bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial seasonality of breeding in red‐necked wallabies (Macropus rufogriseus banksianus
Authors: Higginbottom Karen , Johnson Christopher N.
Published: February 2006

Reproductive data on individually known free‐ranging red‐necked wallabies Macropus rufogriseus banksianus were obtained over a 6 year period. Although this subspecies is essentially a non‐seasonal continuous breeder, more young wallabies emerged permanently from the pouch in spring than in any other season. This partial seasonality of breeding was the combined result of seasonal variation in duration of pouch lives, a tendency for the first young of females to emerge permanently in spring, and seasonal variation in the incidence of reproductive interruptions. It is proposed that the adaptive significance of this partial seasonality is that it maximizes juvenile survival while maintaining a high reproductive rate.
New and little‐known species of Rhagidiidae from talus ecosystems, in the Czech Republic and Austria
Authors: Zacharda Miloslav
Published: February 2006

Two new species of mites,Foveacheles (Proxistella) simulatan.sp. andRhagidia longisetan.sp., are described, and the little‐knownFoveacheles (Proxistella) terricola(C. L. Koch) is redescribed. All species were found inhabiting underground spaces in talus formations in the Czech Republic and Austria.
The oral anatomy of Arctic ruminants: coping with seasonal changes
Authors: Mathiesen S. D. , Sørmo W. , Haga Ø. E. , Norberg H. J. , Utsi T. H. A. , Tyler N. J. C.
Published: February 2006

We studied the feeding apparatus of three species of northern ruminants representative of three feeding types: muskoxen Ovibos moschatus, Norwegian reindeer Rangifer tarandus tarandus and high Arctic Svalbard reindeer Rangifer tarandus platyhrynchus and Siberian musk deer Moschus moschiferus. The shape of the muzzle, the incisor arcade, the incisiform and the molariform teeth indicate that these species are selective feeders, irrespective of their body size or their position on the gazer‐concentrate selector continuum of feeding types. Narrow muzzles seem well adapted for selective feeding on the diminutive but highly nutritious plants, or parts of plants, on tundra swards and Arctic‐alpine meadows and enable the animals to maximize nutrient intake during the short summer. However, their small mouths presumably also restrict reindeer and muskoxen to taking small bites, thereby achieving low rates of dry matter intake when feeding on the very short swards in winter. This is partially obviated by two general strategies; a reduction of energy requirements in winter and, in Norwegian reindeer, migration inland to where foraging conditions are generally more favourable. In Svalbard reindeer, which have little access to lichens or other easy digestible plants in winter, rumen fill increases through the accumulation of slowly fermenting fibrous foods. Despite their narrow muzzles, reindeer and muskoxen are unable to avoid ingesting a certain amount of poor quality forage in winter and cope with this by appropriate modification of digestive function.
Diet composition, rumen papillation and maintenance of carcass mass in female Norwegian reindeer (Rangifer tarandus tarandus) in winter
Authors: Mathiesen S. D. , Haga Ø. E. , Kaino T. , Tyler N. J. C.
Published: February 2006

The uptake of volatile fatty acids (VFAs) from bacterial fermentation of forage in the rumen is enhanced by the presence of papillae which greatly increase the surface area of the mucosa of the rumen. The degree of papillation, expressed as the surface enlargement factor (SEF), seems to be closely related to the level of microbial activity and the rate of production of VFAs in the rumen. In several species of wild ruminants the SEF decreases markedly in winter, apparently in response to a decrease in the quality and availability of forage and also, presumably, in the level of ruminal microbial activity. Contrary to expectation, however, no reduction in the rate of production of VFAs in winter has been detected in semi‐domesticated reindeer at natural pasture in northern Norway. We investigated the body mass, the composition and quality of the diet and the morphology of rumen papillae in adult female reindeer free‐living at natural pasture. Animals were slaughtered in matched aged groups of nine on four occasions: in autumn (September) and winter (November, February and March). The composition and quality of the diet was determined by morphological and chemical analysis of plant fragments recovered from the rumen. The carcass mass of the animals did not differ significantly between collections. The animals ate vascular plants and lichens from 37 different genera. The composition of the diet varied little between months except for the inclusion of a substantial proportion (25.8% of fragments) of lichens in March. The mean density of rumen papillae increased from 55.6 papillae/cm2 in September to 75.7 papillae/cm2 in March (P < 0.001). All other parameters, including the length and perimeter of the papillae and the SEF of the rumen, were lower in March compared with September. However, the mean SEF increased from 8.8 in February to 10.6 in March (P < 0.05), indicating increased ruminal fermentation in late winter. We propose that the increase in the SEF in March might be associated with the increase in the proportion of lichens in the diet. Lichens are highly digestible in reindeer but do not score highly in conventional analyses of diet quality owing to the unusual chemical structure of the structural carbohydrates of which they are composed.
The arctic fox (Alopex lagopus): an opportunistic specialist
Authors: Elmhagen Bodil , Tannerfeldt Magnus , Verucci Paolo , Angerbjörn Anders
Published: February 2006

