A biogeographical profile of the sand cockroach Arenivaga floridensis and its bearing on origin hypotheses for Florida scrub biota

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)
Trip,Justice,Teresa C.,Brewer,Michael S.,Moler,Paul E.,Hopkins,Heidi,B Lamb (Creator)
East Carolina University (ECU )
Web Site: http://www.ecu.edu/lib/

Abstract: Florida scrub is a xeric ecosystem associated with the peninsula"s sand ridges, whoseintermittent Pliocene--Pleistocene isolation is considered key to scrub endemism. Onescrub origin hypothesis posits endemics were sourced by the Pliocene dispersal ofarid-adapted taxa from southwestern North America; a second invokes Pleistocenemigration within eastern North America. Only one study to date has explicitly testedthese competing hypotheses, supporting an eastern origin for certain scrub angiosperms. For further perspective, we conducted a genetic analysis of an endemic arthropod, the Florida sand cockroach (Arenivaga floridensis), with two aims: (1) toreconstruct the peninsular colonization and residence history of A. floridensis and (2)determine whether its biogeographic profile favors either origin hypothesis. We sequenced the cox2 mitochondrial gene for 237 specimens (65 populations) as well asadditional loci (cox1, nuclear H3) for a subset of Florida roaches and congeners. UsingNetwork and Bayesian inference methods, we identified three major lineages whosegenetic differentiation and phylogeographical structure correspond with late Pliocenepeninsula insularization, indicating Arenivaga was present and broadly distributed inFlorida at that time. Stem and crown divergence estimates (6.36 Ma; 2.78 Ma) between A. floridensis and western sister taxa span a period of extensive dispersal bywestern biota along an arid Gulf Coast corridor. These phylogeographical and phylogenetic results yield a biogeographic profile consistent with the western origin hypothesis. Moreover, age estimates for the roach"s peninsular residence complementthose of several other endemics, favoring a Pliocene (or earlier) inception of the scrubecosystem. We argue that eastern versus western hypotheses are not mutually exclusive; rather, a composite history of colonization involving disparate biotas better explains the diverse endemism of Florida scrub.

Additional Information

Language: English
Date: 2017
Arenivaga, dispersal, endemism, Florida platform, Gulf Coast corridor

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