We present the first dated higher-level phylogenetic and biogeographic analysis of the butterfly family Riodinidae. This family is distributed worldwide, but more than 90% of the c. 1500 species are found in the Neotropics, while the c. 120 Old World species are concentrated in the Southeast Asian tropics, with minor Afrotropical and Australasian tropical radiations, and few temperate species. Morphologically based higher classification is partly unresolved, with genera incompletely assigned to tribes. Using 3666 bp from one mitochondrial and four nuclear markers for each of 23 outgroups and 178 riodinid taxa representing all subfamilies, tribes and subtribes, and 98 out of 145 described genera of riodinids, we estimate that Riodinidae split from Lycaenidae about 96 Mya in the mid-Cretaceous and started to diversify about 81 Mya. The Riodinidae are monophyletic and originated in the Neotropics, most likely in lowland proto-Amazonia. Neither the subfamily Euselasiinae nor the Nemeobiinae are monophyletic as currently constituted. The enigmatic, monotypic Neotropical genera Styx and Corrachia (most recently treated in Euselasiinae: Corrachiini) are highly supported as derived taxa in the Old World Nemeobiinae, with dispersal most likely occurring across the Beringia land bridge during the Oligocene. Styx and Corrachia, together with all other nemeobiines, are the only exclusively Primulaceae-feeding riodinids. The steadily increasing proliferation of the Neotropical Riodininae subfamily contrasts with the decrease in diversification in the Old World, and may provide insights into factors influencing the diversification rate of this relatively ancient clade of Neotropical insects. (C) 2015 Elsevier Inc. All rights reserved.
The Aphnaeinae (Lepidoptera: Lycaenidae) are a largely African subfamily of 278 described species that exhibit extraordinary life-history variation. The larvae of these butterflies typically form mutualistic associations with ants, and feed on a wide variety of plants, including 23 families in 19 orders. However, at least one species in each of 9 of the 17 genera is aphytophagous, parasitically feeding on the eggs, brood or regurgitations of ants. This diversity in diet and type of symbiotic association makes the phylogenetic relations of the Aphnaeinae of particular interest. A phylogenetic hypothesis for the Aphnaeinae was inferred from 4.4kb covering the mitochondrial marker COI and five nuclear markers (wg, H3, CAD, GAPDH and EF1) for each of 79 ingroup taxa representing 15 of the 17 currently recognized genera, as well as three outgroup taxa. Maximum Parsimony, Maximum Likelihood and Bayesian Inference analyses all support Heath's systematic revision of the clade based on morphological characters. Ancestral range inference suggests an African origin for the subfamily with a single dispersal into Asia. The common ancestor of the aphnaeines likely associated with myrmicine ants in the genus Crematogaster and plants of the order Fabales.
Of the four most diverse insect orders, Lepidoptera contains remarkably few predatory and parasitic species. Although species with these habits have evolved multiple times in moths and butterflies, they have rarely been associated with diversification. The wholly aphytophagous subfamily Miletinae (Lycaenidae) is an exception, consisting of nearly 190 species distributed primarily throughout the Old World tropics and subtropics. Most miletines eat Hemiptera, although some consume ant brood or are fed by ant trophallaxis. A well-resolved phylogeny inferred using 4915 bp from seven markers sampled from representatives of all genera and nearly one-third the described species was used to examine the biogeography and evolution of biotic associations in this group. Biogeographic analyses indicate that Miletinae likely diverged from an African ancestor near the start of the Eocene, and four lineages dispersed between Africa and Asia. Phylogenetic constraint in prey selection is apparent at two levels: related miletine species are more likely to feed on related Hemiptera, and related miletines are more likely to associate with related ants, either directly by eating the ants, or indirectly by eating hemipteran prey that are attended by those ants. These results suggest that adaptations for host ant location by ovipositing female miletines may have been retained from phytophagous ancestors that associated with ants mutualistically.
