Genetic Analyses and Simulations of Larval Dispersal Reveal Distinct Populations and Directional Connectivity across the Range of the Hawaiian Grouper (Epinephelus quernus)

Abstract

Integration of ecological and genetic data to study patterns of biological connectivity can aid in ecosystem-based management. Here we investigated connectivity of the Hawaiian grouperEpinephelus quernus, a species of management concern within the Main Hawaiian Islands (MHI), by comparing genetic analyses with simulated larval dispersal patterns across the species range in the Hawaiian Archipelago and Johnston Atoll. Larval simulations revealed higher dispersal from the MHI to the Northwestern Hawaiian Islands (NWHI) than in the opposite direction and evidence for a dispersal corridor between Johnston and the middle of the Hawaiian Archipelago. Genetic analyses using mitochondrial DNA (mtDNA) control region sequences and microsatellites revealed relatively high connectivity across the Hawaiian Archipelago, with the exception of genetically distinct populations and higher mtDNA diversity in the mid-Archipelago. These analyses support the preservation of the mid-archipelago as a source of genetic diversity and a region of connectivity with locations outside the Hawaiian Archipelago. Additionally, our evidence for directional dispersal away from the MHI lends caution to any management decisions that would rely on the NWHI replenishing depleted MHI stocks.

Historical Processes and Contemporary Anthropogenic Activities Influence Genetic Population Dynamics of Nassau Grouper (Epinephelus striatus) within The Bahamas

“…We found no significant difference in allelic richness in fish sampled from across the islands, but these values were low and may indicate possible loses of genetic diversity (Pinsky and Palumbi, 2014). The allelic richness results reported here are analogous to other published data for Nassau grouper (Bernard et al, 2016) and E. marginatus (Schunter et al, 2011), but higher than values reported from E. quernus (Rivera et al, 2011). In populations that undergo a bottleneck, rare or unique alleles may be lost, deleterious alleles may become fixed and inbreeding is more likely to occur (Garza and Williamson, 2001).…”

Mesophotic surveys of the flora and fauna at Johnston Atoll, Central Pacific Ocean

“…Kobayashi (2006) used computer simulations and high-resolution current data to identify at least two corridors connecting Johnston Atoll with the Hawaiian Archipelago, an interpretation that is consistent with genetic studies (Rivera et al, 2004(Rivera et al, , 2011Timmers et al, 2011). Additionally, many other studies highlight the strong floral and faunal similarities between Johnston Atoll and the Hawaiian Islands (Gosline, 1955;Buggeln & Tsuda, 1969;Bailey-Brock, 1976;Grigg, 1981;Grigg et al, 1981;Randall et al, 1985;Maragos & Jokiel, 1986;Kosaki et al, 1991;Coles et al, 2001;Maragos et al, 2004;Tsuda et al, 2010).…”

“…Despite its extreme geographical isolation, the very low level of endemism indicates that Johnston is relatively well connected with other parts of the Pacific, particularly Hawai'i (Grigg, 1981;Grigg et al, 1981;Rivera et al, 2004Rivera et al, , 2011Kobayashi, 2006;Timmers et al, 2011). Kobayashi (2006) used computer simulations and high-resolution current data to identify at least two corridors connecting Johnston Atoll with the Hawaiian Archipelago, an interpretation that is consistent with genetic studies (Rivera et al, 2004(Rivera et al, , 2011Timmers et al, 2011).…”

“…Additionally, this study sought to compare the mesophotic biodiversity between Johnston Atoll and the Hawaiian Archipelago, because numerous previous studies have noted strong faunal and floral similarities between these two geographical areas (Gosline, 1955;Buggeln & Tsuda, 1969;Bailey-Brock, 1976;Grigg, 1981;Grigg et al, 1981;Randall et al, 1985;Maragos & Jokiel, 1986;Kosaki et al, 1991;Coles et al, 2001;Maragos et al, 2004;Tsuda et al, 2010). Due to these similarities, Johnston Atoll has been considered an important stepping stone for marine organisms reaching the Hawaiian Archipelago (Grigg, 1981;Grigg et al, 1981), an interpretation that is supported by both genetic (Rivera et al, 2004(Rivera et al, , 2011Timmers et al, 2011) and oceanographic studies (Kobayashi, 2006) that demonstrate strong connectivity between these two regions.…”

Phylogeny of deepwater snappers (Genus Etelis) reveals a cryptic species pair in the Indo-Pacific and Pleistocene invasion of the Atlantic

“…It could be postulated that the thermal regime and depth occupied by Etelis would facilitate connections between the Indian and Atlantic Oceans, but we observe only a single colonization event in the 4 -5 MY history of Etelis resolved here. While few studies exist on the phylogeography of deepwater fishes, the scant literature on this subject indicates high dispersal and biogeographic histories similar to their shallow counterparts (Gaither et al, 2011;Rivera et al, 2011;Andrews et al, 2014, but see Ovenden et al, 2004. One potential point of departure between shallow and deep fishes is the intermittent Indo-Pacific Barrier created by lower sea levels.…”