Using genetics to inform restoration and predict resilience in declining populations of a keystone marine sponge

Abstract

Genetic tools can have a key role in informing conservation management of declining populations. Genetic diversity is an important determinant of population fitness and resilience, and can require careful management to ensure sufficient variation is present. In addition, population genetics data reveal patterns of connectivity and gene flow between locations, enabling mangers to predict recovery and resilience, identify areas of local adaptation, and generate restoration plans. Here, we demonstrate a conservation genetics approach to inform restoration and management of the loggerhead sponge (Spheciospongia vesparium) in the Florida Keys, USA. This species is a dominant, habitat-forming component of marine ecosystems in the Caribbean region, but in Florida has suffered numerous mass mortality events. We developed microsatellite markers and used them to genotype sponges from 14 locations in Florida and a site each in The Bahamas, Belize and Barbuda. We found that genetic diversity levels were similar across all sites, but inbreeding and bottleneck signatures were present in Florida. Populations are highly structured at the regional scale, whilst within Florida connectivity is present in a weak isolation by distance pattern, coupled with chaotic genetic patchiness. Evidence of a weak barrier to gene flow was found in Florida among sites situated on opposite sides of the islands in the Middle Keys. Loggerhead sponge populations in Florida are vulnerable in the face of mass mortalities due to low connectivity with other areas in the region, as well as distance-limited and unpredictable local connectivity patterns. However, our discovery of Florida's high genetic diversity increases hope for resilience to future perturbations. These results provide valuable insight for sponge restoration practice in Florida. Communicated by David Hawksworth.

Omics approaches for conservation biology research on the bivalve Chamelea gallina

“…The high genetic diversity recorded together with the existence of a unique population in the Adriatic Sea confers to this species a higher responsiveness to local environmental perturbations (e.g., overfishing, pollution, and mortality due to microbiological infections), as reported for invertebrate marine species [71][72][73] . Genetic interconnection due to larval dispersion between Adriatic sites represents a fundamental counterforce against local population size decline, thereby increasing the ability of population persistence 74 . Larval dispersion seems to have played a less important role due to the species' limited and patchy distribution along the Italian Tyrrhenian coast and to the separation from the Adriatic population.…”

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

“…Although the Florida Keys formed a single genetic cluster, 8 out of 15 pairs of sites showed significant but low genetic differentiation, with no site consistently emerging as different from the rest-a common pattern in marine systems termed 'chaotic genetic patchiness' (Johnson and Black 1982). Chaotic genetic patchiness with weak or no IBD has also been found in other sponges across the Florida reef tract (DeBiasse et al 2010;Chaves-Fonnegra et al 2015;Richards et al 2016), and in a co-occurring sponge, S. vesparium (Griffiths et al 2020), which shared many sampling sites with this study.…”

“…To date, empirical population genetics studies have been conducted on only four Caribbean sponge species ( Xestospongia muta : López-Legentil and Pawlik 2009 ; de Bakker et al 2016 ; Richards et al 2016 ; Callyspongia vaginalis : DeBiasse et al 2010 ; Cliona delitrix : Chaves-Fonnegra et al 2015 ; Spheciospongia vesparium : Griffiths et al 2020 ). In general, these studies have found strongly differentiated populations throughout the region, including among sites only tens of kilometres apart in some instances.…”

“…In general, these studies have found strongly differentiated populations throughout the region, including among sites only tens of kilometres apart in some instances. However, patterns of regional genetic structure often reflect major ocean currents and hydrology (López-Legentil and Pawlik 2009 ; Chaves-Fonnegra et al 2015 ; Richards et al 2016 ; Griffiths et al 2020 ), and evidence of long-distance dispersal has been found, suggesting irregular transport of larvae, gametes or sponge fragments in ocean currents over large oceanographic distances (DeBiasse et al 2010 ; Chaves-Fonnegra et al 2015 ). These studies reveal the complexities of sponge population genetics in the Caribbean, highlighting the need for further research on this understudied taxon, including locations that have not yet been sampled.…”

Genetic diversity in seedling populations of Dipterocarpus gracilis in Kecubung Ulolanang Nature Conservation Reserve, Indonesia

“…Genetic drift that occurs in this population, the existence of these alleles must be preserved. We suggest the improvement of the connectivity between zones to counterforce declining population size, low genetic diversity, and local extinction (Griffiths et al 2020) . This implies that management should be conducted not only in the zone where D. gracilis are growing but also in the surrounding area as a buffer zone.…”