title: Phylogeographic patterns of a lower intertidal isopod in the Gulf of California and the Caribbean and comparison with other intertidal isopods.
abstract: A growing body of knowledge on the diversity and evolution of intertidal isopods across different regions worldwide has enhanced our understanding on biological diversification at the poorly studied, yet vast, sea-land interface. High genetic divergences among numerous allopatric lineages have been identified within presumed single broadly distributed species.Excirolana mayanais an intertidal isopod that is commonly found in sandy beaches throughout the Gulf of California. Its distribution in the Pacific extends from this basin to Colombia and in the Atlantic from Florida to Venezuela. Despite its broad distribution and ecological importance, its evolutionary history has been largely neglected. Herein, we examined phylogeographic patterns ofE. mayanain the Gulf of California and the Caribbean, based on maximum-likelihood and Bayesian phylogenetic analyses of DNA sequences from four mitochondrial genes (16S rDNA, 12S rDNA, cytochrome oxidase I gene, and cytochrome b gene). We compared the phylogeographic patterns ofE. mayanawith those of the coastal isopodsLigiaandExcirolana braziliensis(Gulf of California and Caribbean) andTylos(Gulf of California). We found highly divergent lineages in both, the Gulf of California and Caribbean, suggesting the presence of multiple species. We identified two instances of Atlantic-Pacific divergences. Some geographical structuring among the major clades found in the Caribbean is observed. Haplotypes from the Gulf of California form a monophyletic group sister to a lineage found in Venezuela. Phylogeographic patterns ofE. mayanain the Gulf of California differ from those observed inLigiaandTylosin this region. Nonetheless, several clades ofE. mayanahave similar distributions to clades of these two other isopod taxa. The high levels of cryptic diversity detected inE. mayanaalso pose challenges for the conservation of this isopod and its fragile environment, the sandy shores.
authors.affiliation: Department of Wildlife and Fisheries Sciences Texas A&M University College Station TX USA.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Hurtado
authors.affiliation: Department of Wildlife and Fisheries Sciences Texas A&M University College Station TX USA.
authors.forename: Mariana
authors.initials: M
authors.lastname: Mateos
authors.affiliation: Department of Wildlife and Fisheries Sciences Texas A&M University College Station TX USA.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
keywords: Caribbean; Cirolanidae; Excirolana braziliensis; Gulf of California; Isopod; Ligia; Ligia baudiniana; Ligia occidentalis; Tylos; Tylos punctatus; cryptic species; marine biodiversity; sandy beach