James P. Pitts

Molecular phylogenetics of Vespoidea indicate paraphyly of the superfamily and novel relationships of its component families and subfamilies

The 24 000+ described species of Vespoidea include many well‐known stinging wasps, such as paper wasps and hornets (Vespidae), velvet ants (Mutillidae), spider wasps (Pompilidae) and ants (Formicidae). The compelling behaviours of vespoids have been instrumental in developing theories of stepwise evolutionary transitions, which necessarily depend on an understanding of phylogeny, yet, existing morphological phylogenies for Vespoidea conflict. We collected molecular data from four nuclear genes (elongation factor‐1α F2 copy, long‐wavelength rhodopsin, wingless and the D2–D3 regions of 28S ribosomal RNA (2700 bp in total)) to produce the first molecular phylogeny of Vespoidea. We analysed molecular data alone and in combination with published morphological data from Brothers and Carpenter. Parsimony analyses left many deeper nodes unsupported, but suggested paraphyly of three families. Total‐evidence Bayesian inference produced a more resolved tree, in which the monophyly of Vespoidea was nevertheless ambiguous. Bayesian inference of molecular data alone returned a well‐resolved consensus with posterior probabilities of over 95% for most nodes. We used this topology as the best estimate of phylogeny at the family and subfamily levels. Notable departures from previous estimates include: (i) paraphyly of Vespoidea resulting from the nesting of Apoidea within a lineage comprising Formicidae, Scoliidae and two subfamilies of Bradynobaenidae; (ii) paraphyly of Bradynobaenidae, Mutillidae and Tiphiidae; (iii) a sister relationship between Rhopalosomatidae and Vespidae; and (iv) Rhopalosomatidae + Vespidae as sister to all other vespoids/apoids. We discuss character evidence in light of the new phylogeny, and propose a new classification of Aculeata that recognizes eight superfamilies: Apoidea, Chrysidoidea, Formicoidea, Pompiloidea, Scolioidea, Tiphioidea, Thynnoidea and Vespoidea.

Cladistic analysis of the fire ants of the Solenopsis saevissima species-group (Hymenoptera: Formicidae)

Results are presented from a phylogenetic study of the fire ants comprising the Solenopsis saevissima species‐group (Hymenoptera: Formicidae). Six most‐parsimonious trees were identified following a cladistic analysis utilizing 18 taxa and 36 morphological characters derived from three castes and two developmental stages. A strict consensus tree recovered the following relationships: (S. daguerrei ((S. electra, S. pusilignis) (S. saevissima (S. pythia (S. interrupta, S. ‘undescribed species’, S. weyrauchi (S. richteri, S. invicta (S. megergates (S. quinquecuspis, S. macdonaghi)))))))). This phylogenetic hypothesis implies trends in fire ant evolution towards both polygyny (multiple egg‐laying queens per colony) and large major worker size. The phylogeny also provides a test of Emerys Rule, which is not supported in its strictest sense because the social parasite S. daguerrei is not the sister species to its host species. A modified version of Emerys Rule is supported, because the social parasite is the sister species to a larger clade containing its hosts, as well as nonhosts.

Illuminating the lack of consensus among descriptions of earth history data in the North American deserts: a resource for biologists.

Understanding the timing of mountain building and desert formation events in western North America is crucial to understanding the evolutionary history of the diverse arid-adapted biota that is found there. While many different, often conflicting descriptions exist regarding geobiotic change in western North America, little work has been done to synthesize these various viewpoints. In this paper we present several case studies that illustrate the differences in the various explanations, based on geological and paleobiological data, detailing mountain uplift and desertification in western North America. The majority of the descriptions detailing mountain building in this area fall into two major periods of uplift, the Laramide uplift (∼70—50 Ma) and the Neogene uplift (∼15—2 Ma), yet it remains unclear which of these events was responsible for the formation of the modern mountains. Like the descriptions of mountain building, various accounts exist detailing the timing of desert formation. Some authors suggest that the deserts existed as far back as 15 Ma while others propose that desert formation occurred as recently as 10,000 years ago. Based on this review of the literature, we suggest that the data on Cenozoic geomorphological evolution of the North American desert landscape is still too coarse and filled with gaps to allow for the development of a robust model of landscape evolution. Instead, this work demonstrates the need for biologists studying the North American biota to realize just how problematic some of the earth history data and models are so that they can build this uncertainty into biogeographic reconstructions.

