Invertébrés Sans Frontières: Large Scales of Connectivity of Selected Freshwater Species among Caribbean Islands

Abstract

The freshwater fauna (crustaceans, molluscs, fish) of many tropical islands in the Caribbean and Pacific share an amphidromous lifecycle, meaning their larvae need to develop in saline conditions before returning to freshwater as juveniles. This community dominates the freshwaters of much of the tropics, but is poorly known and at risk from development, in particular dam construction. Amphidromy can theoretically lead to dispersal between different freshwater areas, even to distant oceanic islands, via the sea. The extent and scale of this presumed dispersal, however, is largely unknown in the Caribbean. Recent genetic work in Puerto Rico has shown that many freshwater species have little or no population structure among different river catchments, implying high levels of connectivity within an island, whereas between-island structure is unknown. We used genetic techniques to infer the geographic scales of population structure of amphidromous invertebrates (a gastropod and a number of crustacean species) between distant parts of the Caribbean, in particular Puerto Rico, Panama and Trinidad. We found virtually no geographic population structure across over 2000 km of open sea for these freshwater species. This implies that they are indeed moving between islands in sea currents as larvae, meaning that continued recruitment requires a continuum of healthy habitat from the freshwater to marine environment. We further discuss the role of amphidromy and suggest its ecological and biogeographic role may be more important than previously presumed.Abstract in Spanish is available in the online version of this article.

Phylogeographic patterning among two codistributed shrimp species (Crustacea: Decapoda: Palaemonidae) reveals high levels of connectivity across biogeographic regions along the South African coast

“…This result correlates with the general notion that genetic differentiation of populations of amphidromous shrimp is rare or at most weakly expressed over larger scales (> 1000 km) [75]. A similar result was encountered in the distantly related palaemonid species, Cryphiops caementarius (see [76]), as well as in amphidromous representatives of the Atyidae [17], the other main family of freshwater shrimps. Interestingly, the hierarchical AMOVA suggests that genetic differentiation does fall within a widely discussed biogeographic barrier between the southern populations and the south-east transition zone in the proximity of Algoa Bay [27].…”

New insight on population genetic connectivity of widespread amphidromous prawn Macrobrachium lar (Fabricius, 1798) (Crustacea: Decapoda: Palaemonidae)

“…Although sampling bias cannot be ruled out, connectivity patterns in M. lar may thus be explained by factors other than geographic distance only. Ocean currents may have a strong influence on population genetic structuring (White et al 2010;Page et al 2013). However, on a large geographical scale, present-day oceanic currents are usually not fully consistent with patterns of connectivity in marine species (Benzie 1998;Lessios 1998;Planes and Fauvelot 2002).…”

“…Crandall et al 2010 and references therein). Accordingly, several population genetic studies have shown that amphidromous organisms with long-lived larvae display low or non-existent genetic structure among populations (Chubb et al 1998;Hodges and Allendorf 1998;Myers et al 2000;Waters et al 2000;Kano and Kase 2004;Berrebi et al 2005;Page et al 2013). However, most of these studies have been undertaken at relatively small geographical scale (i.e., island or archipelago).…”

Is variable connectivity among populations of a continental gobiid fish driven by local adaptation or passive dispersal?

“…Cook et al, 2011;Schmidt et al, 2011a;Page et al, 2012;Hughes, Huey & Schmidt, 2013;Hughes et al, 2014). Molecular markers are often used to explore the life history of diadromous species (e.g.…”