23.4 Natural Selection Constantly Causes Adaptive Evolution Flashcards
What is Relative Fitness?
It is the survival and/or reproductive rate of a genotype (or phenotype) relative to the maximum survival and/or reproductive rate of other genotypes in the population.
What is Disruptive Selection?
Changes in population genetics in which extreme values for a trait are favored over intermediate values.
What is Directional Selection?
The mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.
What is Stabilizing Selection?
A type of natural selection in which genetic diversity decreases and the population mean stabilizes on a particular trait value.
What is Sexual Selection?
The fact that individuals with certain inherited characteristics are more likely than other individuals to obtain mates.
What is Sexual Dimorphism?
It is the differences between two sexes.
Ex. The size, colour ornamentation and behaviour.
What is Intersexual Selection?
Individuals of one sex (females normally) are choosy in selecting their mates from the other sex and prefer “good genes” indicating robust immune system.
What is Intrasexual Selection?
Individuals of one sex compete for the mates of the opposite sex.
What is Neutral Variation?
Differences in DNA sequence that do not confer a selective advantage or disadvantage.
What is Balancing Selection?
When natural selection maintains two or more forms in a population.
What is Heterozygote Advantage?
Heterozygotes at a particular locus have greater fitness than do both kinds of homozygotes (defined in terms of genotype)
What are the 4 reasons why natural selection cannot fashion perfect organisms?
- Can act only on exiting variation.
- Evolution is limitedly historical constraint.
- Adaptations are after compromises.
- Change, natural selection, and the environment interact