Preliminary morphological analysis of relationships between the spider wasp subfamilies (Hymenoptera: Pompilidae): revisiting an old problem

No qualitative cladistic analysis has been performed previously for the subfamily classification of Pompilidae (Hymenoptera). In 1994 Shimizu proposed six subfamilies, but their validity and relationships remain inconclusive. The objective of this study was to perform a quantitative analysis of phylogenetic relationships of the Pompilidae, with emphasis on testing the validity of proposed subfamilies. Two cladistic analyses were performed based on morphological evidence. First, a maximum‐parsimony analysis of Shimizus original morphological data matrix (72 taxa by 54 characters) was conducted, with the data subjected to a heuristic search for the first time with phylogenetic software. The resulting strict‐consensus cladogram yielded a monophyletic Ceropalinae that was sister group to a large polytomy containing members of the remaining five subfamilies. In a second analysis, several of Shimizus characters were re‐examined, and new characters and more taxa were added to the data set. Terminal taxa were coded as species rather than as generic abstractions, and 20 additional morphological characters were introduced. The analysis was based on 77 morphological characters derived from the adults of 84 taxa. This second analysis suggested that Notocyphinae sensu Shimizu (1994) was nested within Pompilinae and that Epipompilinae sensu Shimizu (1994) was nested within Ctenocerinae; neither should retain their status as a separate subfamily. Lastly, Chirodamus s.s., which historically has been a member of the Pepsinae, is placed within the Pompilinae with reservations rather than erecting a new subfamily. After these allowances were made, a strict consensus tree gave the following relationships: (Ceropalinae + (Pepsinae + (Ctenocerinae + Pompilinae))).

A Molecular Method for Associating the Dimorphic Sexes of Velvet Ants (Hymenoptera: Mutillidae)

Abstract For several groups of insects, including the velvet ants, male–female associations are difficult because of extreme dimorphism between the sexes. Many species, or even genera, are known from only a single sex. In this study, we investigate the use of DNA sequences of the internal transcribed spacer regions (ITS1 & ITS2) as a means of associating males and females in velvet ants. We compare ITS sequences between sexes in taxa where the associations are well documented and uncontested. We compare these sequences to other closely related species. The DNA sequence data show little or no variability between sexes, while much greater differences exist between species. This method should prove a valuable technique for making associations between previously unmatched males and females in velvet ants, and likely other hymenopteran taxa.

Repeated evolution in overlapping mimicry rings among North American velvet ants

Müllerian mimicry, in which two or more harmful species share a similar appearance for mutual benefit, is a widely appreciated, yet relatively uncommon natural phenomenon. Although Müllerian mimicry occurs in vertebrates, most studies are focused on tropical, herbivorous invertebrates. Here we identify a large Müllerian mimicry complex in North American velvet ants (Hymenoptera: Mutillidae). These are conspicuous, diurnal parasitoids of bees and wasps that defend themselves with a powerful sting. We investigate morphological and genetic variation and ask whether morphological similarities are the result of convergent evolution or shared ancestry. We find that 65 species in the velvet ant genus Dasymutilla can be placed into one of six morphologically distinct and geographically delimited mimicry rings. Müllerian colour patterns are primarily the result of independent evolution rather than shared, phylogenetic history. These convergent colour syndromes represent one of the largest known Müllerian mimicry complexes yet identified, particularly in the Northern Hemisphere.

Family-Level Divergences in the Stinging Wasps (Hymenoptera: Aculeata), with Correlations to Angiosperm Diversification

Diversification in insects has often been linked to the evolution of angiosperms. The majority of studies reporting this link, however, have been done on herbivorous insects. It remains unclear if the diversification of angiosperms was also influential in the diversification of species-rich, carnivorous insect groups. Here we investigate the timing of the origin and diversification in the stinging wasps (Hymenoptera: Aculeata). We employ a Bayesian Markov chain Monte Carlo relaxed clock approach to estimate divergence times for 13 wasp families and eight superfamilies. Divergence times are calibrated with 12 fossils representing groups in various lineages. Our results indicate that many of the modern aculeate families originated during the Cretaceous and in concert with the diversification of angiosperms. This similarity between diversification ages in wasps and in angiosperms may be due to an increased habitat complexity and prey diversity that early angiosperm forests provided.

