Conserved oviposition preferences in alpine leaf beetle populations despite host shifts and isolation
Davison, Anthony C.
Naisbit, Russell. E.
Date de parution
Ecological Entomology, Blackwell, 2007/32/1/62-69
1. Choosing the plant on which to lay their eggs is the last act of care that most female herbivorous insects bestow upon their offspring. These decisions play a pivotal role in insect–plant interactions, placing host preference under strong selection and contributing to the diversity of phytophagous insects as one of the first traits to adapt to new hosts. <br>2. This study presents a test of whether extreme isolation and exposure to different host plants can produce intra-specific divergence in oviposition preference in alpine insects. Geographic variation should impose selection to fine-tune host plant ranking and specificity to the plants normally encountered, to avoid wasting time during the very limited reproductive season experienced at high altitudes. <br>3. Beetles from five populations of <i>Oreina elongata</i> differing in host availability were offered three natural hosts: <i>Cirsium spinosissimum</i>, <i>Adenostyles alliariae</i>, and <i>Adenostyles glabra</i>. A novel application of a continuation ratio model (logistic regression) was made to sequential no-choice experiments, combined with quasi-likelihood analysis of multiple-choice experiments. <br>4. The results show little geographic variation in host plant choice: all populations strongly preferred <i>Cirsium</i> in multiple-choice trials, and in no-choice experiments laid around 47% of their remaining eggs during each stage, almost regardless of the host present. <br>5. Enemy-free space seems to explain the preference for <i>Cirsium</i>, but isolation and exposure to different plants has clearly not caused local adaptation in host plant ranking or specificity. Reasons for this conservatism despite divergence in other characteristics are discussed.
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Resource Types::text::journal::journal article
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