Evolution and Adaptation

Flashcards about Evolution and Adaptation.

Descent with modification (Evolution by common descent)

Explains diversity and unity of life; all organisms are related through descent from a common ancestor that lived in the past.

Mechanism for the evolutionary process

Adaptation by natural selection.

Adaptation

The match between organisms and their environment; result of natural selection.

Natural Selection

The process (mechanism) of evolution.

Requirements for Evolution by Natural Selection

More offspring are produced than survive; variation among individuals; inheritance of variation; individuals with favorable characteristics are more likely to survive and reproduce.

Deoxyribonucleic acid (DNA)

A molecule composed of two strands of nucleotides that are wound together into a double helix; the order of nitrogenous bases codes for genetic information.

Alleles

Different forms of a particular gene.

Polygenic

When a single trait is affected by several genes.

Pleiotropy

When a single gene affects multiple traits.

Epistasis

When the expression of one gene is controlled by another gene.

Heterozygous

When an individual has two different alleles of a particular gene.

Homozygous

When an individual has two identical alleles of a particular gene.

Codominant

When two alleles both contribute to the phenotype.

Dominant

An allele that masks the expression of the other allele.

Recessive

An allele whose expression is masked by another allele; most harmful alleles are recessive.

Gene pool

Collection of alleles from all individuals in a population.

Random assortment

The process of making haploid gametes in which the combination of alleles that are placed into a given gamete could be any combination of those possessed by the diploid parent.

Mutation

A random change in the sequence of nucleotides in regions of DNA that controls the expression of a gene.

Recombination

The reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material.

Evolution

Change in allele frequency over time.

Genetic drift

A process that occurs when genetic variation is lost due to random variation in mating, mortality, fecundity, and inheritance.

Bottleneck effect

A reduction of genetic diversity in a population due to a large reduction in population size.

Founder effect

When a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation.

Hardy Weinberg Principle

A model used to quantify evolution; assumes no evolution.

Gene pool

All the copies of all alleles in a population.

Fitness/Relative fitness

Genetic contribution to the next generation; fitness compared to other individuals.

Selection

The process by which certain phenotypes are favored to survive and reproduce over other phenotypes.

Stabilizing selection

When individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes.

Directional selection

When individuals with extreme phenotypes experience higher fitness than the average population phenotype.

Disruptive selection

When individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype.

Microevolution

The evolution of populations.

Artificial selection

Selection in which humans decide which individuals will breed; breeding is done with a preconceived goal for the traits in the population.

Industrial melanism

A phenomenon in which industrial activities cause habitats to become darker due to pollution; individuals possessing darker phenotypes are favored by selection.

Macroevolution

Evolution at higher levels of organization including species, genera, families, orders, and phyla.

Speciation

The evolution of new species.

Phylogenetic trees

Hypothesized patterns of relatedness among different groups such as populations, species, or genera; depict which groups evolved from other groups.

Allopatric speciation

The evolution of new species through the process of geographic isolation.

Sympatric speciation

The evolution of new species without geographic isolation.

Polyploid

A species that contains three or more sets of chromosomes; can also give rise to sympatric speciation.

Shared ancestral character (symplesiomorphy)

A character that originated in an ancestor of the taxon

Shared derived character (synapomorphy)

An evolutionary novelty unique to a particular clade

Plesiomorphy

Ancestral trait

Apomorphy

Derived trait

Autapomorphy

A derived character that is unique to a single taxon in our data set