The mechanism to maintain body color variation and its relationship with foraging ecology in orb-web spider

2014 Fiscal Year Final Research Report

• Project/Area Number: 23570037
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Ecology/Environment
• Research Institution: Kyoto Women's University
• Principal Investigator: NAKATA Kensuke 京都女子大学, 現代社会学部, 准教授 (80331031)
• Co-Investigator(Kenkyū-buntansha): SHIGEMIYA Yusuke 長崎総合科学大学, 建築・環境学部, 講師 (00399213)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Keywords: 種内多型 / 色彩変異 / クモ / 円網 / 季節性 / 採餌 / 遺伝形質

Outline of Final Research Achievements

Dorsal abdomen of an orb-web spider, Cyclosa argenteoalba, consists of black and silver colorings. The ratio of black area to dorsal abdominal area ranges 20-100% among spiders. Field observation revealed that, while silvery spiders dominated in spring, darker spider increased in summer. In autumn, silvery spiders dominated again. Web location of darker spiders were restricted in shady habitat in summer, possibly to avoid heating. Nevertheless, darker spiders exhibited higher foraging efficiency than silvery spiders. Body color seemed heritable trait. We did not find any relationship between the spider body color and predation rate or web relocation rate. The ratio of abdomen width to abdomen length, a kind of fitness index, was the highest at individuals exhibiting the intermediate rate of the ratio of black area. These indicate that seasonal change in advantageous body color is the reason to maintain body color variation, although more research is necessary for strong conclusions.

Free Research Field

動物生態学