The effects of clonal reproduction on population demography, genetic structure, and mating pattern of <i>Dicentra canadensis</i>

Many flowering plants can reproduce clonally by propagules derived from vegetative organs. Because clonal propagules often grow near their parents, clonal reproduction can result in spatially aggregated ramets. Clustering of clones can reduce the frequency of pollen transfer between genets if pollinators tend to forage on nearby plants. In extreme cases, clustering of clones may prevent sexual reproduction, especially in plants that require mating between different genotypes to produce seeds. The importance of maintaining dual reproductive strategies to population growth and genetic structure is still poorly understood and evidence for how the interplay between pollinators and clonal structure influences sexual reproduction is scarce. I investigated the effects of clonal reproduction on population growth, pollinator-mediated mating success, and population genetic structure in <i>Dicentra canadensis</i>, a self-incompatible spring ephemeral herb pollinated by bumble bee queens (<i>Bombus</i> spp.). Demographic censuses were conducted over four years in three <i>D. canadensis</i> populations, one in a well-forested site and two in isolated forest remnants, to quantify the relative importance of clonal and sexual reproduction to population growth. Populations in forest remnants produced fewer seeds than that in the well-forested site, although seed production varied significantly among years. Despite strong variation in sexual reproduction, stage-based population models showed stable annual growth rates in all populations and manipulation of pollination had little effect on population growth rates. Populations in forest remnants depended significantly more on clonal than sexual reproduction for population growth, whereas the population in the well-forested site depended equally on both reproductive modes. I compared the range of pollen dispersal with the spatial distribution of compatible mates in the well-forested site to determine if seed set was limited by inadequate pollination between compatible mates. Most flowers received visits by pollinators. Because of the pollinator's tendency to forage on nearby plants, the majority of pollen was deposited on flowers within a few meters from the donor, where fewer than 30% of plants were compatible mates. Simulations with increased extent of pollen carryover increased the number of recipient plants linearly but most pollen still dispersed within 10 m from the donor. My results support the hypothesis of distance-dependent mate limitation on sexual reproduction.I used inter-simple sequence repeat (ISSR) markers to study the spatial genetic structure of three <i>D. canadensis</i> populations. I detected two to 27 putative genets per population. Populations with higher genet diversity also produced more seeds. A lack of mates apparently limits sexual reproduction in populations with extremely low genet diversity. Genets in the genetically diverse populations are spatially structured but genet boundaries become less pronounced with increasing genet diversity. Sexual recombination was a major source of genotypic variation at the well-forested site but not in the forest remnants. Although stable population growth can be maintained by different reproductive strategies in <i>D. canadensis</i>, the resulting genetic structure differed substantially. Spatial aggregation of clone mates combined with restricted pollinator foraging distance can negatively impact sexual reproduction in clonal plants and the effect may be exacerbated in populations with low genet diversity.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Evolution, Ecology and Organismal Biology

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Lin, Chia-Hua

Contributors dc:contributor

• Goodell, Karen

• Ecology

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1366261248

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1366261248