Evolutionary Biology and Phylogenetics Flashcards

Comprehensive vocabulary flashcards covering evolutionary mechanics, historical figures, evidence for evolution (including cetacean fossils), and phylogenetic concepts.

Homology

Similar traits or body structures inherited from a shared common ancestor.

Vestigial trait

A reduced or modified body structure inherited from ancestors that has lost most or all of its original function.

Divergence

An evolutionary pattern where related organisms become increasingly different over time.

Convergence

An evolutionary pattern where unrelated organisms independently evolve similar traits due to living in similar environments or facing similar selective pressures.

Transitional organisms

Organisms that highlight close relationships and show a mix of traits, with some being 'newer' (derived) and some 'older' (ancestral).

Ring species

Populations of organisms where neighboring populations can interbreed, but the populations at the two ends cannot, illustrating gradual speciation.

Radioactive isotope

Unstable forms of elements that break down over time, used to measure the ages of rocks and fossils.

Microevolution

Small-scale changes in allele frequencies within a population over a short period or over generations.

Macroevolution

Large-scale evolutionary changes over long periods, including the formation of new species and higher taxonomic groups.

Natural selection

The primary process of adaptive evolution in which individuals with helpful inherited traits are more likely to survive and reproduce.

Artificial selection

The practice where humans select organisms with desired traits to reproduce, such as in dog breeding and agricultural crops.

Carl Linnaeus

An 18th-century Swedish scientist who developed modern taxonomy to classify organisms and believed species did not change.

Jean-Baptiste Lamarck

An early French naturalist who supported the idea that species change over time through acquired characteristics.

Charles Darwin

An 19th-century English naturalist who proposed that species share a common ancestor and evolve over time through natural selection.

Thomas Malthus

A British economist whose book on population growing faster than available resources inspired Darwin's ideas on competition for survival.

Charles Lyell

A 19th-century Scottish geologist who supported uniformitarianism, arguing that slow geological processes active today were also active in the past.

Alfred Russel Wallace

A 19th-century British naturalist who independently arrived at the idea of natural selection.

Acquired characteristics

Traits developed by an organism during its lifetime due to environmental factors or experience, which are not passed on to offspring.

Inherited characteristics

Traits passed from parents to offspring through genes.

Orthogenesis

An outdated idea proposing that evolution naturally proceeds in a fixed direction due to an internal force within organisms.

Gradualism

The proposition that evolutionary change occurs incrementally through small steps over long periods.

Modern Synthesis

The integration in the 1930s and 1940s of Darwinian natural selection with Mendelian genetics and population genetics.

Scientific fact

An observation that has been repeatedly confirmed.

Scientific hypothesis

A testable proposed explanation for an observation.

Scientific law

A statement describing a consistent, observable pattern in nature.

Scientific theory

A broad, well-supported explanation for how or why natural phenomena occur, backed by extensive evidence and testing.

Adaptation

An inherited feature that enhances an organism's survival and reproduction within a specific environment.

Descent with modification

The concept that organisms inherit traits from ancestors, but these traits accumulate changes over generations.

Transmutation

An older term referring to the transformation of one species into another over time.

Blending inheritance

An outdated hypothesis that parental traits permanently blend together in offspring.

Catastrophism

The geological concept that Earth's historical features were formed primarily by sudden, high-magnitude disasters.

Uniformitarianism

The geological principle that current natural physical processes operate at the same rates and in the same manner as in the past.

Arrector pili

Small muscles attached to hair follicles that contract to make hair stand erect, causing goosebumps.

Auditory bullae

Dense skull bones surrounding and protecting parts of the middle ear; crucial diagnostic features in fossil whales.

Order Cetacea

A group of aquatic mammals including whales, dolphins, and porpoises.

Order Artiodactyla

The group of even-toed hoofed mammals (e.g., hippos, deer, cows) to which whales are closely related.

Astragalus

An ankle bone with a double-pulley shape unique to artiodactyls, found in fossil whales and confirming their evolutionary origin.

Mandibular foramen

An opening in the lower jaw through which nerves and blood vessels pass, housing a fat pad used by whales for underwater hearing.

Great Chain of Being

An ancient, incorrect concept depicting all living organisms arranged in a static, linear hierarchy from 'lower' to 'higher'.

Homoplasy

Phenotypic similarity between species caused by convergent evolution or reversal rather than shared ancestry.

Reversal

An evolutionary event where a lineage reverts from a derived trait back to an ancestral character state.

Pakicetus

A wolf-sized, semi-aquatic whale ancestor from around 48–52 mya with terrestrial limbs and whale-like features in its ear structure.

Ambulocetus natans

A 49-million-year-old transitional whale ('walking whale that swims') that moved on land and swam using spine undulation and hind feet propulsion.

Rodhocetus kasrani

A 46–47 million-year-old fossil whale adapted to shallow marine environments, possessing long webbed feet, reduced limbs, and a flexible spine.

Basilosaurus

A fully aquatic ancient whale species from ~38 mya reaching ~56 feet in length, featuring tiny, disarticulated hind limbs.

Sister taxa

Two phylogenetic lineages that branch from the same immediate common ancestor.

Terminal node

The endpoint of a branch on a phylogenetic tree representing an extant or extinct taxon under study.

Internal node

A point on a phylogenetic tree representing an ancestral population that split into two or more lineages.

Branch

A line on a phylogenetic tree representing an evolutionary lineage connecting nodes.

Root

The base of a phylogenetic tree representing the most recent common ancestor of all taxa in the tree.

Outgroup

A taxon outside the group of interest used to determine the ancestral state of traits.

Cladistics

A taxonomic method that classifies organisms into clades based on shared derived character states.

Monophyletic group

A clade containing an ancestral species and all of its evolutionary descendants.

Topology

The specific pattern of branching connections in a phylogenetic tree.

Synapomorphy

A shared derived character state inherited from the immediate common ancestor of a monophyletic group.

Character matrix

A structured table listing organisms as rows and character traits as columns used in phylogenetic analysis.

Character state

A specific condition or variant of a particular trait.

Paraphyletic group

A group of organisms containing a common ancestor but excluding some of its descendants.

Polytomy

A node in a phylogenetic tree with more than two immediate descendant lineages, indicating unresolved evolutionary relationships.

Parsimony

The rule in phylogenetic analysis preferring the tree topology that requires the fewest total evolutionary changes.

Anagenesis

Evolutionary change occurring within a single lineage over time without branching into separate lineages.

Cladogenesis

Evolutionary change characterized by the branching or splitting of a lineage into two or more distinct lineages.

Crocoduck

A mythical hybrid creature used fallaciously by critics to misrepresent evolution as creating direct combinations of modern species.