At the start of 2011, the journal Philosophical Transactions of the Royal Society A published an issue indicating that temperature changes of
+2°C over previous levels were not only likely by the middle of this century, but that +4°C would probably be realized too. Research published elsewhere is also
starting to show that increases in extreme weather events are clearly related to climate change. From a biological perspective, and in the IPCC Fifth Assessment report
terminology, climate change impacts on the biota are virtually certain (99-100% probable).
For this reason a growing focus of research by the Centre for Invasion Biology is on climate change impacts on biota and how these can be better understood,
forecast, and both mitigated, and adapted too where responses to deal with the primary cause of change are inadequate. In some ways the latter has already happened —
the lifetime of greenhouse gasses in the atmosphere means commitment to considerable climate change and its impacts.
The C·I·B is undertaking several aspects of work in this area, of which three are gaining considerable momentum. First, much emphasis is being
placed on understanding the fundamental, physiological basis of ectotherm (i.e. animal species that rely on external sources of heat mostly, such as insects, reptiles,
amphibians) responses to changing temperature and water regimes (i.e. rainfall amount, event size and frequency). This is reflected in recent work by the Centre and various
collaborators, published in the journals American Naturalist1, Climate Research2, Evolutionary Ecology3,
Functional Ecology4, Journal of Insect Physiology5, and Science6. Significant outcomes thereof are: 1) ectotherm
responses to climate change are likely to be less straightforward than might previously have been thought; 2) climate change is already having substantial effects on these
organisms; 3) climate change seems set in many instances to benefit invasive species compared with their indigenous counterparts. Whilst ectotherms often do not receive as
much prominence in the media as large mammals, they are critical for ecosystem service delivery. For example, springtails play a critical role in soil nutrient cycling in
many systems including those in South Africa7,8.
The second area of work concerns the likely responses of vectors of human and animal diseases, and biological control agents, to climate change. Such species
are all of considerable concern to human development, with vectors typically limiting it, and biological control agents often improving food security and environmental health
(by controlling invasives that impact ecosystem services). Several projects in this area are nearing completion as part of
Stellenbosch University’s HOPE project. These projects use mechanistic modelling to understand fundamental responses
to change, and tie in well with the Centre’s broader focus on understanding climate change and human development impacts on a range of species. Perhaps most prominent amongst the
recent published work in this general area is the investigation of the contributions of climate suitability and human activity to the distribution of the Argentine ant9.
In the third arena, the Centre is engaged in several long-term projects to understand the interactions of impacts of climate change and other environmental change
drivers in the Antarctic region. In particular, it is leading and collaborating on several projects that are either broad-scale or long-term and which seek to understand climate
change effects, both in the past and currently, on the biota of the region. There are large, team-based efforts involving researchers from many countries. Some of this work has
already been published, demonstrating pronounced impacts of climate change in the region and ways in which synergies between climate change and biological invasions can be
mitigated10. Other work has just commenced and a large drive is now on to secure the resources to implement the envisaged approaches, which include DNA-barcoding
and terrestrial remote sensing11.
Much emphasis is being placed on the outcomes of this work, and research undertaken by other groups of researchers, in the Centre’s discussions with policy makers and
the public. Recent examples of such interactions can be found at:
- Clusella-Trullas et al. 2011. Climatic predictors of temperature performance curve parameters in ectotherms imply complex responses to climate change. American Naturalist 177, 738-751. DOI: 10.1086/660021
- Chown et al. 2010. Adapting to climate change: a perspective from evolutionary physiology. Climate Research 43, 3-15. DOI: 10.3354/cr00879
- Janion et al. 2010. Trait means and reaction norms: the consequences of climate change/invasion interactions at the organism level. Evolutionary Ecology 24, 1365-1380. DOI: 10.1007/s10682-010-9405-2
- Chown, S.L. 2011. Discontinuous gas exchange: new perspectives on evolutionary origins and ecological explanations. Functional Ecology, in press. DOI: 10.1111/j.1365-2435.2011.01879.x
- Chown et al. 2011. Water loss in insects: an environmental change perspective. Journal of Insect Physiology 57, 1070-1084. DOI:10.1016/j.jinsphys.2011.05.004
- Clusella-Trullas & Chown. 2011. Technical comment on ‘Erosion of lizard diversity by climate change and altered thermal niches’. Science 332, 537. DOI: 10.1126/science.1195193
- Bengtsson et al. 2011. Variation in decomposition rates in the fynbos biome, South Africa: the role of plant species and plant stoichiometry. Oecologia 165, 225-235. DOI: 10.1007/s00442-010-1753-7
- Janion et al. 2011. Springtail diversity in South Africa. South African Journal of Science, in press
- Roura-Pascual et al. 2011. Relative roles of climatic suitability and anthropogenic influence in determining the pattern of spread in a global invader. Proceedings of the National Academy of Sciences of the U.S.A. 108, 220-225. DOI: 10.1073/pnas.1011723108
- Chown et al. 2011. South Africa’s southern sentinel: terrestrial environmental change at sub-Antarctic Marion Island. In: Observations on Environmental Change in South Africa. L. Zietsman, ed. Sun Press, Stellenbosch, pp. 139-147.
- Wall et al. 2011. Long-term ecosystem networks to record change: an international imperative. Antarctic Science 23, 210. DOI:10.1017/S0954102011000319