Abstract Detail

Pteridology

Riney, Jake [1], Ickert-Bond, Stefanie [2], Metzgar, Jordan [3].

Impacts of Pleistocene glacial cycles on the fern genus Cryptogramma.

As the global climate changes and modelling techniques advance, ecological niche modelling (ENM) has emerged as a powerful and useful tool for conservation. The rock-loving fern genus Cryptogramma is an ideal candidate to study climate change impacts due to their preference for climate-sensitive habitats, such as sky islands and glacial margins. We focused on the three species in the Beringian C. acrostichoides complex: C. acrostichoides, C. raddeana, and their allotetraploid, C. sitchensis. Presence data were collected from herbarium collections, and ENM projections were created using WorldClim bioclimatic variables in Maxent. We generated ENMs predicting suitable habitat in the present day for each species, then projected our models to the last glacial maximum (LGM; 21kya) using paleo-climate data to analyze the ferns’ response to rapid climate change after the Pleistocene. We also projected our models to future climate scenarios (2070; rcp26, rcp45, rcp60, and rcp85), allowing us to identify suitable habitats for each species and focus conservation efforts. We found that C. sitchensis and C. acrostichoides most likely shared coastal refugia in southcentral Alaska and the Coastal Pacific Northwest (including Haida Gwai) during the LGM, and that populations in the western contiguous USA will face critical conservation threats in the near future. We then independently assessed these results using molecular phylogeographic analyses. We constructed a chronogram using a six locus plastid data set (comprising 40 accessions from eight Cryptogramma species and six outgroup taxa), a relaxed-clock model, and two secondary constraints implemented in MrBayes. Most speciation events in crown group Cryptogramma occurred in the Pliocene and Pleistocene. We then reconstructed the phylogeographic history of C. acrostichoides and C. sitchensis during the Pleistocene and Holocene using the chronogram and accession range data in BayArea. These results also support the long-term presence of C. acrostichoides and C. sitchensis in southcentral Alaska, the Coastal Pacific Northwest, and unglaciated portions of the western contiguous USA. If these taxa have persisted long-term through dramatic climatic cycles in refugial locations, these locations may be key regions for surviving anthropogenic climate change.

1 - Virginia Tech, 926 W. Campus Drive, Derring 2119, MC0406, Blacksburg, VA, 24061, United States
2 - University Of Alaska Fairbanks, Dept. Of Biology And Wildlife, UA Museum Herbarium (ALA), 907 Yukon, Fairbanks, AK, 99775.0, United States
3 - 926 W. Campus Dr, MC 0406, Derring Hall 2119, Blacksburg, VA, 24061, United States

Keywords:
Cryptogramma
ferns
ecological niche modelling.

Presentation Type: Oral Paper
Session: PTER1, Pteridology I
Location: San Pedro 1/Starr Pass
Date: Monday, July 29th, 2019
Time: 9:30 AM
Number: PTER1007
Abstract ID:183
Candidate for Awards:Edgar T. Wherry award