Latitudinal and seasonal patterns in clutch size of some single‐brooded British birds

Capsule Daylength, rather than latitude, was found to be an important determinant of variation in clutch size.

Aims To describe the nature of spatial and temporal variation in clutch size, and explore the ecological correlates of these patterns.

Methods We tested the prediction that seasonal declines in clutch size will be greater at higher latitudes. The environmental variables focused on were the influence of daylength, plant productivity, seasonality (i.e. Ashmole's hypothesis) and physiological mechanisms that relate clutch size to ambient temperature. We used data from 1980 to 2003 on spatial variation in clutch size across Britain for single‐brooded species, in which clutch size can be taken as a measure of annual reproductive investment. We included all seven species, from five families, with sufficient data in the British Trust for Ornithology's Nest Record Scheme.

Results There are strong seasonal declines in clutch size but little evidence for latitudinal gradients in clutch size or in latitudinal gradients in the rate of seasonal clutch size decline. Of the environmental variables investigated, daylength had the most marked effect on clutch size; this was positive in diurnal species and negative in the one nocturnal species.

Conclusions Although this study was confined to a relatively small latitudinal range of 8°, we found marked latitudinal gradients in a number of factors thought to drive spatial patterns in clutch size. Moreover, such variation is of sufficient magnitude to generate spatial patterns in other ecological variables in Britain. There is thus no simple explanation for the lack of a latitudinal gradient in clutch size. The results concerning daylength indicate that the time available for foraging is an important determinant of variation in clutch size.     

Dalton Settlement Systems: Reply to Schiffer(2)

Abstract

Schiffer’s comments on Dalton settlement patterns in the November 1975 issue of the Plains Anthropologist neglects important environmental considerations, references a questionable factor analysis, relies on unsubstantiated statements about human behavior and does not provide adequate test implications for the Schiffer model. A refinement of the Morse model is presented in addition to these criticisms.     

Transgressing community: the case of Muslims in a twenty-first-century British city

Abstract

This paper draws on ethnographic research carried out in Birmingham, UK – a city significant for its sizeable Muslim population and its iconic role in the history of minority ethnic settlement in Britain – to consider how associations of place and ethnicity work in different ways to inform ideas about ‘Muslim community’ in twenty-first-century Britain. The paper charts happenings around a local event in an area of majority Asian settlement and how representations of the area as a place of Muslim community were used to implicate it in the ‘war on terror’. The paper goes on to show how this sensibility is disrupted by Muslims themselves through alternative engagements with space and ethnicity. The paper argues that these offer a ground for making Muslim community in ways that actively engage with histories and patterns of ethnic settlement in the city rather than being determined by them.     

Seasonal variation in dry weight and elemental composition of the early developmental stages of Petrolisthes laevigatus (Guérin, 1835) (Decapoda: Porcellanidae) in the Seno de Reloncaví, southern Chile

In the Seno de Reloncaví, southern Chile, seasonal changes in dry weight (DW) and elemental composition (CHN) were studied in embryo (initial embryonic stage), newly hatched zoeae, and newly settled megalopae of a porcelain crab, Petrolisthes laevigatus. Samples were taken throughout the seasons of egg laying (March-December), hatching (August-February), and settlement (October–February). Values of DW and CHN per embryo or larva, respectively, were consistently minimum in the middle of each season and maximum near its beginning and end. Patterns of seasonal variation in early embryonic biomass may thus be carried over to larvae at hatching and, possibly, to the settlement stage. Such carry-over effects may be selectively advantageous, as zoeae released at the beginning or near the end of the hatching season face conditions of poor planktonic food availability in combination with low winter temperatures or decreasing temperatures at the end of summer (enforcing long development duration). Hence, an enhanced female energy allocation into egg production may subsequently translate to enhanced yolk reserves remaining at hatching, allowing for a larval development under unfavourable winter conditions. In summer, by contrast, plankton productivity and temperatures are generally high, allowing for fast larval growth and development. This coincides with minimal biomass and energy contents both at hatching and settlement. In conclusion, our data suggest that seasonal patterns in the biomass of early developmental stages of P. laevigatus may reflect phenotypic variability as an adaptive response to predictable variations in environmental conditions, allowing this species to reproduce in temperate regions with marked seasonality in water temperature and plankton productivity.     

Dinamica dei sistemi a Cymodocea nodosa,Zostera marina e Zostera noltii nel Mediterraneo

Abstract

Data on geographical and depth distribution, sediment granulometry, salinity, biomass variability, below/aboveground biomass ratio, and reproductive strategies of seagrass communities in the Mediterranean Sea were analysed to describe their dynamics patterns.

