Emerging patterns of genetic variation in the New Zealand endemic scallop Pecten novaezelandiae

Abstract

Both historical and contemporary processes influence the genetic structure of species, but the relative roles of such processes are still difficult to access. Population genetic studies of species with recent evolutionary histories such as the New Zealand endemic scallop Pecten novaezelandiae (<1 Ma) permit testing of the effects of recent processes affecting gene flow and shaping genetic structure. In addition, studies encompassing the entire distributional range of species can provide insight into colonization processes. Analyses of genetic variation in P. novaezelandiae (952 individuals from 14 locations, genotyped at 10 microsatellite loci) revealed a weak but significant regional structure across the distributional range of the species, as well as latitudinal gradients of genetic diversity and differentiation: estimates of migration rates supported these patterns. Our results suggest that the observed genetic structure and latitudinal gradients reflect a stepping-stone model of colonization (north to south) and emerging divergence of populations as a result of ongoing limitations to gene flow and insufficient time to reach migration-drift equilibrium. The low levels of interpopulation and interregional genetic differentiation detected over hundreds of kilometres reflect the recent evolutionary history of P. novaezelandiae and stand in contrast to patterns reported for other evolutionary older species at the same spatial scale. The outcomes of this study contribute to a better understanding of evolutionary processes influencing the genetic variation of species and provide vital information on the genetic structure of P. novaezelandiae.

Identifying environmental factors associated with the genetic structure of the New Zealand scallop: linking seascape genetics and ecophysiological tolerance

“…A low but significant level of population genetic structure has been reported for P. novaezelandiae throughout its distributional range in New Zealand (Silva and Gardner, 2015). In the present study, a weak but statistically significant isolation by distance signal was detected and different combinations of environmental variables were correlated with the genetic variation.…”

“…However, for P. novaezelandiae, it appears that the level of genetic differentiation is not a simple function of the geographic distance between populations. For example, it is not evident that the distance between the Chatham Islands and the mainland acts as an important barrier to larval dispersal because there is clear evidence of high levels of connectivity between these remote islands and the NZ mainland that is 850 km to the west (Silva and Gardner, 2015). Other environmental factors such as the subtropical convergence might be facilitating gene flow and thus minimizing the impact of geographic distance between the Chatham Islands and mainland New Zealand.…”

Geographic concordance of genetic barriers in New Zealand coastal marine species

“…Some authors have suggested that this northern restriction may be related to historical processes, such as the colonization of New Zealand from the north (Silva & Gardner, 2015), along with the influence of geological processes (Stevens & Hogg, 2004). Others have suggested that coastal upwelling in the vicinity of Cape Reinga may limit the ability of species to cross this hydrodynamic feature (Veale & Lavery, 2011), or that limitations in habitat availability have restricted successful recruitment around Cape Reinga (Stevens & Hogg, 2004; Jones, Gemmill & Pilditch, 2008; Hannan et al, 2016).…”

Species-specific genetic variation in response to deep-sea environmental variation amongst Vulnerable Marine Ecosystem indicator taxa

“…Seascape genetics as a discipline has advanced dramatically over the last decade as environmental data sets have increased in size and coverage (both spatial and temporal), and as new molecular markers and analytical tools have been developed (reviewed by [32][33][34] ). However, such work has been exclusively focused on coastal and/or shallow water) species and systems, sometimes from the perspective of environmental or evolutionary biology, and sometimes with a management (e.g., fisheries, conservation) focus (e.g., 38,[51][52][53][54][55] ). This study is amongst the first to apply the approach to deep-sea species and environments.…”