Abstract Detail

Sexual dimorphism in bryophytes: Patterns and consequences

La Farge, Catherine [1].

Sexual Dimorphism in Mosses: Pseudautoicy (dwarf males) in the Dicranaceae sensu stricto with a special emphasis on Dicranum.

Mosses require water for the motile, bi-flagellate sperm to fertilize the egg within the archegonium. The phenotypic expression of sex in mosses is diverse in both monoicous and dioicous taxa. Pseudautoicy is a specialized reproductive strategy of dioicous mosses in which spores that germinate on female plants develop into dwarf males. This type of sexuality has been reported in scattered families of the Bryopsida (Ramsay 1979). Epigametophytic development of dwarf males provides a distinct advantage for, otherwise, dioicous taxa by increasing potential fertilization (Sagmo Solli et al. 2000). Recent molecular studies support a revised circumscription of the Dicranaceae (La Farge et al. 2000, 2002; Hedderson 2004), which excludes autoicous taxa and retains dioicous and pseudautoicous taxa. Molecular sequence data (rDNA ITS and cpDNA trnL (UAA)-trnF(GAA)) are used to construct a working phylogenetic hypothesis of subgeneric relationships within Dicranum. Taxon sampling includes taxa that have at one time or other been considered part of the genus Dicranum (Chorisodontium, Dicranoloma, Holomitrium, Leucoloma, Orthodicranum, and Pseudochorisodontium) as well as closely related genera (e.g., Paraleucobryum). Given a phylogenetic framework for the genus Dicranum, the evolution of pseudautoicous taxa is examined, as well as taxonomic implications of the results.

1 - University of Alberta, Department of Biological Sciences, CW 405 Biological Sciences Building, Edmonton, Alberta, T6G 2E9, Canada

Keywords:
pseudautoicy dwarf males Dicranum
Dicranum
dwarf males
Dicranaceae
Dicranoloma
rDNA ITS
cpDNA trnL-F
species phylogeny
Character evolution.

Presentation Type: Symposium
Session: 27-6
Location: Ballroom 3 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 10:45 AM
Abstract ID:644