9. Species, Speciation, & Hybridization Flashcards
Phylogenetic Species Concept
genetic similarity is used to define a species
Sympatric
Used to identify species within a region- different species share same location (rare), close proximity= makes populations similar (gene flow)
Allopatric
Gradual differences across regions (species isolated across regions) & is most common
Biological Species Concept (BSC)
is the most useful species concept we have and leads to the best research on the speciation process
(inability to interbreed means that species are distinct)
Taxonomic/ Morphological definition of species
Based on distinct measurable differences (Phenetic, genetic, ecological and phylogenetic)
Intrinsic mating barriers
Inviability, sterility, or abnormal development of hybrids (caused by gene combination with low fitness- ie: mule)
Extrinsic mating barriers
Ecological mismatch of hybrid phenotype to environment
Pre-zygotic isolation
1) Finding compatible mates & mating
2) Fertilization
(Apple Maggot Flies- different timing of fly mating causing reduction of gene flow)
Post-zygotic barriers
1) Development & growth of zygote (F1)
2) Adult survival & reproduction (F1)
(The mule- intrinsic- can not produce more mules/ sterile)
Adaptive Radiation
The evolution of ecological and phenotypic diversity within a rapidly multiplying lineage as a result of speciation
Caused by…
1)High rates of speciation
2)Origin of key innovation
3)Ecological opportunity
Polyploidy
An organism tissue or cell with more than 2 complete sets of homologous chromosomes
Karyotype
an individual’s complete set of chromosomes
Allo polyploidy (most common type of polyploidy)
(e.g. AA x AA –> AA AA)
Auto polyploidy
arises from duplicated karyotype within a species (e.g. AA –> AA AA)
