Past, Present, and Future Climate Change: Can Palaeoecology Help Manage a Warming World? - Biodiversity Conservation and Environmental Change - page 106

Species adaptation to climate change
Changes in distribution represent only one means of surviving changing climate; species may
change their climatic tolerance through alterations in their life history (e.g. earlier flowering),
or through rapid genetic change (microevolution). Once thought to be immutable, it now
seems that for some species, changing climatic tolerance is an important adaptation to a cli-
mate that is constantly in flux. Adaptation is more likely to be an important response in long-
lived plant species than in highly mobile mammals, birds, and insects, which are more likely
to rapidly change their distribution in response to climate change, thus conserving their
environmental tolerances (Martinez-Meyer et al. 2004).
Palaeoecology will help in identifying species that can adapt to climate change through
changing tolerances (Pearman et al. 2008a, b, 2010, Nogués‐Bravo 2009). While we tend to
think of evolution as a process that occurs over timescales of millions of years, evolution on
much shorter timescales, usually known as eco-evolution or micro-evolution, is increasingly
recognized as an important response to climate change. Some species can evolve rapidly
because of their short generation time, but long-lived species such as trees also have the
potential for rapid adaptation if they have high genetic diversity and large population size. For
example, Pearman et al. (2008b) compared mid-Holocene and present-day climatic toler-
ance for European tree species and found stable climatic tolerance for late succession species
like norway spruce and hornbeam ( Picea abies and Carpinus betulus ), while early succession
species showed larger shifts. Juniper ( Juniperus communis ), a disturbance adapted species,
experienced large changes in climatic niche. Silver fir, hazel, and larch ( Abies alba , Corylus
avellana , Larix decidua ) showed intermediate changes in climatic tolerance. In general,
shade-tolerant, competitively dominant species were less likely to undergo niche shifts than
light-demanding, disturbance-adapted taxa (Pearman et al. 2008b). Alongside climate, the
study showed that competition, anthropogenic disturbance and ability to compete for light,
were all important determinants of species distribution (MacDonald et al. 2008, Pearman
et al. 2008a). In another example, climate models, trained using current distribution of east-
ern hemlock ( Tsuga canadensis ) overpredicted known distributions from the fossil pollen
record at 16,000 21,000 and 24,000 years ago, suggesting that climate tolerance was narrower
in the past (Davis et al. 2005).
Distinguishing which species tolerate, which species move, and which species adapt can
provide insights into appropriate conservation strategies that preserve refugia, facilitate migra-
tion, or preserve adaptive capacity and evolutionary potential (Dawson et al 2011). Knowledge
of the relationship between genetic structure of populations, and the distribution of evolution-
ary lineages can inform the spatial configuration of reserves that best protect genetic diversity
and hence the evolutionary potential that underpins the capacity to adapt (Sgrò et al. 2011).
Climate change, resilience, and tipping points
Though temperature is increasing gradually, species distributions and ecosystem compos-
ition may not change until a critical climatic threshold is crossed, at which point dramatic
reorganization may occur. There may be feedbacks between climate and vegetation that