Plants and Animals: A Similar Mating Dance

PITTSBURGH—Reproduction in flowering plants and in animals may seem like two very different processes. But University of Pittsburgh biologist Tia-Lynn Ashman has examined the reproductive strategies used by both flowering plants and animals, and found that they have many overlapping features. Ashman's review paper, also authored by 14 other researchers worldwide, appeared in the Feb. 13 issue of Science.

"Developing a common language and theory, botanists and zoologists could use each other's methods to understand the whole picture," said Ashman, associate professor in the Department of Biological Sciences.

Flowering plants, called angiosperms, and animals use a range of strategies to increase reproductive success and genetic diversity. Both animals and angiosperms use a very large number of male gametes—sperm cells in animals and pollen grains in angiosperms. To increase their reproductive success, males produce many gametes and attempt to father as many offspring as possible.

In both groups, males compete for access to females. Competition can occur either externally, as when male animals battle for access to a female, or internally, in the female reproductive tract. The environment of the female reproductive tract, as well as other mechanisms, allow females to influence paternity.

Although flowering plants have no control over their mates, attractive or long-lasting flowers may attract more pollinators, increasing the chance of gathering more pollen grains from several donors. Ornamental traits of male animals, such as the feathered tail of the male peacock, can represent a trait that has proliferated because peacocks with colorful tails may have more reproductive success, or fitness. Similarly, flower color or size also may represent such a trait.

Female angiosperms can prevent fertilizations from genetic relatives. Botanists refer to this as self-incompatibility. Similar mechanisms, mostly immune responses, cause infertility in animals.

"By studying animals with plant-like reproduction, such as sessile aquatic animals, and plants with animal-like reproductive strategies, such as orchids, we may uncover the more general mechanism that drive the evolution of these systems," said Ashman.

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