A Global Pattern of Thermal Adaptation in Marine Phytoplankton

Abstract

Rising ocean temperatures will alter the productivity and composition of marine phytoplankton communities, thereby affecting global biogeochemical cycles. Predicting the effects of future ocean warming on biogeochemical cycles depends critically on understanding how existing global temperature variation affects phytoplankton. Here we show that variation in phytoplankton temperature optima over 150 degrees of latitude is well explained by a gradient in mean ocean temperature. An eco-evolutionary model predicts a similar relationship, suggesting that this pattern is the result of evolutionary adaptation. Using mechanistic species distribution models, we find that rising temperatures this century will cause poleward shifts in species' thermal niches and a sharp decline in tropical phytoplankton diversity in the absence of an evolutionary response.

Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus

“…The temperature vs growth curve of the WH8103 strain, isolated in the Sargasso Sea at 28.51N, exhibits a maximum at 28 1C (Moore et al, 1995) and thus supports this conclusion. Our observations support recent surveys which stated that optimum temperature for growth of marine phytoplankton strains is related to the latitude and temperature of their isolation site (Thomas et al, 2012;Boyd et al, 2013), and support field observations that the abundances of the Synechococcus of the 5.1 cluster fall to very low values in the polar oceans, of about hundred cells per ml (Gradinger and Lenz, 1995;Vincent 2000;Not et al, 2004;Cottrell and Kirchman, 2009;Vincent and Quesada, 2012).…”

Deoxygenation alters bacterial diversity and community composition in the ocean’s largest oxygen minimum zone

“…These changes are not mutually exclusive, and could act together to alter microbial distributions, diversity and composition. As these changes in communities can have demonstrable effects on biogeochemical cycling of C (refs [17][18][19] and N (ref. 20), we investigate bacterial community ecology in the OMZ of the Gulf of California (GOC; the body of water defined by the Baja California peninsula and mainland Mexico) and ETNP using pyrosequencing of 16S rRNA genes.…”

Climate Change: Warming Impacts on Marine Biodiversity

“…At the same time, molecular approaches, quantitative genetics and (long-term) evolution experiments need to address temperature effects on selection and mutation in isolation and in combination with other stressors (e.g., acidification). The potential in predicting species occurrence and performance by combining ecological and evolutionary constraints has already been shown in model approaches (Follows et al 2007; Thomas et al 2012). …”

“…Temperature driven shifts in geographic distribution of species will probably lead to increase of biodiversity in high latitudes and decrease of biodiversity in tropics (Beaugrand et al 2015;Thomas et al 2012) with consequences for marine ecosystem productivity. Decrease of the number of cold water species and increasing dominance of warm water species might lead to homogenisation of communities among the globe.…”