bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematic analysis of tongue movements during chemosensory behaviour in the European green lizard, Lacerta viridis (Reptilia: Lacertidae)
Authors: Goosse Véronique , Bels Vincent L.
Published: July 2008

High-speed cinematography (100 frames/s) was used to allow quantitative analysis of the kinematic profiles of tongue and jaw displacements during chemosensory activities in the scleroglossan lizard Lacerta viridis. The types of tongue flicking were simple downward extensions (SDE), single oscillations (SOC), and submultiple oscillations (SMOC) of the tongue out of the mouth. The SMOC type involves a downward or upward movement of the tongue performed before a typical oscillation and it is therefore suggested that this is an intermediate category of flick between the typical SOC and MOC of lizards. Closing and opening of the mouth in SDE, SOC, and SMOC cycles may or may not be separated by a stationary stage during which the jaws are held open at a constant gape. The duration of this stationary interval increases from SDE to SMOC. Gape cycles do not show any division into slow and fast stages. The gape is produced largely by depression of the lower jaw; the upper jaw is slightly elevated by protrusion of the tongue. Patterns of correlation of kinematic variables depicting jaw and tongue movements differed between SDE, SOC, and SMOC. A principal component analysis shows that the three flick types overlap in a multivariate space constructed from the kinematic variables depicting jaw and tongue displacements. Overlap between SOC and SMOC categories is greater than that between SOC, SMOC, and SDE categories. The kinematic patterns of tongue displacement during SMOC in Lacerta viridis show similarities with those of MOC in other lizards and in snakes. Kinematically, the pattern of jaw and tongue displacements of Lacerta viridis during chemosensory activities shows similarities with those that occur during drinking and prey capture.
Variation in laying date, clutch size, egg size, and egg composition of yellow-headed blackbirds (Xanthocephalus xanthocephalus): a supplemental feeding experiment
Authors: Arnold Todd W.
Published: July 2008

I studied the effects of food availability, habitat quality, and timing of breeding on egg production in yellow-headed blackbirds (Xanthocephalus xanthocephalus). Food availability was experimentally manipulated by providing females on six wetlands with supplemental food; six additional wetlands served as unsupplemented controls. Mean nest initiation dates varied by up to 6 d among wetlands, and supplementally fed blackbirds initiated nests 2 d earlier than controls, on average (although this latter difference was not quite significant; P = 0.07). Clutch size declined with laying date, but was unaffected by wetland location, food supplementation, or interactions between these two factors and laying date. Although egg size did not vary among wetlands or in relation to supplemental feeding, egg composition varied with both of these factors. All egg components except wet and dry shell and dry albumen varied among wetlands, whereas total water, wet yolk, and lean yolk were the only components that varied with food supplementation. Large blackbird eggs contained proportionately more water and albumen, but proportionately less yolk and shell. These patterns were somewhat compensatory, such that proportional protein and energy content did not vary with egg size; however, large eggs contained proportionately less fat than did small eggs. Proportional egg composition varied among wetlands (yolk and energy content), but was not affected by supplemental feeding. In general, egg production by yellow-headed blackbirds was not greatly affected by food availability. This may have been due to any of the following four factors: (1) inaccessibility of food supplements owing to competition between male and female blackbirds, (2) insufficient time for females to respond to food supplements, owing to rapid settlement and nest initiation, (3) a nutritionally inappropriate food supplement (i.e., protein availability may not have been enhanced among fed birds), or (4) superabundance of natural foods such that food availability was not limiting egg production.
Genie differentiation in spiny pocket mice of the Liomys pictus species-group (family Heteromyidae)
Authors: Rogers Duke S. , Engstrom Mark D.
Published: July 2008

Electromorphic variation at 33 presumptive genetic loci within and among samples of the Liomys pictus species-group from western, southern, and eastern Mexico was examined. Levels of heterozygosity and polymorphism within samples were low when compared with those of rodents in general, and genie divergence among samples was very high, resulting in a discontinuous distribution of alleles among localities. We hypothesize that some of these geographic discontinuities result from intrinsic barriers to gene flow within L. pictus. Genie variation in or near zones of overlap suggest that the following pairs of taxa segregate as distinct biological species: L. p. plantinarensis and L. spectabilis; L. p. plantinarensis and L. p. pictus; L. p. hispidus and L. p. pictus. Liomys spectabilis is more similar genically to adjacent populations of L. p. pictus in northwestern México than samples of L. pictus are to each other. As presently defined, L. pictus appears to be paraphyletic and probably is a composite of several morphologically cryptic species.
Pivotal and beach temperatures for hawksbill turtles nesting in Antigua
Authors: Mrosovsky N. , Bass Anna , Corliss Lynn A. , Richardson James I. , Richardson Thelma H.
Published: July 2008

Eggs of hawksbill turtles, Eretmochelys imbricata, from Antigua were incubated at constant tempe ratures. The pivotal temperature (the temperature at which 50% of each sex is produced) for the sample was estimated to be 29.2 °C. Sand temperatures at the depth of turtle nests were recorded over two nesting seasons at Pasture Bay, Antigua. Although sand temperatures were sometimes higher than the pivotal temperature, more often they were lower. On this basis, it is unlikely that hatchling hawksbill turtles in this area have the highly female-biased sex ratios reported for some other reptiles.
Proximal costs and benefits of heterospecific social foraging in the Great Tit, Parus major
Authors: Carrascal Luis M. , Moreno Eulalia
Published: July 2008

