Chapter 13: Natural Selection and Microevolution Flashcards
What is a gene pool?
The range of genes and all their alleles present in a population
What can the frequency of polymorphic alleles be affected by?
- Mutation of an allele
- Immigration of individuals
- Emmigration of individuals
- The reproduction rate of various individuals
What are some factors which may change an allele frequency?
- Genetic drift
- The bottleneck effect
- The founder effect
What is genetic drift?
A change in the gene pool of a population as a result of chance; usually occurs in small populations
What is the bottleneck effect?
When a catastrophic event or a period of adverse conditions drastically reduces the size of a population
What is the founder effect?
A type of gene flow that occurs when a few individuals that have become isolated from a larger population do not carry all the alleles that were present in the original population
What is gene flow?
The transfer of alleles that results from emigration and immigration of individuals between populations
What are some negatives and positives of losing allele frequency in a gene pool?
A negative can be that the limited gene pool would create a higher risk of mutation, a positive can be that certain alleles that may cause mutations or a physical disadvantage would be lost.
What are the few proposistions that are the priciple of natural selection leading to evolutionary change?
- Individuals differ from one another
- These variations are caused by mutations and are inheritable
- More offspring are born than can survive
- Some individuals have traits that make them more suited to their environment (viability), making them better to reproduce and pass on their alleles (fecundity)
What is viability in terms of evolutionary change?
Capablility/suitability of living in the environment
What is fecundity in terms of evolutionary change?
A measure of fertility; the capacity to reproduce
What is fitness in terms of natural selection?
The capacity of an individual to survive and pass on viable offspring
What is adaptive evolution?
Changes in populations of organisms that make that population better adapted to its environment over time
What are selection pressures?
A factor that influences the survival of an individual within a population
What are some selection pressures?
- Competition between species for food/territories
- Predator - prey relationships
- Competition within species for food or water
- Competition within species for territories or nesting places
- Sexual selection, traits that sucessfully attract mates