Reliable and abundant resources are likely to favour specialization, while unpredictable environmental variation should favour a generalist strategy. The rodent population cycles of northern latitudes can be seen as both predictable and unpredictable, depending on the scale in time and space. The arctic foxAlopex lagopusis an opportunistic carnivore, but paradoxically, it seems to function as a specialist on fluctuating rodent Arvicolinae populations in most inland areas. We have studied the dietary response of arctic foxes in Sweden during 5 years of varying abundance of Norwegian lemmingLemmus lemmus, and how these changes influenced the reproductive success of the foxes. The arctic fox population on mainland Fennoscandia is threatened by extinction and the situation has deteriorated during the 1980s and 1990s because of an absence of lemming peaks. Our results showed that in all years, lemming was the main prey for arctic foxes, with 85% frequency of occurrence in summer faeces (scats). Bird remains (mainly Passeriformes) were present in 34% of the scats, reindeerRangifer tarandusin 21%, voles and shrews in 4% and haresLepus timidusin 2% of the scats. The occurrences of lemming, bird and larger mammal (reindeer and hare) remains in the scats varied significantly between years. Temporal variations within summer seasons and dietary differences between sub‐areas, indicated that arctic foxes fed opportunistically on the alternative prey types. Den occupancy rates were positively correlated with lemming population densities during the previous winter, indicating a strong numerical response. We conclude that from a functional aspect, the arctic fox in Sweden is a lemming specialist, since lemming is the main prey and their abundance is the best predictor of arctic fox reproductive success. Other prey are used opportunistically in relation to their availability.
Social structure of a polygynous tent‐making bat,Cynopterus sphinx(Megachiroptera)
Authors: Storz Jay F. , Bhat Hari R. , Kunz Thomas H.
Published: February 2006

The social structure of an Old World tent‐making batCynopterus sphinx(Megachiroptera), was investigated in western India. A combination of census and mark–recapture data over 2 years (1996–98) was used to infer the form of the mating system, compositional stability of social groups and mode of new social group formation. The breeding population ofC. sphinxwas subdivided into diurnal roosting colonies, each of which contained one to five discrete roosting groups and often one or more solitary bats in adjacent roosts. Bats most frequently roosted in stem tents constructed in the flower/fruit clusters of the kitul palmCaryota urens. Temporal variation in social structure was assessed using visual census data for a subset of the study population over 3 years (1995–98) spanning six consecutive reproductive periods. The sex and age composition of diurnal roosting groups indicated a polygynous harem‐forming mode of social organization, as groups invariably contained a single adult male, 1–37 reproductive females and their dependent young (n= 33 harems). Harem size averaged 6.1 adults in the wet season (n= 19,sd= 3.5) and 13.6 adults in the dry season (n= 14,sd= 8.5). The same harem social configuration was maintained year‐round, despite a high degree of synchrony and seasonality in the timing of reproduction. Juveniles of both sexes dispersed after weaning and sexually immature bats were never present in harems at the time of parturition. Adult females often remained associated as roostmates from one parturition period to the next, and group cohesion was unaffected by turnover of harem males. Adult females frequently transferred among roosts within the same colony, and harems underwent periodic fissions and fusions. The founding of new harems most often resulted from the fissioning of previously cohesive harems within the same colony. However, some harems contained disproportionate numbers of yearling females, indicating that new groups are also founded by nulliparous females of the same age cohort. A significant degree of heterogeneity in age composition among harems was revealed in the 1998 dry season, but was unrelated to age‐stratification of tent roosts. Although formation of new harems may be non‐random with respect to age composition of the founders, founding events are not restricted to newly created tents and often involve recolonization of previously occupied roosts.
Effects of temporal and spatial variations in food supply on the space and habitat use of red squirrels (Sciurus vulgaris L.)
Authors: Lurz Peter W. W. , Garson P. J. , Wauters Luc A.
Published: February 2006

In non‐native conifer plantations characterized by strong spatial and temporal variations in the availability of tree seeds in Spadeadam Forest, northern England, the home range and habitat use of red squirrels Sciurus vulgaris was very flexible. Males tended to have much larger home ranges than females and core‐areas of most breeding females seemed mutually exclusive. Adult female red squirrels were found to increase their home range and core‐area size in forest patches where food was less abundant. Home‐range size was significantly related to home‐range quality and the extent of overlap by other females. In contrast with high‐quality continuous conifer forests: (1) a considerable proportion of adult males and females at Spadeadam shifted home range, (2) both sexes had much larger home ranges than reported from other habitats in Britain or Belgium. Many ranges were multinuclear, particularly from January onwards, when supplies of seeds become depleted through consumption and seed shed. Squirrels tracked the availability of conifer seeds (lodgepole pine cones throughout the study, Norway spruce cones in spring 1992 and Sitka spruce cones in autumn 1993) and intensively used several non‐adjacent activity centres in temporally food‐rich patches. Consequently, habitat preference changed markedly with time. The squirrels seemed to maximize nitrogen intake and to avoid the smaller seeds when possible. This resulted in an overall preference for a mixed diet of lodgepole pine and spruce seeds and avoidance of Sitka spruce seeds when Norway spruce seeds were available. These results lend support to the hypothesis of Ostfeld (1985) that when food is sparse and patchily distributed, females should develop intrasexual territoriality, concentrating their activity in food‐rich patches, while males should be non‐territorial and adapt their space use to the distribution of females.
Are calcitic layers an effective adaptation against shell dissolution in the Bivalvia?
Authors: Harper E. M.
Published: February 2006

