Correlation between pelagic larval duration and realised dispersal: long-distance genetic connectivity between northern New Zealand and the Kermadec Islands archipelago

Abstract

The extent to which marine populations are ''open'' (panmixia) or ''closed'' (self-recruitment) remains a matter of much debate, with recent reports of high levels of genetic differentiation and self-recruitment among populations of numerous species separated by short geographic. However, the interpretation of patterns of gene flow (connectivity) is often based on a stepping stone model of dispersal that can genetically homogenise even distant populations and blur genetic patterns that may better reflect realised dispersal. One way in which realised long-distance dispersal can be accurately determined is by examination of gene flow of taxa between isolated archipelagos and a mainland where there is no possible stepping stone dispersal across the open ocean. We investigated the genetic structuring of populations of the intertidal gastropod Nerita melanotragus from the subtropical Kermadec Islands and temperate New Zealand's North Island (the mainland), separated by 750 km of open ocean and characterised by contrasting environmental conditions. Analyses of seven microsatellite markers revealed an absence of genetic structuring with low F ST and Jost's D values (from 0.000 to 0.007 and from 0.000 to 0.015, respectively) over large geographic distances and no evidence of isolation by distance among all populations. These results indicate that the realised dispersal of N. melanotragus is of at least 750 km, this species exhibits a very ''open'' form of connectivity and its larvae exhibit sufficient phenotypic plasticity to settle successfully in different environmental conditions, ranging from subtropical to cool temperate.

Marine stepping‐stones: Connectivity of Mytilus edulis populations between offshore energy installations

“…In the North Sea, any stepping-stone effect will be of most importance for epifaunal species with pelagic larval stages of several weeks (e.g., the oyster Ostrea edulis with 10-30 days or the limpet Crepidula fornicata with 14-21 days; Berghahn & Ruth, 2005;Shanks, 2009). Species with much shorter pelagic stages may be unlikely to reach the next subpopulation whereas species with very long pelagic larval stages may be capable of bridging large distances and may not need stepping-stones to colonize distant locations (Reisser, Bell, & Gardner, 2014). Other organisms, such as the nonindigenous Caprella mutica, also use floating objects such as ship hulls or debris for dispersal (Thiel & Gutow, 2005), and some species are transported by ballast water (Drake & Lodge, 2004), enabling them to colonize distant locations.…”

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

“…; Reisser et al . ). It has become clear that even marine invertebrates with a very long pelagic larval duration can exhibit significant genetic differentiation (Thomas & Bell ).…”

Potential connectivity among American lobster fisheries as a result of larval drift across the species’ range in eastern North America

“…The larval phase of lobsters can last 24-110 days or more (MacKenzie 1988), so there is much potential for larvae to drift among lobster MAs. In many other marine species with planktonic larvae, ocean circulation can cause larvae to be dispersed widely (e.g., 100s or 1 000s of km) from their place of origin (Kough et al 2013;Reisser et al 2014), which may limit the ability of 'populations' to self-recruit and result in connectivity (i.e., exchange of individuals and genes) among populations (Cowen et al 2000).…”