Roseli Pellens

Evolution on a shaky piece of Gondwana: is local endemism recent in New Caledonia?

New Caledonia is well known as a hot spot of biodiversity whose origin as a land mass can be traced back to the Gondwanan supercontinent. The local flora and fauna, in addition to being remarkably rich and endemic, comprise many supposedly relictual groups. Does the New Caledonian biota date back to Gondwanan times, building up its richness and endemism over 100 Myr or does it result from recent diversifications after Tertiary geological catastrophic events? Here we use a molecular phylogenetic approach to answer this question with the study of the Neocaledonian cockroach genus Angustonicus belonging to the subfamily Tryonicinae from Australia and New Caledonia. Both geological and molecular dating show that the diversification of this group is less than two million years old, whatever the date of its origin itself. This dating is not consistent with hypotheses of Gondwanan richness and endemism in New Caledonian biota. In other terms, local richness and endemism at the specific level are not necessarily related to an old Gondwanan origin of the Neocaledonian groups.

Phylogeny of Dictyoptera: Dating the Origin of Cockroaches, Praying Mantises and Termites with Molecular Data and Controlled Fossil Evidence

Understanding the origin and diversification of organisms requires a good phylogenetic estimate of their age and diversification rates. This estimate can be difficult to obtain when samples are limited and fossil records are disputed, as in Dictyoptera. To choose among competing hypotheses of origin for dictyopteran suborders, we root a phylogenetic analysis (~800 taxa, 10 kbp) within a large selection of outgroups and calibrate datings with fossils attributed to lineages with clear synapomorphies. We find the following topology: (mantises, (other cockroaches, (Cryptocercidae, termites)). Our datings suggest that crown-Dictyoptera—and stem-mantises—would date back to the Late Carboniferous (~ 300 Mya), a result compatible with the oldest putative fossil of stem-dictyoptera. Crown-mantises, however, would be much more recent (~ 200 Mya; Triassic/Jurassic boundary). This pattern (i.e., old origin and more recent diversification) suggests a scenario of replacement in carnivory among polyneopterous insects. The most recent common ancestor of (cockroaches + termites) would date back to the Permian (~275 Mya), which contradicts the hypothesis of a Devonian origin of cockroaches. Stem-termites would date back to the Triassic/Jurassic boundary, which refutes a Triassic origin. We suggest directions in extant and extinct species sampling to sharpen this chronological framework and dictyopteran evolutionary studies.

Biodiversity Sampling Using a Global Acoustic Approach: Contrasting Sites with Microendemics in New Caledonia

New Caledonia is a Pacific island with a unique biodiversity showing an extreme microendemism. Many species distributions observed on this island are extremely restricted, localized to mountains or rivers making biodiversity evaluation and conservation a difficult task. A rapid biodiversity assessment method based on acoustics was recently proposed. This method could help to document the unique spatial structure observed in New Caledonia. Here, this method was applied in an attempt to reveal differences among three mountain sites (Mandjélia, Koghis and Aoupinié) with similar ecological features and species richness level, but with high beta diversity according to different microendemic assemblages. In each site, several local acoustic communities were sampled with audio recorders. An automatic acoustic sampling was run on these three sites for a period of 82 successive days. Acoustic properties of animal communities were analysed without any species identification. A frequency spectral complexity index (NP) was used as an estimate of the level of acoustic activity and a frequency spectral dissimilarity index (Df) assessed acoustic differences between pairs of recordings. As expected, the index NP did not reveal significant differences in the acoustic activity level between the three sites. However, the acoustic variability estimated by the index Df, could first be explained by changes in the acoustic communities along the 24-hour cycle and second by acoustic dissimilarities between the three sites. The results support the hypothesis that global acoustic analyses can detect acoustic differences between sites with similar species richness and similar ecological context, but with different species assemblages. This study also demonstrates that global acoustic methods applied at broad spatial and temporal scales could help to assess local biodiversity in the challenging context of microendemism. The method could be deployed over large areas, and could help to compare different sites and determine conservation priorities.

Phylogenetic analysis of the endemic New Caledonian cockroach Lauraesilpha. Testing competing hypotheses of diversification

New Caledonia is a tropical hotspot of biodiversity with high rates of regional and local endemism. Despite offering an ideal setting to study the evolution of endemism, New Caledonia has received little attention compared with the other nearby hotspots, particularly New Zealand. Most studies of the Neocaledonian endemism have been carried out at the regional level, comparing the various groups and species present in New Caledonia but absent in neighboring territories. In addition, remarkably high short‐range endemism has been documented among plants, lizard and invertebrates, although these have usually been done, lacking a phylogenetic perspective. Most studies of Neocaledonian endemism have referred to the geological Gondwanan antiquity of the island and its metalliferous soils derived from ultramafic rocks. Very old clades are thought to have been maintained in refugia and diversified on the metalliferous soils. The present study documents the pattern of diversification and establishment of short‐range endemism in a phylogenetic context using the Neocaledonian cockroach genus Lauraesilpha. Mitochondrial and nuclear genes were sequenced to reconstruct phylogenetic relationships among the species of this genus. These relationships, in the light of the species distribution, do not support the hypothesis that species diversified via an adaptive radiation on metalliferous soils and are not consistent with areas of highest rainfall. Species of Lauraesilpha have similar altitudinal ranges and ecological habits and are short‐range endemics on mountains. What our analysis did reveal was that closely related species are found on nearby or contiguous mountains, and thus these formations probably played the key role establishing short‐range endemism (in association with recent climatic changes).

