Chapter 3: Speciation Flashcards
process of species splitting into two/more species
Speciation
able to produce viable and fertile offspring
species
for speciation to occur
a reproductive barrier is needed
barrier that prevents species form mating (physical or non physical)
reproductive barrier
a founder effect isolating population from the original can _____ odds of speciation a lot when natural selection occurs
increase
based on biological species concept what is a species and what are the two kinds of reproductive isolation
species- able to create viable and fertile offsprings
Reproductive isolation prevents species from producing viable fertile offspring
types:
> Prezygotic barrier
> Postzygotic barriers
reproductive barrier that prevents zygote from forming by:
> preventing different species from mating
preventing successful mating
preventing fertilization
Pre-zygotic barriers
5 types of pre-zygotic barriers
Habitat, Temporal, Behavioral, Mechanical, Gametic isolation
Pre-zygotic barrier where 2 species have different habitats
habitat isolation
Pre-zygotic barrier where species breed at different times
Temporal isolation
Pre-zygotic barrier where species have different behaviors (courtship rituals)
behavioral isolation
Pre-zygotic barrier where physical (morphological) differences
Mechanical isolation
Pre-zygotic barrier where fertilization don’t occur for two different species
gametic isolation
3 types of Post-zygotic barriers
reduced hybrid variability, reduced hybrid fertility, hybrid breakdown
post-zygotic barrier where hybrid is too weak and dies or isn’t alive
reduced hybrid viability
post-zygotic barrier where hybrids are sterile
reduced hybrid fertility
post-zygotic barrier where if not 1st gen hybrid then next generations of hybrids will be either weak/sterile
hybrid breakdown
2 types of speciation
allopatric speciation
sympatric speciation
speciation type where:
geographic isolation / physical barrier causes gene flow to be interrupted
ex: species in diff countries
allopatric speciation
gene flow interrupted bc of other reasons that is not a physical barrier (reproductive barrier)
ex: same country
sympatric speciation
3 ways Sympatric speciation occurs
polyploidy, habitat differentiation and sexual selection
sympatric speciation where a random event that leads to extra sets of chromosomes bc of cell division accidents
ex plants can be isolated bc of this (w/out physical barrier) and they can only reproduce successfully by self pollination or by reproducing with other plants that went through the same thing
polyploidy
sympatric speciation where new species are born when ancestral species split up into 2 different habitats (bc new ecological niches) and evolved separately
habitat differentiation
sympatric speciation which is also a form of natural selection where individuals are so picky when choosing a mate and the cycle continues with their offsprings enough for speciation to occur
sexual selection
another term for reproductive barrier
reproductive isolation
an area which members of different species mate and produce hybrids
Hybrid zone
3 possible outcomes for hybrid zone
Reinforcement, Fusion, Stability
hybrid is less fit than parent species, strengthening of reproductive barriers, divergence between species continues
Reinforcement of hybrid zone
hybrid is more fit than both parent species, weakening of reproductive barriers, two species become one
Fusion of hybrid zone
fit hybrids continue to be produced and no significant change to bariers
Stability of hybrid zone
Rates of speciation
speciation can occur rapidly or slowly and can result from changes in few or a lot of genes
genetic mutation precedence of natural selection
Gradual Pattern VS Punctuated Equilibrium
(Speciation rates: can be 4,000 yrs - 40,000, 000 yrs)
Punctuated speciation - occurs rapidly (suggested with fossil records)
theory of gradual pattern/gradualism - is constant and consistent change over long period of time w/out sudden development.
