Evolution of extreme proboscis lengths in Neotropical Hesperiidae (Lepidoptera)

J. A.-S. Bauder*(1), A. D. Warren (2) and H. W. Krenn (1)
(1)Department of Integrative Zoology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
(2)McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida, Gainesville, U.S.A.

The Journal of Research on the Lepidoptera

Volume 47: 65-71

ISSN 0022-4324 (print)
ISSN 2156-5457 (online)

Abstract. Exaggerated morphologies have evolved in insects as adaptations to nectar feeding by natural selection. For example, the suctorial mouthparts of butterflies enable these insects to gain access to floral nectar concealed inside deep floral tubes. Proboscis length in Lepidoptera is known to scale with body size, but whether extreme absolute proboscis lengths of nectar feeding butterflies result from a proportional or disproportional increase with body size that differs between phylogenetic lineages remains unknown. We surveyed the range of variation that occurs in scaling relationships between proboscis length and body size against a phylogenetic background among Costa Rican Hesperiidae. We obtained a new record holder for the longest proboscis in butterflies and showed that extremely long proboscides evolved at least three times independently within Neotropical Hesperiidae. We conclude that the evolution of extremely long proboscides results from allometric scaling with body size, as demonstrated in hawk moths. We hypothesize that constraints on the evolution of increasingly long butterfly proboscides may come from (1) the underlying scaling relationships, i.e., relative proboscis length, combined with the butterfly’s flight style and flower-visiting behaviour and/or (2) developmental constraints during the pupal phase. Lastly, we discuss why butterflies did not evolve similar scaling relationships as hawk moths.

Key Words: skippers, hawk moths, scaling relationship, allometry, flower-visiting behaviour, metamorphosis.

Received: 29 August 2014
Accepted: 29 October 2014

Published online at www.lepidopteraresearchfoundation.org on 1 December 2014

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