Molecular and morphometric variation in two sibling species of the genus Praomys (Rodentia: Muridae): implications for biogeography

The rodent genus Praomys is widely distributed in the African tropics. The species are cryptic, rendering the species taxonomy unclear. There are differences of opinion concerning the specific status of Praomys misonnei and Praomys tullbergi, and their geographical distribution. We sequenced the cytochrome b and/or the 16S gene of 221 specimens from 12 countries in order to evaluate the genetic variability within these two species, and to precisely determine their geographical distribution. Morphological and morphometrical analyses on the sequenced specimens were also performed to find criteria useful for the identification of museum specimens. Our results confirm that P. misonnei and P. tullbergi are two valid species that can be separated by molecular data. However, no single discrete morphological character or simple metric measurement can be used to discriminate them. The percentage of misclassified individuals in multivariate discriminant analysis is relatively high (10%). The two species have allopatric distributions: P. tullbergi occurs in West Africa, from eastern Guinea to western Ghana, and P. misonnei is widely distributed from eastern Ghana to western Kenya. Within P. misonnei we identified three or four major geographical clades: a West Central African clade, an East African clade, a Nigerian clade, and a possible West African clade. Within P. misonnei, high geographical morphometrical variability was also identified. The role of both rivers and Pleistocene forest refugia in promoting speciation within the genus Praomys is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 397–419.     

Structure and function of defensive glands in soldiers of Glossotermes oculatus (Isoptera: Serritermitidae)

The soldier caste represents the most conspicuous realization of termite eusociality, characterized by an extreme anatomical, behavioural, and physiological specialization. Numerous strategies have evolved in soldiers, including extreme adaptations such as self‐sacrifice by autothysis. In the present study, we investigated the structure and function of defensive glands in Glossotermes oculatus soldiers aiming to understand their use in combat. Three glands are involved in defence: labral, frontal, and labial glands. Mandibles are used to bite the enemy, whereas the secretions of labral and labial glands are discharged into the wound. A striking characteristic of G. oculatus is the lack of the frontal pore; the secretion of the frontal gland is discharged by a rupture of the body wall. We hypothesized that this self‐sacrifice is an efficient way of blocking a gallery under attack. A similar development of the frontal gland occurs in Serritermes serrifer, which supports the close relationship between the two genera inferred from morphological and genetic analyses. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 839–848.     

Neurophysiological and Behavioral Changes in Non-Target Wildlife Exposed to Organophosphate and Carbamate Pesticides: Thermoregulation, Food Consumption, and Reproduction

Originally utilized or developed as human poisons, anticholinesterasecompounds are among the most widely used pesticides in the worldand non-target wildlife are frequently exposed. Because thesecompounds primarily act by inhibiting acetylcholinesterase atsynapses within the central and peripheral nervous systems,the potential for altering physiological and behavioral responsesessential for survival and reproduction in exposed animals isgreat. We review the effects of acute but sublethal exposureto organophosphates and carbamates on thermoregulation (hypothermia),food consumption (anorexia and altered foraging behavior), andreproduction (altered hormone levels, reductions in clutch andlitter size, and alterations in reproductive behavior), andthe mechanisms believed to cause them. We believe these arethe direct toxic effects most likely to reduce populations offree-living birds and mammals within treated areas. Data fromstudies of captive birds and laboratory mammals and free-livingindividuals given controlled dosages are included with an emphasison information published within the last 5 years. The limitationsof existing data for determining the biological and regulatorysignificance of these effects are discussed.     

Widespread decoupling of mtDNA variation and species integrity in Grammia tiger moths (Lepidoptera: Noctuidae)

Abstract. We investigate the diversity of the North American tiger moth genus Grammia Rambur (Lepidoptera: Noctuidae) by comparing mitochondrial DNA (mtDNA) ‘barcode’ fragments of cytochrome oxidase I with non‐molecular characters such as morphology, ecology, behaviour and distribution. Mitochondrial DNA genealogy is strikingly at odds with morpho‐species taxonomy for most of the 28 sampled species, as haplotypic polyphyly not only is taxonomically widespread, but involves multiple shared haplotypes among two to four species. Morpho‐ecological traits show that those species sharing haplotypes are often not closely related. Furthermore, high mtDNA divergences occur within species. Haplotypic variation is highly discordant with species taxonomy, but variation at a continental scale reveals significant geographic structuring of haplogroups, transcending morpho‐species boundaries. A nested clade analysis and comparison of non‐molecular with mtDNA data indicate that most discordance between mtDNA and taxonomy in Grammia is explained best by taxonomically and geographically widespread ongoing hybridization events resulting in mtDNA introgression. We hypothesize that broad areas of sympatry, interspecifically compatible genitalic structure, and species overlap in pheromone components facilitate hybridization, with disparate interspecies abundances promoting mitochondrial introgression. The molecular evolution of Grammia challenges the view that interspecific gene exchange occurs rarely and is restricted to recently diverged species. These results show the value of mtDNA in detecting cryptic hybridization, while highlighting the inherent dangers of drawing taxonomic conclusions based solely on mtDNA.     

