The Paternity Pools of Plants

Abstract

Pollen deposited on the stigmas of a given plant is principally from plants in its immediate vicinity (Levin and Kerster 1974). Therefore, the number of males that might sire the progeny of that plant is likely to be much less than the number of males in the population. The number of potential mates for individual females (here, the paternity-pool size) is of interest, because it provides an upper limit to the number of males competing for access to females and to the number of mates among which a female may choose. The mean size of paternity pools and the mean area in which potential mates reside were determined for 17 species of herbs and 8 species of trees from published accounts of pollen dispersion. The paternity pool lies within a circle of radius 3.sigma. and area A = 9.pi..sigma.2. The size of the paternity pool is Ad, where d is the density of pollen-producing plants. In the majority of herbs, most pollen is received by males less than 3 m away. In trees, the distance is about 10 times as great. The paternity-pool area of herbs varied from about 2 m2 to about 300 m2. The paternity-pool area of trees varied from 10 km2 to over 10,000 km2. In herbs, the paternity-pool size varied from 20 to nearly 4000 plants. In trees, the paternity-pool size varied from about 60 to over 30,000 plants. Paternity-pool characteristics are functions of pollen dispersion and are thus subject to variation in space and time. The values presented are considered representative. Characterization of paternity pools provides a framework for better understanding the data from paternity-identification studies and allows insight into the breeding pattern within populations.