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Ecological and Evolutionary Responses to Recent Climate Change

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Annu. Rev. Ecol. Evol. Syst. 2006.37:637-669. Downloaded from arjournals.annualreviews.org<br />

by Sun Yat-Sen University Library on 01/09/07. For personal use only.<br />

Few studies have been conducted at a scale that encompasses an entire species’<br />

range (i.e., a continental scale), with only a moderate number at the regional scale<br />

(e.g., the United Kingdom or Germany). Most have been conducted at local scales,<br />

typically at a research station or preserve. Continental-scale studies usually cover<br />

most or all of a species’ range in terrestrial systems (Both et al. 2004, Bur<strong>to</strong>n 1998a,b,<br />

Dunn & Winkler 1999, Menzel & Fabian 1999, Parmesan 1996, Parmesan et al.<br />

1999). However, even a continental scale cannot encompass the entire ranges of<br />

many oceanic species (Ainley & Divoky 1998, Ainley et al. 2003, Beaugr<strong>and</strong> et al.<br />

2002, Croxall et al. 2002, Hoegh-Gulberg 1999, McGowan et al. 1998, Reid et al.<br />

1998, Spear & Ainley 1999). Terrestrial endemics, in contrast, can have such small<br />

ranges that regional, or even local, studies may represent impacts on entire species<br />

(Pounds et al. 1999, 2006).<br />

Meta-Analyses <strong>and</strong> Syntheses: Globally Coherent<br />

Signals of <strong>Climate</strong>-<strong>Change</strong> Impacts<br />

A h<strong>and</strong>ful of studies have conducted statistical meta-analyses of species’ responses or<br />

have synthesized independent studies <strong>to</strong> reveal emergent patterns. The clear conclusion<br />

across global syntheses is that twentieth-century anthropogenic global warming<br />

has already affected the Earth’s biota (IPCC 2001a; Parmesan 2005a,b; Parmesan<br />

& Galbraith 2004; Parmesan & Yohe 2003; Peñuelas & Filella 2001; Pounds et al.<br />

2005; Root & Hughes 2005; Root et al. 2003; Thomas 2005; Walther et al. 2002,<br />

2005).<br />

One study estimated that more than half (59%) of 1598 species exhibited measurable<br />

changes in their phenologies <strong>and</strong>/or distributions over the past 20 <strong>to</strong> 140 years<br />

(Parmesan & Yohe 2003). Analyses restricted <strong>to</strong> species that exhibited change documented<br />

that these changes were not r<strong>and</strong>om: They were systematically <strong>and</strong> predominantly<br />

in the direction expected from regional changes in the climate (Parmesan &<br />

Yohe 2003, Root et al. 2003). Responding species are spread across diverse ecosystems<br />

(from temperate grassl<strong>and</strong>s <strong>to</strong> marine intertidal zones <strong>and</strong> tropical cloud forests)<br />

<strong>and</strong> come from a wide variety of taxonomic <strong>and</strong> functional groups, including birds,<br />

butterflies, alpine flowers, <strong>and</strong> coral reefs.<br />

A meta-analysis of range boundary changes in the Northern Hemisphere<br />

estimated that northern <strong>and</strong> upper elevational boundaries had moved, on average,<br />

6.1 km per decade northward or 6.1 m per decade upward (P < 0.02) (Parmesan<br />

& Yohe 2003). Quantitative analyses of phenological responses gave estimates of<br />

advancement of 2.3 days per decade across all species (Parmesan & Yohe 2003) <strong>and</strong><br />

5.1 days per decade for the subset of species showing substantive change (>1 day per<br />

decade) (Root et al. 2003).<br />

A surprising result is the high proportion of species responding <strong>to</strong> recent, relatively<br />

mild climate change (global average warming of 0.6 ◦ C). The proportion of wild<br />

species impacted by climate change was estimated at 41% of all species (655 of 1598)<br />

(Parmesan & Yohe 2003). This estimate was derived by focusing on multispecies<br />

studies that reported stable as well as responding species. Because responders <strong>and</strong><br />

Meta-analysis: set of<br />

statistical techniques<br />

designed <strong>to</strong> synthesize<br />

quantitative results from<br />

similar <strong>and</strong> independent<br />

experiments<br />

www.annualreviews.org • <strong>Climate</strong>-<strong>Change</strong> Impacts 641

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