The feeding and vigilance schedules of Great Tits (Parus major) at artificial feeders were studied in winter. We compared the behaviour of birds that foraged in pairs (mono- or hetero-specific) and solitarily. The percentage of time spent foraging was higher when a Great Tit was with an individual belonging to a subordinate species rather than with another Great Tit or a member of the dominant species. When a bird was solitary, time spent foraging was less than when it was with an individual belonging to a subordinate species, and greater than when it was with one belonging to the dominant species. The proportion of time spent vigilant did not differ between Great Tits that foraged with an individual from a dominant species or a subordinate species or with a conspecific, but was higher for solitary birds. Vigilance time of solitary Great Tits, Nuthatches, and three other Parus species was not negatively correlated with interspecific dominance status. In these small passerines, vigilance does not seem to be directed towards the detection of a competitor species. Surveillance for predators and detection of competitor species may be synchronous, nonexclusive tasks. Scanning rate (number of scans per minute of feeding) was the same for Great Tits that fed either solitarily or in pairs, but mean scan duration was significantly shorter for individuals in groups than when solitary. Individual Great Tits benefited from the presence of Coal, Blue, and Crested tits (subordinate Parus species), by a lengthening of the time spent at feeding patches and by conversion of vigilance time into feeding time.
Sex ratio response of the two-spotted spider mite (Tetranychus urticae Koch) to changes in density under local mate competition
Authors: Roeder C. M.
Published: July 2008

The progeny sex ratios produced by mothers in populations that are subject to local mate competition are often a function of the number of females ovipositing in a patch. When the number of colonizing females changes during oviposition, by immigration, emigration, or death, the predicted sex ratio should also change. This was tested by quantifying the sex ratio response of Tetranychus urticae females to changes in the number of ovipositing females in their patch. When a solitary female is accompanied by other ovipositing females after she has oviposited for a period of time, she decreases the female bias of her progeny after the other females arrive. A female ovipositing with patch mates that are removed after a period of time, increases her progeny female bias after the patch mates are removed. Both of these progeny sex ratio patterns are consistent with theoretical predictions, and constitute a response by mothers to mitigate competition for mates among her sons. Females ovipositing alone throughout their ovipositional period produce more males during the first half of their ovipositional period than during the latter period of oviposition. This pattern of male production is not evident when a female is ovipositing with four other females. Solitary mothers may produce more males early during oviposition in anticipation of other females arriving on their patch and ovipositing, a form of bet hedging. If no other females arrive, mothers compensate for their overproduction of males and invest more in females later during oviposition.
Community development of epilithic invertebrates in streams: independent and interactive effects of substratum properties
Authors: Love Sean D. , Bailey Robert C.
Published: July 2008

The composition of macroinvertebrate communities living on rocks in streams depends on arrivals at a particular rock, available microhabitats, and biotic interactions among colonizers. We manipulated the color (dark, light), size (82 – 1320 cm2 surface area), and shape (sphere, rectangle, cube) of individual rocks to assess their independent and interactive effects on the development of the epilithic community and the physical displacement (i.e., disturbance) of the particles. Disturbance depended on the size and shape of the rocks. Smaller particles were more disturbed, while rectangular rocks of a given size had more frequent disturbance events than spheres or cubes. Many interactions among the manipulated factors were detected in their effects on taxonomic richness and total invertebrate abundance and density. Although several commonly observed effects were found (e.g., increased richness with greater substratum complexity and size), these patterns depended in many cases on the particular set of shapes and colors examined. Additionally, the site (5 m2) within the experimental area where a rock was located had strong effects on both disturbance and the invertebrate community. The two most common taxa also differed in their relationship with disturbance on different particle shapes: Chironomidae were relatively common on more frequently disturbed rectangular and cubic shapes, while Simulium were more common on the less disturbed spheres. Generalizations about the effects of substratum characteristics (e.g., size, "complexity") should be made with caution. Different features of the rock itself, qualities of the rock's location at a larger spatial scale, seasonal influences, and variation in response among taxa may all influence the development of the epilithic community in an interactive fashion.
The resident fitness hypothesis and dispersal by yearling female Columbian ground squirrels
Authors: Wiggett Darwin , Boag David A.
Published: July 2008

The emigratory behavior of yearling female Columbian ground squirrels (Spermophilus columbianus) in southwestern Alberta was studied for 25 active seasons among five colonies. From this data set we tested six predictions of the resident fitness hypothesis. The data strongly supported all six predictions: (1) yearling females were highly philopatric; (2) mothers behaved cohesively towards their yearling daughters (adult females tended to shift their home ranges in the presence of yearling daughter(s), often facilitating the recruitment of the latter to the natal site); (3) as densities of adult resident females rose and resource availability on an individual basis presumably declined, agonism from parous mothers and neighboring females caused greater proportions of yearling females to emigrate; (4) sibling daughters competed for access to the natal site when this space became vacant (parous yearlings were more successful than their nonparous siblings, and among the latter, dominant individuals were more successful than their subordinate siblings); (5) resident adult females were highly aggressive towards immigrant yearling females; and (6) resident adult males behaved cohesively with all yearling females, whether resident or immigrant, and were significantly more cohesive towards yearling females than towards yearling males. The results of this study suggest that emigration is not adaptive for yearling female Columbian ground squirrels. Rather, we suggest that female Columbian ground squirrels gain fitness benefits through philopatry and the retention of daughter(s) on the natal site when resources are not limiting.
The development of mesocerebral neurons in the snail Helix aspersa maxima
Authors: LaBerge Shelley , Chase Ronald
Published: July 2008

