Overview on Hyperdiversity
Speciose Taxonomic Groups
Comparative Hyperdiversity
Resources

 

 


 

Speciation

The branching of evolutionary lineages is the process that results in an increase in species biodiversity.

Speciation is driven by theisolation of populations, which may be either allopatric or sympatric.
 
 

 


Allopatric Speciation

Allopatric speciation occurs when populations become geographically separated.

This may occur on a large landscape scale (e.g. as a result of physical barriers such as mountains, valleys, deserts, oceans etc.) or on a smaller scale (e.g. as a result of localised differences in soil conditions, topography, plant species distribution).

Such barriers reduce or prevent migration and dispersal, and hence gene flow, and the isolated populations diverge into new species.

       
 

Sympatric Speciation

Sympatric speciation occurs in populations with overlapping geographical ranges.

Oneform involves polyploidy - the multiplication of entire chromosome sets in new hybrid species, which thus become genetically isolated from their antecedents in one step.

It may also occur if some members of a species thatspecialises on one host, shift their specialisation to a new host nearby. The two populations, isolated by the microhabitat differences of their two hosts, may then divergefurther.

Reproductive isolation may occur as a result size-related assortative mating, misinterpretation ofmating signals or simple incompatibility of male and female genitalia.