Abstract Detail

Pteridology

Kao, Tzu-Tong [1], Rothfels, Carl [2], Pryer, Kathleen [3], Windham, Michael [4].

Diversification of star cloak ferns (Notholaena standleyi Maxon) in the deserts of North America and Mexico.

Notholaenids are an unusual group of ferns that has adapted to xeric environments by evolving flavonoid exudates (farina) on leaf surfaces that help prevent water loss. Recent phylogenetic analyses suggest that the species Notholaena standleyi, widely distributed in the deserts of Mexico and the southwestern United States, may be sister to all other members of the clade. In the past, three chemotypes (infraspecific variants) have been recognized within N. standleyi: “G” (gold), “Y” (yellow), and “YG” (yellow-green). Originally recognized on the basis of farina color and chemistry, these variants also exhibit distinctive geographic ranges and substrate preferences, as well as different spore sizes and ploidy levels. Here, we present analyses of 48 N. standleyisamples spanning most of the geographic distribution of the species. Phylogenetic relationships were inferred using sequence data from five nuclear (ApPEFP_C, gapCpSh, IBR3, SQD1, transducin) and four plastid markers (matK-rps16, ndhF, trnL-trnF, trnG-trnR). Our results identify two additional variants: a previously undetected diploid “C” (cryptic) endemic to south central Mexico and a tetraploid “P” (pallid) restricted to limestone in Arizona and adjacent Mexico. In the plastid trees, the deepest divergence separates the two tetraploid chemotypes (“YG” and “P”) from the three diploids (“G”, “Y”, and “C”). Among the diploids, “C” appears to be sister to “G” and “Y”. Our molecular data also reveal that the two tetraploids are both allopolyploids, suggesting polyploidization through hybridization has played an important role in “within-species” diversification of N. standleyi. Based on ~1000 vouchered localities for N. standleyi, we also estimated ecological niche preferences for the three relatively common chemotypes, “G”, “Y”, and “YG”. Our analyses confirm that these three variants are significantly different from one another ecologically, and that each is associated with a different set of key environmental predictors.

1 - Duke University, Biology, Box 90338, Duke University, Durham, NC, 27705, USA
2 - University Of California Berkeley, University Herbarium And Departmenty Of Integrative Biology, 1001 Valley Life Science Building, Berkeley, CA, 94720, United States
3 - Duke University, Biology, Duke University, Science Drive, Durham, NC, 27708, United States
4 - Duke University, Department Of Biology, Box 90338, Durham, NC, 27708, United States

Keywords:
allopolyploid
amplicon sequencing
biogeography
cheilanthoids
ecological niche modelling
incipient speciation
PacBio
Phylogenetics
Pteridaceae.

Presentation Type: Oral Paper
Session: PTER1, Pteridology I
Location: San Pedro 1/Starr Pass
Date: Monday, July 29th, 2019
Time: 9:00 AM
Number: PTER1005
Abstract ID:672
Candidate for Awards:Edgar T. Wherry award