Topic 8: Speciation Flashcards
Speciation
an ancestral species splits into two or more descendants species that are genetically different from one another and can no longer interbreed.
Microevolution
Evolution at the population level (allele frequency)
Macroevolution
broad patterns of evolutionary change above the species.
Biological Species Concept (BSC)
species is a group of individuals that can interbreed producing viable offspring, and are reproductively isolated from other species. Based on the potential to interbreed.
Morphological Species Concept
based on their physical appearances or structural traits.
Ecological Species Concept
Defined by its role in the environment.
Phylogenetic Species Concept
The smallest group of indivduals that share a common ancestor.
Prezygotic Barriers
Blocks fertilization from occurring.
Habitat isolation
Temporal isolation
Behavioural Isolation
Mechanical Isolation
Gamete Isolation
Habitat Isolation
Two species occupy different habitats
Temporal Isolation
Species breed at different times
Behavioural Isolation
Courtship rituals are unique to species
Mechanical Isolation
Morphological differences prevent successful mating.
Gamete Isolation
unable to fertilize the other species egg.
Postzygotic Barries
Prevents a hybrid from developing into a viable adult.
Reduced Hybrid Viability
Gene of parents species impair the hybrids development or survival
Reduced Hybrid Fertility
Even if hybrid are vigorous, they may be sterile.
Hybrid Breakdown
1st gen hybrid are fertile, but 2nd gen is feeble or sterile.
Allopatric Speciation
A population is geographically divided into two or more isolated groups that are prevented from interbreeding. Creates a reproductive barrier.
Sympatric Speciation
The evolution of a new species from an ancestral species while both continue to inhabit the same geographic region.
Polyploidy Speciation
Changes in the number of chromosomes sets creates genetically distinct descendants that are reproductively isolated from parental forms
Hybrid Speciation
Interbreeding between two related species creates genetically distinct descendants.
Causes of Sympatric Speciation
Habitat Difference, Sexual Selection
Allopolyploids
A species with multiple sets of chromosomes derived from the hybridization of different species. (double of parents)
Autopolyploids
An individual with more than two chromosome sets, derived from one species.
Hybrid Zones
Where the ranges of two speices overlap, allowing for limited interbreeding between genetically distinct populations.
