The evolutionary transition from subsocial to eusocial behaviour in Dictyoptera: Phylogenetic evidence for modification of the “shift-in-dependent-care” hypothesis with a new subsocial cockroach

Cockroaches have always been used to understand the first steps of social evolution in termites because they are close relatives with less complex and integrated social behaviour. Termites are all eusocial and ingroup comparative analysis would be useless to infer the origin of their social behaviour. The cockroach genus Cryptocercus was used as a so-called "prototermite" model because it shows key-attributes similar to the termites (except Termitidae): wood-feeding, intestinal flagellates and subsocial behaviour. In spite of these comparisons between this subsocial cockroach and eusocial termites, the early and remote origin of eusocial behaviour in termites is not well understood yet and the study of other relevant "prototermite" models is however needed. A molecular phylogenetic analysis was carried out to validate a new "prototermite" model, Parasphaeria boleiriana which shows a peculiar combination of these key-attributes. It shows that these attributes of Parasphaeria boleiriana have an independent origin from those of other wood-eating cockroaches and termites. The case of P. boleiriana suggests that a short brood care was selected for with life on an ephemeral wood resource, even with the need for transmission of flagellates. These new phylogenetic insights modify evolutionary hypotheses, contradicting the assumption made with Cryptocercus model that a long brood care is necessary for cooperation between broods in the "shift-in-dependent-care" hypothesis. An ephemeral wood resource is suggested to prompt generation overlap and the evolution of cooperation, even if brood care is shortened.

Abstracts of the 23rd Annual Meeting of the Willi Hennig Society. "Phylogenetics and Evolutionary Biology"

The 23rd annual meeting of the Willi Hennig Society took place in Paris with the support of Muséum national d'Histoire naturelle and CNRS (Centre National de la recherche Scientifique), from the 18th to the 23rd of July 2004. Ninety four participants from 16 countries presented 67 talks and 11 posters. The symposia comprised both methodological contributions and strong analyses of case studies, focusing on hot topics in systematics, methodological advances in phylogenetic analysis, epistemology, phylogenetic analysis of behavioral and ecological traits, phylogeny and coevolution of microbial symbioses, taxon and character sampling, biogeography, and the evolution of arthropods. The student participation was very high with 30 student talks (45%) distributed among all symposia, showing the same healthy trend seen in previous meetings. The present abstracts show how much systematics and phylogenetics are scientifically growing and contribute significantly to all research fields of evolutionary biology in the framework of comparative biology. The Student Awards Committee (Cyrille D'Haese, Diana Lipscomb, John Wenzel) nominated the following winners: Johannes Bergsten, the Hennig Prize ($1000) for "Antagonistic coevolution between the sexes in diving-beetles (Coleoptera: Dytiscidae); phylogeny and experiments in reciprocal illumination", Mahé Ben Hamed, the Brundin Prize ($500) for "Reconstructing the history of Chinese through lexicon. Cladistics, distances and trees" and Lara Lopardo, the Rosen Prize ($250) for the poster "Chilean Anapids and Their Webs, a Phylogenetic Approach (Araneae, Anapidae)".

The origin of a ‘true’ worker caste in termites: mapping the real world on the phylogenetic tree

The evolution of the 'true' worker caste in termites is not decisively inferred by coding and mapping both this character and the foraging behaviour on a phylogenetic tree. Answering to Thompson et al. (2000, 2003), and with reference to Grandcolas and D'Haese (2002), we show that this indecisive inference depends on the correct consideration paid to the outgroups. These last ones could be non subsocial cockroaches, or some wood-eating subsocial cockroaches often considered misleadingly as living ancestors, or even any hemimetabolous insects, all of them would be unambiguously lacking 'true' worker caste and pseudergate caste and not showing the 'one-piece' life type foraging behaviour. These statements derive from observing, coding and mapping the real world on the tree without making ad hoc assumptions. In that respect, because termites do not exist in isolation, apart from the tree of life, mapping the character of interest on the tree must be applied to the outgroups as well.

Living in Atlantic forest fragments: life habits, behaviour, and colony structure of the cockroach Monastria biguttata (Dictyoptera, Blaberidae, Blaberinae) in Espirito Santo, Brazil

The life habits, behaviour, and colony structure of the cockroach Monastria biguttata were studied during 2 years in remnants of the Brazilian Atlantic forest. Monastria biguttata was abundant, conspicuous, and ubiquitous in the semideciduous forest in the north of Espirito Santo, Brazil. It was found in forest fragments of various sizes and disturbance levels, but never in the surrounding plantations. Adults and nymphs were found in colonies of 2.8–11.6 cockroaches, grasping the bark of the underside of dead trunks that were clumped on the ground, in the forest understory. The cockroaches were very sedentary, moved extremely slowly, and immediately froze when disturbed. Based on their brooding behaviour and aggregated distribution on trunks, they appeared to be gregarious with only a slow spread during nymphal development. Brood birth took place during the rainy period, and nymphs developed into adults in a minimum of 2 years. Brood size and egg number in oothecae were not very high (23.0 ± 1.5 and 31.1 ± 1.7 (mean ± SE), respectively). All these traits were analysed to understand the survival of species in forest fragments.