Conventional wisdom, based on properties of reagent‐grade salts, states that organisms which construct their exoskeletons from calcite rather than aragonite have a greater ability to resist dissolution. However, experiments on individual bivalve microstructures show that other factors such as crystal size and the proportion of organic matrix outweigh constituent mineralogy in determining the rate of shell loss in cold waters. Moreover, the loss of shell material was minimal, corresponding to an annual loss in shell thickness of 3–40 μm depending on microstructure. These findings must cast doubt on the commonly held supposition that calcitic layers added to the outside of shells are an adaptation against dissolution in Holocene ‘Aragonite’ seawater.
Abundance, demographics and body condition of a translocated population of St Lucia whiptail lizards (Cnemidophorus vanzoi)
Authors: Dickinson H. C. , Fa J.E.
Published: February 2006

The whiptail lizard Cnemidophorus vanzoi is a large‐bodied teiid found only on two islands (Maria Major and Maria Minor), off St Lucia, West Indies. In May 1995, 42 lizards from Maria Major were introduced to the smaller uninhabited Praslin Island on the same coastline. Three years post‐release, we studied abundance, demography and morphometrics of the translocated lizard population, during a 6‐month period covering wet and dry seasons. Age, sex, snout–vent length (SVL), body mass (BM), tail length, tail regeneration, and overall condition (moulting, reproductive condition, cuts, external parasites) of 107 animals caught during the study are analysed in the present paper. Comparisons are also made with the source population. A body condition index (CI (BM/SVL)), sex ratio (adult males : adult females), age ratio (adults : juveniles), and sexual size dimorphism ratio (SVL adult male : SVL adult females) were calculated for the study population. Distance sampling and mark–re‐sight surveys were used to estimate population size and lizard density. A total of 155 ± 26 individuals were estimated. The lizard population was found to have a high growth rate (r= 0.97–3.95). There were significant seasonal changes in lizard abundance. Seasonal differences in lizard numbers, BM and CI suggest either severe resource limitation during the dry season, or selective aestivation. A high frequency of tail autotomy may point to intense intraspecific competition as the island is relatively free from main predators such as the black rat Rattus rattus. Sex ratio, sexual size dimorphism and sexual dichromatism all indicate a territorial species in a generally non‐territorial family (Teiidae). Some adult males seem to maintain juvenile colours. It is suggested that the introduced population has successfully colonized its new environment and that no significant change in the animals condition or size has occurred during the 3 years since translocation.
Range extension and microhabitat of Lightiella incisa (Cephalocarida)
Authors: De Troch Marleen , Fiers Frank , Vincx Magda
Published: February 2006

During an intensive meiofauna sampling campaign in intertidal seagrass beds along the Caribbean coast of the Yucatán Peninsula (Mexico), 131 specimens of Lightiella incisa (Cephalocarida, Crustacea) were recovered from the sediment. Two‐thirds of the specimens were adults, one‐third were pre‐adults. This collection is the first record of this minute primitive crustacean in the western part of the Caribbean Sea, and extends the known range 3000 km from the type locality of Hastings Bay, Barbados. A detailed sampling protocol and environmental data made it possible to study the microhabitat preferences of this species, and perhaps for cephalocarids in general for the first time. The vertical distribution of L. incisa in the sediment showed a maximum density in deeper layers, i.e. 3–4 and 4–5 cm depth. Nitrate and nitrite concentrations seem to be most closely related to the distribution of L. incisa. It was clear that L. incisa followed polychaetes to deeper sediment layers. In this study we state that L. incisa is an endobenthic species occupying anoxic sediments oxygenated by bioturbation (e.g. Polychaeta) rather than being an animal living in the oxygenated top layers.
Climate, vegetation, and predictable gradients in mammal species richness in southern Africa
Authors: Andrews Peter , O'Brien Eileen M.
Published: February 2006

Many hypotheses have been proposed to account for geographic variations in species diversity. In general these relate to some aspect of climate, particularly climatic variables measuring available or potential energy, but while these relate directly to plant diversity they may only indirectly affect mammal species richness. We have examined these relationships by mapping and correlating mammal species richness in southern Africa (n= 285 species) with 15 climatic variables, two topographic variables, and woody plant species richness (n= 1359 species). The effect of area on richness was held a constant by using an equal‐area grid cell matrix superimposed on species range maps, with each grid cell equal to 25 000 km2. We found that variability in the plant species richness alone accounts for 75% of the variability in mammal species richness. Of the climatic variables, only thermal seasonality approaches this figure, accounting for 69% of the variability, while annual measures of temperature, precipitation or energy account for only 14–35% of variability. Differences from North American mammal diversity studies, where annual temperature, and hence annual potential evapotranspiration (PET), have been found to be more important, are attributed in part to southern Africa's climate and vegetation being largely temperate to tropical, as opposed to temperate to polar in North America. By distinguishing different types of mammal based on size, spatial and dietary guilds, other differences emerge. Strong correlations with annual temperature exist only for large mammals, accounting for 60–67% of the variability in species richness of large mammals compared with <20% for small mammals. Small mammals are strongly correlated with other climatic or vegetation parameters, especially plant richness and thermal seasonality; frugivorous and insectivorous mammal richness is correlated with thermal seasonality and minimum monthly PET; and arboreal and aerial species richness is correlated with plant richness, thermal seasonality and minimum monthly PET. Up to 77% of the variability in richness of arboreal, frugivorous and insectivorous species can be explained by woody plant richness, compared with only 38–48% of the variability in terrestrial herbivores. It is clear from this that different kinds of mammals are differentially affected by climatic and environmental factors, and this explains some of the discrepancies found in earlier studies where no distinction was made between different sizes or guilds of mammal. This result has implications both for the conservation of mammalian communities at the present time and for understanding the evolution and structure of mammalian communities in the past.
Carnivory in the greater noctule bat (Nyctalus lasiopterus) in Italy
Authors: Dondini G. , Vergari S.
Published: February 2006

