determines population growth?
Natality, mortality, immigration, and emigration.
When does a population increase?
When natality + immigration > mortality + emigration.
What is the per capita growth rate formula?
CGR = ΔN / N (change in population size over original size).
What is population density?
Number of individuals per unit area (Dp = N / V).
What is intraspecific competition?
Competition between members of the same species.
What is interspecific competition?
Competition between different species.
What is mutualism?
A relationship where both species benefit.
What is commensalism?
A relationship where one benefits, the other is unaffected.
What is parasitism?
A relationship where one benefits and the other is harmed.
What happens in predator-prey cycles?
Both populations fluctuate; prey increases → predators increase.