Notwithstanding their different latitudinal distribution, they have a similar seasonal biomass variability, deriving both from extrinsic forcing (e.g. light and temperature) and intrinsic species-specific components (e.g. reproduction pattern), these latter being responsible for their different structure and seasonal dynamics.     

Patterns of abundance variation in reef fishes near an artificial reef at Guam

Synopsis Development of the fish community on a submerged 16 m barge and variation in fish abundance on nearby transects were surveyed twice monthly for twenty months. A steady increase in abundance was observed for certain fishes on the barge, whereas a few species exhibited distinct seasonal variation on both the barge and transects. Most of the seasonal species settled between March and May.Some seasonal species appeared to be site selective in their settlement and consequently settled juveniles were clumped in their distribution. An abundance of preferred topographical features may be why settlement was relatively high at the study site and indirectly why predators became significantly (r₃ = 7.67^***, N = 37) more abundant at the study area during the months of maximum prey settlement. Concurrent settlement of several species during the same few months may be important because juveniles become an abundant food source to predators during those few months only. Periodic swamping of predators by abundant juvenile prey may improve the chances for individuals of rarer prey species to be overlooked and therefore be succesfully recruited.     

Discrimination at settlement in barnacles: Laboratory and field experiments on settlement behaviour in response to settlement‐inducing protein complexes

A major driving force to mechanistic studies of barnacle gregarious settlement is to contribute to an understanding of observed patterns of settlement in nature. In particular, how cyprids perceive adult conspecifics and how they discriminate between conspecific and allospecific barnacles are questions which have taxed researchers for nearly 50 years. The putative, active component of adult barnacles to which the cyprids respond has long been known to be a glycoprotein, referred to here as the settlement‐inducing protein complex (SIPC). The present study examines the discriminatory abilities of laboratory‐reared Balanus amphitrite and wild Semibalanus balanoides cyprids at settlement. Using a recently developed nitrocellulose membrane‐choice settlement assay, laboratory studies revealed that both species settled at a significantly higher rate on regions of membrane on which crude conspecific SIPC had been adsorbed compared to untreated regions. Moreover, when offered a choice between conspecific and allospecific SIPC, a trend to greater settlement on the conspecific regions was observed. The membrane assay was also evaluated in field trials using real‐time video footage of cyprid searching behaviour. Of 211 S. balanoides cyprids recorded during exploratory behaviour, only one settled. Exploratory behaviour was, however, clearly associated with regions of the membrane treated with either conspecific or allospecific (B. Amphitrite) SIPC compared to untreated regions. These results are generally in accord with previous reports on the discriminatory abilities of barnacle cyprids and suggest that the membrane assay may be usefully applied to field studies of settlement behaviour.     

Monitoring biofouling communities could reduce impacts to mussel aquaculture by allowing synchronisation of husbandry techniques with peaks in settlement

Fouling organisms in bivalve aquaculture cause significant economic losses for the industry. Managing biofouling is typically reactive, and involves time- and labour-intensive removal techniques. Mussel spat settlement and biofouling were documented over 20 months at three mussel farms within Port Phillip Bay (PPB), Australia to determine if knowledge of settlement patterns could assist farmers in avoiding biofouling. Mussel spat settlement was largely confined to a 2-month period at one farm. Of the problematic foulers, Ectopleura crocea settlement varied in space and time at all three farms, whilst Ciona intestinalis and Pomatoceros taeniata were present predominantly at one farm and exhibited more distinct settlement periods. Within PPB, complete avoidance of biofouling is impossible. However, diligent monitoring may help farmers avoid peaks in detrimental biofouling species and allow them to implement removal strategies such as manual cleaning, and postpone grading and re-socking practices, until after these peaks.     

Evaluating spatiotemporal dynamics of snakebite in Sri Lanka: Monthly incidence mapping from a national representative survey sample

