Molecular Evolution and Speciation

Flashcards covering key concepts from the lecture on molecular evolution and species concepts.

Molecular Clock

Uses neutral mutations to estimate time of divergence between species.

Neutral Mutations

Mutations that do not affect an organism's fitness, accumulating at a steady rate.

Incomplete Lineage Sorting

Occurs when a single gene tree does not match the species tree due to random allele loss.

Hox Genes

Master control genes that serve as blueprints for body segments and are highly conserved across animals.

Transcription Factors

Proteins that switch genes on or off, affecting gene expression and trait development.

Gene Recruitment

The process where a spare gene copy is repurposed for a new function.

Convergent Evolution

When unrelated species evolve similar traits due to similar environmental pressures.

Parallel Evolution

When related species evolve similar traits independently using the same genes.

Biological Species Concept (BSC)

Defines a species as a group that can interbreed and is reproductively isolated.

Morphological Species Concept

Defines species based on physical appearance.

Phylogenetic Species Concept

Defines a species as the smallest group sharing a common ancestor.

Hybrid Sterility

A condition where offspring are healthy but cannot breed, exemplified by mules.

Allopatric Speciation

Speciation caused by geographic separation between populations.

Sympatric Speciation

Speciation that occurs in the same geographic area, often due to polyploidy or habitat differentiation.

Prezygotic Barriers

Factors that prevent mating or fertilization between species.

Postzygotic Barriers

Factors that affect the viability or fertility of hybrid offspring after mating.

Speciation Types

Different pathways through which new species arise, including allopatric and sympatric speciation.