High evolutionary potential of marine zooplankton

Abstract

Open ocean zooplankton often have been viewed as slowly evolving species that have limited capacity to respond adaptively to changing ocean conditions. Hence, attention has focused on the ecological responses of zooplankton to current global change, including range shifts and changing phenology. Here, we argue that zooplankton also are well poised for evolutionary responses to global change. We present theoretical arguments that suggest plankton species may respond rapidly to selection on mildly beneficial mutations due to exceptionally large population size, and consider the circumstantial evidence that supports our inference that selection may be particularly important for these species. We also review all primary population genetic studies of open ocean zooplankton and show that genetic isolation can be achieved at the scale of gyre systems in open ocean habitats (100s to 1000s of km). Furthermore, population genetic structure often varies across planktonic taxa, and appears to be linked to the particular ecological requirements of the organism. In combination, these characteristics should facilitate adaptive evolution to distinct oceanographic habitats in the plankton. We conclude that marine zooplankton may be capable of rapid evolutionary as well as ecological responses to changing ocean conditions, and discuss the implications of this view. We further suggest two priority areas for future research to test our hypothesis of high evolutionary potential in open ocean zooplankton, which will require (1) assessing how pervasive selection is in driving population divergence and (2) rigorously quantifying the spatial and temporal scales of population differentiation in the open ocean.

Mare Incognitum: A Glimpse into Future Plankton Diversity and Ecology Research

“…However, many planktonic species exhibit local adaptation (Peijnenburg and Goetze, 2013;Sjöqvist et al, 2015) or consist of several ecotypes with different environmental preferences, and phenotypic plasticity, dispersal, and evolutionary changes could mitigate climate change impacts as they could help species to adapt to changing conditions (O'Connor et al, 2012). One possibility to account for both local adaptation and phenotypic plasticity is to include a population-dependent component in mixed effect models (e.g., Valladares et al, 2014).…”

Comparative phylogeography of the ocean planet

“…Habitat selection, rather than physical barriers, may be a primary force driving speciation in the pelagic zone (146). Therefore, a biogeographic framework based on water properties is concordant with genetic partitions within species.…”

Reduced up-regulation of gene expression in response to elevated temperatures in the mid-Atlantic population of Calanus finmarchicus

“…At this stage it is difficult to identify which mechanism plays the main role in temperature response in C. finmarchicus, however evidence suggest that both mechanisms may be at play. Local adaptation refers to the genetic differentiation among populations resulting in increased mean fitness in the local environment (reviewed by Savolainen et al, 2013) and it may play a significant role even in the case of planktonic species in the open ocean, leading to population-specific responses to environmental stressors, including global climate change (Peijnenburg and Goetze, 2013;Sanford and Kelly, 2010). Evidence of genetic differentiation among populations of C. finmarchicus has been detected both within and between basins of the North Atlantic (Smolina, 2015;Unal and Bucklin, 2010).…”