Phylogeny

Large blue (Maculinea) butterflies are highly endangered throughout the Palaearctic region, and have been the focus of intense conservation research(1-3). In addition, their extraordinary parasitic lifestyles make them ideal for studies of life history evolution. Early instars consume flower buds of specific host plants, but later instars live in ant nests where they either devour the brood (predators), or are fed mouth-to-mouth by the adult ants (cuckoos). Here we present the phylogeny for the group, which shows that it is a monophyletic clade nested within Phengaris, a rare Oriental genus whose species have similar life histories(4,5). Cuckoo species are likely to have evolved from predatory ancestors. As early as five million years ago, two Maculinea clades diverged, leading to the different parasitic strategies seen in the genus today. Contrary to current belief, the two recognized cuckoo species show little genetic divergence and are probably a single ecologically differentiated species(6-10). On the other hand, some of the predatory morphospecies exhibit considerable genetic divergence and may contain cryptic species. These findings have important implications for conservation and reintroduction efforts.

We present a phylogeny for a selection of species of the butterfly genus Arhopala Boisduval, 1832 based on molecular characters. We sequenced 1778 bases of the mitochondrial genes Cytochrome Oxidase 1 and 2 including tRNA(Leu), and a 393-bp fragment of the nuclear wingless gene for a total of 42 specimens of 33 species, representing all major species groups. Analyses of mtDNA and wingless genes show congruent phylogenetic signal. The phylogeny presented here confirms the monophyly of the centaurus, eumolphus, camdeo and epimuta groups and the amphimuta subgroup. It confirms close relationships between species within the agelastus group, that together with the amphimuta subgroup, centaurus and camdeo groups form a monophyletic group. However, incongruencies with previous taxonomic studies also occur; the amphimuta and silhetensis groups are not monophyletic, as is the genus Arhopala itself. One enigmatic species, A. kinabala, was evaluated further for topology and the support for basal placement of this species is due mainly to the wingless gene. However, in the Parsimony analysis, and subsequent Maximum Likelihood evaluations, certain nodes could not be resolved due to insufficient support. The mtDNA shows extreme AT bias with compositional heterogeneity at 3rd codon positions, which may result in saturation. By contrast, the wingless gene does not show compositional bias, suggesting that poor support is not due solely to saturation. The evaluation of morphological characters used in previous studies on Arhopala systematics on the molecular tree indicates that the macular pattern and the absence of tails at the hind wings show extensive homoplasy. A significant phylogenetic signal (as indicated by T-PTP tests) is present in several of these morphological characters, which are nevertheless of limited use in phylogenetic studies due to their labile nature.

Butterflies in the large Palearctic genus Agrodiaetus ( Lepidoptera: Lycaenidae) are extremely uniform and exhibit few distinguishing morphological characters. However, these insects are distinctive in one respect: as a group they possess among the greatest interspecific karyotype diversity in the animal kingdom, with chromosome numbers (n) ranging from 10 to 125. The monophyly of Agrodiaetus and its systematic position relative to other groups within the section Polyommatus have been controversial. Characters from the mitochondrial genes for cytochrome oxidases I and II and from the nuclear gene for elongation factor 1alpha were used to reconstruct the phylogeny of Agrodiaetus using maximum parsimony and Bayesian phylogenetic methods. Ninety-one individuals, encompassing most of the taxonomic diversity of Agrodiaetus, and representatives of 14 related genera were included in this analysis. Our data indicate that Agrodiaetus is monophyletic. Representatives of the genus Polyommatus ( sensu stricto) are the closest relatives. The sequences of the Agrodiaetus taxa in this analysis are tentatively arranged into 12 clades, only 1 of which corresponds to a species group traditionally recognized in Agrodiaetus. Heterogeneous substitution rates across a recovered topology were homogenized with a nonparametric rate-smoothing algorithm before the application of a molecular clock. Two published estimates of substitution rates dated the origin of Agrodiaetus between 2.51 and 3.85 million years ago. During this time, there was heterogeneity in the rate and direction of karyotype evolution among lineages within the genus. Karyotype instability has evolved independently three times in the section Polyommatus, within the lineages Agrodiaetus, Lysandra, and Plebicula. Rapid karyotype diversification may have played a significant role in the radiation of the genus Agrodiaetus.

