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Abstract Detail

Conservation Biology

Guilliams, C. Matt [1], Hernandez, Adriana I. [2], Hasenstab-Lehman, Kristen [1], Wallace, Lisa [3], Helenurm, Kaius [4].

Population genetic analyses reveal island-based differentiation in the California Channel Islands endemic plant, Malva assurgentiflora (Malvaceae).

Malva assurgentiflora (Kellogg) M.F. Ray (Malvaceae) is a charismatic, perennial shrub endemic to four of the eight California Channel Islands, with plants of unknown provenance occurring on San Nicolas Island. Due in large part to introduced herbivores, the species is now rare and highly localized. Philbrick hypothesized that the plants on the southern islands are morphologically distinct from those on the northern islands. The northern populations are characterized by a pubescent upper leaf surface, a subentire petal apex, and a pubescent filament tube, while the southern populations have a glabrous to subglabrous upper leaf surface, an erose petal apex, and a glabrous to subglabrous filament tube. Philbrick created a new name L. assurgentiflora ssp. glabra for the southern plants. However, an early phylogenetic analysis by Ray failed to find evidence for two evolutionary lineages in M. assurgentiflora corresponding to Philbrick's taxonomic concept based on morphology. As a result, the current state-wide flora does not adopt Philbrick’s concept despite apparent differences in morphology. Here we use allele size data from five microsatellite loci to examine genetic variation and structure among populations across the natural range of the species. Our sampling includes 206 individuals, 23 of which are from the potentially naturally-occurring population on San Nicolas Island. Due to polyploidy in M. assurgentiflora, we are unable to use frequency-based methods. We therefore recoded our data as presence/absence and performed principal coordinate analysis, a neighbor-joining tree building analysis, and a STRUCTURE analysis. Each of these analyses show that the northern and southern populations are genetically distinct. These results support Philbrick's hypothesis on the basis of morphology that plants from the northern and southern Channel Islands may be distinct evolutionary lineages worthy of taxonomic recognition. Plants from San Nicolas Island, including those from horticultural settings in Nicktown, are all genetically similar to northern form genotypes, suggesting that they are introduced to the island. Finally, all analyses show that populations from the southern islands of San Clemente and Santa Catalina are genetically distinct. Future work will evaluate if plants from these islands are morphologically distinct, a finding that would bolster the argument to recognize the plants from San Clemente as a new, single-island endemic taxon.

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1 - Santa Barbara Botanic Garden, 1212 Mission Canyon Road, Santa Barbara, CA, 93105, United States
2 - Cornell University, School of Integrative Plant Sciences, 502 Mann Library, Ithaca, NY, 14853, USA
3 - Old Dominion University, Biological Sciences, Mills Godwin Building Rm. 110, Norfolk, VA, 23529, United States
4 - Department Of Biology, Vermillion, SD, 57069, United States

Channel Islands
island biogeography

Presentation Type: Oral Paper
Session: 40, Conservation Biology I
Location: 106/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 8:45 AM
Number: 40002
Abstract ID:432
Candidate for Awards:None

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