anisogamy

Two main theories have been proposed for the evolution of anisogamy.

The real reason for the evolution of anisogamy is proposed to be fertilization risk.

Fusion of 2 dissimilar gametes is known as anisogamy.

There are several types of anisogamy.

This is ultimately a consequent of anisogamy.

Gametes of two distinct sizes (anisogamy).

So it is fertilization risk and the cooperation of different mating types to deal with it that caused the evolution of anisogamy.

Selection for high gamete encounter rates explains the evolution of anisogamy using plausible assumptions about size relationships of swimming speed and duration.

It is a form of anisogamy (heterogamy) in which the female gamete (e.g. egg cell) is significantly larger than the male gamete and is non-motile.

Chlamydomonass asexual reproduction goes through Zoospores, Palmella stage, Alpanospores and Hypnospores; sexual reproduction through isogamy, anisogamy or oogamy.

In cell biology, heterogamy is a synonym of anisogamy, the condition of having differently sized male and female gametes produced by different sexes or mating types in a species.

Females invest more in offspring prior to mating, due to the differences in gametes in species that exhibit anisogamy, and often invest more in offspring after mating.

In either case, gametes may be externally similar, particularly in size (isogamy), or may have evolved an asymmetry such that the gametes are different in size and other aspects (anisogamy).

Both theories assume that anisogamy originated through disruptive selection acting on an ancestral isogamous population, and that there is a trade-off between larger gamete number and smaller fitness of each gamete, because the total resource one individual can invest in reproduction is fixed.

With G.A. Parker and V.G.F. Smith in 1972, he proposed a leading theory for the evolution of anisogamy and two sexes and in 1979, with G.A. Parker he proposed the Unprofitable Prey Theory of the evolution of bird coloration.