Skin color in a certain species of fish is inherited by a single gene with four different alleles. how many different types of gametes would be possible in this organism?

4

Explanation:

According to Mendel's law of purity of gametes, each gamete contains single allele for a gene. The alleles of a gene segregate during gamete formation and each gamete has one allele for a gene irrespective of the total number of alleles for a gene.  

If the gene for skin color in a fish species has four alleles, an individuals fish would have only two alleles which in turn would segregate during gamete formation.

Since there are four different alleles of the gene (let's assume a,b,c, and d), total possible gametes produced by this organism will be = 4. A gamete can have one of the total 4 alleles making total 4 types of the gametes each with a or b or c or d allele.  

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.