Breaking the mold: behavioral variation and evolutionary innovation in Wendilgarda spiders (Araneae Theridiosomatidae)

The hypothesis that the evolutionary origin of novel behavior patterns may be imprecision in the execution of existing patterns is examined using data from spider web construction behavior. Several aspects of orb construction behavior are both extremely invariable intraspecifically, and highly conserved evolutionarily. The behavior of spiders in the genus Wendilgarda, which build highly modified, simplified webs derived from orbs, is exceptional in being highly variable both within and between species. Reduced intensity of selection for behavioral stereotypy combined with behavioral imprecision may explain the high intraspecific and intra-individual variability in Wendilgarda. This increased variation may in turn explain the unusual interspecific diversity of web designs in this genus.