The neurons in the right mesocerebrum of Helix aspersa participate in the control of sexual behaviour. The purpose of this study was to examine the relationship between reproductive development and the development of mesocerebral neurons. The growth of right mesocerebral neurons was quantified by intracellular filling cells with hexamminecobalt chloride. It was found that the peak growth phase of the neurites preceded the peak growth phase of the penis by about 4 weeks. Comprehensive measurements from sectioned material showed that postembryonic growth in three regions of the brain was expressed as increases in soma diameters but not in neuron numbers. The rate of growth of neurons in the right mesocerebrum was significantly greater than that of neurons in the left mesocerebrum and the right postcerebrum. Ablations of the penis and dart sac did not affect the development of right mesocerebral neurons. Thus, no evidence was obtained for a trophic influence of the peripheral reproductive organs on the mesocerebrum.
The effects of temperature acclimation on protein synthesis rates and nucleic acid content of juvenile cod (Gadus morhua L.)
Authors: Foster A. R. , Houlihan D. F. , Hall S. J. , Burren L. J.
Published: July 2008

Juvenile cod were acclimated to cold (5 °C) and warm (15 °C) water temperatures and fed sandeel at a similar ration size (3% body weight∙day−1) for at least 40 days. After this acclimation period, there were no significant differences in either weight-specific growth rate or weight-specific tissue protein synthesis rates (ventricle, gill, stomach, and intestine) between the cold- and warm-acclimated fish. However, every cold-acclimated tissue examined had a significantly higher RNA concentration (μg RNA∙g tissue−1) than the respective warm-acclimated tissue. Cold-acclimated ventricle and intestine had significantly reduced RNA activities (i.e., translational efficiency, g protein synthesized∙g RNA−1∙day−1) compared with the warm-acclimated tissues. In contrast, the mean RNA activities of cold-acclimated stomach and gill were not significantly different from those of the same tissues in the warm-acclimated fish. These alterations in RNA activity and RNA concentration with temperature acclimation probably represent a thermal compensatory mechanism for protein synthesis and growth in cod at 5 °C. Positive linear relationships were observed between tissue protein synthesis rates and tissue RNA concentrations (μg RNA∙g tissue−1). RNA/protein ratios (μg RNA∙mg protein−1) gave a positive (but statistically insignificant) trend with protein synthesis rates. In contrast, a negative trend (statistically insignificant) was observed between tissue protein synthesis rates and tissue RNA/DNA ratios (μg RNA∙μg DNA−1). The use of RNA measurements as biochemical correlates of growth rate in juvenile cod is discussed.
Daily partitioning of summer habitat and use of space by the snowshoe hare in southern boreal forest
Authors: Ferron Jean , Ouellet Jean-Pierre
Published: July 2008

We investigated daily partitioning of summer habitat and use of space by the snowshoe hare (Lepus americanus) by means of radiotelemetry. Two periods corresponding to low and high activity were considered: resting during daytime and feeding at dawn and dusk. Areas used during the feeding and resting periods overlapped within each home range. During the feeding period, males occupied larger areas than during the resting period, but females did not. Vegetation characteristics were compared between 3 groups of plots corresponding to sites used during the feeding and resting periods and to low-utilization areas. Microhabitat characteristics differed between high-utilization and low-utilization sites, with mature conifer stands and areas with sparse hardwood understory characterizing low-utilization sites. Furthermore, the degree of utilization was related to habitat structure, not to vegetation species composition. Hares were also located more often in ecotones between different habitat types. During the feeding period, hares utilized sites with a greater ground cover of herbs and a lesser cover of ligneous plants, humus, and moss, and with a greater canopy closure, than during the resting period. Hares frequently utilized dense understory during both periods. These results do not support the predictions of Belovsky's model, based on thermal physiology, of snowshoe hare habitat selection according to the time of day.
Cockroaches of the Galápagos Islands, Ecuador, with descriptions of three new species (Insecta: Blattodea)
Authors: Peck Stewart B. , Roth Louis M.
Published: July 2008

