Bio 94 Mid 1 Key Terms

fitness

The ability of an individual to produce viable offspring relative to others of the same species.

adaptation

Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment.

phylogeny

The evolutionary history of a group of organisms.

luca

The last universal common ancestor of cells. This theoretical entity is proposed to be the product of chemical evolution and provided characteristics of life that are shared by all living organisms on Earth today

eukaryote

A member of the domain Eukarya; an organism whose cells contain a nucleus, numerous membrane-bound organelles, and an extensive cytoskeleton. May be unicellular or multicellular

prokaryote

A member of the domain Bacteria or Archaea; a unicellular organism lacking a nucleus and containing relatively few organelles or cytoskeletal components

taxonomy

The branch of biology concerned with describing, naming, and classifying goups of organisms.

scientific name

two parts, made of genus followed by species name

null hypothesis

A hypothesis that specifies what the results of an experiment will be if the main hypothesis being tested is wrong. Often states that there will be no difference between experimental groups.

control

In a scientific experiment, a group of organisms or samples that do not receive the experimental treatment

population

In a scientific experiment, a group of organisms or samples that do not receive the experimental treatment

evolution

In a scientific experiment, a group of organisms or samples that do not receive the experimental treatment

population thinking

A way of thinking that emphasizes the importance of variation among individuals in a population

fossil

Any physical trace of an organism that existed in the past. Includes tracks, burrows, fossilized bones, casts, and so on; in sedimentary rock

sedimentary rocks

A type of rock formed by gradual accumulation of sediment, particularly sand and mud, as in riverbeds and on the ocean floor. Most fossils are found here

transitional feature

A trait that is intermediate between a trait observed in ancestral (older) species and the homologous trait observed in derived (younger) species.

vestigial structure

A reduced or incompletely developed structure that has no function, or reduced function, but is clearly similar to functioning organs or structures in ancestral or closely related species.

homology

Similarity among organisms of different species due to shared ancestry.

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 (e.g., limbs, flowers) that are due to inheritance from a common ancestor

artificial selection

Deliberate manipulation by humans, as in animal 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 individuals 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 trade-off

an inescapable compromise between two traits that cannot be optimized simultaneously; e.g. a peacock with bright feathers attracts a mate but also predators

genetic correlation

A type of evolutionary constraint in which selection on one trait causes a change in another trait as well

population genetics

The branch of evolutionary biology responsible for investigating processes that cause changes in allele and genotype frequencies in populations.

gene pool

All the alleles of all the genes in a certain population.

hardy-weinberg equilibrium

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

no genetic drift, no gene flow, random mating, no migration, no mutations

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; tends to reduce genetic variation in a population

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 middle of the range of phenotypic variation. Reduces overall genetic variation in a population

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.

balancing selection

A mode of natural selection in which no single allele is favored over time and across locations, on average.

heterozygote advantage

A pattern of natural selection that favors heterozygous individuals compared with homozygotes.

frequency-dependent selection

A pattern of selection in which certain alleles are favored only when they are rare; a form of balancing selection; A pattern of selection in which certain alleles are favored only when they are rare; a form of balancing selection

intersexual selection

female choice; individual of one sex chooses an individual of the other sex

intrasexual selection

(usually) male competition; A type of sexual selection driven by competition among members of one sex

sexual dimorphism

Any trait that differs between males and females; explains why some traits differ between sexes of the same species

sexual polymorphism

Any trait that occurs in two or more forms among females and males in a population.

genetic drift

Any change in allele frequencies due to chance; eventually can lead to the fixation or loss of alleles

founder effect

A change in allele frequencies that often occurs when a new population is established from a small group of individuals (founder event) due to sampling error (the small group is not a representative sample of the source population)

genetic bottleneck

A reduction in the diversity of alleles in a population resulting from a sudden decrease in the size of that population (population bottleneck) due to a random event.

gene flow

The movement of alleles between populations; occurs when individuals leave one population, join another, and breed.

mutation

Any permanent change in the hereditary material of an organism (DNA in most organisms, RNA in some viruses). The only source of new alleles in populations.

point mutation

A mutation that results in a change in or an insertion or deletion of a single base pair in DNA.

chromosome level mutation

change in number or composition of chromosomes

lateral gene transfer

Transfer of DNA between two different species rather than parent to offspring