Non-marine Teredolites from the Middle Eocene of southern England

Middle Eocene, non-marine sediments from southern England contain examples of Teredolites borings in two contrasting palaeoenvironmental settings, viz.: (A) as in situ borings in an allochthonous lignite in an abandoned river channel and (B) as bored logs in cross-bedded fluvial sandstones of probable point-bar origin. The lignite is 0.30 m thick, of which the upper 0.20 m is intensely bored. Rounded pebbles of ?charcoal at its base also show small borings. A log in a fluvial sandstone shows densely-packed. radial club-shaped borings. now filled with sandstone. The wood substrate has subsequently been oxidized away. To our knowledge, this is the first detailed account of Teredolites from an ancient freshwater setting.     

Biogeographic area relationships of lowland Neotropical rainforest based on raw distributions of vertebrate groups

Hypotheses of the historic biogeography of Neotropical anurans inhabiting lowland forests were generated using Parsimony Analysis of Endemicity. In order to establish comparisons with the biogeographical patterns of other vertebrates, previous cladistic analyses reported in the literature (for lizards and primates) were extended and reanalysed to match the geographical scope of the anuran analysis. Cladistic analysis of the distribution of 335 anuran species at 14 localities showed two regions that form a basal dichotomy: (1) Central America + Choco and (2) Amazon Basin + Brazilian Atlantic Forest. This result is interpreted as the first vicariance event that separated lowland Neotropical rainforests into Cis-Andean (east from the Andes) and Trans-Andean (west from the Andes) areas. Within the Cis-Andean localities, the earliest separation occurred between the Amazon Basin and the Brazilian Atlantic Forest. Within the Amazon Basin, three distinctive clusters are defined: (1) Belem, (2) Guianan Region, and (3) Upper Amazon Basin. Data sets on the distribution of anurans, lizards, and mammals have strong cladistic signal. Strong congruence exists among the area cladograms of anurans, lizards, and primates. All of them have, or at least did not conflict with: (1) a basal separation between Cis- and Trans-Andean regions, (2) a Central American clade, (3) the Choco Region is sister to the Central American clade, (4) an Amazon Basin clade, (5) an Upper Amazon Basin clade, and (6) a Guianan clade. The area cladograms are dichotomous and therefore do not support biogeographic theories that hypothesize simultaneous isolations of biotas in the Neotropics.     

Capercaillie Tetrao urogallus in Scotland - demography of a declining population

Capercaillie Tetrao urogallus numbers declined in Scottish forests between 1992 and 1997, although the rate (mean 16% per year, 95% CL 1–30%) differed among forests. Hens declined more quickly than cocks despite the sex ratio in chicks favouring females. A probable explanation is that adult cocks lived longer. Juvenile survival was less than adult survival, largely because juveniles were more likely to die from hitting fences. Although poor reproduction was probably the main cause of the decline, this might not have occurred had fence strikes been substantially fewer.     

The Fine Structure of the Scopula-Stalk Region of Vorticella convallaria

ABSTRACT. We examined by SEM and TEM the stalk-scopular junction, the stalk, and stalk formation in Vorticella convallaria Linnaeus, 1767. The stalk sheath is anchored to the walls of the scopular lip and to the scopular cilia by thin fibrils. Experimental extraction of these fibrils weakens this junction enough to separate the stalk from the cell body. Telotrochs escape from the stalk by means of violent contractions of the cell body, accelerated beating of the trochal band cilia, and twisting of the cell body against the stalk. The edges of the scopular lip spread over the scopular cilia after escape and, in some cases, fuse to enclose the entire, aboral scopular surface in a cupola-like structure. The sessile cells contain fewer and smaller scopular granules than telotrochs. The presence of disintegrating scopular granules in the stalk matrix of some sessile cells suggests that they contain material which is secreted over a period of time to form the stalk. Eruptive formation of the initial adhesive pad and quick elongation of the distal part of the stalk suggests a rapid exocytosis of the larger, more numerous granules of the telotroch. The stalk sheath is formed of fibrils making up complete and incomplete compartments peripherally arranged along the major stalk axis.     

Evidence for matrotrophy in the viviparous sea cucumber Leptosynapta clarki: A role for the genital haemal sinus?

Summary

Viviparity, where the embryos develop in the female reproductive system, is a rare form of reproduction in marine invertebrates, being described in only 14 species of echinoderm. In the intraovarian brooding sea cucumber, Leptosynapta clarki Heding 1928 (cf., Sewell et al. 1995), we used direct evidence (changes in energetic content) to show that significant additional nutrients are provided to the embryos during viviparous development (matrotrophy). In the transition from a structure used to produce gametes to a long-term brooding structure there are visual, histological and transmission electron microscopy (TEM) changes in the structure of the ovarian wall. Changes occur primarily in the cells of the visceral peritoneum and involve an increase in size of the connective tissue/genital haemal sinus (CT/GHS). In the latter part of the brooding period the visceral peritoneum returns to a flattened form, and new oocytes develop along the tubule wall. Similar changes in the intraovarian brooding sea cucumber Oneirophanta mutabilis affinis lead us to suggest that there is a role for the genital haemal sinus in providing nutrition during the brooding period in viviparous echinoderms. Future research is suggested to focus on changes in the ovarian wall structure during the different phases of reproduction (gamete production/brooding) in these species.     

