Early stages of orb construction by Philoponella vicina, Leucauge mariana, and Nephila clavipes (Araneae, Uloboridae and Tetragnathidae), and their phylogenetic implications

The uloboridPhiloponella vicina differs from the araneoids Nephila clavipes and Leucauge mariana in one movement made during frame construction, in the ordering of frame construction, in proto-hub removal, and in the highly ordered sequence of operations on adjacent radii just before proto-hub removal. Data from other uloborids suggest that all of these differences may distinguish orb weaving uloborids in general from orb weaving araneoids .N . clavipes differs from the other two species in the order of lines laid during frame construction, in the high variability in the details of frame construction, and in its failure to remove recently laid lines during exploration, radius construction, and frame construction. Frame construction behavior in all three species is more variable than previous reports indicated, and more variable than behavior in later stages of orb construction . In all three species earlier frame construction more often involves breaking lines already present in the web . Similarity between uloborid and araneoid frame construction is more likely to be due to a combination of constructional constraints and inheritance of ancient spinning patterns than previously realized ; it is not clear whether or not it constitutes a synapomorphy uniting the two groups . The failure of N . clavipes to remove recently laid lines during exploration, radius construction, and frame construction is probably plesimorphic . Secondary loss of removal behavior seems unlikely because removal probably confers adaptive advantages . Removal behavior in these contexts and possibly more stereotyped frame construction behavior probably evolved independently in uloborids and araneoids