Abstract Detail



Bryology and Lichenology

Benjamin, Simone [1].

Comparing genetic and expression-based estimates of sex ratios and microsite associations of males and females in Syntrichia caninervis: Bowker et al. revisited.

  Mosses in the genus Syntrichia (Pottiaceae) have diversified extensively in arid environments, often with a heavy reliance upon asexual reproduction and desiccation tolerance. The challenging water relations encountered by non-vascular plants in drylands has resulted in extreme physiological specializations for many Syntrichia species, which may be balanced by reduced allocation of resources to sexual reproduction. Syntrichia caninervis inhabits deserts and drylands worldwide and is notable for its low frequency of sex expression (production of gametangia) and sexual reproduction (production of sporophytes). Like many dioicous (unisexual) moss species, sex expression in S. caninervis is more frequently observed in female gametophytes than males. In 2000, a study ofS. caninervis was conducted in the Mojave Desert which sought to understand sex expression and its association with habitat variables. The results of the study determined that there was an extreme bias towards female sex expression (14 female: 1 male) in the 300 ramets that were collected and surveyed for gametangia. This study also found male sex expression to be restricted to the more shaded microsites under the canopy of shrubs. Although untested, these results led to the assumption that the presence of males is restricted to such sites, which is important for understanding male vs. female fitness and the mechanisms responsible for sex ratio biases in dioicous mosses. To determine whether the sex ratios and microsite associations of male and female ramets based on phenotypic sex expression in the previous study are consistent with actual genetic sex ratios, I re-analyzed the same 300 ramets of S. caninervisused in the original study with a PCR-RE based method designed to discriminate genetic sex in the absence of sex expression. Sex of the 300 original ramets was determined through the use of the PCR-RE and gel electrophoresis was used to visualize the digested DNA. The results confirm a substantially female skewed sex-ratio among the sampled ramets that is consistent with sex ratios based on the presence of gametangia, but contrary to the current assumption, males and females are not specific in their microsite associations. These findings are important to our understating of S. caninervis sex ratios bias, as they confirm differential survival of males and females and different environmental requirements for sex expression, with important implications for the establishment and persistence of local populations.


1 - California State University- Los Angeles, GeoSciences, 1131 Lodi Place, Apt 3, Los Angeles, CA, 90038, USA

Keywords:
bryology
moss
bowker
sex ratio
 Sex Determination
genotypic
phenotypic
syntrichia
caninervis.

Presentation Type: Oral Paper
Number:
Abstract ID:387
Candidate for Awards:A. J. Sharp Award


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