RPG: The Influence of Clonal Reproduction on Population Sex Ratios in Plants

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9726931 McLetchie Many plants occur in populations where males outnumber females or vice versa. In some instances where females outnumber males, reduced sexual reproduction has been observed and attributed to this low male frequency. This planning grant is designed to obtain baseline ecological information that will support a full proposal to study 1) the causes of sex-specific clonal (asexual) reproduction and 2) the effects of this reproduction on the number of males and females in populations. Diplasiolejeunea pellucida, a small tropical plant that grows on living leaves of other plant species will be the focal test species. This species grows on a transient substrate; thus individuals must colonize, grow and sexually or asexually reproduce quickly to colonize new substrate. The activities planned in this study includes: a) collecting demographic data on male and female plants (by monitoring individual plants), b) determining the cause of reduced sexual reproduction (by manipulating male frequency), c) establishing protocols for culturing plants in natural and laboratory conditions, and d) detecting sex-specific DNA markers and clonal structure among plants in the population. This project has broad scientific importance in three main areas of study 1) the contribution of asexual reproduction in reducing population extinction, 2) the causes and consequences of the differences between male and female plants and 3) the relationships of asexual reproduction to other characteristics of the organism (sexual reproduction, growth and survival). Asexual reproduction has been largely ignored in evolutionary studies of plants despite the fact that clonal growth greatly influences survival. Some clonal plants show no sign of aging, making asexual reproduction a distinctive and important ecological and evolutionary trait. Information obtained on Diplasiolejeunea pellucida can be invaluable in modeling sex ratio patterns and consequence s in other plant species that are more difficult to study. Finally, many studies focus on allocation of resources (energy and nutrients) for sexual reproduction, growth and survival. Asexual reproduction is rarely incorporated into these studies yet most organisms (animals, plants, fungi and others) are able to reproduce asexually. This study will contribute to our knowledge of how resource allocation to asexual reproduction affects and is affected by sexual reproduction, growth and survival .