When we look at islands across the planet (think the islands of the galápagos and hawaii) we see that there are a remarkable number of island endemic species, species that are found nowhere else. what is a possible explanation for this observation? sympatric speciation on islands is easier than in mainland environments because rates of chromosomal evolution are higher on islands. extinction rates are lower in islands so species that have gone extinct elsewhere persist on islands. sympatric speciation on islands is easier than in mainland environments because levels of disruptive selection are higher on islands. vicariance events are more common on islands than in mainland environments. island isolation promotes allopatric speciation. island isolation promotes allopatric speciation.

Island isolation promotes allopatric speciation.

Explanation:

Allopatric speciation is a form of speciation (creation of new species) that occurs as a result of geographic isolation. This means that a part of population becomes physically separated from the initial main population. There is no gene flow between these two populations and as a result the two populations  reach a high level  of genetic divergence. They can no longer interbreed which means they become two different species (speciation).

New populations evolve as result of mutation, genetic drift and natural selection.

For example, Galapagos finches are isolated from others by the ocean (geographic isolation).  Because of the isolation, the finches don’t breed with one another. So, they developed unique characteristics and became endemic.

what's the

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.