Latitudinal clines in<Emphasis Type="Italic">Drosophila melanogaster</Emphasis>: Body size,allozyme frequencies,inversion frequencies,and the insulin-signalling pathway |
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Authors: | Email author" target="_blank">Gerdien?de?JongEmail author Zoltán?Bochdanovits |
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Institution: | (1) Evolutionary Population Biology, Utrecht University, Padualaan 8, NL-3584 CH Utrecht, Netherlands |
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Abstract: | Many latitudinal clines exist inDrosophila melanogaster: in adult body size, in allele frequency at allozyme loci, and in frequencies of common cosmopolitan inversions.
The question is raised whether these latitudinal clines are causally related. This review aims to connect data from two very
different fields of study, evolutionary biology and cell biology, in explaining such natural genetic variation inD. melanogaster body size and development time. It is argued that adult body size clines, inversion frequency clines, and clines in allele
frequency at loci involved in glycolysis and glycogen storage are part of the same adaptive strategy. Selection pressure is
expected to differ at opposite ends of the clines. At high latitudes, selection onD. melanogaster would favour high larval growth rate at low temperatures, and resource storage in adults to survive winter. At low latitudes
selection would favour lower larval critical size to survive crowding, and increased male activity leading to high male reproductive
success. Studies of the insulin-signalling pathway inD. melanogaster point to the involvement of this pathway in metabolism and adult body size. The genes involved in the insulin-signalling
pathway are associated with common cosmopolitan inversions that show latitudinal clines. Each chromosome region connected
with a large common cosmopolitan inversion possesses a gene of the insulin transmembrane complex, a gene of the intermediate
pathway and a gene of the TOR branch. The hypothesis is presented that temperateD. melanogaster populations have a higher frequency of a ’thrifty’ genotype corresponding to high insulin level or high signal level, while
tropical populations possess a more ’spendthrift’ genotype corresponding to low insulin or low signal level. |
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Keywords: | Drosophila insulin body size latitudinal cline inversion polymorphism |
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