Ecological opportunity, defined as access to new resources free from competitors, is thought to be a catalyst for the process of adaptive radiation. Much of what we know about ecological opportunity, and the larger process of adaptive radiation, is derived from vertebrate diversification on islands. Here, we examine lineage diversification in the turtle ants (Cephalotes), a species-rich group of ants that has diversified throughout the Neotropics. We show that crown group turtle ants originated during the Eocene (around 46 mya), coincident with global warming and the origin of many other clades. We also show a marked lineage-wide slowdown in diversification rates in the Miocene. Contrasting this overall pattern, a species group associated with the young and seasonally harsh Chacoan biogeographic region underwent a recent burst of diversification. Subsequent analyses also indicated that there is significant phylogenetic clustering within the Chacoan region and that speciation rates are highest there. Together, these findings suggest that recent ecological opportunity, from successful colonization of novel habitat, may have facilitated renewed turtle ant diversification. Our findings highlight a central role of ecological opportunity within a successful continental radiation.
The butterfly family Pieridae comprises approximately 1000 described species placed in 85 genera, but the higher classification has not yet been settled. We used molecular data from eight gene regions (one mitochondrial and seven nuclear protein-coding genes) comprising a total of similar to 6700bp from 96 taxa to infer a well-supported phylogenetic hypothesis for the family. Based on this hypothesis, we revise the higher classification for all pierid genera. We resurrect the tribe Teracolini stat. rev. in the subfamily Pierinae to include the genera Teracolus, Pinacopteryx, Gideona, Ixias, Eronia, Colotis and most likely Calopieris. We transfer Hebomoia to the tribe Anthocharidini and assign the previously unplaced genera Belenois and Dixeia to the subtribe Aporiina. Three lineages near the base of Pierinae (Leptosia, Elodina and Nepheronia + Pareronia) remain unplaced. For each of these, we describe and delineate new tribes: Elodinini Braby tribus nova, Leptosiaini Braby tribus nova and Nepheroniini Braby tribus nova. The proposed higher classification is based on well-supported monophyletic groups and is likely to remain stable even with the addition of more data.
The phylogeny of the butterfly genus Lysandra (Lycaenidae, Polyommatinae) has been intractable using both molecular and morphological characters, which could be a result of speciation due to karyotype instability. Here we reconstruct the phylogeny of the group using multi-locus coalescent-based methods on seven independent genetic markers. While the genus is ca. 4.9 Mya old, the diversification of the extant lineages was extremely recent (ca. 1.5 Mya) and involved multiple chromosomal rearrangements. We find that relationships are uncertain due to both incomplete lineage sorting and hybridization. Minimizing the impact of reticulation in inferring the species tree by testing for mitochondria] introgression events yields a partially resolved tree with three main supported clades: L. punctifera + L. bellargus, the corydonius taxa, and L coridon + the Iberian taxa, plus three independent lineages without apparently close relatives (L. ossmar, L syriaca and L. dezina). Based on these results and new karyotypic data, we propose a rearrangement recognizing ten species within the genus. Finally, we hypothesize that chromosomal instability may have played a crucial role in the Lysandra recent diversification. New chromosome rearrangements might be fixed in populations after severe bottlenecks, which at the same time might promote rapid sorting of neutral molecular markers. We argue that population bottlenecks might be a prerequisite for chromosomal speciation in this group. (C) 2013 Elsevier Inc. All rights reserved.
Most taxonomists agree on the need to adapt current classifications to recognize monophyletic units. However, delineations between higher taxonomic units can be based on the relative ages of different lineages and ⁄or the level of morphological differentiation. In this paper, we address these issues in considering the species-rich Polyommatus section, a group of butterflies whose taxonomy has been highly controversial. We propose a taxonomy-friendly, flexible temporal scheme for higher-level classification. Using molecular data from nine markers (6666 bp) for 104 representatives of the Polyommatus section, representing all but two of the 81 described genera ⁄subgenera and five outgroups, we obtained a complete and well resolved phylogeny for this clade. We use this to revise the systematics of the Polyommatus blues, and to define criteria that best accommodate the described genera within a phylogenetic framework. First, we normalize the concept of section (Polyommatus) and propose the use of subtribe (Polyommatina) instead. To preserve taxonomic stability and traditionally recognized taxa, we designate an age interval (4–5 Myr) instead of a fixed minimum age to define genera. The application of these criteria results in the retention of 31 genera of the 81 formally described generic names, and necessitates the description of one new genus (Rueckbeilia gen. nov.). We note that while classifications should be based on phylogenetic data, applying a rigid universal scheme is rarely feasible. Ideally, taxon age limits should be applied according to the particularities and pre-existing taxonomy of each group. We demonstrate that the concept of a morphological gap may be misleading at the genus level and can produce polyphyletic genera, and we propose that recognition of the existence of cryptic genera may be useful in taxonomy.
