Origins of Six Species of Butterflies Migrating through Northeastern Mexico: New Insights from Stable Isotope (δ2H) Analyses and a Call for Documenting Butterfly Migrations

Jackson W. Kusack,Blanca X. Mora-Alvarez,Keith A. Hobson

doi:10.3390/d13030102

Jackson W. Kusack, Blanca X. Mora-Alvarez + Show 1 more

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https://doi.org/10.3390/d13030102

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Abstract

Determining migratory connectivity within and among diverse taxa is crucial to their conservation. Insect migrations involve millions of individuals and are often spectacular. However, in general, virtually nothing is known about their structure. With anthropogenically induced global change, we risk losing most of these migrations before they are even described. We used stable hydrogen isotope (δ2H) measurements of wings of seven species of butterflies (Libytheana carinenta, Danaus gilippus, Phoebis sennae, Asterocampa leilia, Euptoieta claudia, Euptoieta hegesia, and Zerene cesonia) salvaged as roadkill when migrating in fall through a narrow bottleneck in northeast Mexico. These data were used to depict the probabilistic origins in North America of six species, excluding the largely local E. hegesia. We determined evidence for long-distance migration in four species (L. carinenta, E. claudia, D. glippus, Z. cesonia) and present evidence for panmixia (Z. cesonia), chain (Libytheana carinenta), and leapfrog (Danaus gilippus) migrations in three species. Our investigation underlines the utility of the stable isotope approach to quickly establish migratory origins and connectivity in butterflies and other insect taxa, especially if they can be sampled at migratory bottlenecks. We make the case for a concerted effort to atlas butterfly migrations using the stable isotope approach.

Highlights

Many animals have evolved to migrate in response to seasonal changes in resource abundance [1]
In the Nearctic, one of the most impressive examples of insect migration is provided by the eastern North American monarch butterfly (Danaus plexippus) that annually migrates up to 5000 km from breeding grounds in the USA and Canada to discrete high-altitude overwinter colonies in oyamel fir (Abies religiosa) forests of central Mexico
We found isotopic differences among species (ANOVA F6,470 = 35.9, p < 0.0001), and clearly identified two groups of species corresponding approximately to long-distance migrants (L. carinenta, E. claudia, D. glippus, Z. cesonia) and short-distance migrants (A. leilia, E. hegesia, P. sennae; Table 1, unequal variance t-test: t = 14.8, p < 0.0001)

Summary

Introduction

Many animals have evolved to migrate in response to seasonal changes in resource abundance [1]. Migration is diverse and includes movements resembling dispersal, often at local scales, to intercontinental movements involving multiple generations [2]. Well-known examples of insect migration are often associated with spectacular daytime movements of Lepidoptera, Odonata, and Orthoptera, and include charismatic species (e.g., butterflies, dragonflies). In the Nearctic, one of the most impressive examples of insect migration is provided by the eastern North American monarch butterfly (Danaus plexippus) that annually migrates up to 5000 km from breeding grounds in the USA and Canada to discrete high-altitude overwinter colonies in oyamel fir (Abies religiosa) forests of central Mexico. Many other Lepidoptera are known to migrate seasonally, as indicated by regular mass diurnal movements of individuals, but their origins and destinations remain largely unknown due to the difficulties in tracking small insects [2]

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