adaptation and speciation- 4 Flashcards
what is frequency dependent selection?
The fitness of a phenotype is dependent on its frequency relative to phenotypes in the population
Why does ‘rare’ variation (colour morph) persist in a population?
-though negative frequency dependent selection
- trait persists in low number in the population because as it becomes more common it loses its advantage
(it has an advantage when rare)
Instead of frequency dependent selection it may depend on an actual number. describe example?
New world monkeys
F can either be di or trichromatic
each foraging group can benefit from both types
therefore, there is a threshold number
Why in some cases does frequency dep selection not operate on sex ratios?
Hamilton’s work on social systems shows that unequal ratio persists due to kin selection (close relatedness)
types of mimicry are influenced by what selection?
frequency dep selection
density …….
Constraints on adaptation?
pleiotropy
Linkage (and super gene clusters)
trade offs (trait has more than one purpose)
time frame past history (starting point)
how are species reproductively isolated from each other?
premating and postmating mechanisms
modes of isolation concerned with geography?
allopatric
micro allopatric
sympatric
parapatric (on the continuum between allopatric and sympatric)
In sympatric speciation adaptation can be driven by? and example of?
host shifts
hawthorn fly
what is adaptive radiation?
rapid diversification to occupy different ecological niches
generates a whole new suite of species
island dwarfing example?
when hominids moved to flores island. increased competition. became shorter in stature?
what process can be inferred from phylogenies?
the evolutionary process
is chirality in snails an example of a single speciation gene?
no, as chirality has been shown to be determined by mother not single gene