Electron microscopic identification of the intestinal protozoan flagellates of the xylophagous cockroach Parasphaeria boleiriana from Brazil

Flagellate protozoa of the hindgut of the xylophagous blattid Parasphaeria boleiriana were examined by light and electron microscopy. This species harbours two oxymonad species of the genera Monocercomonoides and Polymastix, the latter bearing Fusiformis bacteria on its surface. A diplomonad was present and has features of the genus Hexamita rather than Spironucleus. In addition, two trichomonads of the genera Monocercomonas and Tetratrichomastix were identified. A precise comparison with species of blattids and other insects was difficult because most of these flagellates have been described only by light microscopy after cell staining and there are few electron microscope studies and no molecular studies. None of the flagellates contained wood fragments in their food vacuoles and so evidently do not participate in the digestion of wood or cellulose.

Colony composition, social behavior and some ecological characteristics of the Korean wood-feeding cockroach (Cryptocercus kyebangensis)

Korean populations of the genus Cryptocercus occur in forested mountains throughout South Korea. They live in monogamous associations in which parents care for their young in complex woody galleries. Single paired adults (23.2%) and one or both parents with their offspring (28.1%) were found most frequently in the field. Among single-parent families adult females (6.7%) were observed more frequently than adult males (1.4%). In families with single or both parents, the mean brood size was 21.6+/-9.4. Oothecae were observed from mid-June to the late July. Oothecae were found in the galleries of only paired adults and never found in families with nymphs. The mean number of eggs per female was 73.7+/-29.8. Most of neonates grew to the third or fourth instar prior to the winter. During the winter, C. kyebangensis in the field remained almost frozen in their galleries, but ones kept in the laboratory continued to grow during winter. Some characteristics of proctodeal feeding behavior are also described based on laboratory observations. We propose that the cold temperate climate, especially of the winter season, is one of the most important causes for the evolution of unusual life history of Cryptocercus including delayed development of nymphs.

Defensive secretion of Therea petiveriana: chemical identification and evidence of an alarm function

The volatile constituents of the supposed defensive secretions of the glandular pouches of the adults of both sexes of the cockroach Therea petiveriana have been shown to contain N-3-methylbutylacetamide (MBA) and N-3-methylbutylpropanamide (MBP), which represented 60% of the volatile fraction. The other 40% included acidic, aromatic, and aldehydic compounds. Behavioral experiments demonstrated that the secretion acts as an alarm pheromone for adults.

A new and independently evolved case of xylophagy and the presence of intestinal flagellates in the cockroach Parasphaeria boleiriana (Dictyoptera, Blaberidae, Zetoborinae) from the remnants of the Brazilian Atlantic forest

Parasphaeria boleiriana is a new example of a xylophagous and subsocial cockroach with intestinal flagellates, which was observed in remnants of the Brazilian semideciduous Atlantic forest. Parasphaeria boleiriana formed galleries by burrowing into the rotten trunks of softwood trees in the forest understory. Females stayed in chambers in the wood with their neonate nymphs for 12.4 ± 6.2 days (mean ± SD), but trophallaxis was not yet observed. According to multiseasonal sampling, nymphal development took longer than 1 year, but adults appeared to be short-lived. Nymphs did not disperse within the trunk during their development but remained relatively aggregated. Parasphaeria boleiriana fed on wood, and their digestive tract harboured five species of flagellates belonging to the order Trichomonadida. All these characteristics contrast with those of other known wood-feeding cockroaches, especially the low adult longevity and short period of brood care, associated with a high prevalence of intestinal flagellates.

The phylogeny of cockroach families: a cladistic appraisal of morpho-anatomical data

Seventy-two morpho-anatomical characters were examined in 221 genera belonging to the families Blattidae, Polyphagidae, Blattellidae, and Blaberidae. They were cladistically analyzed and polarized using two mantids and two termites. As no autapomorphies of the family Blattellidae were found, the constituent subfamilies were used as terminal taxa together with other families. Three trees were found (CI = 0.81 and RI = 0.88, without autapomorphies) that differed only by the position of Nyctiborinae relative to Blattellinae and Ectobiinae. The strict consensus tree was [Blattidae [Polyphagidae [Anaplectinae [[Pseudophyllodromiidae, Blaberidae] [Nyctiborinae, Blattellinae, Ectobiinae]]]]]. The main discrepancies with McKittrick's tree were the monophyly of Polyphagidae (instead of paraphyly) and that the Blaberidae is the sister-group of Pseudophyllodromiinae (instead of the sister-group of Blattellinae, Ectobiinae, and Nyctiborinae). These results made it necessary to elevate the Anaplectinae and Pseudophyllodromiinae to familial status, and to give a new sense to the family Blattellidae, which includes only the subfamilies Blattellinae, Ectobiinae, and Nyctiborinae. This phylogeny was used to test current evolutionary hypotheses concerning sociality and reproductive behaviour; many traits were assumed to be ancestral to all cockroaches (protozoan symbionts and familial life habits) or preadaptive (progressing from advanced oviparity in Blattellidae to ovoviviparity in Blaberidae) that must actually be considered homoplasic.

Le genre Therea Billberg, 1820: position phylogénétique, nouvelles espèces, répartition, valence écologique (Dictyoptera, Blattaria, Polyphaginae)

The genus Therea Billberg, 1820 is redefined as a monophyletic taxon belonging to the group Ergaula + Eucorydia + Therea + Cryptocercus in the subfamily Polyphaginae Kirby, 1904. Three new species, T. regularis, T. defranceschii, and T. hyperguttata, are described as well as T. petiveriana (Linnaeus, 1758) and T. nuptialis (Gerstaecker, 1861). The known distribution of the genus in India extends from dry deciduous forests to more humid formations (between latitudes 19 and 10° N). The species live in areas with mean annual rainfall ranging from 500 to 3800 mm.