Lesson 1: Evolution and Speciation Flashcards
(26 cards)
What is evolution?
Changes in the heritable characteristics of organisms over generations.
What is natural selection?
The process where advantageous heritable traits become more common in a species over time.
What are conserved DNA regions?
DNA sequences that have changed very little over time.
What are homologous structures?
Body parts that look and function differently but share structural similarities.
What are the 3 evidences of evolution?
Homologous structures
Selective breeding
DNA sequences
What are analogous structures?
Structures with similar form and function, but different evolutionary origin.
What is speciation?
The development of new species from pre-existing species over time.
What must happen for speciation to occur?
Reproductive isolation
What is reproductive isolation?
When barriers prevent two populations from interbreeding.
What are the two main categories of reproductive isolation barriers?
Prezygotic isolation
Postzygotic isolation
What is prezygotic isolation?
Occurs before fertilisation can occur (no offspring are produced).
What is postzygotic isolation?
occurs after fertilisation (offspring are either not viable or infertile)
What are the types of prezygotic isolation?
Temporal, behavioural and geographic isolation.
What is temporal isolation?
When two populations reproduce at different times.
What is behavioural isolation?
When two populations exhibit different courtship behaviours or mating patterns.
What is geographic isolation?
When two populations live in different areas.
What is allopatric speciation?
Speciation that occurs when populations are geographically isolated from each other.
What is sympatric speciation?
Speciation that occurs in a single species while living in the same area.
Why does allopatric speciation lead to new species?
Different selection pressures and smaller/less diverse gene pool.
What causes sympatric speciation and requirements?
Meiotic failure during gamete formation. The polyploid offspring must be viable and fertile but cannot interbreed with the original parent population.
What do fertile polyploid offspring usually require?
Two polyploid parents.
Why can’t polyploids usually reproduce with the original parent population?
It produces offspring with an uneven number of chromosome sets, making them infertile.
What is adaptive radiation?
The rapid evolution of multiple species from a common ancestor.
What is polyploidy?
An organism has more than two complete sets of chromosomes in every cell.
