Evolutionary Biology, Population Genetics, and Speciation

A detailed set of vocabulary flashcards covering evolutionary mechanics, population genetics, Hardy-Weinberg equations, speciation barriers, and experimental logic based on lecture material.

Theory in Science

An overarching, tested, and predictive body of evidence supported by extensive observation and experimentation over time, such as evolution by natural selection.

Macaques

The highest level of primates currently permitted in scientific experimentation, replacing highly evolved species like chimpanzees due to shifting societal ethics.

On the Origin of Species

The seminal scientific work published by Charles Darwin in 1859 presenting the theory of evolution by natural selection following his voyage on HMS Beagle.

Gradualism

The geologic concept proposed by James Hutton in the 1700s stating that profound geological features formed slowly and step-by-step over vast spans of time.

Uniformitarianism

The geological principle advanced by Charles Lyell stating that the physical processes operating to shape the Earth today functioned in the same manner in the past.

Binomial Nomenclature

The hierarchical naming system developed by Carolus Linnaeus that assigns each species a two-part scientific name consisting of its genus and specific epithet.

Use and Disuse Hypothesis

Jean-Baptiste Lamarck's incorrect evolutionary mechanism proposing that structures used during an organism's life grow stronger and acquired traits are passed directly to offspring.

Lysenkoism

The rejected scientific doctrine pushed by Trofim Lysenko in the USSR under Stalin, which applied Lamarckian ideas to crops in an attempt to breed cold tolerance in Siberia.

Artificial Selection

The selective breeding of domesticated plants and animals by humans to encourage desirable traits, such as deriving broccoli, cabbage, and brussels sprouts from wild mustard.

Thomas Malthus

An English economist whose writings on human overpopulation, disease, and famine inspired Darwin's understanding of resource competition and overproduction in nature.

Plasmid

A small, circular ring of bacterial DNA separate from the main chromosome, which frequently accumulates mutations conferring antibiotic resistance in bacteria like MRSA.

Homologous Structures

Anatomical features in different species that share a common ancestral origin, such as the mammalian forelimb pattern of one bone, two bones, wrist bones, and digits.

Vestigial Structures

Remnant anatomical features that served important functions in an organism's ancestors but have lost their original function in modern descendants.

Convergent Evolution

The independent evolution of similar structural or functional adaptations in distantly related lineages driven by similar environmental challenges.

Sexual Selection

A form of natural selection in which individuals with specific inherited characteristics are more likely than others to obtain mates, such as the peacock's elaborate tail.

Founder Effect

A type of genetic drift that occurs when a small subset of a population separates to colonize a new location, establishing a new population with limited genetic diversity.

Bottleneck Effect

A drastic reduction in population size caused by a sudden, random event, which severely restricts genetic diversity and can trigger mutational meltdown.

Genotype

The complete genetic constitution and underlying allelic composition of an individual organism.

Phenotype

The observable physical, anatomical, physiological, and behavioral traits of an organism, upon which natural selection directly acts.

Heterozygosity

The proportion or percentage of individuals in a population that possess two different alleles for a given genetic locus.

Allele

A specific variant or alternate form of a gene at a particular locus.

Hardy-Weinberg Equilibrium

A model stating that allele and genotype frequencies in a population remain constant over generations unless specific evolutionary forces act upon neutral alleles.

Hardy-Weinberg Allele Frequency Equation

The formula $p + q = 1$, where $p$ represents the frequency of the dominant allele and $q$ represents the frequency of the recessive allele in a population.

Hardy-Weinberg Genotypic Frequency Equation

The formula $p^2 + 2pq + q^2 = 1$, where $p^2$ represents homozygous dominant individuals, $2pq$ represents heterozygotes, and $q^2$ represents homozygous recessive individuals.

Gene Flow

The movement and exchange of alleles between populations due to the migration of fertile individuals or gametes.

Relative Fitness

The contribution an individual makes to the gene pool of the next generation relative to the reproductive contributions of other individuals in the population.

Directional Selection

Natural selection favoring individuals at one phenotypic extreme, shifting a population's trait distribution toward that extreme over time.

Disruptive Selection

Natural selection favoring individuals at both extreme ends of a phenotypic spectrum over individuals with intermediate phenotypes.

Stabilizing Selection

Natural selection that favors intermediate variants by acting against extreme phenotypes, reducing overall variation for that trait.

Frequency-Dependent Selection

A mode of balancing selection where the fitness of a specific phenotype depends directly on how common or rare it is in the population.

Heterozygote Advantage

A situation in which heterozygous individuals have higher relative fitness than both homozygous dominant and homozygous recessive individuals, such as the $Hb^A Hb^S$ sickle-cell allele pair.

Biological Species Concept

Ernst Mayr's definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Prezygotic Barriers

Reproductive mechanisms that prevent fertilization or mating between different species, preventing the formation of a zygote.

Habitat Isolation

A prezygotic barrier occurring when two species occupy different habitats within the same geographic area and rarely or never encounter one another.

Temporal Isolation

A prezygotic barrier where species breed during different times of the day, different seasons, or different years.

Behavioral Isolation

A prezygotic barrier involving unique courtship rituals, calls, or behavioral displays required for mate recognition.

Mechanical Isolation

A prezygotic barrier caused by structural or anatomical incompatibilities in reproductive organs that physically prevent successful mating.

Gametic Isolation

A prezygotic barrier where molecular or biochemical incompatibilities prevent the sperm of one species from fertilizing the egg of another species.

Cell Theory

The fundamental concept in biology stating that all living organisms are composed of cells and that all modern cells arise from pre-existing cells.

Negative Feedback Loop

A primary homeostatic mechanism wherein a deviation from a set point triggers a physiological pathway that counteracts the change and ceases once the set point is restored.

Alfred Russel Wallace

The British naturalist who independently derived the theory of evolution by natural selection and sent his manuscript to Charles Darwin, prompting the publication of Darwin's findings.

Elephant Problem

Darwin's mathematical demonstration showing that a single pair of slow-reproducing elephants would yield $15,000,000$ descendants in $500$ years without environmental mortality, illustrating overproduction.

Inductive Reasoning

A form of logical thinking that uses specific observations or data points to construct broad general principles or hypotheses.

Deductive Reasoning

A form of logical thinking that applies general theories or established rules to predict specific testable results.

Independent Variable

The specific factor altered or manipulated by an experimenter in a hypothesis, represented as $x$ in the basic predictive model $x \rightarrow y$.

Dependent Variable

The variable measured or observed in an experiment to evaluate the effect of the independent variable, represented as $y$ in the basic predictive model $x \rightarrow y$.