Chapter 13 - How Populations Evolve Flashcards
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.
Adaptation
An inherited character that enhances an organism’s ability to survive and reproduce in a particular environment.
Theory
A widely accepted explanatory idea that is broader in scope than a hypothesis, generates new hypotheses, and is supported by a large body of evidence.
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
A preserved remnant or impression of an organism.
Fossil record
The chronicle of evolution over millions of years of geologic time engraved in the order in which fossils appear in rock strata.
Paleontologist
A scientist who studies fossils.
Stratum
(plural, strata) Rock layer formed when a new layer of sediment covers an older one and compresses it.
Homology (Homo = Similarity)
Similarity in characters resulting from a shared ancestry.
Homologous structures
Structures in different species that are similar because of common ancestry.
Molecular biology
The study of biological structures, functions, and heredity at the molecular level.
Vestigial structure
A feature of an organism that is a historical remnant of a structure that served a function in the organism’s ancestors.
Evolutionary tree
A branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms.
Artificial selection
The selective breeding of domesticated plants and animals to promote the occurrence of desirable traits.
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.
PS: Most mutations don’t become more common because they are not advantageous
Sexual reproduction
The creation of genetically unique offspring by the fusion of two haploid sex cells (gametes), forming a diploid zygote.
Population
A group of individuals belonging to one species and living in the same geographic area.
(All of the same species)
Gene pool
All copies of every type of allele at every locus in all members of the population.
Microevolution
A change in a population’s gene pool over generations.
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.
Genetic drift
A change in the gene pool of a population due to chance. Effects of genetic drift are most pronounced in small populations.
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.
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.
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.
Directional selection
Natural selection in which individuals at one end of the phenotypic range survive and reproduce more successfully than do other individuals.
Stabilizing selection
Natural selection that favors intermediate variants by acting against extreme phenotypes.
Disruptive selection
Natural selection in which individuals on both extremes of a phenotypic range are favored over intermediate phenotypes.
Sexual selection
A form of natural selection in which individuals with certain inherited traits are more likely than other individuals to obtain mates.
Sexual dimorphism
Marked differences between the secondary sex characteristics of males and females.
Balancing selection
Natural selection that maintains stable frequencies of two or more phenotypic forms in a population.
Heterozygote advantage
Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in gene pools.