Despite much research on the socially parasitic large blue butterflies (genus Maculinea) in the past 40 years, their relationship to their closest relatives, Phengaris, is controversial and the relationships among the remaining genera in the Glaucopsyche section are largely unresolved. The evolutionary history of this butterfly section is particularly important to understand the evolution of life history diversity connected to food-plant and host-ant associations in the larval stage. In the present study, we use a combination of four nuclear and two mitochondrial genes to reconstruct the phylogeny of the Glaucopsyche section, and in particular, to study the relationships among and within the Phengaris-Maculinea species.We find a clear pattern between the clades recovered in the Glaucopsyche section phylogeny and their food-plant associations, with only the Phengaris-Maculinea clade utilising more than one plant family. Maculinea is, for the first time, recovered with strong support as a monophyletic group nested within Phengaris, with the closest relative being the rare genus Caerulea. The genus Glaucopsyche is polyphyletic, including the genera Sinia and lolana. Interestingly, we find evidence for additional potential cryptic species within the highly endangered Maculinea, which has long been suspected from morphological, ecological and molecular studies. (C) 2011 Elsevier Inc. All rights reserved.
Transcontinental dispersals by organisms usually represent improbable events that constitute a major challenge for biogeographers. By integrating molecular phylogeny, historical biogeography and palaeoecology, we test a bold hypothesis proposed by Vladimir Nabokov regarding the origin of Neotropical Polyommatus blue butterflies, and show that Beringia has served as a biological corridor for the dispersal of these insects from Asia into the New World. We present a novel method to estimate ancestral temperature tolerances using distribution range limits of extant organisms, and find that climatic conditions in Beringia acted as a decisive filter in determining which taxa crossed into the New World during five separate invasions over the past 11 Myr. Our results reveal a marked effect of the Miocene-Pleistocene global cooling, and demonstrate that palaeoclimatic conditions left a strong signal on the ecology of present-day taxa in the New World. The phylogenetic conservatism in thermal tolerances that we have identified may permit the reconstruction of the palaeoecology of ancestral organisms, especially mobile taxa that can easily escape from hostile environments rather than adapt to them.
Approximately 50 taxa of butterflies in Western Europe have been described as new species or elevated to the level of species during the last 40 years. Many, especially those belonging to the genus Agrodiaetus, have unusually localized, 'dot-like' distributional ranges. In the present study, we use a combination of chromosomal and molecular markers to re-evaluate the species status of Agrodiaetus distributed west of the 17th meridian. The results obtained do not support the current designations of Agrodiaetus galloi, Agrodiaetus exuberans, and Agrodiaetus agenjoi as endemic species with highly restricted distribution ranges, but indicate that these taxa are more likely to be local populations of a widely distributed species, Agrodiaetus ripartii. Agrodiaetus violetae is shown to be a polytypic species consisting of at least two subspecies, including Agrodiaetus violetae subbaeticus comb. nov. and Agrodiaetus violetae violetae. Agrodiaetus violetae is genetically (but not chromosomally) distinct from Agrodiaetus fabressei and has a wider distribution in southern Spain than previously believed. Agrodiaetus humedasae from northern Italy is supported as a highly localized species that is distinct from its nearest relatives. We propose a revision of the species lists for Agrodiaetus taking these new data into account. The results reported in the present study are relevant to animal conservation efforts in Europe because of their implications for IUCN Red List priorities. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 130-154.
