Abstract Detail



Biogeography

Lujan, Theresa [1], Hasenstab-Lehman, Kristen [2], Baldwin, Bruce [3], Lee, Joongku [4], Guilliams, C. Matt [5].

A phylogenetic and morphological analysis of biogeography and dispersal mechanism evolution in Channel Islands endemic Malacothrix (Asteraceae).

Malacothrix DC is a genus of Asteraceae comprising twenty species.  Nine minimum-rank taxa are endemic to the California Channel Islands, making the genus one of the best examples of diversification across this fringing archipelago. Despite this, inferring the evolutionary history of these island endemic Malacothrix has never been the focus of a phylogenetic study. We therefore know little about the number and timing of colonization events in the genus, or morphological features associated with colonization. We sequenced nrITS  data for nine island endemic taxa and three mainland--island taxa, adding our new data to existing sequences from GenBank to infer phylogenetic relationships across 23 minimally ranked taxa, allowing us to examine the history of dispersal to and radiation across the archipelago. Maximum likelihood and Bayesian analyses using the ITS dataset were used to infer phylogeny of Malacothrix. Biogeographic reconstruction suggests four dispersals of Malacothrix between the mainland and islands, at approximately 10, 4, 1.5, and 1 MYA.
Additionally, the loss of features commonly associated with dispersal, a phenomenon noted in other island systems, was tested for Channel Island Malacothrix.  To examine the relationship between presence on an island and loss of traits potentially associated with dispersal, we performed comparative phylogenetic analyses of 5 cypsela and pappus features using our best maximum likelihood tree. Images of fruit features were obtained using SEM and light microscopy and measured with ImageJ software. BinaryGLM analysis reports significantly smaller pappus barb lengths among island taxa.  Preliminary results imply a possible loss in dispersibility, which will be further tested with increased sample size.


1 - California State University, Channel Islands, Biology, One University Drive, Camarillo, CA, 93012, United States
2 - Santa Barbara Botanic Garden, Department of Conservation and Research, 1200 Mission Canyon Road, Santa Barbara, CA, 93105, USA
3 - University Of California, Jepson Herbarium & Dept. Of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, CA, 94720, United States
4 - Chungnam National University, Department Of Environment & Forest Resources, 99 Daehak-ro, Yuseong-Gu, Daejeon, 30, 34134, Korea, Republic of
5 - Santa Barbara Botanic Garden, 1212 Mission Canyon Road, Santa Barbara, CA, 93105, United States

Keywords:
Malacothrix
phylogeny
morphology
biogeography
California Channel Islands.

Presentation Type: Poster This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PBG009
Abstract ID:638
Candidate for Awards:None


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