Hard to catch: experimental evidence supports evasive mimicry.

Most research on aposematism has focused on chemically defended prey, but the signalling difficulty of capture remains poorly explored. Similar to classical Batesian and Müllerian mimicry related to distastefulness, such 'evasive aposematism' may also lead to convergence in warning colours, known as evasive mimicry. A prime candidate group for evasive mimicry are Adelpha butterflies, which are agile insects and show remarkable colour pattern convergence. We tested the ability of naive blue tits to learn to avoid and generalize Adelpha wing patterns associated with the difficulty of capture and compared their response to that of birds that learned to associate the same wing patterns with distastefulness. Birds learned to avoid all wing patterns tested and generalized their aversion to other prey to some extent, but learning was faster with evasive prey compared to distasteful prey. Our results on generalization agree with longstanding observations of striking convergence in wing colour patterns among Adelpha species, since, in our experiments, perfect mimics of evasive and distasteful models were always protected during generalization and suffered the lowest attack rate. Moreover, generalization on evasive prey was broader compared to that on distasteful prey. Our results suggest that being hard to catch may deter predators at least as effectively as distastefulness. This study provides empirical evidence for evasive mimicry, a potentially widespread but poorly understood form of morphological convergence driven by predator selection.

Four hundred shades of brown: Higher level phylogeny of the problematic Euptychiina (Lepidoptera, Nymphalidae, Satyrinae) based on hybrid enrichment data.

Relationships within satyrine butterflies have been notoriously difficult to resolve using both morphology and Sanger sequencing methods, and this is particularly true for the mainly Neotropical subtribe Euptychiina, which contains about 400 described species. Known larvae of Euptychiina feed on grasses and sedges, with the exception of the genus Euptychia, which feed on mosses and lycopsids, and the butterflies occur widely in rainforest, cloudforest and grassland habitats, where they are often abundant. Several previous molecular and morphological studies have made significant progress in tackling the systematics of the group, but many relationships remain unresolved, with long-branch-attraction artifacts being a major problem. Additionally, the monophyly of the clade remains uncertain, with Euptychia possibly not being closely related to the remainder of the clade. Here we present a backbone phylogeny of the subtribe based on 106 taxa, 368 nuclear loci, and over 180,000 bps obtained through hybrid enrichment. Using both concatenation and species tree approaches (IQ-TREE, EXABAYES, ASTRAL), we can for the first time strongly confirm the monophyly of Euptychiina with Euptychia being the sister group to the remainder of the clade. The Euptychiina is divided into nine well supported clades, but the placement of a few genera such as Hermeuptychia, Pindis and the Chloreuptychia catharina group still remain uncertain. As partially indicated in previous studies, the genera Cissia, Chloreuptychia, Magneuptychia, Megisto, Splendeuptychia and Euptychoides, among others, were found to be highly polyphyletic and revisions are in preparation. The phylogeny will provide a strong backbone for the analysis of datasets in development that are much more taxonomically comprehensive but have orders of magnitude fewer loci. This study therefore represents a critical step towards resolving the higher classification and studying the evolution of this highly diverse lineage.

Frequency dependence shapes the adaptive landscape of imperfect Batesian mimicry.

Despite more than a century of biological research on the evolution and maintenance of mimetic signals, the relative frequencies of models and mimics necessary to establish and maintain Batesian mimicry in natural populations remain understudied. Here we investigate the frequency-dependent dynamics of imperfect Batesian mimicry, using predation experiments involving artificial butterfly models. We use two geographically distinct populations of Adelpha butterflies that vary in their relative frequencies of a putatively defended model (Adelpha iphiclus) and Batesian mimic (Adelpha serpa). We found that in Costa Rica, where both species share similar abundances, Batesian mimicry breaks down, and predators more readily attack artificial butterfly models of the presumed mimic, A. serpa By contrast, in Ecuador, where A. iphiclus (model) is significantly more abundant than A. serpa (mimic), both species are equally protected from predation. Our results provide compelling experimental evidence that imperfect Batesian mimicry is frequency-dependent on the relative abundance of models and mimics in natural populations, and contribute to the growing body of evidence that complex dynamics, such as seasonality or the availability of alternative prey, influence the evolution of mimetic traits.

