Abstract Detail

Pteridology

Barrington, David [1], Patel, Nikisha [2].

Insights into allopolyploid speciation in the tropics from Andean páramo species in the fern genus Polystichum (Dryopteridaceae).

Polyploidy is now acknowledged as a critical dimension to successful innovation at the root of major evolutionary events. However, our knowledge of the ecological and geographic dimensions to the origin of allopolyploid species is based almost exclusively on inquiries into North-Temperate lineages and on remote inferences about events that are well past. To address these limitations, a major direction in recent work in our lab has been to resolve the relationships in an array of diploids and their recently originated allopolyploids in the fern genus Polystichum (Dryopteridaceae) in the Andes of tropical South America. We have proceeded by providing a phylogenetic framework for understanding the diversity in the region and documenting evidence of allopolyploidy in an array of Neotropical Polystichum species suitable for modeling the origin of polyploids in the tropics. The lineage, a monophyletic group including an array of alpine and high-montane-forest taxa, has diversified over the last 12 million years in the central and northern Andes. The Andean array of páramo Polystichum species comprises three tetraploids, three diploids, and a diploid so far only known as a genome in a tetraploid. In addition, a high-elevation tetraploid endemic to the Talamanca range of Costa Rica and Panama has an Andean páramo diploid in its heritage. A critical step in resolving the history of these lineages has been the demonstration via phylogenetic work that the northern and central Andes have distinct histories: most of the earlier events in the group’s evolution took place in the central Andes, which were the first to reach elevations required for páramo development; events in the Northern Andes are more recent. The role of diploid Polystichum sodiroi, the most dissected of the Andean páramo species, in this history provides a model for further inquiry and insight into the challenges. Its tetraploid derivative P. gelidum, which includes as its other progenitor the high-alpine P. polyphyllum, is widespread in the northern Andes and extends into Mesoamerica above tree line. The type locality for P. gelidum is the páramo de la Culata, Colombia; it is also the type locality for the unrelated and non-ancestral diploid P. pycnolepis. To further challenge resolving the complex, Moritz collected the types of both species, as sequential numbers, and he mixed the two species in his numbers, leading to a nomenclatural confusion of amazing proportions, only now starting to make sense.

1 - University Of Vermont, Plant Biology, 111 Jeffords Hall, 63 Carrigan Drive, Burlington, VT, 05405, United States
2 - University of Tennessee, Ecology and Evolutionary Biology, Knoxville, TN, 37996, USA

Keywords:
allopolyploidy
Polystichum 
pgiC
Andes
páramos.

Presentation Type: Oral Paper
Session: 5, Pteridology I
Location: 108/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 9:00 AM
Number: 5005
Abstract ID:712
Candidate for Awards:None