Systematic relationships within the genus Trichomanes sensu lato (Hymenophyllaceae, Filicopsida): cladistic analysis based on anatomical and morphological data

Systematics within the genus Trichomanes sensu lato (Hymenophyllaceae, Filicopsida) have continued to be controversial because of the difficulty in identifying homologies and informative characters within high morphological diversity. Systematic relationships are investigated in this study by using a cladistic approach with 31 anatomical and morphological characters from 20 taxa which correspond to the sections defined by Morton. The results broadly confirm Morton's four subgenera: Trichomanes, Didymoglossum, Pachychaetum and Achomanes. The monophyly of Pachychaetum remains fragile and the section Lacostea appears to be excluded from its traditional subgenus (Achomanes). In addition, by producing two major 'ecological' clades (terrestrial and epiphytic), the analysis shows that several selected characters appear to be strongly linked with the ecology which may have a significant influence on the topology.     

Phylogenetic analysis of the Brazilian microendemic Paepalanthus subgenus Xeractis (Eriocaulaceae) inferred from morphology

Paepalanthus subgenus Xeractis (Eriocaulaceae) comprises 28 recognized species endemic to the Espinhaço Range, in Minas Gerais state, Brazil. Most species of the subgenus are restricted to small localities and critically endangered, but still in need of systematic study. The monophyly of the subgenus has already been tested, but only with a few species. Our study presents the first phylogenetic hypothesis within the group, based on morphology. A maximum parsimony analysis was conducted on a matrix of 30 characters for 30 terminal taxa, including all species of the subgenus and two outgroups. The biogeographical hypotheses for the subgenus were inferred based on dispersal–vicariance analysis (DIVA). The analysis provided one most‐parsimonious hypothesis that supports most of the latest published subdivisions (sections and series). However, some conflicts remain concerning the position of a few species and the relationships between sections. The distribution and origin(s) of microendemism are also discussed, providing the ground for conservation strategies to be developed in the region. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 137–152.     

Hybridization, developmental stability, and functionality of morphological traits in the ground beetle Carabus solieri (Coleoptera, Carabidae)

The assessment of developmental stability in hybrids can provide valuable information in the study of species formation because it allows an evaluation of the degree of incompatibility of genetic systems that control developmental processes. The present study assessed the impact of two hybridization events, assumed to have occurred at different times, on developmental instability in the ground beetle Carabus solieri . Developmental instability was estimated in 678 individuals from 27 populations from the fluctuating asymmetry (FA) levels of four morphological traits: the tibia length of middle and hind legs, which are functional structures, and the length and the proximal width of the hind wings, which are vestigial and thus nonfunctional structures. Significant variations of FA levels between populations were shown only for the wing width. For this trait, FA levels in hybrids were higher than in their parental entities for both hybridization events, indicating a significant divergence of the gene systems controlling development between the parental entities in the two hybridization cases. As expected, wing traits exhibited FA levels at least three times higher than leg trait. Finally, the potential interest of vestigial traits in the particular context of hybridization is discussed.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 151–158.     

A global molecular phylogeny of the fern genus Trichomanes (Hymenophyllaceae) with special reference to stem anatomy

To establish a basis for future taxonomic revisions and to infer the evolutionary traits of Trichomanes s.l. , one of two large filmy fern genera, molecular phylogenetic analyses were conducted using chloroplast rbcL sequences. Sampling covered most of the global distribution range of this genus throughout the tropical and temperate zones, as well as all taxonomically significant species by the addition of 51 samples principally from Asia. The evolution of eight selected characters, which were adopted as taxonomic keys and/or putatively reflect morphological regression, was optimized on the retrieved most parsimonious rbcL trees, together with new observations on the stem anatomy of 45 species. The eight robust clades retrieved within Trichomanes in the rbcL phylogeny conflict with the existing classifications. Our results also suggest that the cup-shaped sorus, the primary diagnostic character of the genus, appears in parallel in the Hymenophyllum lineage, as demonstrated by Pleuromanes (typified by Trichomanes pallidum ) included in the lineage. The suggestion that the regressive character states are homoplastic apomorphies in the evolution of the frond size, stem thickness, root system, and stem anatomy (stele and cortex) probably illustrates a strong tendency towards adaptive evolutionary transition in Trichomanes . © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 1–27.     

Impact of severe dry season on net ecosystem exchange in the Neotropical rainforest of French Guiana

The lack of information on the ways seasonal drought modifies the CO₂ exchange between Neotropical rainforest ecosystems and the atmosphere and the resulting carbon balance hinders our ability to precisely predict how these ecosystems will respond as global environmental changes force them to face increasingly contrasting conditions in the future. To address this issue, seasonal variations in daily net ecosystem productivity (NEP_d) and two main components of this productivity, daily total ecosystem respiration (R_Ed) and daily gross ecosystem productivity (GEP_d), were estimated over 2 years at a flux tower site in French Guiana, South America (5 °16′54″N, 52 °54′44″W). We compared seasonal variations between wet and dry periods and between dry periods of contrasting levels of intensity (i.e. mild vs. severe) during equivalent 93‐day periods. During the wet periods, the ecosystem was almost in balance with the atmosphere (storage of 9.0 g C m^?2). Seasonal dry periods, regardless of their severity, are associated with higher incident radiation and lower R_Ed combined with reduced soil respiration associated with low soil water availability. During the mild dry period, as is normally the case in this region, the amount of carbon stored in the ecosystem was 32.7 g C m^?2. Severe drought conditions resulted in even lower R_Ed, whereas the photosynthetic activity was only moderately reduced and no change in canopy structure was observed. Thus, the severe dry period was characterized by greater carbon storage (64.6 g C m^?2), emphasizing that environmental conditions, such as during a severe drought, modify the CO₂ exchange between Neotropical rainforest ecosystems and the atmosphere and potentially the resulting carbon balance.     

Phylogenetic analysis of Eurytominae (Chalcidoidea: Eurytomidae) based on morphological characters

A phylogenetic study of the Eurytominae (Hymenoptera: Chalcidoidea) treating 178 taxa and based on 150 morphological characters is given. Several cladograms using the complete species sample, but obtained with different weightings, are presented. Local studies were also carried out to provide possible alternate topologies. The deep nodes of the trees were unstable and were never supported, but most of the superficial nodes were stable and robust. The results therefore provide support for a generic classification of the subfamily. The large genus Eurytoma– which includes about half of the described species of the subfamily – proved to be polyphyletic, and is redefined in a narrowed sense using putative synapomorphies. Bruchophagus and Prodecatoma were similarly redefined. The genera Philolema and Aximopsis are reconsidered and defined in a broader concept. A number of the species presently included in Eurytoma were transferred to these genera. Finally, 22 new generic synonymies are proposed and 33 species are transferred. The study also demonstrates that the Eurytomidae are polyphyletic. The results strongly support a sister‐group relationship between the Heimbrinae and the Chalcididae. The Rileyinae consist of two groups of unrelated taxa. A redefinition of the subfamily in a more restricted sense is supported by our results. The remaining group, consisting of the traditional Rileyinae, is included in the subfamily Buresiinae. Considered in this way they comprise the genera Buresium and Macrorileya, the latter being a senior synonym of Archirileya. The Buresiinae appear as the sister group of the Eurytominae. We propose to restrict the family Eurytomidae to these two taxa. This sister‐group relationship provides evidence to polarize the biological habits within Eurytominae. The common ancestor of Buresiinae is presumed to parasitize insects (mostly at the egg stage) living in grass stems. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 151 , 441–510.