Maintaining mimicry diversity: optimal warning colour patterns differ among microhabitats in Amazonian clearwing butterflies.

Mimicry is one of the best-studied examples of adaptation, and recent studies have provided new insights into the role of mimicry in speciation and diversification. Classical Müllerian mimicry theory predicts convergence in warning signal among protected species, yet tropical butterflies are exuberantly diverse in warning colour patterns, even within communities. We tested the hypothesis that microhabitat partitioning in aposematic butterflies and insectivorous birds can lead to selection for different colour patterns in different microhabitats and thus help maintain mimicry diversity. We measured distribution across flight height and topography for 64 species of clearwing butterflies (Ithomiini) and their co-mimics, and 127 species of insectivorous birds, in an Amazon rainforest community. For the majority of bird species, estimated encounter rates were non-random for the two most abundant mimicry rings. Furthermore, most butterfly species in these two mimicry rings displayed the warning colour pattern predicted to be optimal for anti-predator defence in their preferred microhabitats. These conclusions were supported by a field trial using butterfly specimens, which showed significantly different predation rates on colour patterns in two microhabitats. We therefore provide the first direct evidence to support the hypothesis that different mimicry patterns can represent stable, community-level adaptations to differing biotic environments.

Into the Andes: multiple independent colonizations drive montane diversity in the Neotropical clearwing butterflies Godyridina.

Understanding why species richness peaks along the Andes is a fundamental question in the study of Neotropical biodiversity. Several biogeographic and diversification scenarios have been proposed in the literature, but there is confusion about the processes underlying each scenario, and assessing their relative contribution is not straightforward. Here, we propose to refine these scenarios into a framework which evaluates four evolutionary mechanisms: higher speciation rate in the Andes, lower extinction rates in the Andes, older colonization times and higher colonization rates of the Andes from adjacent areas. We apply this framework to a species-rich subtribe of Neotropical butterflies whose diversity peaks in the Andes, the Godyridina (Nymphalidae: Ithomiini). We generated a time-calibrated phylogeny of the Godyridina and fitted time-dependent diversification models. Using trait-dependent diversification models and ancestral state reconstruction methods we then compared different biogeographic scenarios. We found strong evidence that the rates of colonization into the Andes were higher than the other way round. Those colonizations and the subsequent local diversification at equal rates in the Andes and in non-Andean regions mechanically increased the species richness of Andean regions compared to that of non-Andean regions ('species-attractor' hypothesis). We also found support for increasing speciation rates associated with Andean lineages. Our work highlights the importance of the Andean slopes in repeatedly attracting non-Andean lineages, most likely as a result of the diversity of habitats and/or host plants. Applying this analytical framework to other clades will bring important insights into the evolutionary mechanisms underlying the most species-rich biodiversity hotspot on the planet.

Incompatible Ages for Clearwing Butterflies Based on Alternative Secondary Calibrations.

The recent publication of a time-tree for the plant family Solanaceae (nightshades) provides the opportunity to use independent calibrations to test divergence times previously inferred for the diverse Neotropical butterfly tribe Ithomiini. Ithomiini includes clades that are obligate herbivores of Solanaceae, with some genera feeding on only one genus. We used 8 calibrations extracted from the plant tree in a new relaxed molecular-clock analysis to produce an alternative temporal framework for the diversification of ithomiines. We compared the resulting age estimates to: (i) a time-tree obtained using 7 secondary calibrations from the Nymphalidae tree of Wahlberg et al. (2009), and (ii) Wahlberg et al.'s (2009) original age estimates for the same clades. We found that Bayesian clock estimates were rather sensitive to a variety of analytical parameters, including taxon sampling. Regardless of this sensitivity however, ithomiine divergence times calibrated with the ages of nightshades were always on average half the age of previous estimates. Younger dates for ithomiine clades appear to fit better with factors long suggested to have promoted diversification of the group such as the uplifting of the Andes, in the case of montane genera. Alternatively, if ithomiines are as old as previous estimates suggest, the recent ages inferred for the diversification of Solanaceae seem likely to be seriously underestimated. Our study exemplifies the difficulty of testing hypotheses of divergence times and of choosing between alternative dating scenarios, and shows that age estimates based on seemingly plausible calibrations may be grossly incongruent.