An analysis of 59 droppings of the greater noctule Nyctalus lasiopterus, collected either during direct handling of the bat or from the bat‐boxes used as shelters in the Pian di Novello Natural Reserve (Tuscany, Italy), has shown that it is a partial carnivore. The content of the samples, collected in October and November of 1995 and in September and October of 1996 and 1997, consisted mainly of bird feathers identified as those of the robin Erithacus rubecula and the blue tit Parus caeruleus. The presence of feathers during the 3 consecutive years of the study period confirms that the diet of the greater noctule in this area is not based exclusively on arthropods as was previously suggested.
Fox (Vulpes vulpes) management in three contrasting regions of Britain, in relation to agricultural and sporting interests
Authors: Heydon Matthew J. , Reynolds Jonathan C.
Published: February 2006

Fox culling practices in three contrasting rural regions (1280–2320 km2) of Britain were investigated by questionnaire surveys of landowners and tenant farmers. Between 50 and 52% of all farmers identified in each region contributed to the survey (total number of replies = 1123). Fox culling was widespread in all regions, with 70–95% of farmers involved either directly or indirectly as hosts. Motivation for culling foxes and the methods employed reflected regional variation in agricultural and game‐shooting interests. Social factors associated with fox‐hunting for sport also played an important role in one region. The contribution to the total fox cull made by communally organized groups operating over large tracts of farmland, and the efforts of individual farmers at a local scale, also varied regionally. The numbers of foxes culled were close to published estimates of annual productivity in British fox populations. Deliberate culling was therefore likely to be the chief cause of fox mortality in these regions. The marked differences in culling practices between these regions provide a strong case that the impact of culling on fox population dynamics must be assessed for regions of this size, as well as at a more local scale. Studies at a national scale (e.g. the whole of Britain) are probably of little biological or sociological significance. The success of different interest groups in achieving their aims, and the consequences of any change in culling practices must also be considered at a similar geographical scale.
Reduced access to olfactory cues and home‐range maintenance in the sleepy lizard (Tiliqua rugosa)
Authors: Zuri I. , Bull C. M.
Published: February 2006

Sleepy lizards Tiliqua rugosa are large, long‐lived, Australian skinks that live in stable home ranges. Previous studies showed that the lizards have a good sense of orientation and navigation towards home. However, since they are active only 4 months in every year, there is a question about which environmental cues enable them to locate their home boundaries. In the present study we determined whether surrounding olfactory and chemical cues are important for the sleepy lizards for home‐range maintenance. In the first part of the study we showed in the laboratory that zinc sulphate (ZnSO4) is a chemical that induces anosmia and prevents detection of chemical cues in sleepy lizards for up to 30 days, with no evident long‐term harm to the animals. We then monitored the location of 50 radio‐tagged sleepy lizards. After determining their home ranges they were divided into three groups: an untreated control, a saline‐treated (sham‐operated) group and a ZnSO4‐treated group. Starting 2 days after the treatment, the home ranges of all lizards were re‐determined within the period that ZnSO4 blocked olfaction. Three variables were calculated comparing home ranges before and after treatments: the change in home‐range size, the distance between the centre of activities of the lizards, and the overlap between the individual home ranges before and after treatments. Lizard home ranges varied from 1.9 ± 0.6 ha to 4.6 ± 1.4 ha before treatment, and 1.3 ± 0.3 ha to 3.1 ± 0.7 ha after treatment. There was no significant effect of treatments or of sex on the home‐range size or on the distances between the centre of activities, or on the overlap between the individual home ranges. Our data indicate that olfaction and vomerolfaction are not a major cue for home‐range maintenance in the sleepy lizards.
A description of the nuchal organ, a possible photoreceptor, in Euprymna scolopes and other cephalopods
Authors: Parry Matthew
Published: February 2006