BackgroundSnakebite incidence shows both spatial and temporal variation. However, no study has evaluated spatiotemporal patterns of snakebites across a country or region in detail. We used a nationally representative population sample to evaluate spatiotemporal patterns of snakebite in Sri Lanka.MethodologyWe conducted a community-based cross-sectional survey representing all nine provinces of Sri Lanka. We interviewed 165 665 people (0.8% of the national population), and snakebite events reported by the respondents were recorded. Sri Lanka is an agricultural country; its central, southern and western parts receive rain mainly from Southwest monsoon (May to September) and northern and eastern parts receive rain mainly from Northeast monsoon (November to February). We developed spatiotemporal models using multivariate Poisson process modelling to explain monthly snakebite and envenoming incidences in the country. These models were developed at the provincial level to explain local spatiotemporal patterns.Principal findingsSnakebites and envenomings showed clear spatiotemporal patterns. Snakebite hotspots were found in North-Central, North-West, South-West and Eastern Sri Lanka. They exhibited biannual seasonal patterns except in South-Western inlands, which showed triannual seasonality. Envenoming hotspots were confined to North-Central, East and South-West parts of the country. Hotspots in North-Central regions showed triannual seasonal patterns and South-West regions had annual patterns. Hotspots remained persistent throughout the year in Eastern regions. The overall monthly snakebite and envenoming incidences in Sri Lanka were 39 (95%CI: 38–40) and 19 (95%CI: 13–30) per 100 000, respectively, translating into 110 000 (95%CI: 107 500–112 500) snakebites and 45 000 (95%CI: 32 000–73 000) envenomings in a calendar year.Conclusions/significanceThis study provides information on community-based monthly incidence of snakebites and envenomings over the whole country. Thus, it provides useful insights into healthcare decision-making, such as, prioritizing locations to establish specialized centres for snakebite management and allocating resources based on risk assessments which take into account both location and season.     

四川省内异地就医联网结算管理实践探索

四川省内基本医疗保险异地就医联网结算试点工作已全面启动。四川省肿瘤医院作为首批联网试点医院,积极顺应联网结算需求,主动创新、完善服务内涵、畅通服务流程,全面落实了实现异地就医即时结算的主要措施,极大方便了异地就医人群,取得了显著的社会效益。异地就医联网结算是一项全新工作,针对运行中存在的问题提出建议,为完善异地医保的服务与管理提供参考。     

The Role of <Emphasis Type="Italic">Habitus</Emphasis> in the Maintenance of Traditional Noongar Plant Knowledge in Southwest Western Australia

We examine the role that habitus, an individual’s or group’s dispositions, has played in the retention of traditional ecological knowledge among the Noongar people of south-western Australia. We sought to determine if current plant knowledge reflects Noongar habitus or, alternatively, the use of fall-back species that were important due to the intermittency of agricultural employment and the social exclusion of Aboriginal people up until at least the 1960s in Western Australia. We compared the seasonal availability of Noongar food plant resources currently known by Noongar Elders to those described at the time of European settlement. We used non-metric Multidimensional Scaling (nMDS) and multivariate statistics to compare the seasonal availability of plant resources with the seasonal availability of work prior to the introduction of civil rights for Aboriginal Australians in the 1960s. We show that the seasonal pattern of plant knowledge has changed little since settlement and that there was no significant relationship between the seasonal availability of work and plant knowledge. This result suggests that prior to 1960 Noongars maintained a reasonably traditional round of seasonal activities involving traditional plant use. We suggest that Noongar habitus guided their response to the colonising culture and helped preserve traditional ecological knowledge.     

Temporal patterns of bird mortality due to road traffic collisions in a Mediterranean region

ABSTRACT

Capsule: There was significant variation on the incidence of road traffic mortality across bird species, due to seasonal and weather effects but also due to differences between years.

Aims: To assess patterns of mortality due to traffic collision for six common bird species over a period of nine years in relation to seasonality and weather.

Methods: Road mortality surveys were performed on four road sections from 2005 to 2013 in southern Portugal. The analysis controlled for survey frequency, and carcass persistence and detectability.

Results: Overall, bird mortality decreased over time and was generally higher during spring and summer months. The lack of strong relationships between the weather variables and the observed mortality patterns suggests the existence of additional factors important in explaining the observed trends.

Conclusions: Our study provides evidence that bird mortality due to collision with vehicles may change between years and was highest during the breeding season. This could have population consequences, and highlights the need to further address large temporal scales in roadkill research.     

Proceedings of the New Zealand Society for Parasitology

Abstract

The influence of supplemental food on Rattus exulans populations was investigated by comparing results on a long established live trapping grid (control) with an experimental grid where a constant amount of wheat was provided each month. Parameters such as time of sexual maturity, length of breeding season, growth rates, body weights, and population cycles were compared and all appeared affected by additional food. The large seasonal fluctuations in natural food still exerted an important influence on demographic patterns.     

Chagas Disease,Migration and Community Settlement Patterns in Arequipa,Peru

Background

Chagas disease is one of the most important neglected tropical diseases in the Americas. Vectorborne transmission of Chagas disease has been historically rare in urban settings. However, in marginal communities near the city of Arequipa, Peru, urban transmission cycles have become established. We examined the history of migration and settlement patterns in these communities, and their connections to Chagas disease transmission.