Revision of Velvet Ant Genus Dilophotopsis Schuster (Hymenoptera: Mutillidae) by Using Molecular and Morphological Data, with Implications for Desert Biogeography

Abstract Taxonomy of the wide-ranging Nearctic velvet ant genus Dilophotopsis Schuster (Hymenoptera: Mutillidae) is reviewed using molecular and morphological comparisons. The validity of the four designated subspecies of Dilophotopsis concolor (Cresson) is examined. Dilophotopsis concolor paron (Cameron) is morphologically and molecularly distinct from the other three subspecies, and it is raised to the species level [D. paron (Cameron), nov. stat.]. Dilophotopsis concolor crassa (Viereck) and Dilophotopsis concolor laredo Schuster are morphologically indistinguishable from the nominative subspecies D. concolor concolor, and they are considered junior synonyms of this species. A key to the species of Dilophotopsis is provided. The distributions of Dilophotopsis species, as well as the genetic variation within D. concolor, are associated with individual arid lands, and they indicate that this genus will be useful in the study of the historical biogeography of the North American arid lands.

Evolution of the nocturnal Nearctic Sphaeropthalminae velvet ants (Hymenoptera: Mutillidae) driven by Neogene orogeny and Pleistocene glaciation.

The influence of historical climatic and geological changes on patterns of species diversification was investigated in a widely distributed group of North American nocturnal mutillids (Hymenoptera: Mutillidae: Sphaeropthalminae), with particular focus on Pleistocene glacial cycles and earlier patterns of Neogene mountain building. We collected molecular data from two nuclear intergenic regions (internal transcribed spacer regions 1 and 2; approximately 2600 bp in total) to produce the first phylogeny of nocturnal Nearctic mutillids. Bayesian inference of the combined data returned a well-resolved tree with posterior probabilities of over 95% for most nodes. This tree suggested the monophyly of the nocturnal, primarily Nearctic, Sphaeropthalminae genera, but the paraphyly of the three largest genera (Odontophotopsis, Photomorphus and Sphaeropthalma). Dates of species divergences were obtained using r8s (PL and NPRS) and BEAST with the date of Dominican amber set at three different dates (15 Ma, 20 Ma, and 45 Ma) to account for uncertainty in the fossil age. The derived dates ranged from the Pleistocene to the Middle Miocene, suggesting that both recent Pleistocene glaciation cycles and older orogenic events, albeit to a somewhat greater extent, were both causes of major diversification in western North America. Examination of other phylogeographical studies using North American desert taxa indicated that diversification patterns are explained by either mountain building or Pleistocene climate change, depending on the taxa in question.

North American velvet ants form one of the world’s largest known Müllerian mimicry complexes

Color mimicry is often celebrated as one of the most straightforward examples of evolution by natural selection, as striking morphological similarity between species evolves in response to a shared predation pressure. Recently, a large North American mimetic complex was described that included 65 species of Dasymutilla velvet ants (Hymenoptera: Mutillidae). Beyond those 65 species, little is known about how many species participate in this unique Müllerian complex, though several other arthropods are thought to be involved as Müllerian mimics (spider wasps) and Batesian mimics (beetles, antlions, and spiders; see references in). Müllerian mimicry is similarity in appearance or phenotype among harmful species, while Batesian mimicry is similarity in which not all species are harmful. Here, we investigate the extent of the velvet ant mimicry complex beyond Dasymutilla by examining distributional and color pattern similarities in all of the 21 North American diurnal velvet ant genera, including 302 of the 361 named species (nearly 84%), as well as 16 polymorphic color forms and an additional 33 undescribed species. Of the 351 species and color forms that were analyzed (including undescribed species), 336 exhibit some morphological similarities and we hypothesize that they form eight distinct mimicry rings (Figure 1A; Supplemental Information). Two of these eight mimicry rings, red-headed Timulla and black-headed Timulla, were not documented in earlier assessments of mimicry in velvet ants, and are newly described here. These findings identify one of the largest known Müllerian mimicry systems worldwide and provide a novel system to test hypotheses about aposematism and mimicry, especially those regarding the evolution of imperfect mimicry.