Speciation Flashcards
Divergent speciation
Phyletic speciation
A species is…
a species is a group of organisms, with similar morphology and physiology, which can (theoretically or actually) interbred with one another to produce fertile offspring
Also known as
The Biological species concept
For a species to evolve into two new species it must be…
split into two GENETICALLY isolated populations
This happens when…
-a particular set of circumstances reduces gene flow between two populations of a species
-over time, genetic differences between the populations (genetic drift or natural selection) start to accumulate
-once sufficient physiological/behavioural changes occur, the populations may become reproductively isolated
This reproductive isolation can be either…
pre-zygotic or post-zygotic
Allopatric speciation
allo=other patric= place
populations in different places
-different environments, different selection pressures, different adaptations
Sympatic speciation
sym=same patric=place
populations in same place
-more common in plants
In allopatric speciation, separation of a small group will often…
…result in the founder effect leading to genetic drift further enhancing the differences between the populations
Speciation can occur when…
…members of two different species interbreed and form fertile offspring but the hybrid formed will have a different number of chromosomes to either parent population
-stops gene flow and reproductively isolates the hybrid organism
Artificial selection
It is the selection for breeding of plants or animals with desirable characteristics by farmers or breeders
Wild type allele
Allele coding for the most common, or normal, characteristic
Populations are usually…
…polymorphic (display more than one distinct phenotype)
Outline the process
-individuals with the desired characteristics are selected and interbred