A type of apparent photoreceptor, the nuchal organ, is described in the sepiolid squid Euprymna scolopes. These vesicles are identified in a variety of other cephalopod species. The nuchal organs have specific structural similarities to the already well‐described photosensitive vesicles. Both organs have a distinct vesiculate structure and possess a rind consisting of several types of cells. Certain rind cells from both organs send processes with microvilli into the lumen of the vesicle forming a core area. Within the cores of both organs numerous microvilli occupy much of the core volume. These histological similarities provide strong evidence that the nuchal organs, like the photosensitive vesicles, are photoreceptors. Three distinct differences also exist between the nuchal organs and photosensitive vesicles: (1) the location of the nuchal organs differs from that of all known photosensitive vesicles in cephalopods; (2) the location of the nuchal organs is highly conservative in decapod cephalopods compared to the varying locations of the photosensitive vesicles; (3) the degree of structural order generally found within photosensitive vesicles is not apparent in the nuchal organs. The function of the nuchal organ is probably different from previously described photoreceptors in cephalopods.
Variation of eye size in butterflies: inter‐ and intraspecific patterns
Authors: Rutowski Ronald L.
Published: February 2006

Differences in behaviour, such as the mate‐locating tactic, may favour the evolution of interspecific and intersexual differences in the structure of the visual system. This notion was tested by examining the relationships between eye size, body size, sex and mate‐locating tactic in 16 species of butterflies. The 16 species were grouped in eight phylogenetically close pairs that differed in the mate‐locating tactic displayed by the males. Eye size was characterized by eye surface area, which was estimated from a set of linear eye measurements made on 10 individuals of each sex in each species. The major findings were that eye surface area was positively correlated with body size both among and within species, males have larger eyes relative to their body size than females, and after controlling for body size and phylogeny, interspecific differences in the mate‐locating tactic of males does not explain interspecific variation in the size of male eyes or in the magnitude of sexual difference in eye size. The optical and behavioural consequences of variation in eye size with body size and sex will await a better understanding of how eye structure varies with size within and between species.
Factors affecting the abundance of rabbits (Oryctolagus cuniculus) in England and Wales
Authors: Trout R. C. , Langton S. , Smith G. C. , Haines‐Young R. H.
Published: February 2006

Data gathered from the Ministry of Agriculture, Fisheries and Food (MAFF) National Rabbit Survey sites in the 1980s showed substantial site‐to‐site and year‐to‐year variation in rabbit Oryctolagus cuniculus abundance. Data on physical and biological factors from 450 sites were collected to seek explanations for this variation. The rabbit abundance index on the 2.25 km transects (walked along the edge of fields, woods, hedges, etc.) was used as the dependent variable for multiple regression and principal components analyses. Additionally, a preliminary attempt at mapping rabbit abundance and distribution in England and Wales using a GIS system was made. Each of the analyses produced a list of the important variables enhancing or reducing rabbit indices. Common to each list were aspects of woodland – area, number of pieces and length of edge; the dryness and patchiness of soils on site; rainfall in late winter, or variables associated with wetness of soil (e.g. number of days with rain, altitude). Other important variables included predator removal policy and the site location nationally. The two strongest components, woodland parameters and predator removal policy, are under human influence. The effects of region, county and year were small, but year‐to‐year variation within sites was larger, suggesting that rabbit populations were reacting markedly to unmeasured variables, e.g. myxomatosis outbreaks. The analysis provides a useful explanation of the factors that affect rabbit populations and a basis for how these factors may be manipulated.
Allozymic variation and systematic relationships of the Octodontidae and allied taxa (Mammalia, Rodentia)
Authors: Köhler N. , Gallardo M. H. , Contreras L. C. , Torres‐Mura J. C.
Published: February 2006

Genetic variation and the allozymic relationships of five families comprising 23 species of hystricognath rodents were examined using electrophoretic data from 19 presumptive gene loci. Direct‐count heterozygosity ranged from 0% to 13.6%, and polymorphism varied from 0% to 36.8%. Fixed allele differences were instrumental for the segregation of taxa as summarized by the Distance Wagner procedure and by majority‐rule consensus trees. The monophyly of the Octodontidae, and the family rank of the Abrocomidae and Ctenomyidae is supported by the data. Monotypic Myocastor coypus is not resolved as a distinct family but appeared within the Caviidae. Within the Octodontidae, paraphyly was detected in polytypic Octodon, whereas a high bootstrap value supported the node containing the desert specialists O. mimax (2n= 56) and Tympanoctomys barreare (2n= 102). The implications of allozymic data as a robust phylogenetic signal that connected biochemical associations to the prediction of tetraploidy in T. barrerae are discussed.
Development of bite strength and feeding behaviour in juvenile spotted hyenas (Crocuta crocuta)
Authors: Binder Wendy J. , Van Valkenburgh Blaire
Published: February 2006

