Unit 1 Terms and Concepts - Evolution and Speciation (Vocabulary)

Vocabulary flashcards covering key Unit 1 terms related to evolution, natural selection, speciation, and related concepts.

Evolution

Change in the heritable traits of a population over generations.

Natural Selection

Process by which heritable traits that improve reproductive success become more common in a population over time.

Charles Darwin

Naturalist who proposed natural selection as the mechanism of evolution; co-discoverer with Alfred Russel Wallace.

Jean-Baptiste Lamarck

Early 19th-century biologist who proposed inheritance of acquired characteristics.

Alfred Russel Wallace

Naturalist who independently conceived natural selection; jointly presented with Darwin.

Fossils

Preserved remains or traces of organisms from the past.

Strata

Layers of sedimentary rock that record chronological deposition and contain fossils.

Inheritance

Transfer of genetic material from parents to offspring.

Variation

Differences among individuals in a population.

Marine Iguana

Galápagos lizard adapted for foraging in marine environments; classic example in evolution.

Descent with Modification

Darwin’s idea that new species arise from common ancestors with changes over time.

Artificial Selection

Human-directed breeding to enhance specific traits.

Environment

External conditions that influence survival and reproduction.

Antibiotic-Resistant Bacteria

Bacteria that survive antibiotics due to resistance traits; example of natural selection.

Homology

Similarity due to shared ancestry, not function.

Vestigial Traits

Inherited structures with reduced or no current function (e.g., human appendix).

Appendix

Vestigial organ in humans with potential ancestral function; remnants of digestive tract.

Pax6 Gene

Developmental gene essential for eye formation; highly conserved across animals.

Biogeography

Geographic distribution of species and ecosystems through space and time.

Plate Tectonics

Theory that explains movement of Earth's lithospheric plates and related features.

Microevolution

Small-scale changes in allele frequencies within populations.

Macroevolution

Large-scale evolutionary changes above the species level, such as speciation.

Gene Flow

Transfer of alleles between populations via migration or interbreeding.

Genetic Drift

Random fluctuations in allele frequencies, especially in small populations.

Mutations

Heritable changes in DNA that create new genetic variation.

Alleles

Different forms of a gene at the same locus.

Gene Pool

Total collection of alleles in a population.

Hardy-Weinberg Equilibrium

Principle that allele and genotype frequencies stay constant in an ideal population with no evolution.

Random Mating

Mating without preference that affects genotype frequencies.

Founder Effect

Loss of genetic variation when a new population is started by a small number of individuals.

Bottleneck Effect

Sharp reduction in population size leading to reduced genetic variation.

Galápagos Finches

Darwin’s finches; diverse beak shapes reflect adaptive radiation to different niches.

Directional Selection

Natural selection that favors one extreme phenotype over others.

Disruptive Selection

Natural selection that favors extreme phenotypes over intermediates.

Stabilizing Selection

Natural selection that favors intermediate phenotypes, reducing variation.

Sexual Selection

Selection for traits that improve mating success, sometimes at a cost to survival.

Soapberry Bugs

Insects that show rapid evolution in beak length in response to host fruit changes.

Heterozygote Advantage

Heterozygous individuals have higher fitness than either homozygote.

Sickle Cell Anemia

Recessive disease; heterozygotes in malaria regions gain protection, illustrating balanced polymorphism.

Biological Species Concept

Species are groups of interbreeding natural populations that are reproductively isolated from others.

Reproductive Isolation

Barriers that prevent gene flow between species, either pre- or postzygotic.

Temporal Isolation

Reproductive isolation due to differences in timing of mating or flowering.

Behavioral Isolation

Prezygotic barriers based on differences in courtship or behavior.

Habitat Isolation

Prezygotic barriers due to populations occupying different habitats.

Hybrid

Offspring produced by two different species or varieties.

Allopatric Speciation

Speciation that occurs when populations are geographically separated.

Sympatric Speciation

Speciation without geographic separation; often via ecological or behavioral isolation.

Alpheus Shrimp

Genus of snapping shrimp; used in studies of speciation and communication.

Cichlid Fishes

Diverse group of fishes in African lakes; notable for rapid adaptive radiation.

Polyploidy

Having more than two complete sets of chromosomes; common in plants and can cause instant speciation.

Allopolyploid

Polyploid with chromosome sets from two different species.

Autopolyploid

Polyploid with multiple chromosome sets from the same species.

Apple Maggot Fly

Rhagoletis pomonella; host shift from hawthorn to apple leading to sympatric processes.

Hybrid Zone

Geographic area where two species meet and produce hybrids.