Thursday, October 14, 2010

Species' Adaptation to Non-Climatic Heat Sources

Recently there has been a lot of interest about how ectothermic animals will be affected by climate change (Helmuth et al.2005 as cited in Marshall et al. 2010). If these animals are unable to adapt to different climates and increased temperatures, they and other species may go extinct. This would be a major issue and would cause many more problems with the environment since many species and ecosystems depend on eachother for survival. According to David J. Marshall, Christopher D. McQuaid and Gray A. Williams, in their study: “Non-climatic thermal adaptation: implications for species' responses to climate warming”, little is known about how ectotherms adapt to non-climatic heat sources, such as solar or geothermal heat (Marshall et al. 2010). By using a rocky-shore snail, Marshall, McQuaid and Williams show that thermal adaptation is mostly caused by non-climatic heat sources. They believe that this information should be included when predicting the effects of global warming: “By separating these factors, we show that thermal adaptation in a rocky-shore snail is principally driven by solar heating, and hence propose that non-climatic adaptation be incorporated into models predicting climate warming effects” (Marshall et al. 2010). Also, this information could be helpful for decreasing the effects of global warming since it shows that ectothermic animals would be able to adapt to and survive increased temperatures (Marshall et al. 2010).

The rocky-shore snail used was called Echinolittorina malacanna (Reid 2007 as cited in Marshall et al. 2010). Marshall, McQuaid and Williams studied these snails in water depths from 2m to 5m in Pantai Tungku, Brunei Darussalam on artificial sea walls (Marshall et al. 2010). Air temperature, operative body temperature (on light and dark rocks), solar irradiance and rock surface temperature were measured every minute for 21 days. Air temperature and solar irradiance were measured every 10 minutes for another week after the original 21 days. The regional air temperature was also measured. Lastly, the snails’ heart rates were used to test the thermal adaptations. Snails were taken to a lab where infrared sensors measured their heart rates every minute while temperature increased from 30°C to 60°C at a rate of 0.25°C per minute (Marshall et al. 2010).

(Marshall et al. 2010)

Marshall, McQuaid and Williams found that the snail body temperature and rock temperature increased faster than the air temperature, and had different maximum temperatures than the air temperature (Marshall et al. 2010). Also, the regional temperatures were lower than the temperatures on the rocks, and the snails on the dark rocks had higher body temperatures than those on the light rocks. Air temperature was similar to snail body temperature only at night when there was no solar heat, on windy days since there is a lot of heat loss, and when there was high atmospheric attenuation. However, this has no effect on the thermal adaptation of the snails since the maximum body temperatures were lower on these days.

Marshall, McQuaid and Williams show that thermal adaptation is mostly compelled by non-climatic heat sources since the snail body temperatures were the highest when solar heat was the highest. The highest temperature for heart function was more than 4.3°C higher than the maximum body temperature of the snails, and was more than 19.4 °C higher than the air temperature. Marshall, McQuaid and Williams show that solar heating, which climate does not affect, is the main factor in the body temperature of the snails (Marshall et al. 2010).

Since non-climatic heat sources are the main factor in body temperature, even if climate change does occur and temperatures increase, the snails should be able to survive (Marshall et al. 2010). This is important information because there has been a lot of concern recently about how ectothermic animals will be affected by climate change. However, since they should be able to survive and adapt to higher temperatures, there should be less damage to the environment and other ecosystems. Many predictions about global warming may be incorrect since most do not take into account the differences between climatic and non-climatic heat sources (Helmuth et al. as cited in Marshall et al. 2010). Hopefully new predictions that do take into account these differences will show less serious effects. Also, hopefully this study will influence more studies looking into the thermal adaptation of other animals and organisms. If ectotherms are able to adapt, perhaps other organisms will also be able to. Marshall, McQuaid and Williams may make a significant impact on climate change with this study.

Marshal, David J., McQuaid, Christopher D. and Williams, Gray A. 2010. “Non-climatic thermal adaptation: implications for species' responses to climate
warming.” Biology Letters. October 2010. University of Guelph.

David Tarascio 0705039

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