Contemporary and historical oceanographic processes explain genetic connectivity in a Southwestern Atlantic coral

Abstract

Understanding connectivity patterns has implications for evolutionary and ecological processes, as well as for proper conservation strategies. This study examined population genetic structure and migration patterns of the coral Mussismilia hispida, one of the main reef builders in the Southwestern Atlantic Ocean. For this, 15 sites were sampled along its entire distributional range employing 10 microsatellite loci. M. hispida was divided into five genetically differentiated populations by Structure analysis. Population structure and migration estimates are consistent with present-day oceanographic current patterns, zones of upwelling and historical sea-level changes. The Central Region and Oceanic Islands populations had the highest genetic diversity, were possibly the main sources of migrants for other populations and presented mutual migrant exchange. This mutual exchange and the high diversity of Oceanic Islands, a peripherical population, is highly interesting and unexpected, but can be explained if these sites acted as refugia in past low sea-level stance. This is the first connectivity study in the region using hyper-variable markers and a fine sampling scale along 3,500 km. These results enlighten the population dynamics of an important reef building species and shows how oceanographic processes may act as barriers to dispersal for marine species, providing valuable information for management strategies.

Dual influence of terrestrial and marine historical processes on the phylogeography of the Brazilian intertidal red alga Gracilaria caudata

“…; in the coral Mussismilia hispida Peluso et al. ) and in the red mangrove tree Rhizophora mangle (Francisco et al. ).…”

“…, Peluso et al. ) and the second one occurs at 21° S–23° S, separating the tropical populations located along the coast where the Brazil Current flows from the sub‐tropical populations influenced by cooler South Atlantic Central Waters (SACW; Santos et al. , da Silva Cortinhas et al.…”

“… and Peluso et al. (). Dotted and shaded areas indicate terrestrial coastal refugia and their boundaries, redrawn from the most historically stable Atlantic forest areas proposed in Carnaval and Moritz ().…”

“…, Peluso et al. ) than to demographic processes linked to Pleistocene climatic changes. Interestingly, intertidal species such as some seaweeds located at the interface of the terrestrial and marine realms may have been affected by past marine and terrestrial climatic fluctuations (Neiva et al.…”

“…Phylogeographic patterns in marine fishes and invertebrates are generally more related to the impact of the strong currents affecting the region and acting as barriers to gene flow (e.g., the bifurcation into two branches of the South Equatorial Current at latitudes 10°-15°S; see Fig. 1; Santos et al 2006, da Silva Cortinhas et al 2016, dos Santos Freitas et al 2017, Peluso et al 2018) than to demographic processes linked to Pleistocene climatic changes. Interestingly, intertidal species such as some seaweeds located at the interface of the terrestrial and marine realms may have been affected by past marine and terrestrial climatic fluctuations (Neiva et al 2014, Cardoso et al 2015.…”