Rapid diversification associated with ecological specialization in Neotropical Adelpha butterflies.

Rapid diversification is often associated with morphological or ecological adaptations that allow organisms to radiate into novel niches. Neotropical Adelpha butterflies, which comprise over 200 species and subspecies, are characterized by extraordinary breadth in host plant use and wing colour patterns compared to their closest relatives. To examine the relationship between phenotypic and species diversification, we reconstructed the phylogenetic history of Adelpha and its temperate sister genus Limenitis using genomewide restriction-site-associated DNA (RAD) sequencing. Despite a declining fraction of shared markers with increasing evolutionary distance, the RAD-Seq data consistently generated well-supported trees using a variety of phylogenetic methods. These well-resolved phylogenies allow the identification of an ecologically important relationship with a toxic host plant family, as well as the confirmation of widespread, convergent wing pattern mimicry throughout the genus. Taken together, our results support the hypothesis that evolutionary innovations in both larvae and adults have permitted the colonization of novel host plants and fuelled adaptive diversification within this large butterfly radiation.

Mutualistic mimicry and filtering by altitude shape the structure of Andean butterfly communities.

Both the abiotic environment and abiotic interactions among species contribute to shaping species assemblages. While the roles of habitat filtering and competitive interactions are clearly established, less is known about how positive interactions, whereby species benefit from the presence of one another, affect community structure. Here we assess the importance of positive interactions by studying Andean communities of butterflies that interact mutualistically via Müllerian mimicry. We show that communities at similar altitudes have a similar phylogenetic composition, confirming that filtering by altitude is an important process. We also provide evidence that species that interact mutualistically (i.e., species that share the same mimicry wing pattern) coexist at large scales more often than expected by chance. Furthermore, we detect an association between mimicry structure and altitude that is stronger than expected even when phylogeny is corrected for, indicating adaptive convergence for wing pattern and/or altitudinal range driven by mutualistic interactions. Positive interactions extend far beyond Müllerian mimicry, with many examples in plants and animals, and their role in the evolution and assembly of communities may be more pervasive than is currently appreciated. Our findings have strong implications for the evolution and resilience of community structure in a changing world.

Comprehensive phylogeny of Pieridae butterflies reveals strong correlation between diversification and temperature.

Temperature is thought to be a key factor influencing global species richness patterns. We investigate the link between temperature and diversification in the butterfly family Pieridae by combining next generation DNA sequences and published molecular data with fine-grained distribution data. We sampled nearly 600 pierid butterfly species to infer the most comprehensive molecular phylogeny of the family and curated a distribution dataset of more than 800,000 occurrences. We found strong evidence that species in environments with more stable daily temperatures or cooler maximum temperatures in the warm seasons have higher speciation rates. Furthermore, speciation and extinction rates decreased in tandem with global temperatures through geological time, resulting in a constant net diversification.

Systematics and evolutionary history of butterflies in the "Taygetis clade" (Nymphalidae: Satyrinae: Euptychiina): towards a better understanding of Neotropical biogeography.

