Macroevolution: speciation Flashcards
What are the 4 species concepts?
- Ecological
- Phylogenetic
- Phenetic
- Biological
Define the ecological species concept.
Individuals that share a niche :use the same resources and occupy the same space
Define the phylogenetic species concept.
Members of the same species share a common ancestor
common ancestry provides genetic similarities
Define the phenetic species concept.
Group of similar individuals – compare morphology, genetics, biochemistry, molecular genetics
Define the biological species concept.
Members of a population that share the same gene pool
-Have the potential to interbreed and produce fertile offspring
Name the limits of the phylogenetic concept.
Not all genes are useful for comparison
Name the limits of the phenetic concept.
- Members of the same species can appear different
- Different species can look alike
Name the limits of the biological concept.
- Not useful for asexually-reproducing species
- Can’t be applied to extinct species
- Can’t be applied to geographically isolated species
Describe the general process of speciation.
a. Something prevents gene flow between populations
b. Populations accumulate genetic differences
c. Selection for increased reproductive isolation
d. Reproductive isolation develops
What are the types of speciation?
Allopatric, sympatric, chromosome
Define allopatric speciation.
A geographic barrier blocks gene flow and populations accumulate differences = selection pushes for reproductive isolation
What are the favoring conditions for allopatric speciation?
- small population
- genetic drift
- new environment
Define sympatric speciation.
Reproductive isolation between species in same geographic area, individuals in small area have different selection pressures= sub-population linked to specific resource + assortative mating
Then isolation pushes for reproductive isolation
What is chromosome speciation and what are the 2 types?
Chromosome changes block gene flow
- Autopolyploidy
- Allopolyploidy
Explain autopolyploidy.
2n doubles chromosome # and becomes 4n (2nx2)
- The 4n is no longer able to breed with 2n (4n x 2n = 3n sterile)
- 4n is reproductively isolated = new species