Competing hypotheses for the etiology of cryptorchidism in Sitka black-tailed deer: an evaluation of evolutionary alternatives

On the Aliulik Peninsula (AP) of Kodiak Island, Alaska, 70% of male Sitka black-tailed deer (SBTD; Odocoileus hemionus sitkensis ) are bilaterally cryptorchid (both testes fail to descend; male is sterile). Both genetic and environmental factors have been proposed as possible causes of this problem. We investigated the possibility that population genetic processes (isolation, inbreeding and genetic drift) have contributed to an increased frequency of cryptorchidism in this population. Overall, SBTD on major islands throughout Alaska have unusually low levels of genetic diversity, though we identified a likely glacial refugium on Prince of Wales Island in the Alexander Archipelago. Within the Kodiak Archipelago, deer on the AP did not exhibit the patterns of genetic isolation, inbreeding and drift that would be expected if cryptorchidism in this population was the result of a founder mutation(s). Instead, our data favor exposure to environmental contaminants as a likely alternative mechanism causing high prevalence of cryptorchidism on the AP.     

The 1918-1919 influenza pandemic in England and Wales: spatial patterns in transmissibility and mortality impact

Spatial variations in disease patterns of the 1918-1919 influenza pandemic remain poorly studied. We explored the association between influenza death rates, transmissibility and several geographical and demographic indicators for the autumn and winter waves of the 1918-1919 pandemic in cities, towns and rural areas of England and Wales. Average measures of transmissibility, estimated by the reproduction number, ranged between 1.3 and 1.9, depending on model assumptions and pandemic wave and showed little spatial variation. Death rates varied markedly with urbanization, with 30-40% higher rates in cities and towns compared with rural areas. In addition, death rates varied with population size across rural settings, where low population areas fared worse. By contrast, we found no association between transmissibility, death rates and indicators of population density and residential crowding. Further studies of the geographical mortality patterns associated with the 1918-1919 influenza pandemic may be useful for pandemic planning.     

The role of early experience and emotionality in social facilitation of pecking in chickens

Three questions were examined relevant to consideration of three possible theoretical analyses of the social facilitative mechanism and its ontogeny. First, the effects of rearing, testing and their interaction on pecking during the first eight days of life were assessed, with a view to examining the role of learning in social facilitation. An attempt was made to resolve several procedural complexities associated with previous results. Second, the effects of these variables on emotionality were considered. Some correspondence might be predicted between behavioural and emotional effects in accordance with a postulated fear-reduction hypothesis. Third, also relevant to examination of the postulated causal relationship between level of fear or arousal induced by the test situation and inhibition of the dominant response, the effects on behaviour of independent manipulation of emotionality were assessed. Results provided some support for the postulated role of emotionality as one of possibly several factors in social facilitation, and also indicated the importance of previous experience in facilitation both as a single factor determining peck rates, and via its interaction with testing conditions. The difficulties posed by these and previous results for the three theoretical analyses described were noted.     

The sliding filament model of muscle contraction. I. Quantum mechanical formalism

The quantum mechanical analog of work is defined and discussed by using a simple hypothetical molecular machine, thus enabling the introduction of clearly defined ideas which are necessary for a molecular discussion of biological machines such as the contractile machinery in striated muscle. The problem of control of such quantum machines is discussed and shown to be possible using the concept of a stimulated transition. The problem of “reversibility” is also discussed and shown to have a satisfactory solution for the orders of magnitude of the forces and velocities involved in muscular contractile machinery.     

Intertidal zonation of animals and plants on rocky shores in the Bristol Channel and Severn Estuary–the northern shores

The vertical distribution of common species of macroalgae and fauna on rocky shores extending through the length of the estuary is described. In the west, the shores are fully marine and exposed to Atlantic waves. In an eastward direction, greater shelter and an increasing tidal range occur along a gradient of salinity and turbidity. The flora and fauna change along this gradient. No single biological feature signals a transition from the Bristol Channel to the Severn Estuary but four arbitrary regions are recognized: a 'marine' section eastwards to Swansea, a 'transitional' section between Swansea and Cardiff, an 'estuarine' section up to Newnham, and the tidal river Severn.     

