BIO 130 Flashcards
Theory
An explanation for a broad class of phenomena that is supported by a wide body of evidence. A theory serves as a framework for the development of new hypotheses.
Evolution
(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, and continue to change, via natural selection, genetic drift, gene flow, and mutation. (2) Any change in the genetic characteristic of a population over time, especially a change in allele frequencies.
Population Thinking
A way of thinking that emphasizes the importance of variation among individuals in a population; the opposite of typological thinking, which ignores variation or considers it unimportant.
Descent with modification
The phrase used by Darwin to describe how species that lived in the past are the ancestors of species existing today, and that species change through time.
Extant Species
a species that is living today
Transitional feature
A trait that is intermediate between a trait observed in ancestral species and the homologous trait observed in derived species
Vestigial Trait
A reduced or incompletely developed structure that has no function, or reduced function, but is nearly similar to functioning organs or structures in ancestral or closely related species.
Homology
Similarity among organisms of different species due to shared ancestry. Features that exhibit such similarity are said to be homologous.
Genetic Homology
Similarity in DNA nucleotide sequences, RNA nucleotide sequences, or amino acid sequences due to inheritance from a common ancestor
Developmental homology
A similarity in embryonic form or developmental processes that is due to inheritance from a common ancestor
Structural Homology
Similarities in adult organismal structures that are due to inheritance from a common ancestor
Morphology
The overall shape and appearance of an organism and its component parts
Artificial Selection
Deliberative manipulation by humans, as in animals and plant breeding, of the genetic composition of a population by allowing only individuals with desirable traits to reproduce
Natural Selection
The process by which individual with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution. The only evolutionary process that produces adaptation.
Fitness
The ability of an individual to produce viable offspring relative to others of the same species
Acclimatization
A change in an individuals phenotype that occurs in response to a change in natural environmental conditions.
Acclimation
A change in a study organisms phenotype that occurs in response to laboratory conditions
Fitness trade-off
In evolutionary biology, an inescapable compromise between two traits that cannot be optimized simultaneously.
Genetic Correlation
A type of evolutionary constraint in which selection on one trait causes a change I another trait as well; may occur when the same gene affect both traits.
Population genetics
The branch of evolutionary biology responsible for investigating processes that cause changes in allele and genotype frequencies in populations.
Natural Selection
Increases the frequency of certain alleles-the ones that contribute to reproductive success in a particular environment
Genetic Drift
Causes allele frequencies to change randomly. In some cases, drift may cause alleles that decrease fitness to increase in frequency
Gene flow
Occurs when individuals leave one population, join another, and breed. Allele frequencies may change when gene flow occurs, beaus arriving individuals introduce alleles to their new population and departing individuals remove alleles from their old population
Mutation
Modifies allele frequencies by continually introducing new alleles. The alleles created by mutation may be beneficial, deleterious(detrimental), or neutral in their effects on fitness.
Gene pool
All the alleles of all the genes in a certain population
Hardy-Weinberg Principle
A principle of population genetics stating that genotype frequencies in a large population do not change from generation to generation in the absence of evolutionary processes and nonrandom mating
Hardy-Weinberg Equilibrium
A state of agreement between observed allele frequencies in a population and allele frequencies predicted by the Hardy-Weinberg principle.
Random Mating
The model assumes that gates from the gene pool combine a random. Individuals are not allowed to choose a mate.
No natural Selection
The model assumes that all members f the parental generation survive and contribute equal numbers of gametes to the gene pool, no matter what their genotype.
No genetic Drift
The model assumes that alleles are picked in their exact frequencies p and q, and nit at different frequencies caused by chance-that is, the model behaves as though the population is infinitely large.
No gene flow
The model assumed that no new alleles are added by immigration or lost through emigration. As a result, all of the alleles in the offspring population come from the original population’s gene pool.
No mutation
The model assumes that no new alleles are introduced into the gene pool.
Inbreeding Depression
The decline ion average fitness that takes place when homozygosity increases and heterozygosity decreases in a population due to inbreeding; results from the exposure if deleterious recessive alleles to selection.
Sexual Selection
A type of natural selection that favors individuals with traits that increase their ability to obtain mates or choose good mates. Compare with ecological selection.
Directional Selection
A mode of natural selection that favors one extreme phenotype with the result that the average phenotype of a population changes in one direction. Generally reduces overall genetic variation in a population. Compare with disruptive selection and stabilizing selection.
Purifying Selection
Selection that lowers the frequency of, or even eliminates, deleterious alleles.
Stabilizing Selection
A mode of natural selection that favors phenotypes near the middles of the range of phenotypic variation. Reduces overall genetic variation in a population. Compare with disruptive selection and directional selection.
Disruptive Selection
A mode of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. Increases overall genetic variation in a population. Compare with stabilizing selection and directional selection.
Purifying Selection
Selection that lowers the frequency of, or even eliminates, deleterious alleles.
Stabilizing Selection
A mode of natural selection that favors phenotype near the middle of the range of phenotypic variation. Reduces overall genetic variation in a population. Compare with disruptive selection and directional selection.
Balancing Selection
A mode of natural selection in which no single allele is favored over time and across locations, on average. An overall balance of fitness and frequency is maintained among alleles.