Ecologically relevant cryptic species in the highly polymorphic Amazonian butterfly Mechanitis mazaeus s.l. (Lepidoptera: Nymphalidae; Ithomiini)

Abstract

The understanding of mimicry has relied on a strong biosystematic framework ever since early naturalists first recognized this textbook example of natural selection. We follow in this tradition, applying new biosystematics information to resolve problems in an especially difficult genus of tropical butterflies. Mechanitis species are important components of Neotropical mimetic communities. However, their colour pattern variability has presented challenges for systematists, and has made it difficult to study the very mimicry they so nicely illustrate. The South American Mechanitis mazaeus and relatives have remained particularly intractable. Recent systematists have recognized one highly polytypic species, whereas earlier work recognized the melanic Andean foothill races as a distinct species: Mechanitis messenoides. Recent molecular evidence suggests M. mazaeus and M. messenoides are genetically well differentiated, but evidence of morphological and ecological differences indicative of separate species was still lacking. Thus, it remains to be conclusively demonstrated whether this is an extreme case of a polymorphic mimetic species, or whether distinct co‐mimetic lineages are involved. Here we provide evidence that M. mazaeus and M. messenoides are ecologically distinct and identify consistent morphological differences in both adult and immature stages. These ecological and morphological differences are correlated with mitochondrial sequence data. In spite of some overlap in almost all traits, wing shape, adult colour pattern, and larval colour pattern differ between the two species, in addition to clutch size and larval host use in local sympatry. Although three well‐differentiated mitochondrial DNA (mtDNA) haplogroups were identified within these two species, one for M. mazaeus and two within M. messenoides, no morphological or ecological differences were found between two mtDNA haplogroups, both of which appear to belong to M. messenoides. We conclude that M. mazaeus and M. messenoides are distinct although highly polymorphic species, each with multiple sympatric co‐mimetic forms, and suggest that further work is needed to clarify the identity of other phenotypes and subspecies of Mechanitis. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 540–560.

Renewed diversification following Miocene landscape turnover in a Neotropical butterfly radiation

“…Three Amazonian radiations, the genus Melinaea (which comprises the rapidly diversifying Melinaea group) and the clade Mechanitis + Forbestra in the backbone and the Brevioleria group in the core group showed increasing speciation rates towards the present. Those radiations may be interpreted as supporting an effect of recent climatic fluctuations during the Pleistocene on the diversification of the Melinaea group (and the Mechanitis + Forbestra clade), although ecological drivers of speciation classically invoked in mimetic butterfly diversification, such as colour pattern and host‐plant shifts, cannot be ruled out (Hill et al, ; Jiggins et al, ; McClure & Elias, , ; McClure et al ). Contrasting with those clades, four other Amazonian radiations showed diversification rates decreasing through time, meaning that diversification was highest immediately after the retreat of the Pebas.…”

Methods for species delimitation in bumblebees (Hymenoptera, Apidae, Bombus): towards an integrative approach

“…Clustering based on Procrustes distances between wing shape do not detect an inter‐taxa differentiation, even between the outgroup and the ingroup despite that wing shape is recognized as a diagnostic character to discriminate morphologically similar taxa in many insect groups (Hill et al . ; Schutze et al . ) including other bumblebee groups (Aytekin et al .…”

Life Cycle and Host Plants ofMechanitis menapis doryssus1(Danainae: Ithomiini) in Mexico

“…Additional morphological evidence is required to support this idea because wing-color pattern is variable in the genus, and identification based solely on this criterion would be inappropriate. For example, observations of wing-color pattern variation in Mechanitis in the Amazon (Hill et al 2012) and the Andes (Giraldo and Uribe 2012) found much variation and few reliable characteristics to allow accurate identification of sympatric species.…”

“…More ecological and morphological data are needed to resolve the taxonomic status of the members of the genus. For butterflies in general and for Ithomiini in particular, information about the immature stages has been successfully used in taxonomic and phylogenetic studies to help resolve systematic questions (Brown and Freitas 1994;Motta 2003;Willmott and Freitas 2006;Lamas 2006, 2008;Freitas and Brown 2008;Bolaños et al 2011;Giraldo and Uribe 2012;Hill et al 2012).…”