Eighteen species of cockroaches are reported to occur on the Galápagos Islands. Five species are endemic and in this paper three of these are described as new species: Chorisoneura cristobalensis Roth, C. carpenteri Roth, and Ischnoptera santacruzensis Roth. Endemic Ischnoptera snodgrasii (McNeill) COMB.NOV. is transferred from Anisopygia, and redescribed. Previous reports of the introduced species Periplaneta brunnea, Nauphoeta cinerea, and Phoetalia pallida could not be confirmed. These species may not have become established or may have become extinct. New records of native or introduced species are given for Holocompsa nitidula, Holocompsa sp., Anaplecta lateralis, Blaberus parabolicus, and Rhyparobia maderae. Of the introduced species, only Periplaneta australasiae, Symploce pallens, and Pycnoscelus surinamensis seem to have invaded native (undisturbed) habitats. The endemic species are partially or wholly flightless. This may not be a result of island life per se, but may be a specialization for life in more homogeneous litter or cave habitats at higher elevations on the islands.
Interactions between bats and arctiid moths
Authors: Dunning Dorothy C. , Acharya Lalita , Merriman Catherine B. , Ferro Lella Dal
Published: July 2008

Many arctiid moths emit trains of ultrasonic clicks upon tactile stimulation and when exposed to trains of ultrasonic pulses like those emitted by bats. We observed the responses of captive big brown bats (Eptesicus fuscus) and free-foraging red bats (Lasiurus borealis) to arctiid moths and similar-sized moths of other families, and the responses of free-flying moths to trains of ultrasonic pulses like those of bats. Both the big brown bats and the red bats ate significantly fewer arctiids than were available to them, but the captive bats were more likely to kill arctiids than were the free-flying ones. The captive bats ate fewer of the arctiids they killed than moths of other families. Muted arctiid moths were caught by the red bats more than intact conspecifics but usually were dropped without being eaten. Free-flying arctiid moths changed their flight paths less in response to trains of ultrasonic pulses than did moths of other families similarly capable of hearing these signals. These results suggest that arctiid moths use their clicks and chemical defenses to protect them from the bats that prey upon them, and that these clicks are aposematic signals that warn bats of unpalatable prey.
Les osidases digestives de l'escargot Helix aspersa: localisations et variations en fonction de l'état nutritionnel
Authors: Charrier Maryvonne , Rouland Corinne
Published: July 2008

Osidases were studied in brown garden snails, Helix aspersa Müller, fed or starved for 4 or 7 weeks. The digestive tract was divided into seven regions: oesophagus, crop, stomach, intestine, rectum, salivary glands, and digestive gland. The results revealed the presence of a large number of enzymes that attack alimentary carbohydrates. However, α-heterosides and starch were poorly hydrolysed, and amylase was not derived from saliva. Enzymatic secretions continued in snails subjected to 7 weeks of starvation and accumulated in the stomach, while these enzymes were active mainly in the oesophagus and the crop during nutrition. Several hypotheses are presented, including that the most active enzymes, mannanases and cellulases, may be secreted both by the salivary glands and by the digestive gland. A similar distribution is postulated for two oligosaccharidases, maltase and saccharase. Since a bacterial flora exists in the digestive tract, we also consider the possibility of a synergistic activity between osidases from the snail and those originating from the microflora.
Postglacial dispersal of freshwater fishes into Ontario
Authors: Mandrak Nicholas E. , Crossman E. J.
Published: July 2008

The present-day distributions of 117 native freshwater fishes in Ontario have been shaped by processes active following the Wisconsinan glacial period, 80 000–10 000 years before present. During this glacial period, these species survived in unglaciated réfugia. To understand the processes that resulted in the recolonization of Ontario by fishes following the last glacial period, the refugial areas occupied by each species were determined using a refugial index, and glacial water bodies used as dispersal routes were identified. The refugial origins of the Ontario populations of 91 species were resolved. Seventy-two species resided in the Mississippian refugium, 13 species in the Atlantic Coastal refugium, 4 species in dual Atlantic Coastal – Mississippian refugia, 1 species in a Missourian refugium, and 1 species in Atlantic Coastal, Mississippian, and Missourian refugia. These conclusions differed significantly from those of other studies. Five general patterns were identified from the distributions of 104 species. In addition, there are 13 species that do not fit any of the general patterns. Most species with similar distributions in Ontario shared the same refugia and dispersal routes in eastern North America, therefore it is hypothesized that historical processes were important in shaping the present-day distributions of Ontario freshwater fishes.
Centipeds (Chilopoda) and Symphyla of the Galápagos Islands, Ecuador
Authors: Shear William A. , Peck Stewart B.
Published: July 2008

Thirteen centiped species and one symphylan are reported from the Galápagos Islands. Hanseniella caldaria (Hansen) is the first symphylan reported from the Galápagos Islands. Among the centipeds, Hemiscolopendra galapagosa Chamberlin is a new synonym of Scolopendra galapagoensis Bollman and should be deleted from the Galápagos list. Cormocephalus andinus Kraepelin, its probable junior synonym C. carolus Chamberlin, and Nannopodellus purpurascens Chamberlin, previously reported from the Galápagos Islands, were not in any collections made from 1974 to the present and may be extinct on the islands. Lamyctes coeculus (Brölemann), Lamyctes fulvicornis Meinert, and Newportia monticola Pocock are new records, and first appear in collections made in 1974. Two new species, Pectiniunguis krausi and Pachymerium perdrai, are described. The former had been misidentified previously as Pectiniunguis albermarlensis Chamberlin. While Pectiniunguis albemarlensis and Scolopendra galapagoensis may be Galápagos endemics, lack of knowledge about the centiped fauna of source areas precludes definitive statements.
Naupliar development of Mesocyclops aequatorialis similis and Thermocyclops consimilis (Copepoda: Cyclopoida) from Lake Awasa, a tropical rift valley lake in Ethiopia
Authors: Dahms H.-U. , Fernando C. H.
Published: July 2008