The so-called "Taygetis clade" is a group of exclusively Neotropical butterflies classified within Euptychiina, one of the largest subtribes in the subfamily Satyrinae. Since the distribution of the ten genera belonging to this group ranges throughout the entire Neotropics, from lowlands to lower montane habitats, it offers a remarkable opportunity to study the region's biogeographic history as well as different scenarios for speciation in upland areas. We inferred a robust and well-sampled phylogeny using DNA sequences from four genes (4035 bp in total) using maximum parsimony and Bayesian inference. We estimated divergence times using the Bayesian relaxed clock method calibrated with node ages from previous studies. Ancestral ranges of distribution were estimated using the dispersal-extinction-cladogenesis (DEC) model as implemented in the program Lagrange. We propose several taxonomic changes and recognize nine well-supported natural genera within the "Taygetis clade": Forsterinaria (subsuming Guaianaza syn. nov.), Parataygetis, Posttaygetis, Harjesia (excluding Harjesia griseola and Harjesia oreba), Pseudodebis (including Taygetomorpha syn. nov.,), Taygetina (subsuming Coeruleotaygetis syn. nov., Harjesia oreba comb. nov., Taygetis weymeri comb. nov. and Taygetis kerea comb. nov.), Taygetis (excluding Taygetis ypthima, Taygetis rectifascia, Taygetis kerea and Taygetis weymeri), and two new genera, one containing Harjesia griseola, and the other Taygetis ypthima and Taygetis rectifascia. The group diversified mainly during late Miocene to Pliocene, coinciding with the period of drastic changes in landscape configuration in the Neotropics. Major dispersals inferred from the Amazon basin towards northwestern South America, the Atlantic forests and the eastern slope of the Andes have mostly shaped the evolution and diversification of the group. Furthermore, expansion of larval dietary repertoire might have aided net diversification in the two largest genera in the clade, Forsterinaria and Taygetis.

Reassessment of the type locality of Euptychiastigmatica Godman, 1905, with the description of two new sibling species from Amazonia (Lepidoptera, Nymphalidae, Satyrinae, Satyrini).

A brief historical review regarding the type locality of Euptychiastigmatica Godman, 1905 was conducted, which suggests that its type locality is actually Rio de Janeiro, Brazil, rather than northeastern Argentina, as previously purported. Consequently, E.stigmatica and its senior synonym E.cyanites Butler, 1871, are regarded to be two species-group names representing a taxon in the euptychiine genus Caeruleuptychia Forster, 1964 known from the Brazilian Atlantic Forest. A lectotype is designated for E.cyanites. Additionally, two closely related species are named and described using an integrative approach with morphological and molecular evidence. Caeruleuptychiaharrisi Nakahara & Freitas, sp. nov. and C.aemulatio Nakahara & Willmott, sp. nov. both occur in Amazonia and COI barcode data recovered these taxa as part of the caerulea clade of Caeruleuptychia.

The sunny butterflies: new species of high montane pierids of the Catasticta poujadei group from the Peruvian Andes (Pieridae, Pierinae, Aporiina).

The Catasticta poujadei group, within the subgenus Hesperochoia Reissinger, is revised. Two new species, C. copernicus Pyrcz & Fhraeus sp. nov., and C. buszkoi Boyer & Pyrcz sp. nov. occurring near the timberline in Junn and Apurmac are described. Catasticta eximia Rber is reinstated as a species separate from C. poujadei, and a new subspecies, C. eximia tapuna ssp. nov., is described. The affinities of the species of the C. poujadei group are evaluated based on COI barcodes. Their distribution and habitats are described.

Revision of the "celia clade" of Pseudodebis Forster, 1964, with Two New Species and Notes on Papilio phorcys Fabricius, 1793 (Lepidoptera: Nymphalidae: Satyrinae).

The species-level classification of the "celia clade" of the nymphalid butterfly genus Pseudodebis Forster, 1964, is revised as part of ongoing revisionary work on this genus. The "celia clade" contains three species, of which two, Pseudodebis darrenthroopi Nakahara & Willmott, n. sp. and P. tigrillo Nakahara & Willmott, n. sp., are described and named herein based on morphology and molecular data. Consequently, we increase the described species diversity of Pseudodebis to 13, with a remarkable six species occurring in the trans-Andean region. We discuss five specific epithets associated with the clade and designate a neotype for Papilio celia Cramer, 1780, and lectotype for Taygetis keneza Butler, 1869, based on the same specimen, thus retaining the status of the former name as a senior objective synonym. We also provide a brief historical review for Papilio phorcys Fabricius, 1793, an enigmatic name currently synonymized under Papilio celia. Nevertheless, we were unable to locate the syntype(s) for this name and the identity of Papilio phorcys remains uncertain, so we retain the current synonymy as a parsimonious approach.

