Climate Change Biology by unknow

Author:unknow
Language: eng
Format: epub
Publisher: CABI
Published: 2011-06-30T16:00:00+00:00

Clearly climate change impact studies are remiss in not at least considering the likely evolutionary consequences for the population(s) of interest.

Many of the examples in this section are descriptive studies or accidental/natural experiments, but the real gold standard for estimating the potential for rapid adaptation is experimental evolution studies. In the following section we examine the admittedly few examples of experimental evolution on traits related to climatic change.

8.5 Experimental Evolution

Reusch and Wood (2007) reviewed 16 examples of experimental evolution, on a variety of organisms, for traits related to climatic change. These studies and their conclusions are summarized in Table 8.1 . It seems clear from these studies that, minimally, many climate-related traits are capable of responding to selection, although this by no means indicates that all such traits are capable of such responses nor that all species will show such responses.

Experimental evolution studies suffer from the same experimental design problems that experimental ecological studies of climatic change suffer from, but two particularly important aspects are: (i) abrupt change in the environment (see also Box 3.1); and (ii) concentration on main effects. With the exception of the Chlamydomonas study (see Box 8.1), all of the studies in Table 8.1 cover fewer than 150 generations, and most cover fewer than 25 generations. These studies begin by suddenly exposing the populations to the selection pressure and following the responses. However, as we pointed out in Chapters 1 and 3 , climatic change may be ‘rapid’ in comparison with historical climatic change, but it is nevertheless gradual from the perspective of the evolving population. The populations will experience a continuous range of intermediate climatic conditions and this can lead to different conclusions compared with what happens when climate changes abruptly (Bell and Collins, 2008). Also, in most selection experiments, it is common to impose a stressful condition but to keep all other aspects of the environment benign and this has caused some to question the value of these experiments (Harshman and Hoffmann, 2000; Reusch and Wood, 2007).

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