A biophysical perspective on dispersal and the geography of evolution in marine and terrestrial systems

Abstract

The fluid mechanics of marine and terrestrial systems are surprisingly similar at many spatial and temporal scales. Not surprisingly, the dispersal of organisms that float, swim or fly is influenced by the fluid environments of air and seawater. Nonetheless, it has been argued repeatedly that the geography of evolution differs fundamentally between marine and terrestrial taxa. Might this view emanate from qualitative contrasts between the pelagic ocean and terrestrial land conflated by anthropocentric perception of within-and betweenrealm variation? We draw on recent advances in biogeography to identify two pairs of biophysically similar marine and terrestrial settings-(i) aerial and marine microplankton and (ii) true islands and brackish seawater lakes-which have similar geographies of evolution. Commonalities at these scales, the largest and smallest biogeographic scales, delimit the geographical extents that can possibly characterize evolution in the remaining majority of species. The geographies of evolution therefore differ statistically, not fundamentally, between marine and terrestrial systems. Comparing the geography of evolution in diverse non-microplanktonic and non-island species from a biophysical perspective is an essential next step for quantifying precisely how marine and terrestrial systems differ and is an important yet under-explored avenue of macroecology.

When is dispersal for dispersal? Unifying marine and terrestrial perspectives

“…Air and sea water differ in their constraints and opportunities for movement and balancing life-history trade-offs due to differences in viscosity, density, terminal velocity, specific heat and oxygen supply (Table 2) (Strathmann, 1990;Denny, 1993;Dawson & Hamner, 2008;Vermeij & Grosberg, 2010). In particular, as described below, passive dispersal is relatively 'easy' in marine realms, but requires 'effort' in terrestrial realms.…”

Widespread Dispersal of the Crown-of-Thorns Sea Star,Acanthaster planci, across the Hawaiian Archipelago and Johnston Atoll

“…The distance traveled during pelagic development is obviously a function of both PLD and of the oceanic currents in which those larvae find themselves [59][60][61][62]. Thus, the mechanism for this widespread dispersal is likely the variable currents that flow along the 2500 km archipelago.…”

Magnificent dimensions, varied forms, and brilliant colors: the molecular ecology and evolution of the Indian and Pacific oceans

“…species ranges in the Indo-Pacific region can span tens of thousands of kilometers, and at evolutionary timescales these ranges are united into enormous genetic neighborhoods created by long-distance dispersal of propagules (Palumbi 1994, Lessios et al 2001, Planes and Fauvelot 2002, crandall et al 2008a. Thus, although the fundamental evolutionary processes that govern biodiversity in the Indo-Pacific region (and the marine biome in general) are probably qualitatively similar to those that govern terrestrial biodiversity, the specific parameters of those processes are likely very different (Mayr 1953, Palumbi 1994, Paulay and Meyer 2002, carr et al 2003, Dawson and Hamner 2008, Grosberg et al 2012, bowen et al 2013. Given the vast size of the Indo-Pacific and the logistical difficulty of making direct observations of marine species distributions and behavior, molecular methods offer us important initial insights into these processes (Palumbi 1997, benzie 1999, Hellberg 2009).…”