Running in circles in phylomorphospace: host environment constrains morphological diversification in parasitic wasps

A host driven parasitoid syndrome: Convergent evolution of multiple traits associated with woodboring hosts in Ichneumonidae (Hymenoptera, Ichneumonoidea)

The evolution of convergent phenotypes is of major interest in biology because of their omnipresence and ability to inform the study of evolutionary novelty and constraint. Convergent phenotypes can be combinations of traits that evolve concertedly, called syndromes, and these can be shaped by a common environmental pressure. Parasitoid wasps which use a wide variety of arthropod hosts have also repeatedly and convergently switched host use across their evolutionary history. They thus represent a natural laboratory for the evolution of trait syndromes that are associated with parasitism of specific hosts and host substrates. In this study, we tested the evolution of co-evolving characters in the highly diverse family Ichneumonidae associated with ovipositing in a specific and well-defined substrate: wood. Using a newly constructed phylogeny and an existing morphological dataset, we identified six traits correlated with the wood-boring lifestyle that demonstrate convergent evolution. At least one trait, the presence of teeth on the ovipositor, typically preceded the evolution of other traits and possibly the switch to parasitism of wood-boring hosts. For each trait, we provide a historical review of their associations with wood-boring parasitoids, reevaluate the function of some characters, and suggest future coding improvements. Overall, we demonstrate the convergent evolution of multiple traits associated with parasitism of woodboring hosts and propose a syndrome in a hyper diverse lineage of parasitoid wasps.

Analyses of head and thorax in Eupomphini (Meloidae) suggest that complex behaviors are not associated to changes in general shape

Our results reject an association between general shape of head and thorax with defensive and courtship behaviors in the studied Eupomphini blister beetles. Instead we found that shape of thorax and head radiated in all directions of the morphospace. We also identified a radical separation between two lineages that could represent future evolutionary constraints for thorax evolution.

Key innovations and the diversification of Hymenoptera

The order Hymenoptera (wasps, ants, sawflies, and bees) represents one of the most diverse animal lineages, but whether specific key innovations have contributed to its diversification is still unknown. We assembled the largest time-calibrated phylogeny of Hymenoptera to date and investigated the origin and possible correlation of particular morphological and behavioral innovations with diversification in the order: the wasp waist of Apocrita; the stinger of Aculeata; parasitoidism, a specialized form of carnivory; and secondary phytophagy, a reversal to plant-feeding. Here, we show that parasitoidism has been the dominant strategy since the Late Triassic in Hymenoptera, but was not an immediate driver of diversification. Instead, transitions to secondary phytophagy (from parasitoidism) had a major influence on diversification rate in Hymenoptera. Support for the stinger and the wasp waist as key innovations remains equivocal, but these traits may have laid the anatomical and behavioral foundations for adaptations more directly associated with diversification.

SPASOS 1.1: a program for the inference of ancestral shape ontogenies

We recently published a method to infer ancestral landmark-based shape ontogenies that takes into account the possible existence of changes in developmental timing. Here we describe SPASOS, a software to perform that analysis. SPASOS is an open-source Windows program written in C. Input data include landmark coordinates for each specimen -with the corresponding information about developmental timing- and a phylogenetic tree showing the relationships among the species sampled. As output, the program produces image files for an easy visualization of the results and data files useful for post-processing. The program incorporates an interpolating function, based on weighting moving averages, which allows analysis of data with scarce information along the ontogenetic trajectory. An empirical evaluation of this function showed its suitability to fill in incomplete ontogenetic trajectories. Finally, we present the results of a reanalysis in SPASOS of a published dataset, where changes in developmental timing were originally inferred by considering PCA scores as shape variables. Both approaches retrieved the same four largest changes in developmental timing, but differed in the ancestral shapes inferred.

Species delimitation, environmental cline and phylogeny for a new Neotropical genus of Cryptinae (Ichneumonidae)

A morphologically unusual Cryptini, Cryptoxenodon gen. nov. Supeleto, Santos & Aguiar, is described and illustrated, with a single species, C. metamorphus sp. nov. Supeleto, Santos & Aguiar, apparently occurring in two disjunct populations in northern and southeastern South America. The highly dimorphic female and male are described and illustrated. The phylogenetic relationships of the new genus are investigated using a matrix with 308 other species of Cryptini in 182 genera, based on 109 morphological characters and molecular data from seven loci. The analyses clearly support Cryptoxenodon gen. nov. as a distinct genus, closest to Debilos Townes and Diapetimorpha Viereck. Species limits and definition are investigated, but despite much morphological variation the analyses at the specimen level do not warrant the division of the studied populations into separate species. The considerable morphological variation is explored with principal component analyses of mixed features, and a new procedure is proposed for objective analysis of colors. The relationship of color and structural variation with altitude and latitude is demonstrated and discussed, representing an important case study for Ichneumonidae. Externally, Cryptoxenodon gen. nov. can be recognized mainly by its unusually large mandibles, but other diagnostic features include clypeus wide; sternaulus complete, distinct and crenulate throughout; areolet closed, about as long as pterostigma width; petiole anteriorly with distinct triangular projection on each side, spiracle near posterior 0.25; propodeum without posterior transverse carina; and propodeal apophyses conspicuously projected.