Question

why does one gender of a particular species look so much different in comparison to the other?

Answer 1

Gender differences in species is due to sexual dimorphism. Sexual dimorphism is differences in characteristic other than the sexual organs such as secondary sex characteristics, size, weight, color, behavioral and cognitive features. Homo sapiens have less sexual dimorphism than most other species. In some species of mammals, males are larger than females. Conversely, in some spiders, the females are larger than the males.

Sexual dimorphism is mostly due to natural selection as it gives an advantage for reproductive success. Male gamebirds are brightly coloured making the targets of predators while the females are drab and can successfully camouflage themselves. Male common pheasants do not live more than 10 months in wild. They also have bright coloration to make them attractive to female counterpart. The female common pheasant on the other hand will live twice as long.

Male deer have antlers which they use as weapons to fight others for breeding rights. As these antlers also will allow only the strongest males to reproduce, thereby passing strong and good characteristic to next generation.

Insects have females that are larger than the males. The larger body size will allow them to lay more eggs. Beaks of some woodpecker species have differences in size and shape. This is required to find food in form of insects in different layers of the bark of a tree.

Hence, gender differences in appearance is required for reproductive success, acquisition of food, better breeding potential by attracting females, survival from predators etc. Sexual dimorphism is usually caused by inheritance of different sexual patterns in the genome.