Karina L. Silva-Brandão

Out of the Andes: patterns of diversification in clearwing butterflies

Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species‐level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene–Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.

Phylogenetic relationships among the Ithomiini (Lepidoptera: Nymphalidae) inferred from one mitochondrial and two nuclear gene regions

Abstract.  A phylogenetic hypothesis for the tribe Ithomiini (Lepidoptera: Nymphalidae: Danainae) is presented, based on sequences of the mitochondrial cytochrome oxidase subunits I and II (COI–COII) region and regions of the nuclear genes wingless and Elongation factor 1‐alpha. Branch support for each clade is assessed, and a partition congruence index is used to explore conflict among gene regions. The monophyly of the clade is strongly supported, as are many of the traditionally recognized subtribes and genera. The data imply paraphyly of some genera and tribes, but largely support recent classifications and phylogenetic hypotheses based on morphological characters.

Biogeographic and diversification patterns of Neotropical Troidini butterflies (Papilionidae) support a museum model of diversity dynamics for Amazonia

BackgroundThe temporal and geographical diversification of Neotropical insects remains poorly understood because of the complex changes in geological and climatic conditions that occurred during the Cenozoic. To better understand extant patterns in Neotropical biodiversity, we investigated the evolutionary history of three Neotropical swallowtail Troidini genera (Papilionidae). First, DNA-based species delimitation analyses were conducted to assess species boundaries within Neotropical Troidini using an enlarged fragment of the standard barcode gene. Molecularly delineated species were then used to infer a time-calibrated species-level phylogeny based on a three-gene dataset and Bayesian dating analyses. The corresponding chronogram was used to explore their temporal and geographical diversification through distinct likelihood-based methods.ResultsThe phylogeny for Neotropical Troidini was well resolved and strongly supported. Molecular dating and biogeographic analyses indicate that the extant lineages of Neotropical Troidini have a late Eocene (33–42 Ma) origin in North America. Two independent lineages (Battus and Euryades + Parides) reached South America via the GAARlandia temporary connection, and later became extinct in North America. They only began substantive diversification during the early Miocene in Amazonia. Macroevolutionary analysis supports the “museum model” of diversification, rather than Pleistocene refugia, as the best explanation for the diversification of these lineages.ConclusionsThis study demonstrates that: (i) current Neotropical biodiversity may have originated ex situ; (ii) the GAARlandia bridge was important in facilitating invasions of South America; (iii) colonization of Amazonia initiated the crown diversification of these swallowtails; and (iv) Amazonia is not only a species-rich region but also acted as a sanctuary for the dynamics of this diversity. In particular, Amazonia probably allowed the persistence of old lineages and contributed to the steady accumulation of diversity over time with constant net diversification rates, a result that contrasts with previous studies on other South American butterflies.

Genetic variability and demographic history of Heliothis virescens (Lepidoptera: Noctuidae) populations from Brazil inferred by mtDNA sequences

Intra- and inter-population genetic variability and the demographic history of Heliothis virescens (F.) populations were evaluated by using mtDNA markers (coxI, coxII and nad6) with samples from the major cotton- and soybean-producing regions in Brazil in the growing seasons 2007/08, 2008/09 and 2009/10. AMOVA indicated low and non-significant genetic structure, regardless of geographical scale, growing season or crop, with most of genetic variation occurring within populations. Clustering analyzes also indicated low genetic differentiation. The haplotype network obtained with combined datasets resulted in 35 haplotypes, with 28 exclusive occurrences, four of them sampled only from soybean fields. The minimum spanning network showed star-shaped structures typical of populations that underwent a recent demographic expansion. The recent expansion was supported by other demographic analyzes, such as the Bayesian skyline plot, the unimodal distribution of paired differences among mitochondrial sequences, and negative and significant values of neutrality tests for the Tajimas D and Fus F(S) parameters. In addition, high values of haplotype diversity (Ĥ) and low values of nucleotide diversity (π), combined with a high number of low frequency haplotypes and values of θ(π)<θ(W), suggested a recent demographic expansion of H. virescens populations in Brazil. This demographic event could be responsible for the low genetic structure currently found; however, haplotypes present uniquely at the same geographic regions and from one specific host plant suggest an initial differentiation among H. virescens populations within Brazil.

A new genus and species of Euptychiina (Lepidoptera: Nymphalidae: Satyrinae) from southern Brazil

This paper describes a new genus and a new species of Euptychiina from open grassland habitats (campos de cima da serra) in southern Brazil. The systematic position of this new taxon is discussed based on morphological and molecular data, and it is considered sister to Taydebis Freitas. Since the campos vegetation is considered endangered due to anthropogenic activities, this butterfly species deserves attention and should be included in future conservation plans for this biome.

