“Developmental studies of appendage formation and patterning in spiders”




Within the field of evolutionary developmental biology (“Evo Devo”), the embryonic development of many new model organisms has been examined to understand molecular mechanisms responsible for the evolutional diversity of appendages within the group of the arthropods. The most basal group of the arthropods are the chelicerates, including the spiders. We want to study the developmental mechanisms of appendage formation in spiders with a focus on the allometric growth of the walking legs. Some spider families have very short and stout legs (e.g. the Theridiidae) while other families have extremely long and slender legs (e. g. Pholcidae). For spiders two main model organisms are well established, namely Cupiennius salei and Parasteatoda tepidariorum (Theridiidae). We additionally established the long legged cellar spider Pholcus phalangioides (Pholcidae). Achaearanea tepidariorum and Pholcus phalangioides show significant differences in leg length in relation to body size. We will characterize the embryonic and postembryonic growth of the legs to find out when and where allometric growth takes place. At the same time differences in growth and patterning between the different appendage types and the same appendage type in different species and different sexes will be recorded and studied, to get an insight in the mechanisms of morphological diversification in spiders.

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A Pholcus phalangioides
B Larve