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Abstract Detail



Biogeography

Levin, Rachel A. [1], Keyes, Edmund [2], Miller, Jill S. [1].

The Galàpagos endemic Lycium minimum (Solanaceae): biogeography, polyploidy, and sexual system.

The genus Lycium (Solanaceae) has been studied in contexts ranging from systematics and biogeography to the evolution of mating and sexual systems. While several species of Lycium occur on islands, only one, L. minimum, is confined exclusively to an island archipelago. Reported from at least nine of the Galàpagos Islands, L. minimum is also the only species of Lycium to occur solely at the equator. Morphologically, the Galàpagos endemic L. minimum is distinguished by its atypical fruit. The majority of Lycium species produce fleshy berries with multiple seeds per fruit, but four species (L. minimum, L. californicum, L. athium, and L. ameghinoi) bear drupaceous fruits containing at most two large seeds. Given its location in the Galàpagos, Lycium minimum has been relatively understudied. The present study provides a much-needed investigation of L. minimum to address questions regarding its evolutionary affinities, biogeography, and sexual system.  Specifically the goals of this study are to: (1) determine the closest living relatives of L. minimum; (2) elucidate biogeographic patterns among L. minimum populations within the Galàpagos Islands; (3) investigate the evolution of drupaceous fruits in Lycium; and (4) infer the sexual system of L. minimum, including assessment of ploidy variation using DNA content measurements. To address the first three goals, we employ plastid and nuclear DNA sequence data. Our findings support a South American origin for the Galàpagos endemic Lycium minimum, with the Argentine L. athium as the closest living relative. In addition, although further research is necessary to determine the specific path, genetic evidence suggests a southeast to northwest colonization of the Galapagos chain. Older islands maintain higher levels of genetic diversity than younger islands, but efficient dispersal via birds ensures a means of gene flow between islands. Finally, morphological and cytological evidence confirms sexual dimorphism and polyploidy in L. minimum, the first documented instance of a dimorphic Lycium species in South America.


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1 - Amherst College, Department Of Biology, McGuire Life Sciences Building, Amherst, MA, 01002, USA
2 - Texas Tech University, Department of Natural Resources Management, Lubbock, TX, 79409, USA

Keywords:
Solanaceae
polyploidy
gender dimorphism
Biogeography
Phylogeny
Galapagos.

Presentation Type: Oral Paper:Papers for Topics
Session: 3
Location: Salmon/Boise Centre
Date: Monday, July 28th, 2014
Time: 11:00 AM
Number: 3011
Abstract ID:576
Candidate for Awards:None


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