Unit 4: Species, Variation and Speciation Flashcards
What are the 6 main concepts of species ?
1) Biological
2) Phylogenetically
3) Morphological
4) Ecological
5) Nominalism
6) Evolutionary significant units
What is a prezygotic barrier ?
Animals that have no chance to mate
What are the 4 main prezygotic isolation mechanisms that exist ?
- Geographical isolation
- Mechanical isolation
- Temporal isolation
- Behavioural isolation
What is a postzygotic barrier ?
Where there is incomplete fertilisation or infertile hybrids are produced
What are the 4 main postzygotic isolation mechanisms that exist ?
- Gamete incompatibility
- Hybrid mortality
- Hybrid breakdown (F2)
- Hybrid infertility (F1)
What is hybridisation ?
The formation of a new species or “extinction’ (Fusion) of 2 and more species
What are the 3 possible outcomes of hybridisation ?
- Reinforcement
- Fusion
- Stability
What is cladogenesis ?
Where a single species splits into two or more distinct species increasing biodiversity
What are the 6 features of speciation ?
- Variation
- Isolation
- Decreased gene flow
- Selection
- Divergence
- Speciation
What is the effect of point mutations near genes ?
- Change in proteins
- Change of gene regulation
What is the effect of duplications or deletions of genes ?
- Gene dose
- Formation of new genes
What is the effect of insertion of mobile elements in genes ?
- Gene regulation
- Protein structure
What are the 3 main sources of genetic variation at chromosome level ?
- Recombination
- Segregation
- Independent assortment
What is allopatric speciation ?
Speciation by geographical isolation that often has barriers that prevent two or more populations from mating
What is vicariance ?
The process by which a geographical barrier (such as a river) divides a population leading to speciation
