Speciation Flashcards
What is the definition of a species?
A group of organisms containing individuals which can produce fertile offspring which can also reproduce.
Why is it difficult to define a species?
It is difficult due to hybridisation as organisms can be produced by two different species and on the odd occasion be fertile.
What is speciation?
Speciation describes the formation of a new species as populations become relatively and reproductively isolated preventing gene flow.
What are ring species?
Ring species is where there are a series of neighbouring populations that can interbreed but the populations at the ends of this ring cannot as they are too distantly related.
What is allopatric speciation?
Allopatric speciation is when two populations become geographically isolated and face different selection pressures.
What are the requirements for allopatric speciation?
There must be a physical barrier between the two populations, there must be no interbreeding between the two populations and their gene pools must stay isolated.
What is sympatric speciation?
Sympatric speciation is the complete opposite of allopatric speciation where two populations become two distinct species while still occupying the same geographical location.
What are the requirements for sympatric speciation to occur?
There must be some sort of barrier to prevent interbreeding between the two populations, The populations must occupy the same geographical location and the two populations must face different selection pressures that select for different traits.
Why can polyploidy cause sympatric speciation?
Polyploidy is the variation of chromosome sets. If offspring of one population are polyploidy they will likely form different functions to the other population leading to sympatric speciation.
What does “Cline” mean?
A pattern of gradual variation between individuals over a geographical area, usually due to different selection pressures.
What does “Deme” mean?
A small group of a population experiencing limited gene flow with members of the larger population.
What is Macroevolution?
Evolution above the species level, for example the evolution of a whole taxonomic group over a long period.
What is Microevolution?
A change in the allele frequencies within a population, usually brought on by natural selection over shorter periods of time.
What are the 6 Prezygotic RIMS?
Geographical, ecological, behavioural, temporal, mechanical and gametic isolation.
What are the 3 Postzygotic RIMs?
Hybrid inviability, Hybrid sterility and Hybrid breakdown.