Bite strength is of great importance to carnivores, as their jaws must produce forces of sufficient magnitude to kill and consume their prey. Spotted hyenas, well known for crushing and consuming bones, were studied to determine how tooth and jaw growth affect bite strength and feeding behaviour. Nine captive individuals, aged 6 months to 2 years of age, were sampled as they grew. At 8‐ to12‐week intervals, morphological measurements that estimated jaw muscle mass, tooth size and skull size were taken. Using a force transducer, bite force was measured directly for these juveniles as well as other captive individuals of different ages. In addition, feeding behaviour and performance were quantified periodically by bone tests in which individuals were offered a sheep femur for 15 min. Behaviour and performance were expected to change with the shift from juvenile to adult dentition. Results were not entirely as expected. Morphological measurements of growth reached a plateau at about 20 months, whereas bite strength increased in a linear fashion up to 5 years of age. A fundamental change in tooth use during bone cracking followed the replacement of deciduous teeth with permanent teeth; the primary area of tooth use moved from anterior to rearmost premolars, increasing the mechanical advantage of the jaw adductors. The timing of this shift seemed to be a function of a decrease in gape limitation as a result of growth as well as caudal movement of the premolars. Our data demonstrated that juvenile hyenas had not achieved adult feeding performance levels at 12 months of age, when they are typically weaned in the wild. This suggests that recently weaned cubs may be at an increased risk of starvation and that selection might favour later weaning times.
Molecular characterization of the freshwater snail Lymnaea natalensis (Gastropoda: Lymnaeidae) on Madagascar with an observation of an unusual polymorphism in ribosomal small subunit genes
Authors: Stothard J. R. , Brémond P. , Andriamaro L. , Loxton N. J. , Sellin B. , Sellin E. , Rollinson D.
Published: February 2006

Recent characterization of nuclear ribosomal small subunit (SSU) genes has shown that variant nucleotides within this region could be useful for species and species group identification within the genus Lymnaea (Gastropoda: Lymnaeidae). This study aimed to characterize a range of populations of Lymnaea natalensis Krauss, 1848 on Madagascar, and addressed two related questions. First, is there any evidence of intraspecific variation of the SSU and, if so, what might be its significance? Secondly, might this variation jeopardize the use of SSU for lymnaeid taxonomy and phylogeny?Lymnaea natalensis (n= 212) was collected from 17 sampling localities, spanning the northern and southern ends of the island. Variation within a selected region of the SSU known to vary between species, the V1 and V2, was assayed by polymerase chain reaction (PCR) linked restriction fragment length polymorphism (RFLP) and denaturing gradient gel electrophoresis (DGGE) analysis. The PCR‐RFLP profiles indicated a striking dimorphism across populations at two restriction site loci (CfoI & MspI) within the E10‐1 helix of the V2 region. The observed RFLP variation was confirmed by direct sequencing and by genomic digestion with subsequent hybridization. Putative heterozygotes were also encountered and in these individuals the SSU arrays composed of two distinct types approximately 1% divergent. A severe departure from Hardy–Weinberg equilibrium with a highly statistically significant (P < 10−5) heterozygote deficiency was found and genetic variation among populations was highly structured (Fst= 0.53). The geographic distribution of the variants was mapped, revealing that one variant was restricted to higher, predominately colder environments and was thought to be an adaptation. The molecular basis of the SSU variation was caused by single nucleotide polymorphisms (SNPs). To test for the possibility of cryptic taxa, an analysis of individuals representative of the SSU variant types with isoenzyme analysis (ISA), randomly amplified polymorphic DNA (RAPDs) and PCR‐RFLP analysis of the ribosomal Internal Transcribed Spacer (ITS) was performed. Little variation was revealed and none that correlated to the groups suggested by SSU, confirming that the SSU variation was intraspecific. The levels of intraspecific divergence of the V1 and V2 within Lymnaea were not appreciably different (1%) from interspecific and would therefore question the validity of these data for lymnaeid taxonomy and phylogeny.
Seasonal variations in thermal energetics of Australian silvereyes (Zosterops lateralis)
Authors: Maddocks Tracy A. , Geiser Fritz
Published: February 2006

Most Australian birds do not migrate over long distances and therefore have to cope with seasonal changes in weather and food availability. We investigated whether the small (11 g) silvereye Zosterops lateralis changes its thermal tolerance from winter to summer. Body mass and body temperature of silvereyes exhibited little seasonal variability. However, metabolic rates (MR) and thermal conductance showed significant changes. Below the thermoneutral zone (TNZ), winter‐acclimatized birds had significantly lower resting MR and thermal conductance than summer‐acclimatized birds. Within the TNZ (∼27.0–33.6 °C winter; ∼25.4–33.5 °C summer) basal MR of winter‐acclimatized birds (2.30 ± 0.29 mL O2 g−1 h−1) was significantly lower than that of summer‐acclimatized birds (2.88 ± 0.43 mL O2 g−1 h−1). The average daily MR also differed significantly between summer and winter largely due to a greater reduction of MR at night and the decreased conductance. Our study shows that small passerines such as silvereyes exhibit seasonal variability in physiology and thermal energetics, even when they live in areas with a relatively mild climate, to help overcome seasonal changes in weather conditions and food availability.
Sperm competition and genetic diversity in the agile antechinus (Dasyuridae: Antechinus agilis)
Authors: Shimmin G. A. , Taggart D. A. , Temple‐Smith P. D.
Published: February 2006

