Speciation & Ploidy Flashcards
allopatric speciation
‘different homeland’
geographic speciation leads to genetic changes over time eventually creating a new species
Sympatric Speciation
‘same homeland’
ecological separation within same region (close enough to interbreed”
Allopatric Specaition can occur via..
Vicariance and dispersal
Vicariance
one population split into two by a barrier and can no longer interbreed with eachother
ex. river splits, mountain range lifts up, continental plates move, glacier moves etc…
Dispersal
one population establishes a second one somewhere else
Foundation species
forms the habitat itself, defines the ecosystem
ex. coral in the coral triangle
Symbiotic relationship
When 2 organisms share a physiologically close relationship
ex. coral and zooxanthellae
NOT always good ex. tapeworm
mutualism
+/+ benefit both species but not required for life
ex. goby fish and shrimp
obligate
required for life
Sympatric Speciation occurs when..
- STRONG disruptive selection AND reduce in gene flow across
- polyploidy
examples of sympatric speciation
Hawthorne vs. Apple Trees
females lay eggs on type of fruit they grew up on
males look for mate on fruit they grew up on
PROMOTES REPRODUCTIVE ISOLATION
Speciation
Allopatry- vicariance & dispersal
Sympatry- disruptive selection AND reduced gene flow & polyploidy
Another way to get Sympatric speciation is…
chromosomal mutation or hybridization that leads to a change in a ploidy
Autopolyploidy
‘self duplication’ whole genome duplication within single species
allopolyploidy
‘other’ duplication of whole genome duplication. duplication combined with hybridization
non disjunction event
chromosome does not split apart -leads to mutation
complete non disjuction
all chromosomes get an extra set
independent assortment
homologous pairs line up in any way on the metaphase plate thus the chromosomes inherited from a given parent are NOT neccesarily passed down together
