TY - JOUR

T1 - Evidence for different thermal ecotypes in range centre and trailing edge kelp populations

AU - King, Nathan G.

AU - McKeown, Niall J.

AU - Smale, Dan A.

AU - Wilcockson, David C.

AU - Hoelters, Laura

AU - Groves, Emily A.

AU - Stamp, Thomas

AU - Moore, Pippa J.

PY - 2019/5

Y1 - 2019/5

N2 - Determining and predicting species' responses to climate change is a fundamental goal of contemporary ecology. When interpreting responses to warming species are often treated as a single physiological unit with a single species-wide thermal niche. This assumes that trailing edge populations are most vulnerable to warming, as it is here where a species' thermal niche will be exceeded first. Local adaptation can, however, result in narrower thermal tolerance limits for local populations, so that similar relative increases in temperature can exceed local niches throughout a species range. We used a combination of common garden temperature heat-shock experiments (8–32 °C) and population genetics (microsatellites) to identify thermal ecotypes of northeast Atlantic range centre and trailing edge populations of the habitat-forming kelp, Laminaria digitata. Using upregulation of hsp70 as an indicator of thermal stress, we found that trailing edge populations were better equipped to tolerate acute temperature shocks. This pattern was consistent across seasons, indicating that between-population variability is fixed. High genetic structuring was also observed, with range centre and trailing edge populations representing highly distinct clusters with little gene flow between regions. Taken together, this suggests the presence of distinct thermal ecotypes for L. digitata, which may mean responses to future warming are more complex than linear range contractions.

AB - Determining and predicting species' responses to climate change is a fundamental goal of contemporary ecology. When interpreting responses to warming species are often treated as a single physiological unit with a single species-wide thermal niche. This assumes that trailing edge populations are most vulnerable to warming, as it is here where a species' thermal niche will be exceeded first. Local adaptation can, however, result in narrower thermal tolerance limits for local populations, so that similar relative increases in temperature can exceed local niches throughout a species range. We used a combination of common garden temperature heat-shock experiments (8–32 °C) and population genetics (microsatellites) to identify thermal ecotypes of northeast Atlantic range centre and trailing edge populations of the habitat-forming kelp, Laminaria digitata. Using upregulation of hsp70 as an indicator of thermal stress, we found that trailing edge populations were better equipped to tolerate acute temperature shocks. This pattern was consistent across seasons, indicating that between-population variability is fixed. High genetic structuring was also observed, with range centre and trailing edge populations representing highly distinct clusters with little gene flow between regions. Taken together, this suggests the presence of distinct thermal ecotypes for L. digitata, which may mean responses to future warming are more complex than linear range contractions.

KW - Range-centre

KW - Trailing-edge

KW - Climate change

KW - Heat shock

U2 - 10.1016/j.jembe.2019.03.004

DO - 10.1016/j.jembe.2019.03.004

M3 - Article

VL - 514-515

SP - 10

EP - 17

JO - Journal of Experimental Marine Biology and Ecology

JF - Journal of Experimental Marine Biology and Ecology

SN - 0022-0981

ER -