Sexual Dimorphism Definition

Sexual dimorphism is the difference seen in the organisms belonging to the same species, except the variation in sexual organs. Thus, males can be identified from the female, despite belonging to same class of species. From the sexual organs, they can be differentiated as well as their morphology like their color, size and shape.

What is Sexual Dimorphism?

Dimorphism originates from a Greek word, which can be broken into two parts, such as “morphe” meaning shape and “dis” meaning twice. Thus, sexual dimorphism, refers to having two forms. Thus, males can be identified from the female, despite belonging to same class of species. However, in sexual monomorphism, both the female and male belonging to same species, are identical and even from their sexual organs can be identified.

When secondary sex traits are visible in species, sexual dimorphism takes place. The characteristics differing are the weight, shape, size, arrangements on the body, color palette, behavior, voice are some of the characteristic which vary in female and male organism.

Sexual Dimorphism Examples

A very common example where differences are seen in the arrangement and the presence of color. For example, the female peacock is more colorful and has beautiful feathers, than the male peacock, thus the plumage type seen in female peacock is subdued and in male it is ornate type. Plumage is used for attracting the opposite partner.

Another example is that of mallard, where male mallard on its head has bright green plumage, whereas female’s have a lighter plumage color. From animals to animals, the variation can be major or very little.

In mammals and humans, males are huge than females. However, the amount of sexual dimorphism seen in humans, is very less. For example, the adult weighs around 78.5kg whereas female weighs around 62kg. The standard deviation seen in males is 12.6kg, thus males could also be lighter than females.

In terms of behavior and voice, males have more stronger and voice than females. Other examples are nesting behavior, searching for food and behavior before mating.