All six naupliar stages of Mesocyclops aequatorialis similis Van de Velde, 1984 and Thermocyclops consimilis Kiefer, 1934 are described. Naupliar development is compared within the subfamily, and external morphological characters are discussed in the light of phylogenetic relationships. Keys for identifying naupliar stages and for separating the two species are provided.
Variation in the preoperculomandibular canal of the johnny darter, Etheostoma nigrum, with associated zoogeographical considerations
Authors: Chapleau François , Cooper J. Andrew
Published: July 2008

A total of 1267 specimens (from 87 stations) of the johnny darter, Etheostoma nigrum, were studied to examine the geographic variation in the numbers of pores on the preoperculomandibular canal. The pore count is bimodal for the total sample. These modes correspond to distinct geographic regions. Fishes from northern Ontario (west and north of Lake Nipigon), Manitoba, Saskatchewan, Minnesota, Wisconsin, Iowa, and the Upper Peninsula of Michigan usually have 7 or fewer pores (mode = 6). Populations from northern Ontario (east and south of Lake Nipigon), southern Ontario, Quebec, Illinois, Indiana, Kentucky, Tennessee, Maryland, Ohio, New York, Pennsylvania, West Virginia, Virginia, North Carolina, South Carolina, and the Lower Peninsula of Michigan have 8 or more pores (mode = 9). The differentiation between morphs predates their present distribution and the morphs probably occupied distinct geographic areas within the Mississippi refugium during the last glaciation. Etheostoma nigrum dispersed north, following two postglacial routes: (i) via the Mississippi River to Lake Agassiz (12 800 years BP) then eastward to the Hudson Bay and James Bay drainages via Lake Barlow–Ojibway (9500 years BP), and (ii) via a northeastern spread from the Great Lakes and Ohio River drainages to the St. Lawrence River and Ottawa River drainages (12 000 years BP).
Borrelia burgdorferi in Ixodes dammini (Acari: Ixodidae) feeding on birds in Lyme, Connecticut, U.S.A.
Authors: Magnarelli Louis A. , Stafford III Kirby C. , Bladen Virginia C.
Published: July 2008

Passerine birds were captured in Japanese mist nets in Lyme, Connecticut, during 1990 and 1991 to collect larval and nymphal Ixodes dammini and to identify potential bird reservoirs for Borrelia burgdorferi, the etiologic agent for Lyme borreliosis. Of the 3291 birds captured and recaptured (32%), 503 in 35 species were parasitized by I. dammini. Ninety-eight of the recaptured birds had ticks attached. Borrelia burgdorferi was detected by indirect immunofluorescence staining in 72 (4.7%) of 1518 larvae and in 114 (23.3%) of 490 nymphs tested. Prevalence of infected larvae was comparatively greater for specimens removed from veeries (21.4%, n = 140 tested), Carolina wrens (15.5%, n = 84), hooded warblers (8.9%, n = 79), and house wrens (8.6%, n = 58). Based on the presence of infected larval ticks on birds, members of these 4 host species have the greatest potential for being reservoirs of B. burgdorferi. Relatively lower percentages of infected larvae (0.3–6.7%) were recorded for 8 other bird species. June through mid-August is a suitable time to isolate B. burgdorferi from natural populations of birds or ticks feeding on avian hosts.
Bionomics of Nodele calamondin Muma (Acarina: Cheyletidae) fed on Lepidoglyphus destructor (Schrank) (Acarina: Glycyphagidae) at two constant temperatures
Authors: Barker Philip S.
Published: July 2008

Nodele calamondin Muma is a predator of other mite species and of small insect larvae. Unmated females produced only male offspring (arrhenotoky), which subsequently mated with their mothers to produce female as well as male offspring. At 29.5 °C these females became adults an average of 47.3 days after the emergence of the mother. Males have one nymphal stage in their development and females have two nymphal stages. Males guarded the quiescent deutonymph females and mating took place as soon as the females emerged as adults. Unmated females lived more than twice as long as mated females and laid about 89% of the number of eggs laid by their mated sisters. The average duration of a generation was 62 days at 25 °C and 34 days at 29.5 °C. Net reproductive rate (ratio of female births in two successive generations) was 20 at 25 °C and 34 at 29.5 °C.
Gonadal histology in the self-fertilizing hermaphroditic fish Rivulus marmoratus (Pisces, Cyprinodontidae)
Authors: Soto Cristina G. , Leatherland John F. , Noakes David L. G.
Published: July 2008

In nature, most individuals of Rivulus marmoratus are reportedly self-fertilizing hermaphrodites. A few rare individuals are males, but females have never been found in the field or laboratory. We describe the gonadal histology of this unique fish, mainly on the basis of light-microscopic studies with some elaboration by electron microscopy. Analysis of gonadal structure and the characterization of the stages of spermatogenesis and oogenesis allowed us to categorize functional gender and to construct the probable sequence of gonadal development in mature individuals. In our laboratory, some hermaphrodites underwent ovarian regression and testicular proliferation to become secondary males. One individual also developed as a primary male. However, the type of male could generally not be distinguished. Testicular tissue composed only a small portion (less than 10%) of the gonad of most hermaphrodites.
Diet composition, prey choice, and breeding success of Long-eared Owls: effects of multiannual fluctuations in food abundance
Authors: Korpimäki Erkki
Published: July 2008

