Clutch size in the swallowtail butterfly,Battus philenor: the role of host quality and egg load within and among seasonal flights in California
✍ Scribed by Marc Tatar
- Publisher
- Springer
- Year
- 1991
- Tongue
- English
- Weight
- 920 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0340-5443
No coin nor oath required. For personal study only.
✦ Synopsis
Clutch size in the pipevine swallowtail of California (Battus phiIenor hirsuta) varies widely within and among two seasonal flights, early and late spring. Pilson and Rausher (1988) proposed that variation in clutch size in a Texan B. philenor population is due to assessment of host quality with subsequent adjustment of clutch size and to differences in motivational state. The assessment hypothesis and a nonexclusive alternative that clutch size is determined by mature egg load were tested for populations in Sacramento, California. Weak and sporadic correlations between host quality and clutch size were found, suggesting that host assessment with adjustment of dutch size is not a strong factor in this population. Clutch size was highly correlated to mature egg load in the early but not in the late spring flight. Yet, females from both flights had similar loads of mature eggs. It is proposed that females lay clutch sizes proportional to egg load, up to a maximum threshold. The threshold may be lowered in the late spring flight in response to changes in overall host quality or to increased egg predation, reducing both the mean clutch size and the correlation between clutch size and egg load. Potential mechanisms for the change in behavior among flights, based on changes in the threshold, are discussed.