To survive, a young toad must complete metamorphosis before the water goes away.This problem affects the Plains spadefoot toad, which lives in the southwestern United States.Plains spadefoot females apply this strategy selectively.When times are good, they prefer males of their own species. Many females choose Mexican spadefoot mates and produce hybrid young. Mexican-Plains hybrids don’t make very good specimens. briggsae hermaphrodites’ life span was reduced, as was their fertility. briggsae hermaphrodites seemed able to anticipate this harm. nigoni males, they could be observed crawling in the opposite direction, as if trying to get away.Only later, at metamorphosis, do they develop lungs.Because of instances of clonality, which can locally be fairly important, some moss species are naturally selfing at high rates without the need to evolve specialized sex structures.
Well, the two basic sex functions are male and female, as long as gametes can be differentiated (big gametes are defined as female, small ones as male –both or none may be motile in plant species, so being able to move is not a feature that we can ascribe to a male gamete as we do in animals).
A lot of the time, interspecies sex is pretty boring. yakuba male also has trouble orienting himself properly. nigoni females have evolved defenses against the aggressive C. Once you start mixing things, it’s really hard to unmix them.
Two unrelated animals find one another by mistake, and nothing much comes of it. In some cases, the two sets of genitals don’t fit together, and the sex causes physical injury. Often, he ends up ejaculating on the female’s outside, or on himself. As it hardens, the semen glues the two insects together. For this reason, Amazon mollies are called sexual parasites. Combine red and blue paint to make purple, and you can’t get the red paint back again. Another factor is this: Hybrids may travel to more distant locations when they reproduce than purebreds do. This problem has its roots in the 1880s, when rainbow trout were first introduced into Montana’s rivers.
In some environments, water collects only in shallow puddles, which can dry up suddenly.
In these environments, the length of the tadpole stage is very important.