The mouse‐like marsupial Antechinus agilis is common to south‐eastern Australia with breeding and life‐history traits being highly synchronous. Mating activity is confined to a 10‐ to 15‐day period in August, at the end of which all males die as a result of a stress‐induced suppression of the immune system. Ovulation occurs at this time and females rely on stored sperm from specialized crypts in the lower isthmus of the oviduct for successful fertilization. Here we report a high incidence of mixed paternity litters, which can be attributed to sperm from multiple males being stored in the isthmic crypts. Data from this study also suggest a possible second male siring advantage in controlled ex situ sperm competition mating trials, irrespective of the delay between the two males being given mating access to the female or of the mating time relative to ovulation. In determining paternity through DNA profiling, population genetic data were obtained that showed significant differences in the genetic heterozygosity between unrelated adults, half siblings and full siblings. We suggest that the isthmic crypts, in addition to storing viable sperm, are capable of releasing a mix of sperm that increases the likelihood of mixed paternity litters. This allows all mating males the opportunity to sire young, increases female reproductive fitness and overall maintains high levels of population genetic heterozygosity in the face of total male mortality annually.
Elucidation of the relationships of spiny‐footed lizards, Acanthodactylus spp. (Reptilia: Lacertidae) using mitochondrial DNA sequence, with comments on their biogeography and evolution
Authors: Harris D. James , Arnold E. Nicholas
Published: February 2006

Mitochondrial DNA sequences consisting of 645 sites from the 12S rRNA and 16S rRNA genes were used to estimate the phylogeny of 15 of the 32 species of spiny‐footed lizards Acanthodactylus. The resultant tree has similarities to that produced from a differentially weighted data set of 32 morphological characters but there are also significant differences. However, combined analysis of molecular and morphological data sets produces the same tree topology as DNA sequence alone. The molecular data confirm that there are distinct eastern and western clades within Acanthodactylus, but place A. boskianus in the former while the A. scutellatus group constitutes a third clade. Species for which only morphological information is available were integrated with the combined tree to give a provisional phylogeny for 31 species. This phylogeny indicates that the ancestor of existing Acanthodactylus probably originated in south‐west Asia and that North Africa was invaded by more than one lineage of the genus. It also suggests that soft aeolian sand habitats may have been independently occupied more than once. Molecular data provide independent evidence that the differential weighting of morphological characters in past analyses was appropriate.
Food habits of jaguars and pumas in Jalisco, Mexico
Authors: Núñez Rodrigo , Miller Brian , Lindzey Fred
Published: February 2006

Jaguars (Panthera onca) and pumas (Puma concolor) are sympatric over much of their geographic range in Mexico and South and Central America. We investigated diets of these felids in and around the Chamela‐Cuixmala Biosphere Reserve in western Jalisco, Mexico. Diets were determined from scat analyses and documentation of prey cadavers. Relative biomass of each prey species consumed by pumas and jaguars was estimated from analysing 65 puma and 50 jaguar scats collected from 1995 to 1998. Both jaguars and pumas fed mainly on mammals, with white‐tailed deer (Odocoileus virginianus) dominating the biomass of the diet of each species (54% and 66% respectively). There was a high degree of overlap between jaguar and puma diets, but pumas had a broader food niche than jaguars, and their ability to exploit smaller prey may give them an advantage over jaguars when faced with human‐induced habitat changes.
Genetic variation and prevalence of blood parasites do not correlate among bird species
Authors: Poulin Robert , Marshall Leigh J. , Spencer Hamish G.
Published: February 2006

Models of host–parasite co‐evolution suggest that parasites can exert frequency‐dependent selection on their hosts, favouring rare alleles that confer resistance against widespread parasites and thus contributing to the maintenance of genetic variation, at some loci at least. If parasites are important in maintaining variation at many loci, then host species incurring a high prevalence of parasite infections should exhibit greater levels of genetic variation than host species incurring a lower prevalence. Using data from electrophoretic studies and from field surveys of haematozoan infections, we constructed a dataset including 103 species of North American and European birds to test this prediction. After controlling for sampling effort and phylogenetic influences, we found no relationship between parasite prevalence and either heterozygosity or polymorphism. These results do not support a role for parasites in the overall maintenance of genetic variation via frequency‐dependent selection.
Development of thermoregulation in the sugar glider Petaurus breviceps (Marsupialia: Petauridae)
Authors: Holloway Joanne C. , Geiser Fritz
Published: February 2006

Young, relatively undeveloped sugar gliders Petaurus breviceps have been observed to be left alone in the nest while the mother forages and may be subject to considerable thermal or energetic stress. As no information is available on the development of thermoregulation in this species, which begins reproduction in winter, we measured resting metabolic rate (RMR), body temperature (Tb) and thermal conductance over a range of ambient temperatures (Ta) in 10 sugar gliders from c. 55 days of age until they had grown to adult size. Sugar gliders were unable to maintain a stable Tb over a Ta range of 30–15 °C until the age of 95–100 days, although they raised RMR somewhat as Ta decreased. Further growth resulted in a steady decrease in mass‐specific RMR, an increase in Tb and a substantial decrease in thermal conductance. Our study shows that young gliders below the age of 100 days rely largely on heat produced by adults to maintain a high Tb, but are well able to cope with regular falls in Tb of > 10 °C and a concomitant decrease of RMR. This thermal tolerance and reduction in energy expenditure should allow the mother to forage and replenish her own body fuels while her offspring are left alone in the nest.
Brain growth in mallards, Pekin and Muscovy ducks (Anatidae)
Authors: Gille Uwe , Salomon Franz‐Victor
Published: February 2006

