Abstract Detail

Systematics Section/ASPT

Worcester, Lindsey [1], Fishbein, Mark [2].

Phylogeny and Biogeography of Arid-Adapted Milkweeds (Podostemma Clade, Asclepias L., Apocynaceae).

Biogeographic disjunctions, separation of ranges between closely related species, raise questions of how biogeographic processes explain these patterns. Disjunctions are important because they are evidence of the ongoing story of speciation in response to geologic and environmental events. The Sierra Madre Occidental (SMO) separates closely related milkweed species in the Podostemma clade of Asclepias. Relationships among species in this clade were not fully resolved with chloroplast DNA sequences. Introns in three conserved nuclear loci (COSII) were sequenced for the seven species of Podostemma milkweeds and outgroups. Gene trees for each locus were estimated using maximum likelihood and a species trees was estimated in a multilocus coalescent framework using *BEAST2. Relationships among early diverging species in the Podostemma clade conflict with results from the chloroplast phylogeny, with Asclepias arenaria placed as sister to the remainder of the clade. Relationships among five of species are unresolved due to incongruent patterns of allele sharing between species, likely due to incomplete lineage sorting or introgression. Species do not form eastern and western clades, which does not support a vicariant event involving the SMO.

1 - Oklahoma State University, Botany, 301 Physical Sciences, Stillwater, OK, 74078, USA
2 - Oklahoma State University, Dept Of Botany, 301 Physical Science, Stillwater, OK, 74078, USA

Keywords:
Asclepias
Phylogenetics
Podostemma clade
COSII loci
biogeography
Sierra Madre Occidental
Cochise Filter Barrier.

Presentation Type: Oral Paper:Papers for Sections
Session: 19
Location: Salon 9/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 4:45 PM
Number: 19013
Abstract ID:337
Candidate for Awards:None