| Research Abstract |
The objective of this study is to clarify foraging specialization and the evolution of life history traits in kleptoparasitic Argyrodes spiders. To achieve this, I examined 1) foraging mode and host range, 2) plasticity in foraging mode, 3) life history traits, 4) construction of molecular phylogenetic tree.
1) Host eating and prey / silk eating were the two major foraging modes in Argyrodes. Species whose main foraging mode was prey stealing inhabited orb-web spiders, except for A. fissifrons. This may be related to the abundant small prey left on orb-webs.
2) A. flavescens exclusively steal prey when prey were abundant, while it often eat silk in other seasons. Silk eating appears to be the alternative foraging mode under poor food availability. Previous studies suggested that host eating was the alternative tactics in species living in three-dimensional webs.
3) Host eaters and A. fissifrons had a univoltine life cycle, while small species stealing prey and silk showed a multivoltine life cycle. Probably this is related to the prey availability.
4) We determined the sequence of mitochondrial DNA for six species of Argyrodes and two species of Achaearanea and constructed the phylogenetic tree. A. saganus and A. fur formed a clade, suggesting that host eating and prey / silk stealing evolved independently.
It appears that Argyrodes developed multivoltine life cycle by changing its foraging mode from host eating to prey stealing.
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