Abstract Detail

Biogeography

Wickell, David A. [1], Windham, Michael D. [2], Beck, James Benjamin [3].

Does asexuality confer a short-term evolutionary advantage? The case of the widespread apomictic fern Myriopteris gracilis (Pteridaceae).

Although asexual reproduction is generally seen as an evolutionary dead end, this strategy appears to have provided a short-term benefit in some taxa. For example, a short-term advantage to asexuality has been considered an important component of “geographical parthenogenesis”, a common pattern in which asexual taxa display a wider distribution than their sexual relatives. However, these seemingly broad distributions may be an illusion created by multiple, morphologically cryptic, asexual lineages that each occupy a relatively small area. Myriopteris gracilis is a North American asexual triploid fern species with a particularly large range. We ask: 1) is M. gracilis exclusively asexual? and 2) does M. gracilis comprise a single wide-ranging asexual lineage, or multiple, more geographically restricted lineages? Sexuality was assessed by counting spores/sporangium in 573 specimens from across the species range, and lineage structure was assessed with both plastid DNA sequence and Genotyping By Sequencing (GBS) SNP datasets. Spore counting identified no sexual populations, establishing that the sexual diploid progenitor of M. gracilis is either extinct or so limited in its distribution that it does not contribute to the extensive range of the species. The plastid data estimated the crown age of M. gracilis at ca. 2.5 mya and identified two morphologically distinctive lineages exhibiting minimal geographic overlap. These groups were further subdivided by the GBS data, revealing at least seven asexual lineages of varying distributions, none of which approached the total size of M. gracilis’ range. The total M. gracilis distribution therefore overstates the success of any one asexual lineage, and by extension, the potential short-term benefit of asexual reproduction in this species.

1 - Wichita State University, Biological Sciences, 1845 Fairmount, 537 Hubbard Hall, Wichita, KS, 67260, USA
2 - DUKE UNIVERSITY, Department Of Biology, BOX 90338, DURHAM, NC, 27708, USA
3 - Wichita State University, Biology, 1845 Fairmount, Box 26, Wichita, KS, 67260-0026, USA

Keywords:
asexual reproduction
Döpp-Manton sporogenesis
genotyping by sequencing.

Presentation Type: Oral Paper
Session: 13, Biogeography
Location: Sundance 3/Omni Hotel
Date: Monday, June 26th, 2017
Time: 2:30 PM
Number: 13005
Abstract ID:224
Candidate for Awards:None