Barn Swallows Hirundo rustica disperse seeds of Rooikrans Acacia cyclops, an invasive alien plant in the Fynbos Biome

Rooikrans Acacia cyclops is an invasive plant species in the coastal region of South Africa, especially the Fynbos Biome. It is endemic to southwestern Australia. Seeds are bird-dispersed, mostly by frugivores and granivores. We report that at one locality in South Africa, Barn Swallows Hirundo rustica , normally regarded as obligate foragers of aerial arthropods, also consumed the seeds and associated arils of Rooikrans shrubs and trees. The seeds were voided and the arils digested. Three thousand Barn Swallows in the region where this was observed conceivably consumed and voided two million Rooikrans seeds during the 5-month non-breeding period. Barn Swallows are therefore dispersers of Rooikrans seeds. Many of the bird species known to consume Rooikrans seeds are territorial, so that seeds are not dispersed far beyond existing acacia stands. Barn Swallows cover large distances between feeding areas and roosts, and could therefore disperse seeds far from existing stands. This development adds urgency to the need to eradicate Rooikrans from the Fynbos Biome.     

Recent decline in precipitation and tree growth in the eastern Mediterranean

We present evidence of a recent drying in the eastern Mediterranean, based on weather and tree‐ring data for Samos, an island of the eastern Aegean Sea. Rainfall declined rapidly after the late 1970s following trends for the entire Mediterranean and was associated with reduced tree‐ring width in Pinus brutia. The most recent decline led to the lowest annual radial stem increment after the last 100 years (as far as records reach). As moisture availability decreased best correlations of tree growth with rainfall were obtained for progressively longer integration periods (1–2 years in moister periods, 5–6 years during the severe dryness of 20th century's last decades), suggesting increasing dependency in deep soil water. Such long‐term integration periods of tree‐growth responses to precipitation have not been reported before. They may reflect a tree‐rooting pattern adapted to cope with even several successive dry years. In late summer 2000, moisture reserves became exhausted, however, and a substantial fraction of low altitude pines died, including some 80‐year‐old trees, which underlines the exceptional extent this trend had reached. Our findings provide empirical support for Intergovernmental Panel on Climate Change projections derived from global circulation models that the Mediterranean, its eastern basin in particular, should become drier as temperature rises, as was the case in the recent past.     

Electron transfer of dissolved organic matter and its potential significance for anaerobic respiration in a northern bog

We investigated electron transfer processes of dissolved organic matter (DOM) and their potential importance for anaerobic heterotrophic respiration in a northern peatland. Electron accepting and donating capacities (EAC, EDC) of DOM were quantified using dissolved H₂S and ferric iron as reactants. Carbon turnover rates were obtained from porewater profiles (CO₂, CH₄) and inverse modeling. Carbon dioxide was released at rates of 0.2–5.9 mmol m⁻² day⁻¹ below the water table. Methane (CH₄) formation contributed <10%, and oxygen consumption 2% to 40%, leaving a major fraction of CO₂ production unexplained. DOM oxidized H₂S to thiosulfate and was reduced by dissolved ferric iron. Reduction with H₂S increased the subsequently determined EDC compared to untreated controls, indicating a reversibility of the electron transfer. In situ redox capacities of DOM ranged from 0.2 to 6.1 mEq g⁻¹ C (EAC) and from 0.0 to 1.4 mEq g⁻¹ C (EDC), respectively. EAC generally decreased with depth and changed after a water table drawdown and rebound by 20 and −45 mEq m⁻², respectively. The change in EAC during the water table fluctuation was similar to CH₄ formation rates. In peatlands, electron transfer of DOM may thus significantly contribute to the oxidation of reduced organic substrates by anaerobic heterotrophic respiration, or by maintaining the respiratory activity of sulfate reducers via provision of thiosulfate. Part of the anaerobic electron flow in peat soils is thus potentially diverted from methanogenesis, decreasing its contribution to the total carbon emitted to the atmosphere.     

Morphometric and morphological delineation of southern African species of Aethomys (Rodentia: Muridae)

Five species of African rock rats, Aethomys namaquensis, A. granti, A. silindensis, A. nyikae and A. chrysophilus, have to date been recognized in southern Africa. While the first three species are craniometrically well-delineated, morphometric analysis of cytogenetically known and other specimens of A. chrysophilus revealed that it comprises two sympatric, morphologically similar species, the nominate species and the newly recognized A. ineptus. This is in agreement with observations on cranial morphology and earlier investigations involving cytogenetics, protein electrophoresis, and gross sperm and bacular morphology. Contrary to published reports, the Central African A. nyikae does not extend into southern Africa, and the single previous record from eastern Zimbabwe is probably based on a misidentification.     

Experiments on food preference and chemical sense in Pycnogonida

Food choice experiments were carried out with three species of pycnogonids: Nymphon rubrum, N. gracile , and Endeis spinosa.
Running sea-water that had circulated over different possible food-sources (hydroids, actiniarians, octocorals, synascidians) was offered to the pycnogonids at one side of a basin, pure sea-water or sea-water that had flowed over a different source of food at the other.
The experiments, though few in number, seemed to indicate that:
(1) Pycnogonids are capable of detecting the presence or absence of various coelenterate species.
(2) They are able to discriminate between different food-sources, i.e. the nature of the chemical substances produced by the food determines the degree of attraction.
(3) The preferential sequence for the three pycnogonids tested is: Nymphon rubrum prefers Dynamena over Tubularia and Laomedea ; these are preferred over Actinia and Metridium ; there is no attraction to Alcyonium. Nymphon gracile prefers Laomedea over Dynamena. Endeis spinosa prefers Laomedea over Dynamena ; these are preferred over Actinia ; there is no attraction to Morchellium.
(4) Experimental amputation of appendages indicates a high probability that the chemo-receptors of the pycnogonids are not located on the chelifores, palps, or ovigers. They may be located (a) all over the body, possibly in innervated epidermal bristles; and/or (b) in the distal part of the proboscis, bearing sensory setae; and/or (c) on the walking legs.