BIO182 EX2

Adaptation: A heritable trait that enhances an organism's survival and reproduction in its specific environment.

Allele Frequency: The proportion of a particular allele (variant of a gene) within a population.

Allopatric Speciation: The formation of new species through geographic isolation of populations, which prevents gene flow.

Analogous Structures: Features in different species that have similar functions but evolved independently and do not share a recent common ancestor.

Artificial Selection: The process by which humans intentionally breed organisms with desirable traits.

Behavioral Isolation: A prezygotic reproductive barrier based on differences in courtship rituals or other behaviors that prevent interbreeding between species.

Biological Fitness: An individual's ability to survive and produce viable, fertile offspring relative to other individuals in the population.

Bottleneck Effect: A form of genetic drift that occurs when a sudden reduction in population size leads to a loss of genetic diversity and a non-representative allele frequency in the surviving population.

Clade: A group of organisms that includes a common ancestor and all of its descendants (a monophyletic group).

Cladistics: A method of classifying organisms into groups (clades) based on shared derived characteristics (synapomorphies).

Cladogram: A branching diagram that illustrates the hypothesized evolutionary relationships between taxa based on cladistic analysis.

Convergent Evolution: The independent evolution of similar traits in distantly related species due to adaptation to similar environments or ecological niches.

Directional Selection: A mode of natural selection that favors one extreme phenotype over other phenotypes, causing a shift in the population's trait distribution.

Dispersal: A form of allopatric speciation where a small number of individuals colonize a new geographic area, leading to reproductive isolation from the original population.

Divergent Evolution: The process by which populations of a common ancestor evolve and accumulate differences, potentially leading to speciation.

Evolution: Change in the allele frequency of a population over time.

Fixation: The point at which an allele has a frequency of 100% in a population, and all other alleles for that gene have been lost.

Founder Effect: A form of genetic drift that occurs when a new population is established by a small number of individuals, who may carry a non-representative subset of the alleles from the parent population.

Gametic Barrier: A prezygotic reproductive barrier where the eggs and sperm of different species are incompatible and cannot fuse to form a zygote.

Gene Flow: The movement of alleles between populations due to the migration of individuals or the dispersal of gametes.

Genetic Drift: Random fluctuations in allele frequencies from one generation to the next, particularly significant in small populations.

Gradualism: A model of speciation that proposes species diverge slowly and gradually over long periods through a series of intermediate forms.

Habitat Isolation: A prezygotic reproductive barrier where two species live in different habitats within the same geographic area and rarely encounter each other.

Hardy-Weinberg Equilibrium: A principle stating that the allele and genotype frequencies in a population will remain constant from generation to generation in the absence of certain evolutionary influences.

Homologous Structures: Features in different species that share a common underlying anatomical structure due to shared ancestry, although their function may have diverged.

Hybrid Inviability: A postzygotic reproductive barrier where hybrid offspring (resulting from the mating of two different species) fail to survive or develop.

Hybrid Zone: An area where closely related species interact and interbreed, forming hybrids.

Macroevolution: Evolutionary change on a large scale, encompassing the origin of new taxonomic groups at or above the level of species.

Microevolution: Evolutionary change within a population, such as changes in allele frequencies over generations.

Mutation: A permanent change in the DNA sequence of an organism.

Natural Selection: The differential survival and reproduction of individuals with certain heritable traits, leading to the accumulation of those advantageous traits in the population over time.

Nonrandom Mating: A pattern of mating in which individuals do not mate randomly; this can change genotype frequencies in a population.

Outgroup: A distantly related group of organisms used as a reference point when analyzing the evolutionary relationships of the ingroup.

Parapatric Speciation: The formation of new species from adjacent populations that experience reduced gene flow across a hybrid zone and diverge due to different selective pressures.

Peripatric Speciation: A form of allopatric speciation where a small, isolated population (often experiencing the founder effect) diverges from the main population.

Phylogenetic Tree: A branching diagram that represents the evolutionary relationships among a set of organisms or genes.

Phylogeny: The study of the evolutionary history and relatedness of organisms.

Polyphyletic Group: A grouping of organisms that does not include their most recent common ancestor; the group contains members with independent evolutionary origins for the included traits.

Postzygotic Barriers: Reproductive isolation mechanisms that occur after the formation of a hybrid zygote.

Prezygotic Barriers: Reproductive isolation mechanisms that prevent mating or block fertilization from occurring between different species.

Punctuated Equilibrium: A model of speciation that proposes species diverge relatively rapidly in short bursts of change, followed by long periods of stasis with little evolutionary change.

Reinforcement: The process by which natural selection strengthens prezygotic barriers to reproduction when hybrids between two species have low fitness.

Reproductive Isolation: The inability of two populations to interbreed and produce viable, fertile offspring, leading to the formation of distinct species.

Sexual Selection: A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

Sister Taxa: Two evolutionary lineages that share the most recent common ancestor in a phylogenetic tree.

Speciation: The process by which new biological species arise.

Stabilizing Selection: A mode of natural selection that favors intermediate phenotypes over extreme phenotypes, reducing phenotypic variation in the population.

Sympatric Speciation: The formation of new species within the same geographic area, typically due to reproductive isolation mechanisms that arise without physical separation.

Taxon (plural: Taxa): A unit of classification in biology, such as a species, genus, family, etc.

Temporal Isolation: A prezygotic reproductive barrier where two species breed during different times of day, different seasons, or different years, preventing interbreeding.

Vicariance: A form of allopatric speciation where a geographic barrier arises and divides a previously continuous population into two or more isolated populations.