Reproductive isolating mechanisms Prezygotic isolating mechanisms Geographic isolation Ecological isolation Behavioral isolation Temporal isolation Mechanical isolation Prevention of gamete fusion ID: 674910
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Slide1
ISOLATION
EQ
: What
are the types of isolation that lead to speciation?Slide2
Reproductive
isolating
mechanismsPrezygotic isolating mechanismsGeographic isolationEcological isolationBehavioral isolationTemporal isolationMechanical isolationPrevention of gamete fusionReproductive isolationPostzygotic isolating mechanismsHybrid inviability or infertility
2
TYPES OF ISOLATIONSlide3
Geographic isolation-
involves
physical barriers that divide a population into two or more groups
Isthmus of Panama formed 3 million years ago
Ex: snapping shrimp on each side will not mate with one another they snap at each other insteadSlide4
Grand Canyon speciation of squirrels due to geographic isolation Slide5
Populations can become isolated in several ways.
Behavioral
isolation- is caused by differences in courtship or mating behaviorsChanges in chemical scents, mating dances, songs or signals can prevent mating
Ex: Fireflies produce patterns of flashes that attract their mates. Over 2000 species of FF are isolated based on the patterns of flashesSlide6
Ecological isolation
Ecological isolation
. Individuals mate in their preferred habitat, and therefore do not meet individuals of other species with different ecological preferences.Slide7
Behavioral isolation
Blue-
fotted boobies select mates after an elaborate courtship displayWill not mate with other boobies7Slide8
Temporal
isolation- when
timing
prevents mating/reproduction between populations
Ex: The Monterey Pine and the Bishop pine have different pollination periods. (February/April)
Bishop pineSlide9
Field crickets’ reproductive isolation due to temporal isolationSlide10
Mechanical isolation
Structure of the male and female
copulatory organs may be incompatibleBees may carry the pollen of one species on a certain place on their bodies; if this area does not come into contact with the receptive structures of the flowers of another plant species, the pollen is not transferred10Slide11
Prevention of gamete fusion
In animals that shed gametes directly into water, the eggs and sperm derived from different species may not attract or fuse with one another
In plants, the growth of pollen tubes may be impeded in hybrids between different species11Slide12
Reproductive isolation occurs when members of different populations
can no longer mate successfully
with one anotherIt is the final step of becoming separate speciesSlide13
x
=
sterile
♀
♂
Hybrid
inviability
or infertility