Cryptic biodiversity and phylogeographic patterns of SeychelloisLigiaisopods

Abstract

Ligia isopods are conspicuous inhabitants of rocky intertidal habitats exhibiting several biological traits that severely limit their dispersal potential. Their presence in patchy habitats and low vagility may lead to long term isolation, allopatric isolation and possible cryptic speciation. Indeed, various species of Ligia have been suggested to represent instead cryptic species complexes. Past studies; however, have largely focused in Eastern Pacific and Atlantic species of Ligia, leaving in doubt whether cryptic diversity occurs in other highly biodiverse areas. The Seychelles consists of 115 islands of different ages and geological origins spread across the western Indian Ocean. They are well known for their rich biodiversity with recent reports of cryptic species in terrestrial Seychellois organisms. Despite these studies, it is unclear whether coastal invertebrates from the Seychelles harbor any cryptic diversity. In this study, we examined patterns of genetic diversity and isolation within Ligia isopods across the Seychelles archipelago by characterizing individuals from locations across both inner and outer islands of the Seychelles using mitochondrial and nuclear markers. We report the presence of highly divergent lineages of independent origin. At Aldabra Atoll, we uncovered a lineage closely related to the Ligia vitiensis cryptic species complex. Within the inner islands of Cousine, Silhouette, and Mahé we detected the presence of two moderately divergent and geographically disjunct lineages most closely related to Ligia dentipes. Our findings suggest that the Seychelles may harbor at least three novel species of Ligia in need of description and that these species may have originated independently.

Out of Asia: mitochondrial evolutionary history of the globally introduced supralittoral isopodLigia exotica

“…Thus, it is possible that cryptic diversity occurs within the L. exotica clade . High levels of cryptic diversity have been reported in numerous studies of Ligia and other intertidal isopods regarded as single broadly distributed species ( Hurtado, Lee & Mateos, 2013 ; Hurtado, Mateos & Liu, 2017 ; Hurtado et al, 2016 ; Hurtado, Mateos & Santamaria, 2010 ; Santamaria et al, 2017b ; Santamaria et al, 2016 ; Santamaria, Mateos & Hurtado, 2014 ; Santamaria et al, 2013 ).…”

“…Ligia exotica , thus, may not be as common as previously thought in these regions, and scattered isolated introduced populations might occur within the range of native lineages, as observed in the Caribbean (see below). South Asia is home to Ligia dentipes Budde-Lund, 1885, which has a broad distribution that spans the Nicobar Islands, Andaman Islands, Maldives, Seychelles, Sri Lanka, and Thailand ( Santamaria et al, 2017b ; Taiti, 2014 ). Three divergent (12–15% divergence at the COI gene) lineages of L. dentipes were detected in a study that surveyed the Seychelles, Sri Lanka, and Thailand ( Santamaria et al, 2017b ).…”

“…South Asia is home to Ligia dentipes Budde-Lund, 1885, which has a broad distribution that spans the Nicobar Islands, Andaman Islands, Maldives, Seychelles, Sri Lanka, and Thailand ( Santamaria et al, 2017b ; Taiti, 2014 ). Three divergent (12–15% divergence at the COI gene) lineages of L. dentipes were detected in a study that surveyed the Seychelles, Sri Lanka, and Thailand ( Santamaria et al, 2017b ). Similarly, the eastern coast of Africa harbors two highly divergent lineages of Ligia vitiensis (Dana, 1853), one distributed in Tanzania, Seychelles, and Madagascar, and the other in Tanzania ( Santamaria et al, 2017b ).…”

“…Three divergent (12–15% divergence at the COI gene) lineages of L. dentipes were detected in a study that surveyed the Seychelles, Sri Lanka, and Thailand ( Santamaria et al, 2017b ). Similarly, the eastern coast of Africa harbors two highly divergent lineages of Ligia vitiensis (Dana, 1853), one distributed in Tanzania, Seychelles, and Madagascar, and the other in Tanzania ( Santamaria et al, 2017b ). Other species reported in East Africa, but lacking molecular data, are: Ligia ferrarai Kersmaekers & Verstraeten, 1990 in Madagascar; Ligia pigmentata Jackson, 1922 in Somalia (also reported in the Red Sea and Persian Gulf; although records for this last basin have been questioned; Khalaji-Pirbalouty & Wägele, 2010 ); and Ligia malleata Pfeffer, 1889 in Tanzania, which is possibly a synonym of L. exotica ( Schmalfuss, 2003 ).…”

Molecular approaches uncover cryptic diversity in intertidalLigiaisopods (Crustacea, Isopoda, Ligiidae) across the southern Africa coastline

“…Recent phylogeographic work on coastal invertebrate species has led to the discovery of cryptic diversity in poorly dispersing species around the world (e.g., Chan, Tsang & Chu, 2007 ; Hurtado, Lee & Mateos, 2013 ; Radulovici, Sainte-Marie & Dufresne, 2009 ; Santamaria et al, 2017 ; Santamaria et al, 2016 ; Santamaria, Mateos & Hurtado, 2014 ; Santamaria et al, 2013 ; Varela & Haye, 2012 ). In South Africa, cryptic diversity has been reported for several coastal invertebrate taxa ( Evans et al, 2004 ; Mmonwa et al, 2015 ; Reynolds, Matthee & Von der Heyden, 2014 ; Ridgway et al, 2001 ; Teske et al, 2007 ; Zardi et al, 2007 ), including direct-developing crustacean peracarids.…”