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Optimizing development time in a seasonal environment: The 'ups and downs' of clinal variation
1Research and Resource Services, Department of Fisheries and Oceans, P. O. Box 5667, A1C 5X1, St. John's, Newfoundland.
Abstract:
This paper explores the problem of adapting development time to changes in the length of time conditions are favourable for growth and reproduction ('season length'). It is shown that systematic changes in season length along some gradient such as latitude can generate either simple clines in development time or 'saw-tooth' clines. The relationship between development time and body size gives rise to a corresponding variation in body size. The generation of a 'saw-tooth' cline does not require sharp environmental changes. Both types of clinal variation are observed in insects.
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Transcription is the process of synthesizing RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. Additionally, many other proteins and regulatory sequences are involved in the proper synthesis of messenger RNA (mRNA). Regulation of transcription is responsible for the differentiation of all the different types of cells and often for the proper cellular response to environmental signals.
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