Methodology/Principal Findings

This was a qualitative study that employed focus group discussions and in-depth interviews. Five focus groups and 50 in-depth interviews were carried out with 94 community members from three shantytowns and two traditional towns near Arequipa, Peru. Focus groups utilized participatory methodologies to explore the community''s mobility patterns and the historical and current presence of triatomine vectors. In-depth interviews based on event history calendars explored participants'' migration patterns and experience with Chagas disease and vectors. Focus group data were analyzed using participatory analysis methodologies, and interview data were coded and analyzed using a grounded theory approach. Entomologic data were provided by an ongoing vector control campaign. We found that migrants to shantytowns in Arequipa were unlikely to have brought triatomines to the city upon arrival. Frequent seasonal moves, however, took shantytown residents to valleys surrounding Arequipa where vectors are prevalent. In addition, the pattern of settlement of shantytowns and the practice of raising domestic animals by residents creates a favorable environment for vector proliferation and dispersal. Finally, we uncovered a phenomenon of population loss and replacement by low-income migrants in one traditional town, which created the human settlement pattern of a new shantytown within this traditional community.

Conclusions/Significance

The pattern of human migration is therefore an important underlying determinant of Chagas disease risk in and around Arequipa. Frequent seasonal migration by residents of peri-urban shantytowns provides a path of entry of vectors into these communities. Changing demographic dynamics of traditional towns are also leading to favorable conditions for Chagas disease transmission. Control programs must include surveillance for infestation in communities assumed to be free of vectors.     

Aboriginal Demographic Changes in Central Texas

Abstract

Over the past decade a wealth of information about the types, location and density of aboriginal campsites in Central Texas has been gathered. During the same period, chronological ordering has been refined and studies have begun to focus upon changes in man to land relations in time and space. Using the available paleoenvironmental data, an explanatory model is proposed which reconstructs the shifting settlement patterns and population densities which preceded the widely dispersed historic Anglo American settlement of Central Texas in the 1800s.     

A bacterial polysaccharide biosynthesis-related gene inversely regulates larval settlement and metamorphosis of Mytilus coruscus

Abstract

Larval settlement and metamorphosis is essential for the development of marine invertebrates. Although polysaccharides are involved in larval settlement and metamorphosis of Mytilus coruscus, the molecular basis of polysaccharides underlying this progression remains largely unknown. Here, the roles of the polysaccharide biosynthesis-related gene 01912 of Pseudoalteromonas marina ECSMB14103 in the regulation of larval settlement and metamorphosis were examined by gene-knockout technique. Compared with biofilms (BFs) of the wild-type P. marina, Δ01912 BFs with a higher colanic acid (CA) content showed a higher inducing activity on larval settlement and metamorphosis. Deletion of the 01912 gene caused an increase in c-di-GMP levels, accompanied by a decrease in the motility, an increase in cell aggregation, and overproduction of CA. Thus, the bacterial polysaccharide biosynthesis-related gene 01912 may regulate mussel settlement by producing CA via the coordination of c-di-GMP. This work provides a deeper insight into the molecular mechanism of polysaccharides in modulating mussel settlement.     

Development in an estuarine fouling community: The influence of early colonists on later arrivals

Summary Experiments were performed to determine if earlier colonists inhibited, enhanced, or were necessary for establishment of later colonists during development of an estuarine fouling community at Lewes, Delaware. We determined the significance of earlier stages on the successional process by functionally removing early colonizing species. Since settlement of sessile invertebrates onto our experimental test plates was seasonal, we were able to accomplish functional removal of early colonists by putting out clean test panels after these species had ceased settling. Comparisons between panels initially submerged at three different times in 1974 and 1975, and between panels put out at one-month intervals throughout the study (to describe seasonal settlement patterns) allowed us to determine interactions between adult populations of earlier colonists and colonizing individuals of later arriving species.The dominant sessile species in our system and their times of settlement were: a barnacle (Balanus improvisus) — April through June, a polychaete (Hydroides dianthus) — July and August, a tunicate (Molgula manhatensis) — June through October, a hydroid (Tubularia crocea) — July through October, and a mussel (Mytilus edulis) — November through April. All successional series eventually came to be dominated by M. edulis, and it persisted as the dominant for over a year.A variety of species interactions were observed. M. edulis inhibited colonization by all other dominants and B. improvisus partially inhibited settlement of M. manhattensis. The presence of adult M. manhattensis had no influence on summer settlement of T. crocea, but the hydroids enhanced settlement of tunicates in the fall. During both years of our study, larger settlements of mussels were noted on panels harboring tunicates and hydroids than on bare surfaces. H. dianthus, on the other hand, became established only on bare substrates, and colonization was almost totally inhibited by other dominants.Development in our fouling community did not conform to any single model of community development presented to date. Instead, components of several models were observed within our relatively simple (in terms of number of species) system. For example, facilitation (enhancement of later colonists by earlier ones) and inhibition (resistance of earlier colonists to invasion by later colonists) were both observed. However, we found no evidence earlier colonists were essential for establishment of the next developmental stage. In fact, inhibitory interactions appeared to be much more prevalent than facilitative interactions. The former may also have more profound effects on community development since they more often determine eventual species compositions.     