Common voles (Microtus epiroticus) were the main prey of Long-eared Owls (Asio otus) breeding in western Finland during 1977 – 1989. They constituted, on average, 58% (range < 15 to > 75%) of the number of prey. Field voles (Microtus agrestis), common shrews (Sorex araneus), bank voles (Clethrionomys glareolus), and water voles (Arvicola terrestris) were the most frequent alternative prey. The owls showed strong preference for common voles over the alternative prey species and this preference increased with vole density. If the common vole is the most profitable prey of Long-eared Owls, the between-years variation in the diet was consistent with the three predictions of the conventional model of the optimal diet theory. (1) Predators should feed on the most valuable prey type when prey are abundant. There was a positive correlation between the abundance of common voles and their proportions in the food. (2) No relationships for alternative prey types agreed with the prediction that the inclusion of a prey type in the diet depends only on the abundance of the preferred prey. (3) As predicted by the optimal diet theory, the diet width expanded when the density of common voles decreased and shrank when vole density increased. Annual breeding density (range 0.0–0.4 nests/km2), mean clutch size (3.0 – 6.3), and mean brood size (0.0 – 3.5) were positively related to the spring abundance of common and field voles. Accordingly, it is adaptive for Long-eared Owls to breed in a good area for voles. Because vole abundances in Fennoscandia fluctuate markedly between years and asynchronously between areas, Long-eared Owls should stay in the same area in the increase phase of the vole cycle, but move away when voles decline.
Flock composition and foraging behavior of greater snow geese (Chen caerulescens atlantica)
Authors: Bélanger Luc , Bédard Jean
Published: July 2008

We studied the foraging behavior of greater snow geese (Chen caerulescens atlantica) staging in a Scirpus tidal marsh along the St. Lawrence Estuary in Quebec during fall 1985 and 1986 and spring 1986 and 1987. Among all foraging activities, grubbing (feeding on underground plant parts) ranked first (>50%), but important seasonal differences were observed. Geese spent less time grubbing and more time searching and grazing on newly emerging shoots in spring than in fall. Our study also revealed differences in the foraging behaviors of birds of differing social status. We found that juveniles spent more time searching for food than adults, particularly in fall. Males also spent more time alert than females, at least in fall. We also observed behavioral differences among adults of different social status (member of a family, paired bird, and unpaired bird). Solitary unpaired birds devoted less time grubbing and, consequently, more time searching for food, than paired birds in fall. Finally, paired and family-member adult birds adopted a similar foraging strategy, spending more time searching and grazing in spring than in fall.
Testing responses to forest edges: the example of black-tailed deer
Authors: Kremsater Laurie L. , Bunnell Fred L.
Published: July 2008

Variations in deer response to edge habitat have been attributed to three sources: (1) differences in habitat mosaics among study areas, (2) inconsistent definition of habitat deemed available to a deer, and (3) differences in edge characteristics. The potential influences of these factors were evaluated using data for black-tailed deer (Odocoileus hemionus columbianus) collected on Vancouver Island, B.C. Edges were defined among clear-cut, second-growth, and old-growth habitats. Deer distributions and movements were determined using radiotelemetry. Little response of deer to edges was detectable where habitat was a fine-grained mosaic of forage and cover areas. Where forage and cover occurred in clearly distinct habitats, responses to edge were apparent. Techniques defining area available to wildlife in use–availability analyses differ among studies. We found that the impact of changing the area considered to be available mattered little when habitats were finely interspersed. We could not unequivocally separate effects of differences in habitat mosaics from effects of differences in vegetative characteristics of edge habitat, but results were consistent with other findings that edges are less important when forage and cover are interspersed. We discuss the implications of our findings for the interpretation of research results.
Most Paleozoic Protorthoptera are ancestral hemipteroids: major wing braces as clues to a new phylogeny of Neoptera (Insecta)
Authors: Kukalová-Peck Jarmila , Brauckmann Carsten
Published: July 2008

