Seascape genetics of the spiny lobster Panulirus homarus in the Western Indian Ocean: Understanding how oceanographic features shape the genetic structure of species with high larval dispersal potential

Abstract

This study examines the fine‐scale population genetic structure and phylogeography of the spiny lobster Panulirus homarus in the Western Indian Ocean. A seascape genetics approach was used to relate the observed genetic structure based on 21 microsatellite loci to ocean circulation patterns, and to determine the influence of latitude, sea surface temperature (SST), and ocean turbidity (KD490) on population‐level processes. At a geospatial level, the genetic clusters recovered corresponded to three putative subspecies, P. h. rubellus from the SW Indian Ocean, P. h. megasculptus from the NW Indian Ocean, and P. h. homarus from the tropical region in‐between. Virtual passive Lagrangian particles advected using satellite‐derived ocean surface currents were used to simulate larval dispersal. In the SW Indian Ocean, the dispersion of particles tracked over a 4‐month period provided insight into a steep genetic gradient observed at the Delagoa Bight, which separates P. h. rubellus and P. h. homarus. South of the contact zone, particles were advected southwestwards by prevailing boundary currents or were retained in nearshore eddies close to release locations. Some particles released in southeast Madagascar dispersed across the Mozambique Channel and reached the African shelf. Dispersal was characterized by high seasonal and inter‐annual variability, and a large proportion of particles were dispersed far offshore and presumably lost. In the NW Indian Ocean, particles were retained within the Arabian Sea. Larval retention and self‐recruitment in the Arabian Sea could explain the recent genetic divergence between P. h. megasculptus and P. h. homarus. Geographic distance and minimum SST were significantly associated with genetic differentiation in multivariate analysis, suggesting that larval tolerance to SST plays a role in shaping the population structure of P. homarus.

Population genetic structure and connectivity of the seagrass Thalassia hemprichii in the Western Indian Ocean is influenced by predominant ocean currents

“…In general, there is a gap of knowledge on marine genetic patterns in the WIO region (Ridgway & Sampayo, 2005), but see for example studies on corals (Souter, Henriksson, Olsson, & Grahn, 2009;van der Ven et al, 2016), spiny lobster (Singh, Groeneveld, Hart-Davis, Backeberg, & Willows-Munro, 2018), and fish (Muths, Gouws, Mwale, Tessier, & Bourjea, 2012;Visram et al, 2010). The available population genetic data indicate that the WIO is a unique T. hemprichii within the WIO, conservation planning and implementation of marine protection should be considered at the regional scale-across national borders.…”

Seascape genetics of the stalked kelp Pterygophora californica and comparative population genetics in the Santa Barbara Channel

“…Oceanographic distance has proven to be a better predictor of genetic connectivity than Euclidian distance in several marine systems (Weersing and Toonen 2009, Singh et al 2018, including kelps (Alberto et al 2011, Johansson et al 2015, Durrant et al 2018). Oceanographic distance has proven to be a better predictor of genetic connectivity than Euclidian distance in several marine systems (Weersing and Toonen 2009, Singh et al 2018, including kelps (Alberto et al 2011, Johansson et al 2015, Durrant et al 2018).…”

“…Oceanographic transit time. Oceanographic distance has proven to be a better predictor of genetic connectivity than Euclidian distance in several marine systems (Weersing and Toonen 2009, Singh et al 2018, including kelps (Alberto et al 2011, Johansson et al 2015, Durrant et al 2018. In our previous work (Alberto et al 2011), we combined data on population genetics, habitat availability, Euclidian distance, and oceanographic connectivity (derived using a Lagrangian particle simulation model) in a multiple regression model to determine the best predictors of amongsite genetic differentiation of Macrocystis pyrifera in the Santa Barbara Channel.…”

Genetic structure and life history are key factors in species distribution models of spiny lobsters

“…Females release larvae with a prolonged (4-6 months) drifting dispersal phase (George, 2005;Phillips & Booth, 1994). The long drifting larval phase is susceptible to the effects of climate change, especially variability in the strength and direction of ocean currents and water temperature (Singh et al, 2018(Singh et al, , 2019. P. homarus comprises three subspecies based on geography and morphological characteristics (Berry, 1974).…”

“…The aims of this study were to investigate the effects of genetic partitioning on predictions of current and future areas of habitat suitability for the commercially important spiny lobster Panulirus homarus, using SDMs. Genetic and oceanographic barriers derived from Singh et al (2018) were incorporated in the SDMs, and the results were contrasted with SDMs that treated P. homarus as a single homogenous unit (i.e., all subspecies combined). We took both larval dispersal and benthic life history phases into account by modeling sea surface and benthic environmental data layers.…”