Campbell Biology: Evolution, Population Genetics, and Speciation

Comprehensive vocabulary flashcards covering evolutionary mechanisms, population genetics, and speciation based on Chapters 22, 23, and 24 of Campbell Biology.

Artificial Selection

The process by which humans modify other species over generations by selecting and breeding individuals that possess desired traits.

Natural Selection

A process in which individuals with certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Adaptation

An inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.

Methicillin-Resistant Staphylococcus aureus (MRSA)

A dangerous pathogenic strain of Staphylococcus aureus that evolved resistance to penicillin by 1945 and to methicillin by 1961.

Homology

Similarity in anatomical or molecular characteristics resulting from shared common ancestry.

Vestigial Structures

Remnants of features that served an important function in an organism's ancestors but have reduced or no function in the modern organism.

Evolutionary Tree

A branching diagram that reflects hypotheses about the evolutionary relationships among different groups of organisms.

Convergent Evolution

The independent evolution of similar, or analogous, features in distantly related lineage groups.

Analogous Traits

Characteristics that share similar function, but not common ancestry, arising when groups independently adapt to similar environments.

Microevolution

Evolutionary change below the species level, consisting of changes in allele frequencies in a population over generations.

Sexual Selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates.

Sexual Dimorphism

Marked differences between the secondary sex characteristics of males and females of the same species.

Intrasexual Selection

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

Intersexual Selection

Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice.

Good Genes Hypothesis

The hypothesis proposing that female mate preference evolves because the preferred male trait is an indicator of overall male genetic quality.

Balancing Selection

Natural selection that maintains two or more phenotypic forms in a population's gene pool.

Frequency-Dependent Selection

Selection in which the fitness of a phenotype depends on how common it is in the population.

Heterozygote Advantage

Greater reproductive success of heterozygous individuals compared to homozygous individuals, tending to preserve variation in a gene pool.

Directional Selection

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.

Disruptive Selection

Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than individuals with intermediate phenotypes.

Stabilizing Selection

Natural selection that favors intermediate variants by acting against extreme phenotypes.

Gene Pool

The aggregate of all copies of every allele at all loci in a population.

Hardy-Weinberg Equilibrium

The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work.

Genetic Drift

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next; most pronounced in small populations.

Founder Effect

Genetic drift that occurs when a few individuals become isolated from a larger population and establish a new population whose gene pool differs from the source population.

Bottleneck Effect

Genetic drift that occurs when the size of a population is drastically reduced by a sudden environmental change, leaving a surviving gene pool that is no longer genetically representative of the original population.

Gene Flow

The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.

Speciation

An evolutionary process by which one species splits into two or more species.

Macroevolution

Evolutionary change above the species level, including the origin of new groups of organisms through a series of speciation events.

Biological Species Concept

Definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such groups.

Reproductive Isolation

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring.

Hybrid

Offspring that results from the interspecific mating of individuals from two different species.

Prezygotic Barriers

Reproductive barriers that impede mating between species or hinder fertilization if mating is attempted.

Habitat Isolation

A prezygotic barrier in which two species encounter each other rarely or not at all because they occupy different habitats, even though they are not isolated by physical barriers.

Temporal Isolation

A prezygotic barrier in which species that breed at different times of the day, different seasons, or different years cannot mix their gametes.

Behavioral Isolation

A prezygotic barrier in which courtship rituals and other unique behaviors act as effective barriers to mating between species.

Mechanical Isolation

A prezygotic barrier in which morphological differences prevent the successful completion of mating.

Gametic Isolation

A prezygotic barrier in which the sperm of one species is unable to fertilize the eggs of another species.

Postzygotic Barriers

Reproductive barriers that prevent hybrid zygotes created by different species from developing into viable, fertile adults.

Reduced Hybrid Viability

A postzygotic barrier in which genes of different parent species interact and impair the hybrid's development or survival in its environment.

Reduced Hybrid Fertility

A postzygotic barrier in which hybrid offspring mature into healthy adults but are completely or largely sterile.

Hybrid Breakdown

A postzygotic barrier in which first-generation hybrids are viable and fertile, but their offspring in the next generation are feeble or sterile.

Morphological Species Concept

Definition of a species in terms of measurable anatomical and structural features.

Ecological Species Concept

Definition of a species in terms of its ecological niche, focusing on the sum of how members interact with nonliving and living parts of their environment.

Allopatric Speciation

The formation of new species in populations that are geographically isolated from one another.

Sympatric Speciation

The formation of new species in populations that live in the same geographic area.

Polyploidy

A chromosomal alteration in which an organism possesses more than two complete chromosome sets due to an accident during cell division.

Autopolyploid

An individual that has more than two chromosome sets derived from a single species.

Allopolyploid

A fertile individual or species with multiple sets of chromosomes derived from two different species.

Hybrid Zone

A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.

Reinforcement

In evolutionary biology, a process in which natural selection strengthens prezygotic barriers to reproduction, reducing the formation of unfit hybrids.

Fusion

A process in hybrid zones where substantial gene flow weakens reproductive barriers, causing two species to fuse back into a single species.

Stability

An outcome in a hybrid zone where hybrid individuals continue to be produced due to ongoing gene flow from parent populations outside the zone.

Punctuated Equilibria

In the fossil record, long periods of apparent evolutionary stasis in a species punctuated by sudden periods of rapid morphological change during speciation.