Lec 9: Diversification - Origin of Species Flashcards
The most specific unit of taxonomic classification is…
the species
What is biological classification?
a classification of individuals based on a set of CHARACTERS
What is speciation dependent on?
limited or absent gene flow
What factors cause a population to stop exchanging genes?
- geographic or physical barriers
- different courtship behaviors
- different breeding seasons
- different periods of activity
What contributes to differences in 2 newly separated populations?
natural selection, mutation, genetic drift
What is genetic drift?
the change in frequency of different genes in a population over time
In which type of population is genetic drift most likely to occur by chance?
in small populations
What are the 3 ways you can define a species?
- morphological species concept
species with different phenotypic traits are classified as different species - biological
species are members of a population that interbreed in nature and produce fertile offspring - phylogenetic
species are groups of individuals that share a common ancestor
What are the limitations to the biological species concept?
- not all species reproduce sexually
- we can’t test populations’ ability to mate
What is allopatry?
species in geographic isolation
What is parapatry?
- species with ranges directly adjacent to each other, ranges overlap slightly
What is sympatry?
Species existing in the same geographic location
What are the different ways for parapatric speciation to occur?
1) one population enters a new open niche, niche causes population to evolve, eventually enough difference to speciate
2) environment differs across a large range
- populations at far edges become different
- middle individuals either disappear or become one of the two pops
Explain reproductive isolation. Which type of speciation does it occur in?
Reproductive isolation occurs in sympatric speciation.
- reproductive methods are incompatible
- due to different courtship rituals, chromosome duplication, mutations
Does sexual dimorphism result in greater species diversity
yes
