BIO120: Adaptation and Biodiversity - Vocabulary Review

Comprehensive vocabulary flashcards covering the fundamental concepts, mechanisms, and historical frameworks of evolutionary biology presented in BIO120 Lectures 1 through 8.

Biological Evolution

The change in inherited attributes of populations across generations.

Microevolution

Evolutionary patterns and processes observed within species.

Macroevolution

Evolutionary patterns and processes observed among species.

Biodiversity

The diversity of life on Earth; defined as the number and kinds of living organisms in a given area.

Adaptation (State)

Any trait that makes an organism better able to survive or reproduce in a given environment.

Adaptation (Process)

The evolutionary process that leads to the origin and maintenance of traits that make an organism better able to survive or reproduce in a given environment.

Uniformitarianism

The geological principle articulated by Charles Lyell stating that present-day geological processes (such as erosion, earthquakes, and volcanoes) can explain the history of the Earth.

Homology

Similarity of characteristics of two or more species that is due to inheritance from a common ancestor.

Vestigial Structures

Features inherited from an ancestor that are reduced in morphology and function, and are homologous to functional structures in related species.

Genotype

The genetic constitution of an organism defined in relation to a particular gene or gene combinations, specifying the identity of both alleles at a gene locus in diploids.

Phenotype

A feature or trait of an organism as observed (such as body size, fur color, enzyme activity, or mRNA expression level).

Genome

The entirety of an organism's DNA, including both protein-coding genes and non-coding regions.

Heterozygosity ($H$)

The fraction of individuals in a population that are heterozygous, averaged across gene loci.

Polymorphism ($P$)

The proportion of gene loci that possess $2$ or more alleles within a population.

Haplotype

A specific set of alleles located on a single chromosome that is inherited together from one parent.

Genetic Drift

Stochastic change in the frequency of an existing gene variant (allele) across generations due to random sampling chance, exerting stronger effects in small populations.

Fixation

The evolutionary state that occurs when a polymorphic locus becomes monomorphic due to the loss of all alternative alleles in a population.

Gene Flow

The movement of genetic material or alleles between populations.

Mutation-Selection Balance (Classical School)

A population genetics model proposing that mutation and purifying selection dominate evolution, keeping deleterious variants transient and maintaining low levels of polymorphism and heterozygosity.

Balancing Selection (Balance School)

A population genetics model proposing that natural selection actively maintains genetic diversity over the long term through mechanisms such as heterozygote advantage and frequency-dependent selection.

Neutral Theory

The theory formulated by Motoo Kimura stating that the vast majority of molecular genetic variation is selectively neutral, meaning alternative alleles do not differ in relative fitness.

Fitness (Darwinian Fitness)

The relative genetic contribution of an individual to the next generation compared to other individuals, resulting from differences in viability and fertility.

Selective Advantage

The degree to which individuals bearing a specific genotype are better adapted to a given environment, reflecting relative differences in fitness.

Agent of Selection

Any specific external factor (abiotic, biotic, or anthropogenic) that directly influences the differential survival and reproduction of individuals bearing a particular trait.

Stabilizing Selection

A mode of selection on quantitative traits that favors average or intermediate phenotypes while selecting against phenotypic extremes.

Directional Selection

A mode of selection on quantitative traits that favors individuals at one extreme of the phenotypic distribution, shifting the population mean over time.

Disruptive Selection

A mode of selection on quantitative traits that favors individuals at both phenotypic extremes while selecting against intermediate phenotypes.

Selective Sweep

An evolutionary process where strong positive selection drives a beneficial allele to increase rapidly in frequency, causing neutral alleles at closely linked flanking loci to hitchhike along with it.

Parthenogenesis

A form of asexual reproduction in which an embryo develops directly from an unfertilized egg.

Clonal Propagation

A form of asexual reproduction that produces genetic replicas of the parent organism without involving an egg.

Two-Fold Cost of Meiosis

The transmission disadvantage of sexual reproduction where a sexual female contributes only $50\%$ of her gene copies to each offspring compared to an equivalent asexual female.

Tangled Bank Hypothesis

A hypothesis for the maintenance of sexual reproduction proposing that genotypic diversity provides a competitive advantage in spatially heterogeneous environments.

Red Queen Hypothesis

A hypothesis for the maintenance of sexual reproduction proposing that continuous genetic variation is required for populations to adapt to temporally changing biological environments, such as co-evolving parasites.

Inbreeding

Mating between individuals that are more closely related than expected by chance in a randomly mating population.

Outbreeding

Mating between individuals that are less closely related than expected by chance in a randomly mating population.

Selfing (Self-Fertilization)

The fusion of male and female gametes derived from meiotic reductive division within a single individual; the most extreme form of inbreeding.

Inbreeding Depression

The reduction in viability and fertility observed in inbred offspring relative to outcrossed offspring, caused primarily by the increased homozygosity of recessive deleterious alleles.

Sexual Dimorphism

Systematic phenotypic differences between male and female individuals of the same species.

Primary Sex Characteristics

Anatomical structures and physiological traits that are directly involved in the production or transmission of gametes.

Secondary Sex Characteristics

Phenotypic traits that distinguish the sexes but are not directly involved in gamete production or transmission, often developing at sexual maturity or during the breeding season.

Sexual Selection

Differences in reproductive success among individuals resulting from competition for access to mates or fertilization opportunities.

Anisogamy

A reproductive system characterized by the production of two distinct gamete types differing in size: a large, nutrient-rich gamete (egg/ovule) and a small, motile gamete (sperm/pollen).

Intrasexual Selection

A form of sexual selection involving competition among members of the same sex (typically males) for access to mating or fertilization opportunities.

Intersexual Selection

A form of sexual selection where individuals of one sex (typically females) actively choose mates from among members of the opposite sex based on specific phenotypic displays.

Sensory Bias Hypothesis

The hypothesis proposing that female mate preferences evolve initially for non-reproductive reasons (such as food detection) and are subsequently exploited by male display traits.

Population

A group of individuals of a single species occupying a given geographic area at the same time.

Population Bottleneck

A sharp, temporary reduction in population abundance followed by a rebound, causing a stochastic loss of genetic diversity.

Founder Event

The establishment of a new population by a small number of colonizing individuals carrying only a subset of the genetic diversity found in the ancestral source population.

Isolation by Distance

The accumulation of local genetic differentiation between populations as a function of geographic distance, caused by geographically limited dispersal.

Phenotypic Plasticity

The capacity of a single genotype to produce different phenotypes in response to distinct environmental conditions through modifications in development, growth, or behavior.

Reciprocal Transplant Study

An experimental approach where genotypes from contrasting environments are grown across each environment to decouple genetic effects from environmental effects and test for local adaptation.