dimorfism

Dimorphism is the condition in which two distinct forms, or morphs, exist within a single species or population. The term is used across biology to describe differences that can be morphological, behavioral, physiological, or ecological, and it is not limited to reproductive organs.

The most common usage is sexual dimorphism, where males and females differ in size, coloration, ornamentation, or other secondary traits that influence mating success. But dimorphism also occurs outside the sexes: seasonal dimorphism can produce different appearances or behaviors at different times of the year; ecological or geographic dimorphism can arise when two morphs exploit different niches or habitats within the same species.

Causes of dimorphism include genetic differences, hormonal regulation, sexual selection, and environmental pressures that favor alternative strategies or appearances. Dimorphism can influence ecology and evolution by affecting mate choice, predation risk, resource use, and the distribution of individuals among ecological roles.

Dimorphism is distinct from polymorphism. Dimorphism refers to two morphs; polymorphism refers to more than two morphs within a population.

In plants, dimorphism can occur in dioecious species where male and female individuals produce different flowers. In animals, examples range from peacocks and deer with notable male traits to color or pattern differences between sexes in many bird species. Understanding dimorphism sheds light on how diversity within a species is maintained and shaped by ecological and evolutionary forces.