Considerations on the Systematics of Neotropical Pierina, with the Description of Two New Species of Phulia Herrich-Schäffer from the Peruvian Andes (Lepidoptera: Pieridae, Pierinae, Pierini).

A comparative analysis of high-Andean Pierina was carried out, including a total of 25 species. Based on morphological evidence, with an emphasis on venation and genitalia and molecular data, using three genetic markers, we confirm the recent subjective synonymy of the generic names Tatochila Butler, 1870, Piercolias, Staudinger, 1894, Hypsochila Ureta, 1955, Infraphulia Field, 1958, Pierphulia Field, 1958, and Theochila Field, 1958 with Phulia Herrich-Schäffer, 1867. Two new species are described, namely Phulia stoddardi Pyrcz & Cerdeña n. sp., from the Andes of Central Peru, which occurs at an unusually high altitude of close to 5000 m a.s.l. in dry puna habitat, and Phulia phantasma Lamas, Willmott & Boyer n. sp., from dry montane forests in northern Peru and southern Ecuador. An overview of high-elevation butterflies is presented, with some discussion on adaptations to this environment.

Rapid diversification and not clade age explains high diversity in neotropical Adelpha butterflies.

Latitudinal gradients in species richness are among the most well-known biogeographic patterns in nature, and yet there remains much debate and little consensus over the ecological and evolutionary causes of these gradients. Here, we evaluated whether two prominent alternative hypotheses (namely differences in diversification rate or clade age) could account for the latitudinal diversity gradient in one of the most speciose neotropical butterfly genera (Adelpha) and its close relatives. We generated a multilocus phylogeny of a diverse group of butterflies in the containing tribe Limenitidini, which has both temperate and tropical representatives. Our results suggest there is no relationship between clade age and species richness that could account for the diversity gradient, but that instead it could be explained by a significantly higher diversification rate within the predominantly tropical genus Adelpha. An apparent early larval host-plant shift to Rubiaceae and other plant families suggests that the availability of new potential host plants probably contributed to an increase in diversification of Adelpha in the lowland Neotropics. Collectively, our results support the hypothesis that the equatorial peak in species richness observed within Adelpha is the result of increased diversification rate in the last 10-15 Myr rather than a function of clade age, perhaps reflecting adaptive divergence in response to the dramatic host-plant diversity found within neotropical ecosystems.

Fifty years without a name: a new species of Splendeuptychia Forster (Lepidoptera: Nymphalidae: Satyrinae).

A new satyrine butterfly species, Splendeuptychia tupinamba Freitas, Huertas Rosa, sp. nov. (Nymphalidae: Satyrinae), is described. This species is found throughout a large geographical range in Brazil, Argentina and Paraguay, predominantly in the Cerrado domain, with some records in neighboring Amazonia and Atlantic Forest. Morphology and molecular data indicate that this species is part of a clade that includes Splendeuptychia ashna (the type species of the genus Splendeuptychia), and several species placed in the recently described genus Nubila Viloria, Andrade Henao, 2019.

A new euptychiine butterfly species from south Brazil and taxonomic rearrangements for Taydebis Freitas, 2013 and Hermeuptychia Forster, 1964 (Lepidoptera: Nymphalidae: Satyrinae).

A new species of Taydebis Freitas, 2003 from south Brazil is described using comparative morphology and species distributions. Also, based on morphology, we transfer Neonympha melobosis Capronnier, 1874 (formerly placed in Paryphthimoides Forster, 1964) to Taydebis, and recognize Euptychia peculiaris Butler, 1874 as its junior synonym (syn. nov.). Furthermore, the monotypic Prenda Freitas Mielke, 2011 is herein treated as junior synonym of Taydebis based on morphology, molecular and ecological evidence. Species of Taydebis are endemic and restricted to south Brazil, and now comprises three species: Taydebis guria Zacca, Casagrande Mielke sp. nov., T. melobosis comb. nov. and T. clarissa Freitas Mielke comb. nov. To continue clarifying Euptychiina taxonomy, Euptychia undulata Butler, 1867 (also formerly placed in Paryphthimoides) is transferred to Hermeuptychia Forster, 1964, and we provide additional information on its taxonomy, morphology, and distribution. Diagnoses, illustrations, and distributional maps are provided for all taxa except T. clarissa comb. nov.

