Vocabulary Flashcards: Evolution, Speciation, Phylogeny, and Animal Form & Function

A comprehensive set of vocabulary terms and concise definitions covering evolution, speciation, phylogeny, and animal form and function as presented in the notes.

Evolution

Change in heritable traits of a population over generations due to variation and selection.

Natural selection

Differential survival and reproduction of individuals with favorable heritable traits.

Adaptation

A heritable trait that increases an organism's fitness in its environment.

Descent with modification

Darwinian idea that new species arise from old ones through accumulated changes.

Fitness

An individual's reproductive success or contribution of its genes to the next generation.

Inheritance of acquired characteristics

Lamarck idea that environment induced changes can be inherited; now discredited.

Convergent evolution

Independent evolution of similar traits in unrelated lineages due to similar pressures.

Divergent evolution

Evolution of related lineages into different forms from a common ancestor.

Homologous structures

Structures with similar embryonic origin indicating shared ancestry.

Vestigial structures

Remnants of traits that were functional in ancestors but are reduced now.

Analogy (homoplasy)

Similar features arising independently in different lineages due to similar pressures.

Fossils

Preserved remains used to trace historical changes and transitions.

On the Origin of Species

Darwin book (1859) presenting evolution by natural selection.

Linnean Society papers

1858 joint presentation by Darwin and Wallace on natural selection.

Biological species concept

Species are groups of interbreeding populations producing fertile offspring.

Reproductive isolation

Barriers that prevent gene flow between populations.

Prezygotic barriers

Barriers that prevent fertilization before zygote forms.

Postzygotic barriers

Barriers after fertilization such as hybrid inviability or sterility.

Allopatric speciation

Speciation due to geographic separation of populations.

Vicariance

Geographic barrier that physically splits a population.

Dispersal

Movement of individuals to a new area creating a new population.

Sympatric speciation

Speciation within a shared geographic area without barriers.

Polyploidy

Having extra complete chromosome sets; common in plant speciation.

Autopolyploidy

Polyploidy arising within a single species.

Allopolyploidy

Polyploidy via hybridization between species.

Hybrid inviability

Hybrids fail to develop or survive.

Hybrid sterility

Hybrids survive but cannot reproduce.

Adaptive radiation

Rapid diversification from a single ancestor into many niches.

Island biogeography

Islands promote isolation and diversification of species.

Founder effect

Change in allele frequencies when a new population starts from a small group.

Bottleneck effect

Sudden population size reduction changing allele frequencies by chance.

Polymorphism

Existence of two or more alleles or forms in a population.

Genetic variance

Total genetic variation present in a population.

Heritability

Proportion of phenotypic variation due to genetic differences.

Hardy-Weinberg

Principle that allele and genotype frequencies remain constant in a non evolving population; p+q=1 and p^2+2pq+q^2=1.

Mutation

Change in DNA that introduces new alleles and variation.

Gene flow

Movement of alleles among populations via migration of individuals or gametes.

Genetic drift

Random fluctuations in allele frequencies, stronger in small populations.

Nonrandom mating

Mating patterns that are not random, altering genotype frequencies.

Stabilizing selection

Favors intermediate phenotypes and reduces variation.

Directional selection

Shifts a population toward one extreme phenotype.

Diversifying (disruptive) selection

Favors extreme phenotypes over intermediates.

Frequency dependent selection

Fitness of a phenotype depends on its frequency in the population.

Sexual selection

Selection based on mating success leading to traits that may reduce survival.

Monophyly

A group that includes a common ancestor and all its descendants.

Clade

A monophyletic group within a phylogenetic tree.

Monophyletic

Describing a group that contains an ancestor and all its descendants.

Synapomorphy

Shared derived character that defines a clade.

Maximum parsimony

The simplest evolutionary explanation with the fewest changes.

Binomial nomenclature

Two part Latin name for a species: genus and species.

Domain

Highest taxonomic rank; three domains: Bacteria, Archaea, Eukarya.

Kingdom

Second highest taxonomic rank within a domain.

Phylum

Major taxonomic category below kingdom.

Class

Taxonomic category below phylum.

Order

Taxonomic category below class.

Family

Taxonomic category below order.

Genus

Taxonomic category below family; first part of a species name.

Species

Fundamental unit of classification; interbreeding and fertile offspring.

Subspecies

Geographically or morphologically distinct populations within a species.

Phylogeny

Evolutionary history and relationships among organisms.

Systematics

Study that integrates data to understand evolutionary relationships.

Phylogenetic tree

Diagram showing evolutionary relationships and history.

Rooted tree

Phylogenetic tree with a common ancestor at the base.

Unrooted tree

Phylogenetic tree showing relationships without a designated ancestor.

Sister taxa

Two descendants that split from the same branch point.

Branch point (node)

Location on a phylogenetic tree where lineages diverge.

Clade

Monophyletic group that shares a common ancestor.

Synapomorphy

Shared derived trait defining a clade.

Maximum parsimony

Method choosing the simplest explanation with the fewest changes.

Synapomorphy

Shared derived character that defines a clade.

Eukarya

One of the three domains; organisms with complex cells.

Binomial nomenclature

Two part name used for species; genus and species.

Amniotic egg

Egg with protective membranes; a trait defining the Amniota clade.

Endotherm

Animal that maintains a constant body temperature via internal heat.

Ectotherm

Animal whose body temperature follows the environment.