Stingless bees (Meliponini) constitute a diverse group of highly eusocial insects that occur throughout tropical regions around the world. The meliponine genus Melipona is restricted to the New World tropics and has over 50 described species. Melipona, like Apis, possesses the remarkable ability to use representational communication to indicate the location of foraging patches. Although Melipona has been the subject of numerous behavioral, ecological, and genetic studies, the evolutionary history of this genus remains largely unexplored. Here, we implement a multigene phylogenetic approach based on nuclear, mitochondrial, and ribosomal loci, coupled with molecular clock methods, to elucidate the phylogenetic relationships and antiquity of subgenera and species of Melipona. Our phylogenetic analysis resolves the relationship among subgenera and tends to agree with morphology-based classification hypotheses. Our molecular clock analysis indicates that the genus Melipona shared a most recent common ancestor at least similar to 14-17 million years (My) ago. These results provide the groundwork for future comparative analyses aimed at understanding the evolution of complex communication mechanisms in eusocial Apidae. (C) 2010 Elsevier Inc. All rights reserved.
The orchid bees constitute a clade of prominent insect pollinators distributed throughout the Neotropical region. Males of all species collect fragrances from natural sources, including flowers, decaying vegetation and fungi, and store them in specialized leg pockets to later expose during courtship display. In addition, orchid bees provide pollination services to a diverse array of Neotropical angiosperms when foraging for food and nesting materials. However, despite their ecological importance, little is known about the evolutionary history of orchid bees. Here, we present a comprehensive molecular phylogenetic analysis based on similar to 4.0 kb of DNA from four loci [cytochrome oxidase (CO1), elongation factor 1-alpha (EF1-alpha), arginine kinase (ArgK) and RNA polymerase II (Pol-II)] across the entire tribe Euglossini, including all five genera, eight subgenera and 126 of the approximately 200 known species. We investigated lineage diversification using fossil-calibrated molecular clocks and the evolution of morphological traits using disparity-through-time plots. In addition, we inferred past biogeographical events by implementing model-based likelihood methods. Our dataset supports a new view on generic relationships and indicates that the cleptoparasitic genus Exaerete is sister to the remaining orchid bee genera. Our divergence time estimates indicate that extant orchid bee lineages shared a most recent common ancestor at 27-42 Mya. In addition, our analysis of morphology shows that tongue length and body size experienced rapid disparity bursts that coincide with the origin of diverse genera (Euglossa and Eufriesea). Finally, our analysis of historical biogeography indicates that early diversification episodes shared a history on both sides of Mesoamerica, where orchid bees dispersed across the Caribbean, and through a Panamanian connection, thus reinforcing the hypothesis that recent geological events (e.g. the formation of the isthmus of Panama) contributed to the diversification of the rich Neotropical biota. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 552-572.
Ants are a dominant feature of terrestrial ecosystems, yet we know little about the forces that drive their evolution. Recent findings illustrate that their diets range from herbivorous to predaceous, with "herbivores'' feeding primarily on exudates from plants and sap-feeding insects. Persistence on these nitrogen-poor food sources raises the question of how ants obtain sufficient nutrition. To investigate the potential role of symbiotic microbes, we have surveyed 283 species from 18 of the 21 ant subfamilies using molecular techniques. Our findings uncovered a wealth of bacteria from across the ants. Notable among the surveyed hosts were herbivorous "turtle ants'' from the related genera Cephalotes and Procryptocerus (tribe Cephalotini). These commonly harbored bacteria from ant-specific clades within the Burkholderiales, Pseudomonadales, Rhizobiales, Verrucomicrobiales, and Xanthomonadales, and studies of lab-reared Cephalotes varians characterized these microbes as symbiotic residents of ant guts. Although most of these symbionts were confined to turtle ants, bacteria from an ant-specific clade of Rhizobiales were more broadly distributed. Statistical analyses revealed a strong relationship between herbivory and the prevalence of Rhizobiales gut symbionts within ant genera. Furthermore, a consideration of the ant phylogeny identified at least five independent origins of symbioses between herbivorous ants and related Rhizobiales. Combined with previous findings and the potential for symbiotic nitrogen fixation, our results strongly support the hypothesis that bacteria have facilitated convergent evolution of herbivory across the ants, further implicating symbiosis as a major force in ant evolution.
