Frayed at the edges: selective pressure and adaptive response to abiotic stressors are mismatched in low diversity edge populations

By G. Pearson, A. Lago‐Lestón, Catarina F Mota. 2009

216 citations recorded by the source corpus.

1 Theory predicts that population structure and dynamics affect a population's capacity for adaptation to environmental change. For isolated, small and fragmented populations at the trailing edge of species distributions, loss of genetic diversity through random genetic drift may reduce adaptive potential and fitness levels for complex traits. This has important consequences for understanding population responses to, for example changing climate, but has rarely been tested in natural populations. 2 We measured the intertidal thermal environment and tidal exposure (emersion) times for natural populations of the intertidal seaweed Fucus serratus at the centre (southwest UK) and southern edge (northern Portugal) of its range in the Eastern Atlantic, and for a congener, F. vesiculosus, whose range extends further south to Morocco. Fitness‐related traits of individuals at each location were measured in common garden experiments: physiological resilience to desiccation and heat shock (PSII quantum yield), and the molecular phenotype of the heat shock response (quantitative PCR of heat shock protein gene transcripts). 3 The realized thermal environment experienced by F. serratus was similar at the centre and southern edge of its distribution because the maximum shore height (and emersion period) was reduced in southern populations. For F. vesiculosus, thermal maxima were higher and occurred more frequently in the south, although maximum vertical height (emersion time) remained similar to central populations. 4 Edge populations of F. serratus were less resilient to desiccation and heat shock than central populations, and expression of heat shock genes was higher at the same temperature, suggesting greater cellular stress. In contrast, there was no evidence for physiological divergence in heat shock response in F. vesiculosus, and little variation in gene expression. 5 Synthesis. We provide evidence that compared with range‐centre populations upper intertidal limits of F. serratus at the southern edge are ‘pruned back’ by abiotic stressors. Rather than being locally adapted, these small populations are less resilient to abiotic stresses and experience greater cellular stress during heat shock. These results suggest that ongoing climate forcing factors may threaten small, fragmented rear edge populations because of inherently reduced fitness and lower adaptive capacity relative to larger central populations.

Subfields: Ecology, Global and Planetary Change, Oceanography

View Paper: https://www.semanticscholar.org/paper/6ccfa9b431b92830709896cec1373f568d218835

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Citations in the corpus

Can we predict ectotherm responses to climate change using thermal performance curves and body temperatures? (2016, background): “This variation can alter predictions of population dynamics at range edges under climate change (Pearson et al. 2009).”
The phylogeographic architecture of the fucoid seaweed Ascophyllum nodosum: an intertidal ‘marine tree’ and survivor of more than one glacial–interglacial cycle (2010, background): “In contrast, the frequent observation of central, high-diversity areas is often the result of either: (1) secondary trailing-edge effects (Hampe & Petit, 2005), in which the southernmost populations are at the species’ physiological limits, leaving maladapted genotypes (Pearson et al., 2009), smalle”
Relative influences of ocean acidification and temperature on intertidal barnacle post-larvae at the northern edge of their geographic distribution (2010, background): “However, the effect of climatic variables should be greatest where a range edge is set mainly by physical factors (Pearson et al., 2009).”
Climate Change Impacts on Seagrass Meadows and Macroalgal Forests: An Integrative Perspective on Acclimation and Adaptation Potential (2018, background): “However, the loss of genetic variability is likely to act against local adaptation of marginal populations (Pearson et al., 2009).”
European seaweeds under pressure: Consequences for communities and ecosystem functioning (2015, background): “Although genetic differentiation favors local adaptation and therefore persistence, the reduced genetic diversity of such range edge populations might limit evolvability (Pearson et al., 2009).”
Side matters: Microhabitat influence on intertidal heat stress over a large geographical scale (2011, background): “, 2010) and algae (Pearson et al., 2009), data from the present work showed that even low-shore organisms are periodically exposed to temperatures exceeding 30 °C.”
Drought-driven change in wildlife distribution and numbers: a case study of koalas in south west Queensland (2011, background): “For example, research on European mussels indicates that populations with low genetic diversity at the southern or trailing edge of their range are less adapted to heat stress than central populations (Pearson et al. 2009).”
Beyond long-term averages: making biological sense of a rapidly changing world (2014, background): “The importance of local and regional drivers such as wave splash and the timing of the tides is known to create geographic mosaics in stress in intertidal ecosystems, so that physiological stress is not well correlated with latitude for some species [1,36,81].”
Hidden signals of climate change in intertidal ecosystems: What (not) to expect when you are expecting (2011, background): “, 2006b), and likely in other parts of the world (Finke et al., 2007; Mislan et al., 2009; Pearson et al., 2009) may exist over a series of “thermal mosaics” rather than simple latitudinal gradients that cannot be explained based upon measurements of air or water temperature.”
Coral Reef Algae (2011, background): “Small and fragmented edge populations may be more susceptible to changes in thermal stress because of inherently lower fitness and lower adaptive capacity due to random genetic drift (Pearson et al. 2009); this may effectively enhance the invasive ability of tropical algae.”
Upwelling areas as climate change refugia for the distribution and genetic diversity of a marine macroalga (2016, background): “Neutral genetic clusters associated with specific environmental regimes may display different physiological tolerances to environmental stress, and thus have unique adaptive potential that can be important for species survival (Pearson et al., 2009; Zardi et al., 2013; Saada, 2014).”