Host range oscillations in nymphalid butterflies: a phylogenetic investigation
(English)Manuscript (preprint) (Other academic)
It has been suggested that phenotypic plasticity is a major factor in the diversification of life, and that variation in host range in phytophagous insects is a good model for investigating this claim. We explore the use of angiosperm plants as hosts for nymphalid butterflies, and in particular the evidence for past oscillations in host range and how they are linked to host shifts and diversification. At the level of orders of plants, a relatively simple pattern of host use emerges, despite the 100 million years of history of the family Nymphalidae. The ancestral host order was very likely Rosales. Later, major host shifts occurred to Gentianales (and even later Solanales) in the Danainae; to Arecales (and even later Poales) in the ”satyrines”; to Malpighiales as the main host order in the ”heliconiines”; and to Lamiales within Nymphalinae. We review the evidence that these host shifts and the accompanying diversifications were associated with transient polyphagous stages, as suggested by the ”oscillation hypothesis” of Janz & Nylin. In addition, we investigate all currently polyphagous nymphalid species (in terms of feeding on more than one host order) and demonstrate that the state of polyphagy is rare and has a weak phylogenetic signal and a very apical distribution in the phylogeny; we argue that these are signs of its transient nature. We contrast our results with data from the bark beetles Dendroctonus, where a more specialized host use is instead the apical state, and suggest that this is simply a stage during a single oscillation when host range is decreasing.
Ecology Evolutionary Biology Zoology
IdentifiersURN: urn:nbn:se:su:diva-71319OAI: oai:DiVA.org:su-71319DiVA: diva2:484600