Evolution and Phylogeny Flashcards
Evolution occurs through
emergence, divergence, and extinction of species
Neutralist Theory
Says that many mutations are mutual, causing polymorphisms to be maintained.
Truest theory of variation
Selectionist Theory
Many polymorphisms are maintained in the population
Species are defined as
a group of individuals that actually or potentially interbreed in nature
Reproductive Isolation occurs through
prezygotic and postzygotic mechanisms
Prezygotic Mechanisms..
Don’t choose to or cannot mate with each other
1.temporal isolation
2.behavioral isolation
3.mechanical isolation
4.ecological isolation
Postzygotic Mechanisms…
Progeny is sterile or inviable
1. Hybrid inviability
2. Hybrid sterility
3. Hybrid breakdown
The biological species concept is
when members of a species are capable of inter-mating and producing fertile progeny
How is the molecular clock used in studies of evolution?
Differences in sequence between present-day organisms can be used to date past evolutionary events
Allopatric Speciation
when geographic barriers initiate speciation by blocking gene flow
Sympatric Speciation
occur in a single interbreeding population without geographical barriers
Anagenesis vs Cladogenesis
-Anagenesis: evolution within a lineage over time
-Cladogenesis: splitting of one lineage into two, once branches diverge they evolve separately
Paralogs vs Orthologs
-Paralogs: homologous sequences found in the same species
-Orthologs: homologous sequences found in different species
More constraints on a nucleotide sequence means
fewer changes are tolerated
OTU
Operational Taxonomic Unit, based on differences in the DNA not necessarily different species
