Chapter 15 Quiz Flashcards
When allein principles remain constant, a population is in genetic equilibrium.
Hardy-Weinberg Principle
One expression of a particular trait symbolized by a single letter.
Allele
Any change in allelic frequencies in a population.
Genetic Drift
A group of individuals with a different allele frequency than the original population.
Founder Affect
A population declines to a very low level and then rebounds.
Bottleneck
Operates to eliminate extreme expressions of a trait when the average expression leads to higher fitness.(Selection against both extremes)
Stabilizing Selection
Increases the expression of an extreme version of a trait and increases fitness.(Selection against one extreme)
Directional Selection
Removes individuals with average traits, but retains individuals expressing extreme traits.(Selection against the mean.)
Disruptive Selection
Drives change in the frequency of a trait based on the ability to attract a mate.
Sexual Selection
Operate before fertilization occurs which prevent reproduction.
Prezygotic Isolation Mechanisms
Operate after fertilization and ensure that the resulting offspring remains infertile.
Postzygotic Isolating Mechanisms
Occurs when populations are divided by a physical barrier. Most common type of speciation according to scientists.
Allopatric Speciation
Occurs without physical barrier; populations remain in close proximity. Common in plants.
Sympatric Speciation
Takes place when a large number of species arise from a single common ancestor in response to an ecological opportunity.
Adaptive Radiation
When evolution proceeds in small, gradual steps.
Gradualism
Occurs in rapid spurts of genetic change, causing rapid speciation that punctuate long periods of little change.
Punctuated Equilibrium
Directed breeding to produce offspring with desired traits.
Artificial Selection
Cumulative change in a group of organisms through time.
Evolution
Some competitors would be better equipped for survival than others, less equipped would die.
Natural Selection
Newly evolved features, such as feathers, that do not appear in the fossils of common ancestors.
Derived Trait
More primitive features, such as teeth and tails, that do not appear in ancestral forms.
Ancestral Trait
Anatomically similar structures inherited from a common ancestor.
Homologous Sturucture
Structures that are reduced forms of functional structures in other organisms.
Vestigial Structure
Can be used for the same purpose and be superficially similar in construction, but are not inherited from a common ancestor.
Analogous Structure
Early, pre-stage of an organism‘s development.
Embryo
The field in which distribution of plants and animals around the world is studied.
Biogeography
The measure of the relative contribution an individual trait makes to the next generation.
Fitness
A suite of morphological adaptations that allow an organism to blend into its environment
Camouflage
A type of morphological adaptation, where a species evolves to resemble other species.
Mimicry
