Self-study
Populations of a shrimp species at eleven different Indonesian coral reefs show substantial genetic differences from one reef to another. ████ ██ ██████████ ███████ ███ ██████ ██████ █████ ████████ ████████ █████ ████ ██████ ███████ ███ █████████ ██████ █████ █████ █████ ███ ███████████ ██ ██████████ ███ ██████ ███████████ ██████████████████
"Surprising" Phenomenon
Why are shrimp at different coral reefs genetically distinct when ocean currents mix up baby shrimp between populations?
Objective
A hypothesis resolving this discrepancy must explain why the intermingling of baby shrimp between reefs is not enough to make those shrimp genetically indistinguishable. It will imply that baby shrimp exchanged between reefs do not breed with each other, or that their interbreeding is not enough to blur the genetic lines between populations.
12.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ ███████████ ███████ ███████████ █████ ███ ██████ ████████████
a
The genetic differences ███████ ███ ██████ ███████████ ███ ████ ████ ███████████ ████ █████ ███████ ██████ ███ ███ █████ ██████ ████████
This does not explain why the shrimp are genetically distinct. If the shrimp have similar genetics, their failure to interbreed is more surprising, not less.
b
The individual shrimp ██████ █ █████ ██████████ ██ ███ █████ ██████████ █████ ████ ██████ ████ ███ ███████ ████████████ ████ ██████ █████ ██ ██████████ █████████████ ██████ ███ ████ ███████████
This deepens the mystery. If the shrimp are capable of interbreeding despite significant genetic differences, then their failure to interbreed between reefs is more surprising.
c
Before breeding, shrimp ██ ███ ███████ ████████ ███████ ████ ██ ███ █████ ████ ██ █████ ████ ████ ████████
This explains why the shrimp populations do not interbreed. Baby shrimp carried to other reefs do not breed until traveling back to their home reefs, so shrimp born at different reefs do not breed with each other.
d
Most shrimp hatched ██ █ █████ ██████████ █████ ████ ███ ██ ██████ ███████ ██ ████ █████ ████ ████ ████████ ███ ██████ ██ ██████
This deepens the mystery. If most shrimp leave their home reef by breeding age, the genetic distinguishability of shrimp between reefs is more surprising.
e
Ocean currents probably █████ ████ ██ ███ ████ ██████ ███████ ██ █ █████ ██████████ █████ ████ ███ ████ ███ ████ █████ ██████ ████ ██ ███████ █████ █████
This does not state that shrimp are rarely exchanged between reefs, only that many do not end up at any reef. It does not explain why the baby shrimp that are exchanged between reefs fail to breed with each other.