The moth genus Nemoria (Lepidoptera: Geometridae) includes 134 described species whose larvae and adults display a considerable range of phenotypic plasticity in coloration and morphology. We reconstructed the phylogeny of 54 species of Nemoria and seven outgroups using characters from the mitochondrial genes, Cytochrome Oxidase I and II (COI and COII), and the nuclear gene, Elongation Factor-a (EF-1a). Maximum parsimony, maximum likelihood and Bayesian inference were used to infer the phylogeny. The 54 ingroup species represented 13 of the 15 recognized species groups of Nemoria [Ferguson, D.C., 1985. Fasc. 18.1, Geometroidea: Geometridae (in part). In: Dominick, R.B. (Ed.), The Moths of America North of Mexico, Fasc. 18.1. Wedge Entomological Research Foundation, Washington; Pitkin, L.M., 1993. Neotropical emerald moths of the genera Nemoria, Lissochlora and Chavarriella, with particular reference to the species of Costa Rica (Lepidoptera: Geometridae, Geometrinae). Bull. Br. Mus. Nat. Hist. 62, 39–159], and the seven outgroups came from four tribes of Geometrinae. These data support Nemoria as a monophyletic group and largely recover the species groupings proposed in previous taxonomic analyses using morphological characters. Phenotypic plasticity of larvae is not correlated with plasticity of adults among those species of Nemoria where life histories are known, and appears to be evolutionarily labile for both life history stages: Species exhibiting larval phenotypic plasticity, such as N. arizonaria and N. outina, are placed in several distinct clades, suggesting that this trait has evolved multiple times, and species displaying adult phenotypic plasticity are likewise distributed throughout the phylogeny. A comparative analysis of the biogeographic history of Nemoria supports a South American origin for the genus with multiple introductions into North America, and an application of published substitution rates to the phylogram provides an age estimate of 7.5 million years.
Background: Evolutionary genetics provides a rich theoretical framework for empirical studies of phylogeography. Investigations of intraspecific genetic variation can uncover new putative species while allowing inference into the evolutionary origin and history of extant populations. With a distribution on four continents ranging throughout most of the Old World, Lampides boeticus ( Lepidoptera: Lycaenidae) is one of the most widely distributed species of butterfly. It is placed in a monotypic genus with no commonly accepted subspecies. Here, we investigate the demographic history and taxonomic status of this widespread species, and screen for the presence or absence of the bacterial endosymbiont Wolbachia.Results: We performed phylogenetic, population genetic, and phylogeographic analyses using 1799 bp of mitochondrial sequence data from 57 specimens collected throughout the species' range. Most of the samples(> 90%) were nearly genetically identical, with uncorrected pairwise sequence differences of 0 0.5% across geographic distances > 9,000 km. However, five samples from central Thailand, Madagascar, northern Australia and the Moluccas formed two divergent clades differing from the majority of samples by uncorrected pairwise distances ranging from 1.79-2.21%. Phylogenetic analyses suggest that L. boeticus is almost certainly monophyletic, with all sampled genes coalescing well after the divergence from three closely related taxa included for outgroup comparisons. Analyses of molecular diversity indicate that most L. boeticus individuals in extant populations are descended from one or two relatively recent population bottlenecks.Conclusion: The combined analyses suggest a scenario in which the most recent common ancestor of L. boeticus and its sister taxon lived in the African region approximately 7 Mya; extant lineages of L. boeticus began spreading throughout the Old World at least 1.5 Mya. More recently, expansion after population bottlenecks approximately 1.4 Mya seem to have displaced most of the ancestral polymorphism throughout its range, though at least two early-branching lineages still persist. One of these lineages, in northern Australia and the Moluccas, may have experienced accelerated differentiation due to infection with the bacterial endosymbiont Wolbachia, which affects reproduction. Examination of a haplotype network suggests that Australia has been colonized by the species several times. While there is little evidence for the existence of morphologically cryptic species, these results suggest a complex history affected by repeated dispersal events.
