The definition of Speciation and Species
Speciation is the formation of a new species.
There are two different species concepts:
1. Biological Species Concept - This defines a species as a group of organisms with similar morphology and physiology that can interbreed to produce fertile offspring. CANNOT be used to classify organisms that reproduce assexually, and organisms only known as fossils, bones etc.
2. Phylogenetic (evolutionary) Species Concept - Species is a group of organisms that is geographically isolated and morphologically and behaviourally distinct from other species, although they may still be able to interbreed with individuals of different species.
Types of Speciation
Ecological barriers - There is a physical barrier seperating two groups of organisms, resulting in them evolving into different species. eg. mountain ranges.
Temporal barriers - Unable to interbreed due to being reproductively active at different times of the year.
Reproductive barriers - There are reasons why they cannot reproduce:
1. They have different courtship behaviour.
2. Mechanical problems with mating eg. size differences.
3. Gamete incompatibility - Gametes will not fuse to produce an zygote.
4. Zygote inviability - The zygote is unable to develop properly, so it dies.
5. Hybrid sterility - Any offspring are unable to produce gametes.