IV.Gymnosperm

The gymnosperms are heterosporous; they produce haploid microspores and megaspores

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Polygamy

Polygamy is a system in which either males or females' mate with more than one partner in a breeding season.

1. In polygyny

2. In polyandry

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Polygynous

In polygyny, one male mates with more than one female in a single breeding season, but females mate only with one male.

In species with male-male competition, males are often substantially larger than females, a phenomenon called sexual dimorphism.

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Condition favor polygyny

Resource-based polygyny - Choosing dominant males, a female may be gaining access to good resources.

Harem mating structures - Sometimes males defend a group of females without commanding a resource - based territory. 

Ex- horses and zebras, some deer, lions, and seals.

Communal courting - In some instances, particularly in birds and mammals, males display in designated communal courting areas called leks.

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Polyandrous

In polyandrous mating systems, one female mates with many males.

Honeybees are polyandrous because the queen often mates with multiple males.

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Promiscuous

In promiscuous mating systems, each male or female may mate with multiple partners.

Chimpanzees, bonobos and Intertidal and terrestrial mollusks

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