A multispecies approach reveals hot spots and cold spots of diversity and connectivity in invertebrate species with contrasting dispersal modes

Abstract

Genetic diversity is crucial for species' maintenance and persistence, yet is often overlooked in conservation studies. Species diversity is more often reported due to practical constraints, but it is unknown if these measures of diversity are correlated. In marine invertebrates, adults are often sessile or sedentary and populations exchange genes via dispersal of gametes and larvae. Species with a larval period are expected to have more connected populations than those without larval dispersal. We assessed the relationship between measures of species and genetic diversity, and between dispersal ability and connectivity. We compiled data on genetic patterns and life history traits in nine species across five phyla. Sampling sites spanned 600 km in the northwest Mediterranean Sea and focused on a 50-km area near Marseilles, France. Comparative population genetic approaches yielded three main results. (i) Species without larvae showed higher levels of genetic structure than species with free-living larvae, but the role of larval type (lecithotrophic or planktotrophic) was negligible. (ii) A narrow area around Marseilles, subject to offshore advection, limited genetic connectivity in most species. (iii) We identified sites with significant positive contributions to overall genetic diversity across all species, corresponding with areas near low human population densities. In contrast, high levels of human activity corresponded with a negative contribution to overall genetic diversity. Genetic diversity within species was positively and significantly linearly related to local species diversity. Our study suggests that local contribution to overall genetic diversity should be taken into account for future conservation strategies.

Molecular phylogeny of historical micro-invertebrate specimens usingde novosequence assembly

“…Firstly, as discussed earlier, Calpensia shares important morphological traits 425 with Steginoporella and its relatives even though it currently nominally belongs to the 426 phylogenetically more derived, but one-size-fits all family Microporidae (Gray, 1848;Jullien, 427 1888). Secondly, the Myriapora cox1 gene has previously been amplified utilizing barcoding 428 primers (Cahill et al, 2017). We can therefore confirm the placement of Myriapora (BLEED 429 1197) in the main phylogeny ( Fig.…”

Lessons from photo analyses of Autonomous Reef Monitoring Structures as tools to detect (bio-)geographical, spatial, and environmental effects

“…We cannot conclude whether the significant differences found among sites (within sea) are due to typical spatial effects (the fact not all species could colonize ARMS in distinct sites within a year, due to limited connectivity) or to some purely environmental effects (that is, involving the filter of natural selection) that differed among sites. For the North West Mediterranean region, we have evidence from population genetics data of numerous species that gene flow and dispersal are limited between the sites of the present study, despite their proximity (Cahill et al, 2017;De Jode, 2018). In 20 locations from the same area, a metabarcoding study of established coralligenous communities revealed a strong effect of the location but also strong effects of the physical environment such as depth, or slope, which were varying within locations) on community composition (indeed the same proportion of the variance, respectively 20% and 19%, was explained by location and by depth) (De Jode, 2018).…”

From seascape ecology to population genomics and back. Spatial and ecological differentiation among cryptic species of the red algae Lithophyllum stictiforme/L. cabiochiae, main bioconstructors of coralligenous habitats

“…Comparing F ST value in this study (F ST global 0.0464) with those obtained by Cahill et al (2017) using data from several invertebrate species sampled in the same geographic area, the C1 species would correspond to the lecithotroph "larval type" species in terms of dispersal capacities. Both population genomics and cryptic species composition patterns showed a differentiation between the Côte Bleue, and the east part of the Bay of Marseille.…”

“…Amplicons were sequenced, and Miseq Reads were processed as described in Cahill et al (2017) with a few exceptions. For the plastid marker, psbA, sorting was done as in Cahill et al (2017) for mitochondrial loci with slight modifications: sequences were retained if the total number of reads was ≥ 20 (i.e. 20X coverage) and the count ratio ≤ 0.14 (i.e.…”