Oceanographic features and limited dispersal shape the population genetic structure of the vase sponge Ircinia campana in the Greater Caribbean

Abstract

Understanding population genetic structure can help us to infer dispersal patterns, predict population resilience and design effective management strategies. For sessile species with limited dispersal, this is especially pertinent because genetic diversity and connectivity are key aspects of their resilience to environmental stressors. Here, we describe the population structure of Ircinia campana, a common Caribbean sponge subject to mass mortalities and disease. Microsatellites were used to genotype 440 individuals from 19 sites throughout the Greater Caribbean. We found strong genetic structure across the region, and significant isolation by distance across the Lesser Antilles, highlighting the influence of limited larval dispersal. We also observed spatial genetic structure patterns congruent with oceanography. This includes evidence of connectivity between sponges in the Florida Keys and the southeast coast of the United States (>700 km away) where the oceanographic environment is dominated by the strong Florida Current. Conversely, the population in southern Belize was strongly differentiated from all other sites, consistent with the presence of dispersal-limiting oceanographic features, including the Gulf of Honduras gyre. At smaller spatial scales (<100 km), sites showed heterogeneous patterns of low-level but significant genetic differentiation (chaotic genetic patchiness), indicative of temporal variability in recruitment or local selective pressures. Genetic diversity was similar across sites, but there was evidence of a genetic bottleneck at one site in Florida where past mass mortalities have occurred. These findings underscore the relationship between regional oceanography and weak larval dispersal in explaining population genetic patterns, and could inform conservation management of the species.

The Relationship Between Microbiomes and Selective Regimes in the Sponge Genus Ircinia

“…The results of Griffiths et al (2021) and our current study are congruent in that Panamanian I. campana and Floridian I. campana appear in different clusters. Given their observations, Griffiths et al (2021) suggested that I. campana might represent a case of cryptic speciation, although they restrict this proposal to a population inhabiting the Sapodilla Cayes that appeared particularly divergent from the remaining clusters. Given our BFD * results, we would like to append that cryptic speciation in I. campana, which curiously tracks microbiome divergence, could be a phenomenon that encompasses populations in addition to the one at Sapodilla Cayes.…”

“…The polyphyly of I. campana is a result that departs from conventional knowledge about this species, which is typically regarded as monophyletic and is one of the Ircinia in the Caribbean whose gross phenotypic features are expected to track species boundaries. Interestingly, a recent publication (Griffiths et al, 2021) used microsatellite genotyping of host sponges to uncover a trend of high genetic population structure among geographically distant I. campana populations, which were found to constitute four distinct admixture clusters. The results of Griffiths et al (2021) and our current study are congruent in that Panamanian I. campana and Floridian I. campana appear in different clusters.…”

“…Interestingly, a recent publication (Griffiths et al, 2021) used microsatellite genotyping of host sponges to uncover a trend of high genetic population structure among geographically distant I. campana populations, which were found to constitute four distinct admixture clusters. The results of Griffiths et al (2021) and our current study are congruent in that Panamanian I. campana and Floridian I. campana appear in different clusters. Given their observations, Griffiths et al (2021) suggested that I. campana might represent a case of cryptic speciation, although they restrict this proposal to a population inhabiting the Sapodilla Cayes that appeared particularly divergent from the remaining clusters.…”

Screening of the antimicrobial activity of marine sponge extracts from Martinique

“…It is made available under a preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in highly diversified chemical natures [3][4][5][6]. The marine ecosystems of Martinique are rich in sponges [7][8][9][10][11][12], however, they are undervalued [13]. The aim of this study is to increase our knowledge of Martinique's sponges and their potential antimicrobial activity.…”

“…Marine sponges produce abundant secondary biomolecules and have highly diversified chemical natures [3-6]. The marine ecosystems of Martinique are rich in sponges [7–12], however, they are undervalued [13]. The aim of this study is to increase our knowledge of Martinique’s sponges and their potential antimicrobial activity.…”