Blowfly strike in England and Wales: the relationship between prevalence and farm and management factors

Abstract. In order to develop and evaluate control strategies for blowfly strike, a greater understanding of the epidemiology is essential. A postal survey of sheep farmers yielded information about ten farm and management factors and their relationship to blowfly strike prevalence. The risk of a farm reporting at least one case of blowfly strike increased as flock size and stocking density increased (adjusted odds ratio of 1.13 for an increase in flock size of 100 sheep and 1.38 for an increase in stocking density of ten sheep per hectare). As farm altitude increased, the risk of blowfly strike decreased (adjusted odds ratio 0.67 for an increase in farm altitude of 100 m). The risk of high strike prevalence (more than 2% of sheep struck) decreased as both farm altitude and flock size increased. High strike prevalence was also associated with on-farm sheep carcase disposal (odds ratio 1.35). Farmers in the south-west of England were more likely to report at least one case of blowfly strike and high strike prevalence compared to all other regions.     

Assessment of a silhouette trap for sampling zoophilic blackflies (Diptera: Simuliidae)

A collapsible animal-type silhouette trap was designed to catch zoophilic female blackflies (Diptera: Simuliidae) which feed on the head or ventral surface of cattle. The trap was assessed for its ability to sample attacking blackflies by comparison with simultaneous manual catches from a bait cow, in an enzootic bovine onchocerciasis area in North Wales. In thirteen 1-hour collections, the trap provided a representative sample of the blackfly population in terms of the relative abundance of species. There was a strong correlation between the catch sizes from both methods (r = +0.73), and the body site feeding preferences for all species were similar with both trap and cow. There was no significant difference between the Onchocerca spp. infection rates of flies caught by either method.     

Species composition and larval habitats of blowfly (Calliphoridae) populations in upland areas in England and Wales

1. Bait trapping at upland sites in England and Wales, mainly at 400-700 m altitude, showed that Calliphora vomitoria L. usually outnumbered all other blowflies. C.vicina R.-D., C.loewi End. and C.alpina Zett were usually present in much lower numbers, with the last-named occurring at north Pennine sites, but being replaced by C.subalpina Ringd. at a south Pennine (Peak District) and a Welsh site. Catches normally included Cynomya mortuorum L., and Phormia terraenovae R.-D. was present at about half of the sites, usually in low numbers. 2. Lucilia spp. (predominantly L.caesar L.) were often abundant in catches at 300-430 m, but were absent or rare at 500 m and above, except at certain times. 3. Exposure of mouse carcasses at north Pennine upland sites, and rearing of adults from them, showed that they were colonized in a very indeterminate variable way by C.vicina, C.loewi, C.alpina and Cy.mortuorum, with dominant and subsidiary species varying in identity and numbers within periods as short as 3 weeks. 4. Sampling of large carcasses, i.e. hill sheep casualties in Co. Durham, showed that C.vomitoria predominated as the blowfly colonist, with C.vicina and Cy.mortuorum in much smaller numbers.     

Scutelluid trilobites from the Silurian of New South Wales

Abstract: Twenty‐six species (nineteen of them formally named) of scutelluid trilobites belonging to eight genera are described from limestones of the lower Wenlock to Ludlow Mirrabooka Formation and its stratigraphical equivalents in the Orange district of New South Wales. Two genera, Borenoria and Mirrabooka, are new. Japonoscutellum, previously employed mainly for several species from Japan, is a globally widely distributed genus in rocks of middle Llandovery to Ludlow age and includes a number of species previously assigned to Kosovopeltis. Japonoscutellum is remarkably diverse in the faunas from Orange where it is represented by eleven species, one of them known also from Kazakhstan. Flexiscutellum and Tosacephalus are regarded as junior synonyms of Decoroscutellum and Kosovopeltis, respectively. The homology of various scutelluid cephalic structures is discussed, in particular the cephalic borders and border furrows that have routinely been misidentified; the term ‘bolus’ is introduced for the variably developed swelling that is enclosed by S1 on the glabella of most scutelluids. New species are Australoscutellum iota, A. microps, A. pulex, A. trica, Borenoria cirrita, Decoroscutellum planes, Eoscutellum annosum, Illaenoscutellum tryo, Japonoscutellum borenorense, J. crassum, J. diascetum, J. gephyricum, J. guttulatum, J. serangicum, J. strabo, Kosovopeltis trepida, K. xynon and Mirrabooka harryi. Some of these trilobites show strong affinity with species from the Kurosegawa Terrane of south‐western Japan and the Chu‐Ili Terrane of Kazakhstan, as previously reported also for the effaced Illaenina from the same limestones. Australoscutellum and Mirrabooka are presently known only from eastern Australia. The new genus Securifrons is proposed for several species previously assigned to Kosovopeltis or Eokosovopeltis from the Sandbian or Katian to Llandovery of North Greenland, Canada, Scotland, South China and New South Wales.