Post‐hatching changes in brain mass were investigated in mallards and four stocks of domesticated ducks, using growth curve analysis and allometry. The birds varied in age between hatching and 154 days. Percentage brain size at hatching in ducks varies between 22.5% and 28% which fits well into the precocial category. Brain growth shows a sigmoid course. The point of inflection is very early when compared to other organs. However, growth is slow after passing the growth rate maximum. Pekins show higher absolute brain masses than mallards. However, the growth patterns with respect to time are very similar among stocks. Strongly negative allometry is found with allometric exponents between 0.31 and 0.37 with the highest value in mallards. Allometrically, there is an increasing reduction of brain mass in Pekins when compared to mallards to about 12.5% in adults. No differences were found between mallards and either Muscovies or the Muscovy × Pekin cross. The reduction in relative brain size in domesticated animals when compared to their wild ancestors is generally attributed to a decrease in functional demands resulting from the artificial environment. Because brain growth is more conservative and less influenced by selection than body weight, we assume that this reduction is, at least in part, a result of the constancy of brain growth patterns.
Shark‐inflicted mortality on a population of harbour seals (Phoca vitulina) at Sable Island, Nova Scotia
Authors: Lucas Z. , Stobo W. T.
Published: February 2006

Shark‐inflicted mortality on harbour seals Phoca vitulina on Sable Island, Nova Scotia, was studied from 1980 to 1997, based on carcasses washed up on shore. During this period, pup production declined dramatically from over 600 in 1989 to 40 in 1997. Between 1980 and 1992, pup deaths only were recorded, and only during the May–June pupping period, while deaths in all age groups were recorded year‐round between 1993 and 1997; 458 pups, 23 juveniles and 241 adults were found. Shark‐inflicted mortality in pups, as a proportion of total production, was under 10% during 1980–93, roughly 25% in 1994–95, and increased to 45% in 1996. Shark‐inflicted mortality occurred in all months except December, January and February, with c. 80% of the pups killed during the pupping period, and 97% of the adults killed outside the pupping period. The decline in pup production was not only a result of reduced recruitment owing to pup mortality. A greater proportion of reproductive females than males was killed. We estimate that shark‐inflicted mortality on pups and adult females reduced pup production on Sable Island by 43 to 154 pups annually between 1993 and 1997. Our results indicate that sharks are having an impact on Sable Island harbour seals, possibly to the extent of limiting population growth, or contributing to the observed population decline. Potential reasons for this increased mortality are discussed.
Hyperextended call note repertoire of the endemic Madagascar treefrog Boophis madagascariensis (Rhacophoridae)
Authors: Narins P. M. , Lewis E. R. , McClelland B. E.
Published: February 2006

Vocalizations of Boophis madagascariensis (Rhacophoridae) males were recorded in a mid‐elevation rain forest in eastern Madagascar. Call notes made by males of this species were classified into 28 types. This represents the largest known call repertoire of any amphibian. The calls range widely in spectral characteristics from a narrowband, nearly pure‐tone to broadband ‘rip’ notes, to even broader band, pulsatile ‘iambic’ notes consisting of up to 23 pulses. Even considering all ‘iambic’ notes as variants of one type, there remain eight distinct call notes produced by this species. Morphological analysis of the vocal musculature of B. madagascariensis revealed no obvious adaptations for unusual glottal flexibility or function. Playback studies using a subset of the call notes as stimuli were carried out in the animals' natural habitat to determine the functional significance of several of the call notes. At the lowest playback levels, there was a significant tendency for males to produce rip notes in immediate response to either rip or iambic note stimuli. At the higher playback levels, we identified one sequence of iambic notes that consistently evoked a significant iambic note response from males. A permutation test on call note transitions during spontaneous calling revealed that call note pairs occurred inconsistently and unpredictably. The evolutionary significance of an extended vocal repertoire, matched counter‐calling and a random call note production scheme is discussed.
Arable habitat use by wood mice (Apodemus sylvaticus). 1. Macrohabitat
Authors: Todd I. A. , Tew T. E. , Macdonald D. W.
Published: February 2006

Wood mice Apodemus sylvaticus were radio‐tracked in an area covering three cereal fields, which was notionally divided into 5×5 m squares; each of these squares was classified to one of four habitat types (hedgerow, wheat, barley and oil‐seed rape). From a sample of 79 radio‐tracked wood mice, yielding 8500 fixes, we defined home‐range boundaries and estimated for two seasons: (a) the extent to which each habitat was present in each individual's home range relative to its overall availability in the surrounding landscape; (b) the extent to which each habitat was used by the mice relative to its abundance within a home range. Hedgerow ranked highest in preference (as distinct from use) for all comparisons made in both winter and summer. In winter, home ranges contained significantly more hedgerow than barley and wheat, and significantly more rape than wheat. Animals also used the habitats within their home ranges non‐randomly, with a significant preference for hedgerow. In summer, home ranges contained significantly less rape than other habitats. Habitats within home ranges were used at random. Seasonal patterns in habitat use appeared to be largely a response to seasonal disturbance and the availability of cover in the fields.