Winter gas exchange between the atmosphere and snow-covered soils on Niwot Ridge,Colorado, USA

Background: There is a growing interest in understanding the gas exchange between the atmosphere and seasonally snow-covered regions, especially in light of projections that climate change will alter the timing and extent of seasonal snow cover. In snow-covered ecosystems, gas fluxes are due both to microbial activity in the snow-covered soils and to chemical and physical reactions with the various gases and/or dissolved constituents in the snowpack. Niwot Ridge, in the Colorado Rocky Mountains, has one of the most extensive sets of measurements of winter gas exchange globally.

Aims: Our goal was to examine the temporal patterns and environmental controls on Niwot Ridge of gas fluxes for gases with different sources and sinks.

Methods: Here, we review the concentrations and fluxes that have been measured for carbon dioxide, nitrous oxide, methane, nitrogen oxides, ozone, gaseous elemental mercury and volatile organic carbon compounds.

Results and Conclusions: We looked for similarities and differences among the gases, but in many cases, the origin, fate and controls of these fluxes still need to be determined. However, we believe that many of the biologically driven reactions are the result of exponential growth of a winter microbial community during the long period of stable environmental conditions under the seasonal snowpack.     

Chemical induction of settlement and metamorphosis of Capitella capitata Sp. I (Polychaeta) larvae by juvenile hormone-active compounds

Summary

The influence of juvenile hormone (JH)-active chemicals on the settlement and metamorphosis of metatrochophore larvae of the polychaete annelid Capitella sp. I of the Capitella complex has been investigated. These studies demonstrate that JH-active chemicals are able to induce settlement and metamorphosis of Capitella larvae, and that these effects may possibly be mediated by protein kinase C induction. Evidence for the presence of JH-active compounds in marine sediments is also presented, suggesting that these chemicals may serve a natural role as chemical cues for settlement and metamorphosis for Capitella larvae in the marine environment.     

Phylogenetic restriction of plant invasion in drought‐stressed environments: Implications for insect‐pollinated plant communities in water‐limited ecosystems

BackgroundPlant–pollinator community diversity has been found to decrease under conditions of drought stress; however, research into the temporal dimensions of this phenomenon remains limited. In this study, we investigated the effect of seasonal drought on the temporal niche dynamics of entomophilous flowering plants in a water‐limited ecosystem. We hypothesized that closely related native and exotic plants would tend to share similar life history and that peak flowering events would therefore coincide with phylogenetic clustering in plant communities based on expected phenological responses of plant functional types to limitations in soil moisture availability.LocationGaliano Island, British Columbia, Canada.MethodsCombining methods from pollinator research and phylogenetic community ecology, we tested the influence of environmental filtering over plant community phenology across gradients of landscape disturbance and soil moisture. Floral resource availability and community structure were quantified by counts of flowering shoots. We constructed a robust phylogeny to analyze spatial and temporal variation in phylogenetic patterns across the landscape, testing the significance of the observed patterns against a randomly generated community phylogeny. Phylogenetic metrics were then regressed against factors of disturbance and soil moisture availability.ResultsCritical seasonal fluctuations in floral resources coincided with significant phylogenetic clustering in plant communities, with decreasing plant diversity observed under conditions of increasing drought stress. Exotic plant species in the Asteraceae became increasingly pervasive across the landscape, occupying a late season temporal niche in drought‐stressed environments.Main conclusionResults suggest that environmental filtering is the dominant assembly process structuring the temporal niche of plant communities in this water‐limited ecosystem. Based on these results, and trends seen elsewhere, the overall diversity of plant–pollinator communities may be expected to decline with the increasing drought stress predicted under future climate scenarios.