New evidence on the systematic and phylogenetic position of Parides burchellanus (Lepidoptera: Papilionidae)

Parides burchellanus is considered a rare and threatened swallowtail species restricted to central Brazil. It shows considerable morphological similarity to Parides panthonus jaguarae, with which it shares both geographical range and larval host plant. At present, P. burchellanus and P. panthonus are believed to be distinct species, based on minor differences in male genitalia. In this study, the phylogenetic and systematic position of P. burchellanus in relation to three subspecies of P. panthonus (P. p. jaguarae, P. p. lysimachus and P. p. aglaope) was evaluated using molecular evidence: the complete sequence of the mtDNA genes COI and COII and of the nuclear gene EF‐1α (c. 3300 bp). In addition, the informativeness of the ‘barcode’ region next to the 5′ end of COI (c. 650 bp) was evaluated for delimiting these taxa. Individual analysis by neighbour‐joining, using Kimura 2‐parameter distance model, and by maximum parsimony showed that P. p. jaguarae + P. p. lysimachus + P. p. aglaope + P. burchellanus form a strongly supported monophyletic clade, and all molecular regions consistently recovered P. p. jaguarae and P. burchellanus as sister species. The genetic divergence among the subspecies of P. panthonus and P. burchellanus is equivalent to the divergence among conspecifics of other species of Parides, and smaller than the interspecific divergence among different sister species of this genus. The results support the proposal that P. p. jaguarae and P. burchellanus are likely to be synonymous, and suggest that P. burchellanus can be considered conspecific with P. panthonus. The taxonomic classification of P. burchellanus should be revised on the basis of the molecular data.

Morphological and molecular marker contributions to disentangling the cryptic Hermeuptychia hermes species complex (Nymphalidae: Satyrinae: Euptychiina)

The genus Hermeuptychia is common and widespread through the Americas, from Argentina to the southern United States of America. All eight recognized species within Hermeuptychia are small and brown, with very similar interspecific external morphologies and intraspecifically variable ocelli patterns that render taxonomic identification based on morphology difficult. In our study, we surveyed variability within Hermeuptychia, and evaluated species boundaries based on molecular data (sequences of the ‘barcode’ mitochondrial DNA COI gene) and morphology (mainly male genitalia), using a phylogenetic approach. We found eight DNA‐based and 12 morphological groups in our sampling. Species names were assigned based mainly on comparisons with male genitalia morphology descriptions corresponding to name‐bearing type specimens. Morphological and DNA variability were highly congruent, with the exception of group H, the Hermeuptychia cucullina complex. Also, the barcode region showed a clear threshold for intra‐ and interspecific mean distances around 2%. Based on these results, we circumscribe the species boundaries in the genus Hermeuptychia and discuss conflicts between mitochondrial genes and classic morphological approaches for identifying and delimiting species. Our study revealed cryptic diversity within an ubiquitous genus of Neotropical butterflies.

Genotyping-by-sequencing approach indicates geographic distance as the main factor affecting genetic structure and gene flow in Brazilian populations of Grapholita molesta (Lepidoptera, Tortricidae)

The oriental fruit moth Grapholita molesta is one of the major pests of stone and pome fruit species in Brazil. Here, we applied 1226 SNPs obtained by genotyping‐by‐sequencing to test whether host species associations or other factors such as geographic distance structured populations of this pest. Populations from the main areas of occurrence of G. molesta were sampled principally from peach and apple orchards. Three main clusters were recovered by neighbor‐joining analysis, all defined by geographic proximity between sampling localities. Overall genetic structure inferred by a nonhierarchical amova resulted in a significant ΦST value = 0.19109. Here, we demonstrate for the first time that SNPs gathered by genotyping‐by‐sequencing can be used to infer genetic structure of a pest insect in Brazil; moreover, our results indicate that those markers are very informative even over a restricted geographic scale. We also demonstrate that host plant association has little effect on genetic structure among Brazilian populations of G. molesta; on the other hand, reduced gene flow promoted by geographic isolation has a stronger impact on population differentiation.

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.

Genetic structure and gene flow among Brazilian populations of Heliothis virescens (Lepidoptera: Noctuidae).

ABSTRACT Population genetic studies are essential to the better application of pest management strategies, including the monitoring of the evolution of resistance to insecticides and genetically modified plants. Bacillus thuringiensis Berliner (Bt) crops have been instrumental in controlling tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), a pest that has developed resistance to many common insecticides once used for its management. In our study, microsatellite markers were applied to investigate the genetic structure and patterns of gene flow among Brazilian populations of H. virescens from cotton, Gossypium hirsutum L., and soybean, Glycine max (L.) Merr., fields, aiming to propose means to improve its management in the field. In total, 127 alleles were found across nine microsatellites loci for 205 individuals from 12 localities. Low levels of gene flow and moderate to great genetic structure were found for these populations. Host plant association, crop growing season, and geographic origin were not responsible for the genetic structuring among Brazilian populations of H. virescens. Other factors, such as demographic history and seasonal variability of intrapopulation genetic variation, were suggested to be molding the current pattern of genetic variability distribution.