Examining growth rate and starvation endurance in pit‐building antlions from Mediterranean and desert regions

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The Miocene palaeobathymetry and palaeoenvironments of Carriacou, the Grenadines, Lesser Antilles

Carriacou, a small island in the Grenadines, Lesser Antilles, has a Cenozoic rock record that has been important in interpreting the geologic history of the Southern Lesser Antilles Arc Platform. The Lower‐Middle Miocene sedimentary succession of the southeast and east coasts, consisting of the Belmont, Kendeace, Carriacou and Grand Bay formations, has been interpreted as a shallowing‐upward sequence from turbidite basin to nearshore?/beach? palaeoenvironments. An earlier interpretation of the Belmont Formation as having been deposited in shallow water is at variance with the turbiditic nature of the succession; the included fossils are considered allochthonous. However, an interpretation of the Grand Bay Formation as deep water is supported by multiple lines of evidence, including sedimentology (turbidites), ichnology (autochthonous association of burrows typical of deep‐water environments) and palaeontology (terrestrial, planktic, and shallow and deep water benthic species mixed together). The minimum depth of deposition of the Grand Bay Formation was 150–200 m. This suggests that the (unseen) contact between the Carriacou and Grand Bay formations is either an unconformity, formed following rapid deepening of the basin, or a fault, the Grand Bay Formation being deposited in a separate basin from the shallowing‐upwards Belmont‐Kendeace‐Carriacou formations, against which it is now juxtaposed     

Stand selection by birds in Scots pinewoods in Scotland: the need for more old-growth pinewood

A study at Abernethy Forest, Scotland, examined stand selection by some of the birds of conservation concern that inhabit pinewoods. Abernethy Forest was ideally suited for the study because all four main stand types of forest development (stand initiation, stem exclusion, understorey reinitiation and old-growth) were represented. Capercaillies Tetrao urogallus (both males and females) and crossbills Loxia spp. preferred old-growth pinewood in winter, and Redstarts Phoenicurus phoenicurus and Tree Pipits Anthus trivialis preferred old-growth in summer. Great Spotted Woodpecker Dendrocopos major selected snags in old-growth to excavate nest and roost sites. In winter, Crested Tits Parus cristatus had a weak selection for old-growth stands and Bullfinches Pyrrhula pyrrhula preferred stands at initiation. Possible reasons for these preferences are put forward. Although the area of conifer woodland in Scotland is 888 000 ha, it largely comprises North American species destined to be cut before reaching old-growth. Old-growth pinewood in Scotland is largely confined to the fragments of ancient native pinewood, amounting to only 16 000 ha. To conserve some pinewood birds of conservation concern, a mechanism to allow more Scots Pine Pinus sylvestris woods to reach and remain in an old-growth state needs to be pursued.     

Trifluralin herbicide-induced resistance of melon to fusarium wilt involves expression of stress- and defence-related genes

To identify genes involved in trifluralin herbicide-induced resistance of melon to Fusarium oxysporum f. sp. melonis , suppression subtractive hybridization (SSH) and cDNA-amplified fragment-length polymorphism (cDNA-AFLP) were used. A total of 123 clones—60 of which have never been isolated from melon—were isolated, sequenced and annotated. A significant proportion (35%) of the total 123 clones exhibited similarity to genes that have been formerly described as stress- or defence-related. Thirty-two selected clones were subjected to a detailed expression analysis, one-third of which were found to be up-regulated in response to trifluralin treatment and/or fusarium inoculation. The putative roles of seven of these clones in stress are discussed. Furthermore, the expression of four stress-related and up-regulated genes was enhanced when the plants were subjected to salinity stress, suggesting that trifluralin induces a general stress response which protects the plant against fusarium wilt.     

FOOD-INDUCED BODY PIGMENTATION QUESTIONS THE TAXONOMIC VALUE OF COLOUR IN THE SELF-FERTILIZING SLUG CARINARION SPP

Body pigmentation is a popular taxonomic marker in slugs to discriminateclosely related species. However, the genetic background ofbody pigmentation is known only for a few species, while inmany others body pigmentation is influenced by age, food and/orclimate. In this study, we investigated the effects of differentfood items on body pigmentation expression in two selfing pulmonategastropods, Arion (Carinarion) silvaticus and Arion (Carinarion) fasciatus.Both species mainly differ in the distribution of yellow-orangegranules on the body, which in A. fasciatus are concentratedin lateral bands, and in A. silvaticus are evenly scattered.Animals were raised individually under the same conditions, whilethey laid eggs as a consequence of selfing. This F₁ generation wasafterwards divided into two groups, which were fed with different fooditems. A diet of carrot, lettuce or paper had no effect on the distributionof the yellow-orange granules in A. silvaticus, but provokeda loss of the yellow-orange lateral bands in A. fasciatusso that externally these F₁ specimens became similar to A. silvaticus.In both species, a diet of nettle resulted in a strong yellow-orangepigmentation, which often formed yellow-orange lateral bands.These results indicate that food can probably influence the'species-specific' body pigmentation in Carinarion, and thusquestion the reliability of colour traits to distinguish A.silvaticus and A. fasciatus. (Received 5 May 2000; accepted 29 September 2000)