Lecture flashcards: Speciation, Evolution, and Phylogenetics (Darwin's finches, allopatric/sympatric, adaptive radiation)

A set of practice flashcards covering speciation concepts (allopatric and sympatric), reproductive isolation, adaptive radiation, polyploidy, phylogenetics, and related evolutionary topics drawn from the notes.

What is the Biological Species Concept?

A species is a group that can interbreed and produce fertile offspring.

Name three other species concepts mentioned in the notes.

Morphological, ecological, and genetic species concepts.

List the prezygotic isolation mechanisms.

Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation.

List the postzygotic isolation barriers.

Reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

What is prezygotic isolation?

Barriers that prevent fertilization from occurring before or during mating.

What is postzygotic isolation?

Barriers that occur after fertilization, reducing the fitness of hybrids.

Name two Heliconius species mentioned in the notes.

H. cydno and H. melpomene (also listed: H. sapho, H. pachinus, H. hewitsoni, H. erato).

Define allopatric speciation.

Speciation that occurs when populations become geographically isolated.

What are the two processes that cause allopatric speciation?

Dispersal (colonization) and vicariance (geographic barrier formation).

What is geographic isolation?

A physical barrier that splits populations and prevents gene flow.

What causes divergence in allopatric speciation?

Mutation, genetic drift, and natural selection.

What does genetic isolation mean in the context of allopatric speciation?

The isolated populations become genetically distinct and reproductively incompatible.

What geological event facilitated allopatric speciation about 3.5 million years ago?

The rise of the Isthmus of Panama, separating Caribbean and Pacific populations.

What is vicariance?

A geographic barrier splits a population into subgroups, leading to divergence.

What is sympatric speciation?

Speciation that occurs in the same geographic area without physical separation.

Name external factors that promote sympatric speciation.

Ecological isolation and mate selection.

Name internal factors that promote sympatric speciation.

Chromosomal mutations leading to polyploidy and instant reproductive isolation.

What is polyploidy?

Having more than two complete sets of chromosomes.

How can polyploidy drive sympatric speciation?

Chromosome doubling creates a reproductively isolated lineage from the parent population.

Give examples of crops where polyploidy is common.

Cotton, oats, potatoes, bananas, peanuts, barley, plums, apples, sugarcane, coffee.

What is adaptive radiation?

Rapid diversification of an ancestral species into many new forms.

Which group is a classic example of adaptive radiation in Africa?

Cichlid fishes in Lake Victoria.

What is microevolution?

Change in allele frequencies within populations over time.

What is macroevolution?

Evolution above the species level over longer timescales.

Differentiate background extinctions from mass extinctions.

Background extinctions are ongoing, routine losses; mass extinctions involve the loss of a large proportion of species (e.g., ~90%).

What is a monophyletic group?

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

What is the difference between homologous and analogous characters?

Homologous traits arise from shared ancestry; analogous traits arise from convergent evolution and do not reflect shared ancestry.

Do phylogenies change with new data?

Yes, especially with molecular data that can revise evolutionary relationships.

What is the purpose of phylogenetic trees?

To show evolutionary relationships among species and higher taxa.

How is phylogenetics relevant to disease evolution?

Phylogenetics helps trace the evolution and spread of pathogens.

What is the Anthropocene?

An epoch characterized by significant human impact on Earth's geology and ecosystems.

What are punctuated equilibrium and gradualism in evolution?

Punctuated equilibrium: long stasis with brief rapid changes; gradualism: slow, steady evolutionary change.

What is allopatric speciation by dispersal?

A small group migrates to a new area, becomes geographically isolated, and diverges.

What is allopatric speciation by vicariance?

A geographic barrier splits a population, leading to divergence.