Speciation Basics
This is the process in which one population diverges into a new species due to genetic differences.
What is speciation?
This selection type results in more individuals with average traits.
What is stabilizing selection?
A type of barrier preventing the fertilized egg from developing fully
What is zygote mortality?
Speciation due to a gepgraphical barrier
allopatric speciation
This type of isolating mechanism occurs when two species can't mate due to physical barriers like mountains or rivers.
What is geographical isolation?
This selection results in two peaks and discourages the average trait from reproducing
What is disruptive selection?
Mechanisms occurring before a zygote can form, preventing mating
What are pre-zygotic isolating mechanisms?
speciation due to niche differentiation in the same habitat
sympatric speciation
When species breed at different times of the year, this type of isolation occurs
What is temporal isolation?
This selection causes the bell curve to shift due to pressure on one end of the trait spectrum.
What is directional selection?
This type of isolation is due to different mating behaviors or signals in animals
What is behavioral isolation
How we know a new species has now formed
There is no gene flow due to RIM's - no fertile offspring are able to be produced if the 2 groups come back together
An isolating mechanism where hybrid offspring, such as mules, survive but cannot reproduce.
What is hybrid sterility?
A real-world example where two frog species have different mating seasons, illustrating this type of isolation.
What is temporal isolation?
Sperm failing to survive in the reproductive tract of another species exemplifies this barrier.
What is gametic isolation?
Changes in allele frequencies in a population due to chance
Genetic drift
This occurs when chromosome numbers in plants double, leading to immediate reproductive isolation.
What is polyploidy?
When hybrid offspring manage to reproduce asexually and gradually develop into a new species.
What is hybrid speciation?
In dragonflies, the male’s claspers and female’s mating position illustrate this type of isolation.
What is mechanical isolation?
The five fingers of evolution leading to speciation
natural selection, sexual selection, shrinking populations due to founders and the bottleneck effect, migration, mutation