Read each example and decide whether each would increase or decrease the genetic variation in the gene pool of that population. a zebra migrates to join a different herd of zebras. competition for sunlight leads to taller trees. the dna of a snake changes to make its venom stronger. a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

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.