Molecular systematics is frequently beset with phylogenetic results that are not fully resolved. Researchers either state that the absence of resolution is due to character conflict, explosive speciation, or some combination of the two, but seldom do they carefully examine their data to distinguish between these causes. In this study, we exhaustively analyze a set of nuclear and mitochondrial nucleotide data for the Asian tropical butterfly genus Arhopala so as to highlight the causes of polytomies in the phylogenetic trees, and, as a result, to infer important biological events in the history of this genus. We began by using non-parametric statistical methods to determine whether the ambiguously resolved regions in these trees represent hard or soft polytomies. In addition we determined how this correlated to number of inferred changes on branches, using parametric maximum likelihood estimations. Based on congruent patterns in both mitochondrial and nuclear DNA sequences, we concluded that at two stages in the history of Arhopala there have been accelerated instances of speciation. One event, at the base of the phylogeny, generated many of the groups and subgroups currently recognized in this genus, while a later event generated another major clade consisting of both Oriental and Papuan species groups. Based on comparisons of closely related taxa, the ratio of instantaneous rate of evolution between mitochondrial and nuclear DNA evolution is established at approximately 3:1. The earliest radiation is dated between 7 and 11 Ma by a molecular clock analysis, setting the events generating much of the diversity of Arhopala at well before the Pleistocene. Periodical flooding of the Sunda plateau during interglacial periods was, therefore, not responsible for generating the major divisions in the genus Arhopala. Instead, we hypothesize that large-scale climatic changes taking place in the Miocene have induced the early acceleration in speciation. (C) 2003 Elsevier Inc. All rights reserved.

The estimated 6000 species of Lycaenidae account for about one third of all Papilionoidea. The majority of lycaenids have associations with ants that can be facultative or obligate and range from mutualism to parasitism. Lycaenid larvae and pupae employ complex chemical and acoustical signals to manipulate ants. Cost/benefit analyses have demonstrated multiple trade-offs involved in myrmecophily. Both demographic and phylogenetic evidence indicate that ant association has shaped the evolution of obligately associated groups. Parasitism typically arises from mutualism with ants, arid entomophagous species are disproportionately common in the Lycaenidae compared with other Lepidoptera. Obligate associations are more common in the Southern Hemisphere, in part because highly ant-associated lineages make up a larger proportion of the fauna in these, regions. Further research on phylogeny and natural history, particularly of the Neotropical fauna, will be necessary to understand the rote ant association has played in the evolution of the Lycaenidae.

This study examines the pattern of opsin nucleotide and amino acid substitution among mimetic species 'rings' of Heliconius butterflies that are characterized by divergent wing colour patterns. A long wavelength opsin gene, OPS1, was sequenced from each of seven species of Heliconius and one species of Dryas (Lepidoptera: Nymphalidae). A parsimony analysis of OPS1 nucleotide and amino acid sequences resulted in a phylogeny that was consistent with that presented by Brewer & Egan in 1997, which was based on mitochondrial cytochrome oxidase I and II as well as nuclear wingless genes. Nodes in the OPS1 phylogeny were well supported by bootstrap analysis and decay indices. An analysis of specific sites within the gene indicates that the accumulation of amino acid substitutions has occurred independently of the morphological diversification of Heliconius wing colour patterns. Amino acid substitutions were examined with respect to their location within the opsin protein and their possible interactions with the chromophore and the G-protein. Of the 15 amino acid substitutions identified among the eight species, one nonconservative replacement (A226Q) was identified in a position that may be involved in binding with the G-protein. (C) 2001 The Linnean Society of London.

Despite the fact that Bicyclus anynana has become an important model species for wing-pattern developmental biology and studies of phenotypic plasticity, little is known of the evolutionary history of the genus Bicyclus and the position of B. anynana. Understanding the evolution of development as well as the evolution of plasticity can be attempted in this species-rich genus that displays a large range of wing patterns with variable degrees of phenotypic responses to the environment. A context to guide extrapolations from population genetic studies within B. anynana to those between closely related species has been long overdue. A phylogeny of 54 of the 80 known Bicyclus species is presented based on the combined 3000-bp sequences of two mitochondrial genes, cytochrome oxidase I and II, and the nuclear gene, elongation factor I alpha. A series of tree topologies, constructed either from the individual genes or from the combined data, using heuristic searches under a variety of weighting schemes were compared under the best maximum-likelihood models fitted for each gene separately. The most likely tree topology to have generated the three data sets was found to be a tree resulting from a combined MP analysis with equal weights. Most phylogenetic signal for the analysis comes from silent substitutions at the third position, and despite the faster rate of evolution and higher levels of homoplasy of the mitochondrial genes relative to the nuclear gene, the latter does not show substantially stronger support for basal clades. Finally, moving branches from the chosen tree topology to other positions on the tree so as to comply better with a previous morphological study did not significantly affect tree length. (C) 2001 Academic Press.

