Chapter 24: AP Biology

Speciation

Origin of new species; key evolutionary process.

Evolutionary Theory

Explains species origin and population evolution.

Microevolution

Allele frequency changes within a population.

Macroevolution

Large-scale evolutionary changes above species level.

Biological Species Concept

Species defined by interbreeding and viable offspring.

Reproductive Isolation

Biological barriers prevent species from interbreeding.

Hybrid

Offspring from crosses between different species.

Prezygotic Barriers

Prevent fertilization before zygote formation.

Postzygotic Barriers

Prevent hybrid offspring from developing or reproducing.

Hybrid Breakdown

F1 hybrids fertile; later generations less viable.

Hybrid Sterility

Viable hybrids that are sterile due to chromosomal differences.

Hybrid Inviability

Hybrid embryos fail to develop or survive.

Habitat Isolation

Species prefer different habitats, reducing encounters.

Temporal Isolation

Different breeding schedules prevent reproduction.

Behavioral Isolation

Species fail to recognize each other as mates.

Mechanical Isolation

Incompatible sexual organs prevent reproduction.

Gametic Isolation

Sperm and egg incompatibility prevents fertilization.

Morphological Species Concept

Defines species by shared structural traits.

Ecological Species Concept

Species defined by ecological niche and interactions.

Phylogenetic Species Concept

Species as smallest group sharing a common ancestor.

Allopatric Speciation

Geographic isolation leads to new species formation.

Sympatric Speciation

New species form without geographic separation.

Punctuated Equilibrium

Long periods of stasis interrupted by rapid change.

Gradualism

Continuous, slow evolutionary changes over time.

Polyploidy

Organisms with extra chromosome sets due to meiosis errors.

Autopolyploidy

Extra chromosome sets arise within a single species.

Allopolyploidy

Extra chromosome sets from hybridization between species.

Habitat Differentiation

Population exploits new niche, leading to isolation.

Sexual Selection

Mate choice based on specific traits influences speciation.

Genetic Basis of Speciation

Speciation results from changes in one or many genes.