Abstract Detail

Reticulate evolution and biogeography in ferns and lycophytes - a colloquium honoring Dr. David Barrington

Kuo, Li-Yaung [1].

Long-distance dispersal and geographical range expansions of the polyploid lineages in Deparia ferns (Athyriaceae; Polypodiales).

Homosporous ferns reply mostly on wind-carried spores for their dispersal and population colonization. Colonizing success of the sexual ferns in the resulting haploid spore and gametophyte would depend on the ability of the gametophyte to become bisexual and to self-fertilize. Such gametophytic selfing would produce a completely homozygous sporophyte, which would likely suffer from inbreeding depression and be unlikely to found a new population. Presumably, gametophytes generated from spores of polyploid or apomictic species are better able to produce viable sporophytes for efficient colonization because deleterious alleles are masked by heterozygosity preventing from inbreeding depression. To test the hypothesis that polyploid or apomictic ferns are better colonizers than sexual diploid ones, I have studied the links between cytotypes and distribution range in Deparia ferns with analyses of phylogenetic biogeography and phylogeography. The results of phylogenetic biogeography suggest that the dispersal rate was slightly higher in the polyploids than in diploids, and that, in the Hawaiian species, a long-distance dispersal from East Asia to the Hawaiian Islands was coupled with an allopolyploidization. All five species showing infraspecific range expansions are found with polyploidization concurrently. For one of these five species´╝ŹDeparia lancea, the cytogeographical and phylogeographical results further demonstrate that widespread autopolyploids (sexual tetraploids and hexaploids) in Asia are the results of oversea dispersal and rapid range expansions. By contrast, the diploids are sexual and found to be restricted in the Taiwan Island. These empirical cases from Deparia ferns support that evolution of polyploids are usually accompanied with an increased colonization ability, and a reproductive feature of inbreeding or apomixis might play an important role this high colonization ability.

1 - Institute of Molecular & Cellular Biology, National Tsing Hua Universi, Hsinchu, Taiwan


Presentation Type: Colloquium Presentations
Number: 0006
Abstract ID:129
Candidate for Awards:Edgar T. Wherry award

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