There are several species of widowbirds in the genus Euplectes found in East and southern Africa. They tend to live in grasslands and shrubby savannahs, and are finch sized. When it is not the breeding season, both males and females have rather drab brownish or buff colorations that provide good camouflage in the grass and shrubs. But at the beginning of the breeding season, male widowbirds molt and then grow black feathers over most of their bodies. Epaulettes at the junction of the wing and body develop that are brightly colored with reds and sometimes yellows. Some species produce chevrons on their wings, and a few also grow extraordinarily long tail feathers, some of them up to a foot and a half long. During the mating season, the males establish a territory that they must defend from other males. They build several frames for nests within the territory and try to attract females to mate with. Part of their efforts include complicated displays during flight. When a female chooses a male, she will line one of the nest frames in his territory with grasses, lay her eggs, and raise the chicks there. Some males will attract multiple breeding females within their territories. The male does not significantly contribute during this part of the reproductive process. Once the breeding season is over, the males molt once more and produce the drab and nondescript feathers again. In studies of one such species of widowbirds, the red-collared widowbird (Euplectes ardens), researchers found that the males with nesting territories tended to have redder epaulets than males without nesting territories. In a study of a second species, the long-tailed widowbird (Euplectes progne), researchers artificially altered the length of the tails of multiple males with females and active nests in their territories. They shortened some tails, cut and glued back on the same length tail feathers on some, and glued extra-long tails on others. They left some of the males’ tail lengths unaltered. When they counted how many new females had established nests in the males’ territories, it turned out that the males with the glued on extra-long tails had significantly greater success than all of the other males with an average of almost two more active nests than the males in all of the other groups. (Adapted from Gibson 2008.)
A. Does the redness of the epaulets affect reproduction for the red-collared widowbirds (Euplectes ardens)? If yes, how does it impact reproduction?
B. Is this natural selection? What kind of natural selection? Discuss the three necessary and sufficient conditions in your answer.
C. Is this natural selection? What kind of natural selection? Discuss the three necessary and sufficient conditions in your answer.