Bio 104 test 1

When humans have modified other species by selecting and breeding individuals with desired traits.

The outcome of natural selection: modifications accumulated from generation to generation that can ultimately result in new species.

Change in allele frequencies in a population over time.

• • #1: Members of a population often vary greatly intheir traits
• • #2: Traits are inherited from parents to offspring
• • #3: All species are capable of producing moreoffspring than the environment can support
• • #4: Owing to lack of food or other resources, manyof these offspring do not survive

• Direct observations of evolution
• The fossil records
• Homology
• Biogeography

Heritable traits that increase an individual's fitness.

Mechanism of evolution theorized by Darwin and Wallace. Individuals whose heritable traits enable them to survive in their environment and successfully produce offspring which themselves survive and reproduce well will contribute a greater proportion of their genes to the next generation, leading to changes in allele frequencies through time.

Genetic variation refers to diversity in gene frequencies.

• Changes to allele frequencies within species or populations.
• consists of adaptations that evolve within a population, confined to one gene pool

refers to evolutionary change above the species level, this is the cumulative effect of many speciation and extinction events. Reproductive isolation.

Genetic changes in a population due to random processes, (catastrophe)  such as a founder event, in which only a few individuals (and their specific subset of the genes in a population) start a new population.

Type of genetic drift. A subsample of the original population has different allele frequencies from the parent population.

A form of genetic drift that occurs as a result of a rapid decrease in the gene pool of a population; usually associated with a rapid decrease in effective population size, that decreases genetic diversity and potentially decreases population fitness because negative alleles may accumulate

Mechanism of evolution involving the transfer of alleles between populations

A single mutation on a strand of DNA can still produce the same amino acid when transcribed into RNA, then translated by the ribosome.

Maintains genetic variation in the formof hidden recessive alleles

favors individuals at one end of the phenotypic range

favors individuals at both extremes of the phenotypic range

favors intermediate variants and acts against extreme phenotypes

is competition among individuals of one sex (often males) for mates of the opposite sex.

often called mate choice, occurs when individuals of one sex (usually females) are choosy in selecting their mates

• 1. Selection can act only on existing variations
• 2. Evolution is limited by historical constraints
• 3. Adaptations are often compromises
• 4. chance: natural selection and the
• environmentinteract

• is a group of populations whose members have the potential to interbreed in nature andproduce viable, fertile offspring; they do not breed successfully with other populations.
• Only used for sexual creatures.

defines a species by structural features

views a species in terms of its ecological niche

defines a species as thesmallest group of individuals on a phylogenetic tree

Gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations.

Allo = Other site

Example: A flood creates a river with two different ecosystems on both sides.

Takes place in geographically overlapping populations. Example: birds living together but recognizing only certain mating calls.

It is a region in which members of different species mate and produce hybrids

• When closely related species meet in a hybridzone, there are three possible outcomes:
• – Reinforcement or strengthening of reproductive barriers
• – Fusion or weakening of reproductive barriers
• – Stability or continued formation of hybrid individuals

is the accumulation of differences between groups which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection.

Example: Darwin's Finches

describes the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups. 

Example: Bats, birds, and insects have all evolved wings separately.

Smooth, gradual evolutionary change.

Species traits relatively constant, interrupted by brief, sudden, and abrupt strong selective pressures. Most of the time evolution is in stasis.

Evolutionary process by which populations diverge to form new species. Affected by environment.