CH03: Species Range Shifts

FIGURE 3.1 Bleached coral. El Niño events in 1982–1983 and 1997–1998 bleached corals in reefs throughout the world. Bleaching is an increasingly common phenomenon even in non-El Niño years. This coral head in St. Croix bleached in 1995. Source: Courtesy U.S. National Oceanic and Atmospheric Administration.

FIGURE 3.2 1997–1998: A deadly year for corals. The right panel shows corals bleached in the El Niño event of 1997–1998. The left panels show a single coral head pre- and postbleaching: (a) prebleaching, (b) bleached coral head, (c) partially recovered coral head, and (d) fully recovered postbleaching. Left Source: Manzello et al. (2007); Right Source: Courtesy U.S. National Oceanic and Atmospheric Administration

FIGURE 3.3 Coral bleaching events. As global mean temperature rises, the frequency of events that exceed the bleaching threshold increases. The threshold varies in different regions. These global maps illustrate the severity of bleaching in the 1998 El Niño, which was the first major global bleaching event, and recorded bleaching in 2006. Every major coral reef region in the world has now suffered moderate to severe bleaching events. Source: Marshall and Schuttenberg (2006).

FIGURE 3.4 Edith’s checkerspot butterfly range shift. Southern populations of Edith’s checkerspot butterfly are becoming extinct (shaded squares) more frequently than northern and montane populations, resulting in a northward and upslope range shift. Source: Parmesan (1996). Reprinted with permission from Nature.

FIGURE 3.5 Edith’s checkerspot butterfly (Euphydryas editha). Source: From http://www.nps.gov/pinn/naturescience/butterfly.htm.

FIGURE 3.6 Penguins and climate change. Emperor penguin (Aptenodytes forsteri) populations are declining in Antarctica with climate change. Source: Photo courtesy of NOAA. Photographer: Giuseppe Zibordi.

FIGURE 3.7 Shifting krill in Southern Oceans. Krill abundance is decreasing in areas bordering Antarctica, whereas salp densities are increasing. Krill depend on ice algae for summer population growth. Declining sea ice due to climate change reduces algal density and depresses krill populations. Salps increase in their place. The maps show the change in krill (top) and salp (bottom) abundance. These changes have had profound impacts on food webs in the southern oceans. Source: Atkinson et al. (2004). Reproduced with permission from Nature.

FIGURE 3.8 Correlation between sea ice and krill density from region shown in Figure 3.7. Source: Atkinson et al. (2004). Reproduced with permission from Nature.

FIGURE 3.9 The silver-spotted skipper (Hesperia comma) has expanded its range threefold in Britain since 1982. Source: Pimm (2001). Reproduced with permission from Nature

FIGURE 3.10 Large-winged forms increase in expanding range margins. Insects have longer wings in expanding range margins. The conehead bush cricket, Conocephalus discolor (a), and Roesel’s bush cricket, Metrioptera Roeselii (b), have undergone recent range expansions due to climate change. Blue circles indicate historical range, with yellow and red circles denoting progressive expansion in these species. Long-winged forms are more common in populations on the range margin (c and d). Locations with fewer years since first observation are recently colonized areas on the range margin. Source: Thomas et al. (2001a). Reproduced with permission from Nature.

FIGURE 3.11 Climate-linked invasion. Invasion of exotic plant species is correlated with reduced drought days in Switzerland. Removal of climatic stress may remove important constraints on the spread of these species. Source: Walther et al. (2002). Reproduced with permission from Nature.

FIGURE 3.12 The quiver tree, Aloe dichotoma. A. dichotoma is a bellwether of climate change. Populations are declining in the north and at lower elevations, with the only northern stronghold remaining at high elevation (Foden et al., 2007). Source: Photo from Wikimedia commons.

FIGURE 3.13 Drying trends in Monteverde cloud forest, Costa Rica. Number of dry days per year in Monteverde and departure of nearby sea surface temperature from long-term average. Note the long-term increase in the number of dry days and the peak in 1987, which is the year of the disappearance of the golden toad. Source: Pounds et al. (1999). Reproduced with permission from Nature.

FIGURE 3.14 Changes in diversity in Arctic lakes. Diatom diversity has increased in arctic lakes owing to warming during the second half of the twentieth century. An increase in diversity in sampled lakes is indicated for the arctic and in more detail for four regions with especially rich records in the insets. Source: Smol et al. (2005) © National Academy of Sciences U.S.A.

FIGURE 3.15 Expanding malaria zone. Malaria is currently rare in the highlands of Zimbabwe (left panel). Malaria parasites mature up to 10 days more rapidly under projected temperature increases. This allows the disease to persist in formerly inhospitable areas. The right panel shows the projected spread of malaria into the Zimbabwe highlands by 2050 due to this effect. Orange and red colors denote suitable conditions for malaria transmission, and blue-green colors areas with poor conditions for transmission. Source: Patz and Olson (2006) © National Academy of Sciences U.S.A.

Arctic fox (a) and red fox (b). Source: From (a) Wikimedia Commons and (b) U.S. Fish and Wildlife Service.

Pika (Ochotona princeps) in typical rocky habitats.

Keel-billed toucan (Ramphastos sulfuratus). Source: From Wikimedia Commons.

Projected changes in 17 (yellow) and 13 °C (white) isotherms that limit the distribution of avian malaria under current and 2 °C warming conditions. Changes are shown for Hanawi Reserve (blue boundary) on the island of Maui (a), Hakalau Refuge (blue boundary) on Hawaii (b), and the Alakai swamp region on the island of Kauai (c). Source: Benning et al. (2002) © National Academy of Sciences U.S.A.