Since the time of Darwin(1), evolutionary biologists have been fascinated by the spectacular adaptations to insect pollination exhibited by orchids. However, despite being the most diverse plant family on Earth(2), the Orchidaceae lack a definitive fossil record and thus many aspects of their evolutionary history remain obscure. Here we report an exquisitely preserved orchid pollinarium (of Meliorchis caribea gen. et sp. nov.) attached to the mesoscutellum of an extinct stingless bee, Proplebeia dominicana, recovered from Miocene amber in the Dominican Republic, that is 15-20 million years (Myr) old(3). This discovery constitutes both the first unambiguous fossil of Orchidaceae(4) and an unprecedented direct fossil observation of a plant-pollinator interaction(5,6). By applying cladistic methods to a morphological character matrix, we resolve the phylogenetic position of M. caribea within the extant subtribe Goodyerinae (subfamily Orchidoideae). We use the ages of other fossil monocots and M. caribea to calibrate a molecular phylogenetic tree of the Orchidaceae. Our results indicate that the most recent common ancestor of extant orchids lived in the Late Cretaceous (76-84 Myr ago), and also suggest that the dramatic radiation of orchids began shortly after the mass extinctions at the K/T boundary. These results further support the hypothesis of an ancient origin for Orchidaceae.
We investigate the geographical and historical context of diversification in a complex of mutualistic Crematogaster ants living in Macaranga trees in the equatorial rain forests of Southeast Asia. Using mitochondrial DNA from 433 ant colonies collected from 32 locations spanning Borneo, Malaya and Sumatra, we infer branching relationships, patterns of genetic diversity and population history. We reconstruct a time frame for the ants' diversification and demographic expansions, and identify areas that might have been refugia or centres of diversification. Seventeen operational lineages are identified, most of which can be distinguished by host preference and geographical range. The ants first diversified 16-20 Ma, not long after the onset of the everwet forests in Sundaland, and achieved most of their taxonomic diversity during the Pliocene. Pleistocene demographic expansions are inferred for several of the younger lineages. Phylogenetic relationships suggest a Bornean cradle and major axis of diversification. Taxonomic diversity tends to be associated with mountain ranges; in Borneo, it is greatest in the Crocker Range of Sabah and concentrated also in other parts of the northern northwest coast. Within-lineage genetic diversity in Malaya and Sumatra tends to also coincide with mountain ranges. A series of disjunct and restricted distributions spanning northern northwest Borneo and the major mountain ranges of Malaya and Sumatra, seen in three pairs of sister lineages, further suggests that these regions were rain-forest refuges during drier climatic phases of the Pleistocene. Results are discussed in the context of the history of Sundaland's rain forests.
That chromosomal rearrangements may play an important role in maintaining postzygotic isolation between well-established species is part of the standard theory of speciation. However, little evidence exists on the role of karyotypic change in speciation itself-in the establishment of reproductive barriers between previously interbreeding populations. The large genus' Agrodiaetus (Lepidoptera: Lycaenidae) provides a model system to study this question. Agrodiaetus butterflies exhibit unusual interspecific diversity in chromosome number, from n = 10 to n = 134; in contrast, the majority of lycaenid butterflies have n = 23/24. We analyzed the evolution of karyotypic diversity by mapping chromosome numbers on a thoroughly sampled mitochondrial phylogeny of the genus. Karyotypic differences accumulate gradually between allopatric sister taxa, but more rapidly between sympatric sister taxa. Overall, sympatric sister taxa have a higher average karyotypic diversity than allopatric sister taxa. Differential fusion of diverged populations may account for this pattern because the degree of karyotypic difference acquired between allopatric populations may determine whether they will persist as nascent biological species in secondary sympatry. This study therefore finds evidence of a direct role for chromosomal rearrangements in the final stages of animal speciation. Rapid karyotypic diversification is likely to have contributed to the explosive speciation rate observed in Agrodiaetus, 1.6 species per million years.
