Global drivers of recent diversification in a marine species complex

Abstract

Investigating historical gene flow in species complexes can indicate how environmental and reproductive barriers shape genome divergence during speciation. The processes influencing species diversification under environmental change remain one of the central focal points of evolutionary biology, particularly for marine organisms with high dispersal potential. We investigated genome‐wide divergence, introgression patterns and inferred demographic history between species pairs of all six extant rock lobster species (Jasus spp.), which have a long larval duration of up to two years and have populated continental shelf and seamount habitats around the globe at approximately 40oS. Genetic differentiation patterns reflected geographic isolation and the environment (i.e. habitat structure). Eastern Pacific species (J. caveorum and J. frontalis) were geographically more distant and genetically more differentiated from the remaining four species. Species associated with continental shelf habitats shared a common ancestry, but are geographically distant from one another. Similarly, species associated with island/seamount habitats in the Atlantic and Indian Oceans shared a common ancestry, but are also geographically distant. Benthic temperature was the environmental variable that explained most of the genetic differentiation (FST), while controlling for the effects of geographic distance. Eastern Pacific species retained a signal of strict isolation following ancient migration, whereas species pairs from Australia and Africa, and seamounts in the Indian and Atlantic oceans, included events of introgression after secondary contact. Our results reveal important effects of habitat and demographic processes on the recent divergence of species within the genus Jasus, providing one of the first empirical studies of genome‐wide drivers of diversification that incorporates all extant species in a marine genus with long pelagic larval duration.

Genome-wide SNPs in the spiny lobster Panulirus homarus reveal a hybrid origin for its subspecies

“…Then the best model’s parameters were optimized using 100 simulations. Further details of model selection and analysis were as described in Silva et al [ 16 ] and Portik et al [ 41 ]. The conversion of the obtained demographic parameters to biological units (N ref , mutation rate and generation time) was carried out as per Silva et al [ 16 ].…”

“…Further details of model selection and analysis were as described in Silva et al [ 16 ] and Portik et al [ 41 ]. The conversion of the obtained demographic parameters to biological units (N ref , mutation rate and generation time) was carried out as per Silva et al [ 16 ]. For comparison, equivalent demographic analyses were also performed using approximate Bayesian computation in DIYABC [ 42 ] with the same demographic scenarios simulated for one million summary statistics per scenario.…”

“…In marine organisms, genome-wide SNP discovery has been of considerable assistance in improving our understanding of the degree of population genetic differences [ 12 , 13 ], detection of secondary contact [ 14 ], and the effect of local environmental adaptation [ 15 ]. The joint allele frequency spectrum (AFS) from genome-wide SNP data has recently been used successfully to investigate historical demography of several non-model marine species (e.g., [ 16 ]). Understanding the degree of secondary contact, admixture and the potential fitness of hybrids or parental populations can also be useful for aquaculture, through an understanding of the genetic diversity within target species, and by helping to identify the source of unique broodstock.…”

Does marine geospatial/environmental variation affect genetic variation? A meta-analysis

“…These taxa have populated the continental shelf and seamount habitats in a narrow latitudinal band in the Southern hemisphere across the Pacific, Atlantic and Indian Oceans (Booth, 2006). In this study, Silva et al (2021) reported that benthic temperature is associated with the differentiation between species/populations from island/seamount and continental shelf habitats. This finding suggests that temperature may limit reproduction between species-specific populations (which are adapted to local benthic temperatures) since this factor has been associated with embryological development in lobsters (Benestan et al, 2016).…”

“…It is important in the future to be able to achieve predictions on a global scale, as some authors have recently suggested. An example is the outcome reported by Silva et al (2021), who suggested that benthic temperature is associated with the differentiation between species/populations across rock lobsters, Jasus spp., along a narrow latitudinal band in the Southern hemisphere. This is undoubtedly the limitation that the discipline of seascape genetics is facing -to be able in the future to inform management and conservation -but more efforts and collaborative networks are necessary to achieve such macroecological goals.…”