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Speciation and extinction causes and processes

Inheritance, variation and evolution • The development of understanding of genetics and evolution

Key concepts

What you'll likely be quizzed about

  • A species is a group of organisms that can interbreed and produce fertile offspring.
  • New species arise when populations of the same species become reproductively isolated and accumulate genetic differences until interbreeding is no longer possible.
  • Speciation requires interruption of gene flow followed by divergence through mutation, selection, or drift.

Flashcards

Test your knowledge with interactive flashcards

How can disease drive extinction?

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Novel pathogens can rapidly kill significant portions of a population that lack immunity, quickly reducing numbers and potentially causing local or total extinction if recovery fails.

Key notes

Important points to keep in mind

Species are defined by the ability to produce fertile offspring; reproductive isolation creates new species.

Types of isolation: geographic, behavioral, temporal, and ecological; cause → no gene flow → divergence.

Natural selection and genetic drift alter allele frequencies; both can drive speciation based on population size and environment.

Small populations experience inbreeding and loss of variation, increasing extinction risk.

Habitat loss, overexploitation, invasive species, and rapid environmental change drive extinction; catastrophic events cause mass extinctions.

Fossils provide direct evidence of past species and extinction patterns; fossil record gaps may obscure gradual changes.

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