Mixed mating and its ecological impact on an endangered plant: Crocanthemum canadense (L.) Britt.
LE3 .A278 2017
Bachelor of Science
Reproductive biology has important implications for the genetic makeup and demography of a population. By playing a major role in controlling genetic diversity, the mating strategy utilized by a species can help predict the adaptability and future viability of populations. The objective of this study was to provide a comprehensive understanding of the unique mixed mating system utilized by an endangered plant, illuminating potential related ecological repercussions. Crocanthemum canadense(L.) Britt. (Rockrose or Canada Frostweed) is a small perennial herb listed as critically imperiled under the Nova Scotia Endangered Species Act. Rockrose exhibits a unique mixed mating system called dimorphic cleistogamy, whereby a single plant produces both cross-pollinating open flowers and self-pollinating closed flowers temporally separated within a single season. The seasonal transition from one floral type to an other was assessed by comparing several floral characteristics using various microscopic analyses. Moreover, seed production in a field-based exclusion trial and pollen-ovule ratios of flower types were compared to determine the dominant mating strategy of the plants. Seed viability characteristics were also compared between flower types to determine if a difference in fitness existed between progeny from crossed versus self-pollinated flowers. Results indicate that flowers gradually change in morphology and reproductive strategy within a season, with transitional states between dominantly cross-pollinating and obligate self-pollinating flowers. Seeds from late-season closed flowers had a lower percentage germination success than open flowers, revealing a possible decrease in fitness of progeny from closed flowers. An increase in the infestation rate of open flowers by larvae of Mompha capella in comparison to previous records in 2014 was also documented. By consuming seeds from open flowers predispersal, the florivorous moth larva further exaggerates the number of inbred seeds produced per plant relative to outcrossed seeds, decreasing a plant’s contribution to the genetic diversity of subsequent generations and ultimately posing risks for the adaptability and success of future Rockrose population
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