Mapping extrinsic traits such as extinction risks or modelled bioclimatic niches on phylogenies: does it make sense at all?

An increasing variety of extrinsic traits are used in comparative studies aimed at testing evolutionary hypotheses. After briefly reviewing the relevant literature, it appears that three different problems are implied by this trend. Some extrinsic traits are only surrogates for phenotypic traits, and should be redefined to better fit the requisites for phylogenetic analysis, such as selective regimes and extinction risks. Some others are already adequately defined and cannot be made less extrinsic, such as taxon age, geographical distribution, associates (parasites, symbionts, etc.), and bioclimatic modelled niches. Because they are not heritable, they should not be analysed by optimization onto a tree, but are better considered in sister‐group comparisons or within a reconciliation procedure, as already done for areas of biogeography.

Edaphic macroarthropod communities in fast-growing plantations of Eucalyptus grandis Hill ex Maid (Myrtaceae) and Acacia mangium Wild (Leguminosae) in Brazil

Abstract This study compares the edaphic macroarthropod communities from experimental plantations of Acacia mangium and Eucalyptus grandis, both 7 years old, and from the primary forest, all located on the table-land region in the state of Espirito Santo (Brazil). Most of the taxonomic groups analyzed reach densities as high, or higher, in the plantations as in the primary forest. Four points however differentiate the communities of both plantations from that of the forest: the absence of Diplura and Pseudoscorpionida; the lower relative abundance of ants; the dominance of some non-social arthropods; and the concentration of a great percentage of macroarthropods in the litter layers. All these features seem to reflect a higher complexity in the decomposition subsystem of the primary forest, which is expected since it is a natural ecosystem. Regarding agroecosystems, the community under A. mangium shows a lower seasonal variation of total densities and a higher density of Blattaria, Isopoda, Coleopteran larvae and Lepidopteran larvae. These differences are apparently a consequence of the greater quantity of leaf litter, rich in nutrients, accumulated on the soil in this plantation. Therefore, both plantations create a propitious environment for macroarthropod communities. But A. mangium seems to provide better conditions to the soil communities, and thus it seems to be an important alternative to conciliate the wood production and the recuperation of edaphic communities in areas surrounding the remnants of the Atlantic forest.

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.

Phylogenetic analysis of social behavior evolution in [Zetoborinae + Blaberinae + Gyninae + Diplopterinae] cockroaches: an update with the study of endemic radiations from the Atlantic forest

We updated the phylogenetic analysis of the evolution of habitat choice and social habits in the cockroach group of [Zetoborinae + Blaberinae + Gyninae + Diplopterinae] (Dictyoptera: Blaberidae) elaborated by Grandcolas (1998b). The original phylogenetic matrix was updated with new data obtained in the Brazilian Atlantic forest for the genera Parasphaeria and Zetobora (Zetoborinae), Monastria, Petasodes (Blaberinae) and Pycnoscelus (Pycnoscelinae) (one outgroup). These new data did not change the tree topology but showed that the fauna of the Atlantic forest has a complex evolutionary origin with several different radiations, one of which is local, and behavioral convergences or originalities.

Perfil e florística de dois trechos de mata litorânea no Município de Maricá - RJ

In the Cardosa Island, located in the Marica lagoon system, a floristic survey (especially of woody plants) was carried out and profile diagrams were drawn in order to compare the vegetation of two contiguous areas: an area on quaternary sandy terrain and other on the top of a small hill (Table-land). In each area a 2 x 60m transect was delimited and every shrub, tree or liana with diameter at the base of the stem (DSB) ³ 2,5cm inside of it was recorded and drawn. 276 herbaceous and woody individuals, belonging to 69 species and 33 families, were sampled. The percentage of species and families restricted to one area , and the structural features relative to density, crown width, proportion of trees and lianas and the presence of basal ramification of the stem showed differences between the two areas. Both formations showed floristic and physiognomic similarities with restingas forests. The adequacy of the transect width, as well as of the minimum DSB used in the profile diagrams were also discussed. The profile diagram was considered an useful instrument for the study and comparison of forests physiognomic structures.

Climate and Soil Type Together Explain the Distribution of Microendemic Species in a Biodiversity Hotspot

The grasshopper genus Caledonula, endemic to New Caledonia, was studied to understand the evolution of species distributions in relation to climate and soil types. Based on a comprehensive sampling of 80 locations throughout the island, the genus was represented by five species, four of which are new to science, of which three are described here. All the species have limited distributions in New Caledonia. Bioclimatic niche modelling shows that all the species were found in association with a wet climate and reduced seasonality, explaining their restriction to the southern half of the island. The results suggest that the genus was ancestrally constrained by seasonality. A molecular phylogeny was reconstructed using two mitochondrial and two nuclear markers. The partially resolved tree showed monophyly of the species found on metalliferous soils, and molecular dating indicated a rather recent origin for the genus. Adaptation to metalliferous soils is suggested by both morphological changes and radiation on these soils. The genus Caledonula is therefore a good model to understand the origin of microendemism in the context of recent and mixed influences of climate and soil type.