dimorphism

[ dahy-mawr-fiz-uhm ]

noun

1. Zoology. the occurrence of two forms distinct in structure, coloration, etc., among animals of the same species. Compare sexual dimorphism.
2. Botany. the occurrence of two different forms of flowers, leaves, etc., on the same plant or on different plants of the same species.
3. Crystallography. the property of some substances of crystallizing in two chemically identical but crystallographically distinct forms.

dimorphism

/ daɪˈmɔːfɪzəm /

noun

1. the occurrence within a plant of two distinct forms of any part, such as the leaves of some aquatic plants
2. the occurrence in an animal or plant species of two distinct types of individual
3. a property of certain substances that enables them to exist in two distinct crystalline forms

dimorphism

/ dī-môr′fĭz′əm /

1. The existence of two distinct types of individual within a species, usually differing in one or more characteristics such as coloration, size, and shape. The most familiar type of dimorphism is sexual dimorphism, as in many birds (where the male is often more brightly colored than the female), spiders (where the male is often smaller than the female), horned and tusked mammals (where horns and tusks are often present in the male but not the female), and in some species of deep-sea anglerfish (where the male is reduced to a tiny parasitic form attached for life to the much larger female). Fungi also display dimorphism. For example, the same species may exist as a small, budding yeast under some conditions, but as a mass of long hyphae under others.
2. The occurrence, among plants, of two different forms of the same basic structure, either on the same plant or among individuals of the same species. The common ivy Hedera helix produces juvenile leaves with prominent lobes under conditions of low light, but adult leaves of more rounded shape under conditions of greater light.
3. The characteristic of a chemical compound to crystallize in two different forms. Potassium feldspar, for example, can crystallize as either orthoclase (at higher temperatures) or microcline (at lower temperatures).

Derived Forms

• diˈmorphic, adjective

Word History and Origins

Origin of dimorphism¹

First recorded in 1825–35; dimorph + -ism

Example Sentences

Differences in cancer incidence and progression between men and women have been known for decades, but a detailed understanding of sexual dimorphism in relation to cancer biology is still limited.

From Science Daily

It is an extreme case of what is known as sexual size dimorphism, and one that fits within a longstanding narrative that male mammals tend to be larger than female ones.

From New York Times

The main groups in which the phenomenon has been recorded include animal species which feature strong sexual dimorphism; most often insects, especially butterflies, crustaceans, spiders, even lizards and rodents.

From Science Daily

Differences in body size between females and males of a species, a phenomenon called sexual size dimorphism, correlate with social structure.

From Scientific American

“They have found that Rosetta stone fossil that allows us to really confirm these theories about sexual dimorphism,” Bicknell says.

From Scientific American