The enigmatic and artificial Protorthoptera is the largest Paleozoic order of Neoptera. Typical hemipteroid head characters (inflated clypeus, styletal mouthparts) are here reported for "Protorthoptera" fossils and linked with the basic venational braces of hemipteroid wings. The "order" is recognized as being mostly composed of extremely primitive hemipteroids. Two new Late Carboniferous gerarid wings are described: Osnogerarus trecwithiensis n.gen., n.sp. from the Westphalian D of Osnabrück, Germany, and Cantabrala gandli n.gen., n.sp. from the Lower Stephanian (Cantabrian) of the Cantabrian Mountains, northwestern Spain. Several ground-plan characters of hemipteroids are described: head with visible segmentation; polyramous thoracic legs bearing exites and with trochanter not fused to prefemur; ovipositor with cutting ridges; the medial wing vein is shown as not the complete media (= M), but only the media posterior (= MP); the arculus is diagnosed as a cross-vein turned into an important brace; two radial sectors (RA and RP) originate separately from the radial basivenale; and the anal brace is formed by AA1. The hemipteroid stem-assemblage comprised (i) the gerarid line (extinct) with a long MP–CuA fusion replacing the arculus (derived) and with a repeatedly forked CuP (primitive), and (ii) the paoliid line with an arculus (a convex mp–cua cross-vein) (primitive) and a simple CuP (derived). The paoliids are the probable ancestors of modern hemipteroids. The Hemiptera (Sternorrhycha + Auchenorrhyncha + Coleorrhyncha + Heteroptera) lost the ScA + vein to a V-shaped notch or a flexion line (synapomorphy). Geraridae, Paleozoic and Recent Insecta, and all Arthropoda have demonstrably polyramous legs in the ground plan. Use of the taxon "Uniramia" is erroneous in every aspect. A new method using major venational braces is offered to define the wings of all higher neopteran taxa and to resolve the uncertain relationships between some modern orders. Polyneoptera (plecopteroids + orthopteroids + blattoids) is a polyphyletic taxon, and should be abandoned. Blattoids are not directly related to orthopteroids, but are the sister-group of hemipteroids + endopterygotes. An updated basic phylogenetic scheme of Neoptera proposed here comprises the following clades: (Pleconeoptera (Orthoneoptera (Blattoneoptera (Hemineoptera + Endoneoptera)))).
Relationship between testate amoebae (Protozoa: Rhizopoda) and microenvironmental parameters on a forested peatland in northeastern Ontario
Authors: Charman D. J. , Warner B. G.
Published: July 2008

The relative abundance of species of testate amoebae (Testacea; Rhizopoda) was established from 107 surface moss samples from a forested peatland in northeastern Ontario. These were related by multivariate analysis to a number of microenvironmental conditions including soil moisture content, water table, bulk density, humification, dominant peat component, pH, peat depth, depth of living moss, dominant surface moss species, vegetation type, microtopographical position, and artificial drainage. Moisture conditions play a key role in determining the species assemblages, pH being a secondary factor. Other environmental parameters related to species assemblages do not necessarily indicate a direct ecological link but are also associated with moisture and nutrient conditions. Individual species are ranked in terms of their preferred moisture conditions and compared with data from Finland. Certain species are restricted to either dry or wet conditions while others tolerate a wide range of moisture. Calculating weighted averages of substrate moisture contents for a greater range of species sampled from a larger number of sites will allow the development of transfer functions for constructing palaeomoisture curves from peatlands.
Discord between field and laboratory sex ratios of the water mite Neumania papillator Marshall (Acari: Unionicolidae)
Authors: Proctor Heather C.
Published: July 2008

I regularly sampled a pond in southern Ontario throughout the ice-free season in 1990 to determine adult phenology of the water mite Neumania papillator. Adult mites were present from 23 April to 9 November. Sex ratios in field samples were strongly male biased from 25 June to 2 November; however, mites raised from deutonymphs (juveniles) in the laboratory showed strongly female-biased sex ratios. Experiments indicated that differences in field and laboratory sex ratios could not be explained by differential susceptibility of the sexes to predation or starvation. Sex-biased distribution or trappability, or environmental sex determination may explain sex-ratio differences.
A method for reconstruction of zebra mussel (Dreissena polymorpha) length from shell fragments
Authors: Hamilton Diana J.
Published: July 2008

Zebra mussels (Dreissena polymorpha) are subject to size-selective predation by several species of diving ducks and fish in Europe and North America. Ingested mussels are crushed, but the internal septum in the umbonal region of the mussel usually remains intact. Using mussels collected at Point Pelee, Lake Erie, I showed that there is a strong relationship between the length of the septum and of the mussel (r2 = 0.96). I compared this with a similar relationship developed for European zebra mussels and tested both models on mussels collected from Point Pelee and from Stoney Point, Lake St. Clair. Septal length relative to mussel length was greatest at Stoney Point and least at Point Pelee. The European estimates fell between the two. I concluded that to obtain accurate estimates of mussel length when investigating size-selective predation on zebra mussels, the relationship between mussel and septal lengths should be determined at each study location.
Lack of evidence for a biological alarm clock in bats (Myotis spp.) hibernating under natural conditions
Authors: Thomas Donald W.
Published: July 2008

Noting that captive hibernating big brown bats (Eptesicus fuscus) aroused from bouts of torpor at precise times of the day (17:00–19:00), Twente and Twente (J. W. Twente and J. Twente. 1987. Can. J. Zool. 65: 1668–1674) hypothesized the existence of a temperature-compensated, non-free-running biological alarm clock that regulated the timing of arousals in bats. I tested this hypothesis in a natural hibernaculum used by little brown bats (Myotis lucifugus), northern long-eared bats (Myotis septentrionalis), and big brown bats (E. fuscus) by recording the timing of periods of activity with an ultrasonic detector and an electronic datalogger. Although there was significantly (2.5–4.0 times) more activity during the night than during the day, the pattern of activity did not conform with that observed in the laboratory. Bats were found to be active at all times of the day and there was little evidence of a concentration of activity around the period 17:00–19:00 as observed in the laboratory. Over three measurement periods in early winter and midwinter, the mean activity times were 18:54 ± 4.5 h, 23:48 ± 5.0 h, and 23:18 ± 5.2 h. The high variation around the mean times indicates that bats aroused and were active at most times of the night. If a biological alarm clock exists in bats, it is only weakly expressed under natural conditions.
Storage and translocation of integumentary calcium during the moult cycle of the terrestrial isopod Oniscus asellus (L.)
Authors: Steel C. G. H.
Published: July 2008

