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Impacts of Climate Warming on Arctic Aphids: A Comparative Analysis
Jeffrey S. Bale
No. 47, Animal Responses to Global Change in the North (1999), pp. 38-47
Published by: Oikos Editorial Office
Stable URL: http://www.jstor.org/stable/20113225
Page Count: 10
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The diversity of plants and animals, including invertebrate taxa such as aphids, decreases with increasing latitude from the temperate to the Arctic region. The dominant biotic and abiotic features of the arctic environment (short growing season, low levels of precipitation and incident radiation, poor quality soils and low primary productivity), the most important of which is the year round low average temperature, are collectively unfavourable for terrestrial arthropods compared with conditions in the temperate zone. The main factors determining the impacts of climate warming on arctic aphids are the type of life cycle of the species, its current distribution and abundance, and the level of any constraints imposed by low temperatures on development and survival. On a south-north latitudinal transect comparing aphid species from the temperate zone through the sub-Arctic to the high-Arctic, a number of progressive changes are apparent. There are a fewer generations per year, a decreasing proportion of anholocyclic (asexual) clones, less winged aphids (alates) and an increasing independence of the life cycle from environmental regulation. An extreme adaptive life cycle occurs in some high-Arctic species in which the fundatrix gives birth directly to both sexual morphs which then produce the overwintering eggs. Climate is not a major limitation on the distribution of temperate species but in the high-Arctic the occurrence and abundance of aphids differs in patches of host plant which are only 1 m apart. The wider distribution of high-arctic species follows subtle thermal gradients. Overwintering eggs and active stages (viviparae) of arctic species are more cold hardy than their temperate counterparts. Temperature elevation of 2-3°C through the summer season increased the rate of development, survival to adult and density of overwintering eggs of the high-arctic aphid Acyrthosiphon svalbardicum. A similar but less pronounced response was observed with the closely related Acyrthosiphon brevicorne at two sub-arctic sites, supporting the hypothesis that the ecological effects of climate warming will be greatest in severe environments at the most northerly latitudes.
Ecological Bulletins © 1999 Oikos Editorial Office