Population Genetics Flashcards
(28 cards)
Define population
A population is a group of individuals of the same species that live in the same geographic area and have the potential to interbreed.
Define gene pool
The gene pool is the total collection of all the genes (and all of their alleles) present in a population at a given time. It represents the entire genetic diversity of that population.
What are the conditions for Hardy-Weinberg Equilibrium?
- No mutations
- Random mating
- No natural selection
- Extremely large population size
- No gene flow
What does the Hardy-Weinberg principle describe?
A population that is not evolving. Population can evolve at some loci while being in HWE at other loci.
What is natural selection?
The process by which organisms with traits that better suit their environment tend to survive and reproduce more successfully. Meaning that the more advantageous allele is passed on.
What does selection result in?
Alleles being passed to the next generation in proportions that differ from those in the present generation.
What can natural selection cause?
Adaptive evolution
What is adaptive evolution?
A process in which traits that enhance survival or reproduction increase in frequency over time.
What are the 3 types of adaptive evolution?
- Directional selection
- Disruptive selection
- Stabilising selection
What is directional selection?
Selection favours one of the extremes
What is disruptive selection?
Selection favours both of the extremes
What is stabilising selection?
Selection against both of the extremes
What does genetic drift describe?
It describes how allele frequencies fluctuate unpredictably from one generation to the next.
How does genetic drift reduce genetic variation?
Through the random loss of alleles
What is the founder effect?
A type of genetic drift; occurs when a few individuals become isolated from a larger population. Allele frequencies in the small founder population can be different from those in the larger parent population.
What is the bottleneck effect?
A type of genetic drift; occurs when there is a drastic reduction in population size due to a sudden change in the environment. The resulting gene pool may no longer be reflective of the orginal population’s gene pool. If the population remains small, it may be further affected by genetic drift.
List the important key points on genetic drift (4)
- Significant in small populations
- Can cause allele frequencies to change at random
- Can lead to a loss of genetic variation within populations
- Can cause harmful alleles to become fixed
What is gene flow?
Consists of the movement of alleles among populations. Alleles can be transferred through the movement of fertile individuals or gametes
Gene flow tends to increase variation among populations over time. True or False?
False. Gene flow tends to reduce variation among populations over time by making their gene pools more similar.
How can gene flow impact a population’s ability to survive in its local environment?
Gene flow can affect adaptation to local environments. The introduction of new alleles might be beneficial, harmful, or neutral depending on the specific environment and the alleles involved.
What is sexual selection?
A process in which individuals with certain inherited characteristics are more likely to acquire mates than other individuals of the same sex.
What can sexual selection lead to?
Sexual dimorphism; marked differences between the sexes in secondary sexual characteristics.
What is intrasexual selection?
Direct competition among individuals of one sex (usually males) for mates of the opposite sex.
What is intersexual selection?
Occurs when individuals of one sex (usually females) are choosy in selecting their mates.
