M5: Mechanism of Speciation Flashcards
Population whose members can interbreed & produce viable, fertile offspring.
species
Reproductively compatible
Ernst Mayr (Evolutionary Biologist)
species
a process by which two species that could otherwise produce hybrid offspring are prevented from doing so.
ISOLATION
How new species is formed?
Populations become _________ , ___________populations evolve independently.
How new species is formed?
Populations become isolated, isolated populations evolve independently.
are mechanisms that prevent closely related species from interbreeding.
Reproductive Barriers
Stops two species from producing viable, fertile offspring.
Reproductive Barriers
PREZYGOTIC ISOLATION
g_________
e__________
T______
m_____________
b______________
g_______
PREZYGOTIC ISOLATION
geographic
ecological
temporal
mechanical
behavioral
gametic
POSTZYGOTIC ISOLATION
hybrid s________
hybrid v________
hybrid b__________
POSTZYGOTIC ISOLATION
hybrid sterility
hybrid viability
hybrid breakdown
Also known as pre - reproductive barrier
prevent mating between two closely related species.
Prezygotic Barrier
Physical barrier separate ancestral species.
New species appear in different areas.
Geographic Isolation
Species occur in same region, but occupy different habitats so they rarely encounter each other
- Ecological isolation
Two closely related species reproduce at different times of the day, season, or year.
- Temporal “time” isolation
Unique behavioral patterns & rituals isolate species.
- identifies members of species.
- attract mates of same species.
- Behavioral isolation/ Ethological isolation
Auditory stimuli -
Breeding calls
Visual stimuli -
Mating Dances
Chemical stimuli -
Pheromones
Morphological differences can prevent successful mating
- Mechanical isolation
differences in their reproductive organs prevent interbreeding
- Mechanical isolation
A mechanism of reproductive isolation which inhibits mating between two distinct species, by ensuring that their gametes don’t interact with each other.
- Gametic isolation
Sperm of one species may not be able to fertilize eggs of another species
- Gametic isolation
Prevent hybrid offspring from developing into a viable, fertile adult
Postzygotic barriers
Chromosomes of parents differ in number or structure thus meiosis in hybrids will fail to produce a normal gametes.
Hybrid sterility
Genes of different parents can impair or stop the development of the hybrid.
- Hybrid viability
First generation of hybrids are fertile and viable
Succeeding generations are sterile.
- Hybrid Breakdown
Geographical barrier
Separate two large populations.
Allopatric
Geographical barrier
Separate a small number of species from the whole population.
Peripatric
No geographical barrier
Leave in the same habitat
the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region.
Sympatric
No geographical barrier
Leave within the same habitat.
Slight difference in the habitat, new niche.
a species is spread out over a large geographic area
Parapatric
wghat are the 4 modes of speciation
A________
P___________
S____________
P____________
allopatric
peripatric
sympatric
parapatric