The roles of wing color pattern and geography in the evolution of Neotropical Preponini butterflies.

Diversification rates and evolutionary trajectories are known to be influenced by phenotypic traits and the geographic history of the landscapes that organisms inhabit. One of the most conspicuous traits in butterflies is their wing color pattern, which has been shown to be important in speciation. The evolution of many taxa in the Neotropics has also been influenced by major geological events. Using a dated, species-level molecular phylogenetic hypothesis for Preponini, a colorful Neotropical butterfly tribe, we evaluated whether diversification rates were constant or varied through time, and how they were influenced by color pattern evolution and biogeographical events. We found that Preponini originated approximately 28 million years ago and that diversification has increased through time consistent with major periods of Andean uplift. Even though some clades show evolutionarily rapid transitions in coloration, contrary to our expectations, these shifts were not correlated with shifts in diversification. Involvement in mimicry with other butterfly groups might explain the rapid changes in dorsal color patterns in this tribe, but such changes have not increased species diversification in this group. However, we found evidence for an influence of major Miocene and Pliocene geological events on the tribe's evolution. Preponini apparently originated within South America, and range evolution has since been dynamic, congruent with Andean geologic activity, closure of the Panama Isthmus, and Miocene climate variability.

Revalidation of Vareuptychia Forster, 1964, description of Vanima gen. nov., and notes on Euptychia cleophes Godman amp; Salvin, 1889 (Lepidoptera: Nymphalidae: Satyrinae).

Vareuptychia Forster, 1964 stat. rest. is revalidated and comprises two species, V. similis (Butler, 1867) comb. rest. and V. themis (Butler, 1867) comb. nov. Vanima Zacca, Casagrande Mielke gen. nov. is described to contain Euptychia labe Butler, 1870 (the type species), E. palladia Butler, 1867 and E. lesbia Staudinger, [1886]. The taxonomy of these two genera was initially revised based on morphological and distributional data, and subsequently tested and supported with a Maximum Likelihood analysis using four genes (COI, GAPDH, RpS5 and EF1-a). Lectotypes are designated for Euptychia similis Butler, 1867, E. themis Butler, 1867, E. undina Butler, 1870 and E. lesbia Staudinger, [1886]. No DNA sequences were obtained for Euptychia cleophes Godman Salvin, 1889 but its transfer to Megisto Hübner, [1819] is supported by morphological evidence. For all taxa treated in this study, a taxonomic catalog, diagnosis, (re)description and illustrations of adults, venation and genitalia are provided, as well as comments on intraspecific variation, sexual dichromatism, ecology and distribution maps.

A revision of the new genus Amiga Nakahara, Willmott & Espeland, gen. n., described for Papilioarnaca Fabricius, 1776 (Lepidoptera, Nymphalidae, Satyrinae).

We here propose a new, monotypic genus, Amiga Nakahara, Willmott & Espeland, gen. n., to harbor a common Neotropical butterfly, described as Papilioarnaca Fabricius, 1776, and hitherto placed in the genus Chloreuptychia Forster, 1964. Recent and ongoing molecular phylogenetic research has shown Chloreuptychia to be polyphyletic, with C.arnaca proving to be unrelated to remaining species and not readily placed in any other described genus. Amigaarnaca gen. n. et comb. n. as treated here is a widely distributed and very common species ranging from southern Mexico to southern Brazil. A neotype is designated for the names Papilioarnaca and its junior synonym, Papilioebusa Cramer, 1780, resulting in the treatment of the latter name as a junior objective synonym of the former. A lectotype is designated for Euptychiasericeella Bates, 1865, which is treated as a subspecies, Amigaarnacasericeella (Bates, 1865), comb. n. et stat. n., based on molecular and morphological evidence. We also describe two new taxa, Amigaarnacaadela Nakahara & Espeland, ssp. n. and Amigaarnacaindianacristoi Nakahara & Marín, ssp. n., new subspecies from the western Andes and eastern Central America, and northern Venezuela, respectively.