Biology Chapter 13 Vocab Flashcards
Adaptation
An inherited character that enhances an organism’s ability
to survive and reproduce in a particular environment.
Artificial Selection
The selective breeding of domesticated plants and
animals to promote the occurrence of desirable traits.
Balancing Selection
Natural selection that maintains stable frequencies
of two or more phenotypic forms in a population.
Bottleneck effect
Genetic drift resulting from a drastic reduction
in population size. Typically, the surviving population is no longer
genetically representative of the original population.
Directional selection
Natural selection in which individuals at one
end of the phenotypic range survive and reproduce more successfully
than do other individuals.
Disruptive selection
Natural selection in which individuals on
both extremes of a phenotypic range are favored over intermediate
phenotypes.
Evolution
Descent with modification; the idea that living species are
descendants of ancestral species that were different from present-day
ones; also, the genetic changes in a population from generation to
generation.
Fossil record
The chronicle of evolution over millions of years of geologic
time engraved in the order in which fossils appear in rock strata.
Founder effect
Genetic drift that occurs when a few individuals
become isolated from a larger population and form a new population
whose gene pool is not reflective of that of the original population.
Gene flow
The transfer of alleles from one population to another as a
result of the movement of individuals or their gametes.
Gene pool
All copies of every type of allele at every locus in all members
of the population.
Genetic drift
A change in the gene pool of a population due to chance.
Effects of genetic drift are most pronounced in small populations.
Hardy-Weinberg equilibrium
The state of a population in which
frequencies of alleles and genotypes in a population remain constant
from generation to generation, provided that only Mendelian segregation
and recombination of alleles are at work.
Heterozygote advantage
Greater reproductive success
of heterozygous individuals compared with homozygotes; tends
to preserve variation in gene pools.
Homologous structures
Structures in different species
that are similar because of common ancestry.
Homology
Similarity in characters resulting from a
shared ancestry.
Microevolution
A change in a population’s gene pool over
generations.
Mutation
A change in the genetic information of a cell; the ultimate
source of genetic diversity. A mutation also can occur in the DNA or
RNA of a virus.
Natural selection
A process in which individuals with certain inherited
traits are more likely to survive and reproduce than are individuals
that do not have those traits.
Population
A group of individuals belonging to one species and living
in the same geographic area.
Relative fitness
The contribution an individual makes to the gene pool
of the next generation, relative to the contributions of other individuals
in the population.
Sexual dimorphism
Marked differences between the
secondary sex characteristics of males and females.
Sexual selection
A form of natural selection in which individuals
with certain inherited traits are more likely than other individuals to
obtain mates.
Stabilizing selection
Natural selection that favors intermediate variants
by acting against extreme phenotypes.
