sexual dimorphism - differences in the structure of this male and female organisms of the same species.It is widely distributed among representatives of dioecious animals or plants, and manifests itself in physical symptoms such individuals:
- size.Males are distinguished from females by their size, for example, representatives of amphibians, females are larger.
- Hairs.For example, it may be a human presence in men beard.
- color.For example, in birds - color feathers.
- Skin.Expressed in additional education and secondary sexual characteristics.For example, deer antlers, or a comb cocks.
- teeth.In male mammals, such as walrus and elephant tusks are slightly larger than females.
Thus, sexual dimorphism can be called a measure of polygamy (its level), and the brighter it is expressed, the greater the differences in the contributions of male and female in the care of their offspring.Sometimes the PD can be manifested in such symptoms, which reduce the viability of their respective owners.So bright plumage, loud singing and the pungent smell of some birds often attract the attention of predators that poses a risk to their lives.This is caused, most likely, not natural selection and sexual selection.
Sexual dimorphism is of several forms:
- Reproductive PD - is a constant based on gender, both primary and secondary, which are different for both sexes and are relevant to the process of reproduction.This hormonal form of sexual dimorphism, the task of which - draw up a program for both sexes.
- Modification sexual dimorphism - is temporary and is due to changes in the female as a result of selection.In this case there are new genes that have been tested in male DNA.
PD considered as the relationship of male and female qualities, aimed at the formation of attraction to each other, which creates the need for a physical and psychological human playing.Thus, it aims to reproduce in a generation, with the genetic level there is the creation and development of biological control of the most profitable for the individual qualities.
should be said that sexual dimorphism is manifested in a large number of physiological, physical and behavioral differences between individuals of different sex.So, through the female acts stabilizing selection, the male sex creates the possibility of evolutionary variability.Modern science gives a clear explanation for sex differences at every level of development of the organism.
animals PD is characterized by differences in the structure of the copulatory organs and secondary sexual characteristics.It is customary to distinguish seasonal and permanent sexual dimorphism.Wherein the first does not depend on seasonal conditions.
human sexual dimorphism is expressed in a stronger development of the skeleton and muscles, as well as hair in males.In a female are more developed breast cancer, the width of the hips and more.
Plants PD expressed differences in the structure and size of the stems, foliage density, the structure of the flowers and in many ways different.
Thus, the emergence and development of sexual dimorphism in all organisms is caused by the influence of natural and sexual selection.This modern biology has a lot of arguments in favor of the PDP is expressed not only in the structure and functioning of the sexual organs, it also encompasses secondary, tertiary, and distant from the symptoms of sexual function, which refer to physical systems and their functions.We can say that all of these characteristics relate to all levels of organization of matter, from the molecular level and ending with the organismic.