The Australian fauna is composed of several major biogeographical elements reflecting different spatial and temporal histories. Two groups of particular interest are the Gondwanan Element, reflecting an ancient origin in Gondwana or southern Gondwana (southern vicariance hypothesis), and the Asian Element, reflecting a more recent origin in Asia, Eurasia or Laurasia (northern dispersal hypothesis). Theories regarding the origin and evolution of butterflies (Hesperioidea, Papilionoidea) in Australia are controversial, with no clear consensus. Here, we investigate the phylogenetic and historical biogeographical relationships of the subtribe Aporiina, a widespread taxon with disjunct distributions in each of the major zoogeographical regions. Attention is paid to origins of the subtribe in the Australian Region for which several conflicting hypotheses have been proposed for the Old World genus Delias Hubner. Our phylogenetic reconstruction was based on analysis of fragments of two nuclear genes (elongation factor-1 alpha, wingless) and one mitochondrial gene (cytochrome oxidase subunit 1) for 30 taxa. Phylogenetic analyses based on maximum parsimony, maximum likelihood and Bayesian inference of the combined data set (2729 bp; 917 parsimony informative characters) recovered six major lineages within the monophyletic Aporiina, with the following topology: (Cepora + Prioneris + (Mylothris + (Aporia + Delias group + Catasticta group))). Given a probable age of origin of the stem-group near the Cretaceous/Tertiary boundary (69-54 Mya), followed by diversification of the crown-group in the early to mid Tertiary (57-45 Mya), we show that an origin of the Aporiina in either southern Gondwana or Laurasia is equally parsimonious, and that dispersal has played a major role in shaping the underlying phylogenetic pattern. We tentatively conclude that an origin in southern Gondwanan is more likely; however, neither hypothesis satisfactorily explains the present-day distribution, and additional lower-level phylogenies are needed to determine the directionality of dispersal events of several taxa and to reject one hypothesis over the other. Dispersal is inferred to have occurred primarily during cooler periods when land bridges or stepping-stones were available between many of the zoogeographical regions. (c) 2007 The Linnean Society of London.
Two alternative hypotheses for the origin of butterflies in the Australian Region, that elements dispersed relatively recently from the Oriental Region into Australia (northern dispersal hypothesis) or descended from ancient stocks in Gondwana (southern vicariance hypothesis), were tested using methods of cladistic vicariance biogeography for the Delias group, a diverse and widespread clade in the Indo-Australian Region. A phylogenetic hypothesis of the twenty-four species-groups recognized currently in Delias and its sister genus Leuciacria is inferred from molecular characters generated from the nuclear gene elongation factor-1 alpha (EF-1 alpha) and the mitochondrial genes cytochrome oxidase subunits I and II (COI/COII) and NADH dehydrogenase 5 (ND5). Phylogenetic analyses based on maximum parsimony, maximum likelihood and Bayesian inference of the combined dataset (3888 bp, 1014 parsimony informative characters) confirmed the monophyly of Delias and recovered eight major lineages within the genus, informally designated the singhapura, belladonna, hyparete, chrysomelaena, eichhorni, cuningputi, belisama and nigrina clades. Species-group relationships within these clades are, in general, concordant with current systematic arrangements based on morphology. The major discrepancies concern the placement of the aganippe, belisama and chrysomelaena groups, as well as several species-groups endemic to mainland New Guinea. Two species (D. harpalyce (Donovan), D. messalina Arora) of uncertain group status are currently misplaced based on strong evidence of paraphyly, and are accordingly transferred to the nigrina and kummeri groups, respectively. Based on this phylogeny, a revised systematic classification is presented at the species-group level. An historical biogeographical analysis of the Delias group revealed that the most parsimonious reconstruction is an origin in the Australian Region, with at least seven dispersal events across Wallacea to the Oriental Region. The eight major clades of Delias appear to have diverged rapidly following complete separation of the Australian plate from Gondwana and its collision with the Asian plate in the late Oligocene. Further diversification and dispersal of Delias in the Miocene-Pliocene are associated with major geological and climatic changes that occurred in Australia-New Guinea during the late Tertiary. The 'out-of-Australia' hypothesis for the Delias group supports an origin of the Aporiina in southern Gondwana (southern vicariance hypothesis), which proposes that the ancestor of Delias + Leuciacria differentiated vicariantly on the Australian plate.