Publication Date:
2020-07-02
Description:
The plasticity of different kelp populations to heat stress has seldom been investigated
excluding environmental effects due to thermal histories, by raising a generation under common
garden conditions. Comparisons of populations in the absence of environmental effects
allow unbiased quantification of the meta-population adaptive potential and resolution of
population-specific differentiation. Following this approach, we tested the hypothesis that
genetically distinct arctic and temperate kelp exhibit different thermal phenotypes, by comparing
the capacity of their microscopic life stages to recover from elevated temperatures.
Gametophytes of Laminaria digitata (Arctic and North Sea) grown at 15˚C for 3 years were
subjected to common garden conditions with static or dynamic (i.e., gradual) thermal treatments
ranging between 15 and 25˚C and also to darkness. Gametophyte growth and survival
during thermal stress conditions, and subsequent sporophyte recruitment at two
recovery temperatures (5 and 15˚C), were investigated. Population-specific responses were
apparent; North Sea gametophytes exhibited higher growth rates and greater sporophyte
recruitment than those from the Arctic when recovering from high temperatures, revealing
differential thermal adaptation. All gametophytes performed poorly after recovery from a
static 8-day exposure at 22.5˚C compared to the response under a dynamic thermal treatment
with a peak temperature of 25˚C, demonstrating the importance of gradual warming
and/or acclimation time in modifying thermal limits. Recovery temperature markedly
affected the capacity of gametophytes to reproduce following high temperatures, regardless
of the population. Recovery at 5˚C resulted in higher sporophyte production following a 15˚C
and 20˚C static exposure, whereas recovery at 15˚C was better for gametophyte exposures
to static 22.5˚C or dynamic heat stress to 25˚C. The subtle performance differences
between populations originating from sites with contrasting local in situ temperatures support
our hypothesis that their thermal plasticity has diverged over evolutionary time scales.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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