Abstract Detail

Colloquia: Moss: from deep phylogeny and model organisms.

Goffinet, Bernard [1], Shaw, A.J. [2], Cox, Cymon [3].

Current understanding of phylogeny and phylogenetic diversity in bryophyte tree of life.

Bryophytes compose the second largest division among extant land plants. The lineage diverged from the ancestor to hornworts and polysporangiophytes in the lower Devonian. Main lineages differ in the organization of the sporophyte, with a) subdivisions defined by the mode of dehiscence, presence of a sporophytic stalk and the origin of the sporogenous tissue, and b) classes, within the largest lineage, the Bryophytina, defined by the architecture of the peristome, composed on teeth lining the sporangial mouth, and involved in controlling spore dispersal. Evolutionary trends emerge from inferences from extensive sampling of genomic loci, but discrete phylogenetic relationships among the main lineages, in particular among peristomate mosses remain ambiguous. Incongruence between phylogenetic inferences from molecular and morphological characters suggests that morphological traits suffer from extensive homoplasy, in part explained by extensive and repeated reduction in complexity. Mosses lacking a dehiscing, peristomate or stomatose sporangium occur throughout the Bryophytina, with for example the model system Physcomitrella and the distantly related Micromitrium acquiring similar highly reduced moss bodies. Finally, the distribution of unresolved nodes (polytomies) along the moss tree of life, may be indicative of burst or punctuated evolution. Often regarded as living fossils, bryophytes continued to diversify throughout the last 400 my, with some families considered to have diversified only in the last 20 my. Furthermore, recent speciation events resulting from genetic isolation following recent long-distance dispersal or from interspecific hybridization are increasingly documented. Finally, phylogenetic divergences within morphologically “uniform” lineages reveal that cryptic speciation is common and suggest that the true extant taxic diversity of the Bryophyta is underestimated.
The Physcomitrella genome project triggered numerous studies emphasizing the evolution of gene function withinembryophytes. The development of new technologies focusing on gene expressions combined with the potential of homologous recombination creates, however, opportunities to identify the genetic basis of fundamental developmental processes in mosses, and to begin reconstructing the fundamental tool kit of mosses and developing a sporophytic genome project.

Broader Impacts:

1 - University of Connecticut, Ecology and Evolutionary Biology, 75 Northeagleville road, Storrs, CT, 06269-3043, USA
2 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
3 - Universidade do Algarve, Plant Systematics and Bioinformatics Research Group (PSB), Faculdade de Ciências e Tecnologia (FCT), Ed.7,, Rm 2.77, Campus de Gambelas, Faro, 8005-139, Portugal

Keywords:
Bryophyta
Physcomitrella
phylogeny
diversification
reduction.

Presentation Type: Symposium or Colloquium Presentation
Session: C1
Location: Ballroom D/Convention Center
Date: Monday, August 2nd, 2010
Time: 8:45 AM
Number: C1002
Abstract ID:371