Phylogenetic relationships among 26 South African species in the tribe Aphnaeini (Lepidoptera: Lycaenidae) were inferred from DNA characters of the mitochondrial gene cytochrome oxidase I (COI), using maximum-parsimony methods. The resulting phylogenetic estimate supports the systematic hypothesis made by Heath (1997, Metamorphosis, supplement 2), based on morphological characters, that at least three preexisting genera (Chrysoritis, Poecilmitis, and Oxychaeta) should be collapsed into the single monophyletic genus Chrysoritis. Two of the species groups described by Heath within Chrysoritis are also monophyletic, while one is paraphyletic and thus unsupported by the molecular data. Strong node support and skewed transition/transversion ratios suggest that two Chrysoritis clades contain synonymous species. Aphytophagy appears as a derived feeding strategy. Evolutionary patterns of ant association indicate lability at the level of ant genus, while association with different ant subfamilies may have played an ancestral and chemically mediated role in the diversification of South African aphnaeines. ©

The sequence evolution of the nuclear gene wingless was investigated among 34 representatives of three lepidopteran families (Riodinidae, Lycaenidae, and Nymphalidae) and four outgroups, and its utility for inferring phylogenetic relationships among these taxa was assessed. Parsimony analysis yielded a well-resolved topology supporting the monophyly of the Riodinidae and Lycaenidae, respectively, and indicating that these two groups are sister lineages, with strong nodal support based on bootstrap and decay indices. Although, wingless provides robust support for relationships within and between the riodinids and the lycaenids, it is less informative about nymphalid relationships. Wingless does not consistently recover nymphalid monophyly or traditional subfamilial relationships within the nymphalids, and nodal support for all but the most recent branches in this family is low. Much of the phylogenetic information in this data set is derived from first- and second-position substitutions. However third positions, despite showing uncorrected pairwise divergences up to 78%, also contain consistent signal at deep nodes within the family Riodinidae and at the node defining the sister relationship between the riodinids and lycaenids. Several hypotheses about how third-position signal has been retained in deep nodes are discussed. These include among-site rate variation, identified as a significant factor by maximum likelihood analyses, and nucleotide bias, a prominent feature of third positions in this data set. Understanding the mechanisms which underlie third-position signal is a first step in applying appropriate models to accommodate the specific evolutionary processes involved in each lineage.

For several species of lepidoptera, most of the similar to 350-bp mitochondrial control-region sequences were determined. Six of these species are in one genus, Jalmenus; are closely related; and are believed to have undergone recent rapid speciation. Recent speciation was supported by the observation of low interspecific sequence divergence. Thus, no useful phylogeny could be constructed for the genus. Despite a surprising conservation of control-region length, there was little conservation of primary sequences either among the three lepidopteran genera or between lepidoptera and Drosophila. Analysis of secondary structure indicated only one possible feature in common-inferred stem loops with higher-than-random folding energies-although the positions of the structures in different species were unrelated to regions of primary sequence similarity. We suggest that the conserved, short length of control regions is related to the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In addition, determination of flanking sequences for one Jalmenus species indicated (i) only weak support for the available model of insect 12S rRNA structure and (ii) that tRNA translocation is a frequent event in the evolution of insect mitochondrial genomes.

Many organisms make a living from seratching each other's backs. and many survive at the expense of othcrs. Once a complex interaction has arisen between two organisms. what elfect can such a relationship have on their subsequcnt cvolution·! This pllpcr will consider thc evolutionary conscquences of ussocintions UIllOlIg Iycllcnid buttcrflics, their host plants, unts. purusitoids. lind prcdators. Thc Lycacllidac llfC cspecially intcrc.'1ting from an ccologicul and evolutionary pcrspcctivc because they exhibit dramatic variety in their life histories. The larvae of many species associate with ants, and these relationships can be parasitic. commensal, or mutualistic. larvae cun be carnivorous or hcrbivorous: and some species interact with many species of ants, whereas others are species-specific. It is partly because of this complexity and diversity that the lycaenidae have not been studied as intensively as other buUerny families, and I will discuss at least three problems that have hampered our understanding of their ecology and evolution. In particular. more must be learned about the nature of the exocrine secretions of lycaenid larvae, and whether they function to reward. appease, and/or deceive their associated ants. The association between lycaenids and ants has had several important evolutionary consequences, and I will show how these relate to the question of why there are so many species of Iycaenid buuernies. Finally. I will discuss an unresolved pattern in the biogeography oflycaenid buuernies: association with ants in general, and species-specific interactions in particular, are far more common among Iycaenids found in Ethiopian, Oriental. and Australasian regions than among those from the Holarctic.