Why was the reduction of the bison population to under 1,000 individuals a bottleneck event for the species?
a. it drastically reduced the gene pool of the species.
b. it reduced the territorial range available to the species.
c. foreign genes were introduced by crossbreeding with cattle.
d. it reduced the prevalence of recessive traits

a. It drastically reduced the gene pool of the species.

The fast reduction in the number of American bison meant that the gene pool of the population decreased as many gene variants were lost. This is called a population bottleneck. It results in a very low level of genetic diversity. In the case of the bison, the change was caused by human activity, but other factors can also cause such reductions in population, such as environmental disaster or habitat destruction that results in the death of living creatures.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

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