From Complete Orb to Semi-Orb Webs: Developmental Transitions in the Web of Nephilengys Cruentata (Araneae: Tetragnathidae)

摘要: Marked developmental changes in web pattern provide an opportunity to assess the degree of interdependency between building routines. The first webs tropical orb spider Nephilengys cruentata are small, closely knit, complete webs, built a great variety sites. Older spiders 'incomplete' orbs, which lack upper components (frame, radii, spirals), and silken, cylindrical retreat, placed near ceiling or corner, opens into hub. We studied transition from stage semi-orb stage, recording several parameters stages retreat formation. Two types ontogenetic were identified: global increases size (allometric growth) gradual suppression (vertical asymmetry). difference lower parts was evidenced curves describe development: whereas growth part usually followed linear trends, trends quadratic, means decreasing rates. Turning points (the temporal threshholds at passed increasing trends) not simultaneous: they clustered two transitional periods. During period, number viscid dry spirals, percentage orbs with empty sector inclination had turning points; during second horizontal diameter, length radii percent occurrence tent-like retreats. Our results (changes governed by different rules; asynchrony part; independence emergence modifications it is normally associated) reinforce modular conception control building. This has implications for understanding evolution patterns: aspects program could be independently subjected selection, leading specialized webs. uncoupling algorithms opens, evolutionary level, possibility structural novelties