The calcium content of pieces of integument of standardized size from various regions of the body was measured at all 15 stages of the intermoult cycle. Calcium resorbed from the posterior integument during premoult is stored mainly in the sternal calcium deposits of the anterior region, which contain 20% of total body calcium in late premoult. Earlier arguments that the deposits are not a store of calcium are refuted. These deposits are similar to gastroliths in both structure and function. After posterior ecdysis, calcium in the deposits is resorbed rapidly and employed in calcification of the new posterior exocuticle. Calcium is then resorbed from the general anterior integument within 24 h and may accumulate transiently in the haemolymph. During this period resorption of integumentary calcium and calcification proceed simultaneously in the anterior and posterior regions of the animal. Ecdysis of the anterior region then occurs, and calcium from the haemolymph is employed in calcification of the new anterior exocuticle. Forty-eight percent of intermoult calcium content is conserved. However, both exuviae are eaten and it is argued that further calcium is conserved by resorption from the exuviae within the gut. It is suggested that this calcium, together with dietary calcium, is employed in calcification of the endocuticle after ecdysis. It is proposed that comparable events occur in all crustaceans that conserve calcium, but are rendered especially dramatic in isopods, owing to the unusual biphasic pattern of cuticle secretion.
Chromosomal and mitochondrial DNA variation in four laboratory populations of collared lemmings (Dicrostonyx)
Authors: Engstrom Mark D. , Baker Allan J. , Eger Judith L. , Boonstra Rudy , Brooks Ronald J.
Published: July 2008

Genetic differentiation among populations and speciation in Dicrostonyx is hypothesized to have resulted from either allopatric divergence in glacial refugia during the Wisconsin or sympatric processes uncorrelated with refugial isolation. We examined chromosomal and mitochondrial DNA variation in four laboratory colonies, representing three species, in a preliminary evaluation of these hypotheses. Chromosomal variation is extensive among populations, diploid numbers ranging from 38 to 50. Autosomal variation appears to be due primarily to Robertsonian rearrangements and additions of supernumerary chromosomes, and is geographically unpatterned. Sex chromosome morphology is geographically structured and correlated with proposed southern and northern refugia. Restriction fragment analysis of mitochondrial DNA revealed two ancient, divergent genotypic assemblages, corresponding to geographic distributions of sex chromosomes. Autosomal variation, and any resulting reproductive isolation, probably is recent and uncorrelated with refugial history, whereas divergence of sex chromosomes and disparate mitochondrial assemblages likely predate the Wisconsin.
Retention of herring Clupea harengus larvae inside Minas Basin, inner Bay of Fundy
Authors: Bradford Rodney G. , Iles T. Derrick
Published: July 2008

Minas Basin is one of the most tidally active and rapidly flushed macrotidal embayments in the world. But despite this, ichthyoplankton surveys in 1983 and 1984 have shown that herring larvae from spring spawnings inside the basin are retained and metamorphose there about 4 months after hatching. Both yolk-sac and post-yolk-sac larvae with a length range of about 5–20 mm are found in association at individual stations. Published growth rates suggest a residence time for the large larvae of 50–100 days, which agrees with the known lapsed time between first spawning and the time of the surveys of 60 days. The time for 1% retention of passive contaminants, estimated from known physical oceanographic characteristics, is 5 days. Distributions of smelt larvae and herring larvae within the basin are mutually discrete, which confirms the phenomenon of retention and demonstrates that the maintenance of position is effected by mechanisms that are stock and species specific. The estimated absolute size of the Minas Basin herring stock is at the lower end of the scale for herring stocks generally, and is associated with a correspondingly small retention area. This supports the view that absolute size is determined to a large extent by the area occupied by the larval stage.
Lipid accumulation by migrating monarch butterflies (Danaus plexippus L.)
Authors: Gibo David L. , McCurdy Jody A.
Published: July 2008

The migration of Danaus plexippus during the late summer in southern Ontario in 1986 lasted for about 8 weeks and consisted of three phases, an early phase characterized by increasing abundance, a middle phase of peak abundance, and a late phase characterized by declining abundance. As the season progressed, systematic changes were observed in wet mass, dry mass, lean dry mass, lipid mass, and forewing length. Wet mass, lean dry mass, and forewing length were similar for early- and middle-phase individuals, but declined in late-phase migrants. Lipid mass peaked in the middle phase of the migration and then declined abruptly in the late phase. Dry mass also peaked in the middle phase, reflecting changes in lipid mass and lean dry mass. We hypothesize that the observed changes in lipid mass and lean dry mass over the 8 weeks resulted from changes in population structure as well as seasonal changes in the weather, and in availability of nectar. Opposing conclusions reached in previous studies of lipid accumulation in D. plexippus are probably the result of failure to control for phase of migration.