bluuebunny/crossref_metadata_2025 huggingface dataset:
Milt quality, parasites, and immune function in dominant and subordinate Arctic charr
Authors: Liljedal Ståle , Folstad Ivar
Published: June 2003

Within a species, different males may display different mating strategies. For example, some males may be selected to invest in attractiveness and mate guarding, whereas others are selected for increased sperm production and sneaky breeding. In systems with a hierarchical structure, dominant males are expected to adopt mate-guarding behaviour and subordinate males sneaky-breeding behaviour. In this study, we kept wild-caught and sexually ripe male Arctic charr (Salvelinus alpinus) in size-matched pairs and determined social rank from the number of aggressive encounters. After 4 days, subordinate males showed symptoms of stress, with higher blood glucose and erythrocyte levels than dominant males. There were no differences between dominant and subordinate males in parasite intensities or immune activity, measured as levels of granulocytes and lymphocytes in blood. Although subordinate males had smaller testes than dominant males, they still had a higher density of sperm cells and higher sperm numbers relative to the size of their testes. These results can be explained as indicating adaptation of subordinate males for reproduction in an unfavourable role, always exposed to sperm competition and out of synchrony with females' egg release. Our results suggest that rapid changes in social rank may affect ejaculate production.
Demography of barren-ground grizzly bears
Authors: McLoughlin Philip D , Taylor Mitchell K , Cluff H Dean , Gau Robert J , Mulders Robert , Case Ray L , Boutin Stan , Messier François
Published: June 2003

Between May 1995 and June 1999, we equipped 81 barren-ground grizzly bears (Ursus arctos) with satellite radio collars within a study area of 235 000 km2, centred 400 km northeast of Yellowknife, Northwest Territories, Canada. We used data from radiotelemetry to estimate survival rates, reproductive parameters, and the finite rate of increase of the population (λ). The annual survival rate of adult females was estimated at 0.979 (95% confidence intervals (CI) = 0.9550.998), while the survival rate of adult males was 0.986 (95% CI = 0.9421.0). The cub survival rate was 0.737 (95% CI = 0.6000.844) and the yearling survival rate was 0.683 (95% CI = 0.5140.821). Cub litter size averaged 2.23 (SE = 0.13, n = 35), while yearling litter size decreased to a mean of 1.86 (SE = 0.12, n = 35). The mean litter size of females with 2-year-olds was 1.85 (SE = 0.15, n = 20). The mean birth interval was 2.8 years (SE = 0.3 years, n = 17). The mean reproductive interval, which is calculated by excluding the loss of whole litters from the sample, was 3.9 years (SE = 0.4 years, n = 9). Mean litter size divided by mean birth interval yielded an annual natality rate of 0.81 cubs per adult female per year. The mean age at first parturition was 8.1 years (SE = 0.5 years, n = 10). We believe the population to be currently stable or slightly increasing (λ = 1.033, 95% CI = 1.0081.064).
Foraging behaviour by gray wolves on salmon streams in coastal British Columbia
Authors: Darimont C T , Reimchen T E , Paquet P C
Published: June 2003

Spawning salmon (Oncorhynchus spp.) are important resources for terrestrial ecosystems and often shape the ecological strategies of organisms with which they co-evolve. Gray wolves (Canis lupus), primarily predators of ungulates, are sympatric with salmon over large areas, but the relationship between the two remains poorly understood. We report here observations of direct and indirect evidence of salmon predation by wolves in several watersheds of coastal British Columbia and in detail report on the foraging behaviour of four wolves at one river during September and October 2001. Wolves oriented themselves upstream during detection and pursuit of salmon. The pooled mean capture rate was 21.5 salmon/h and mean efficiency (successes/attempt) was 39.4%. In most cases, wolves consumed only heads of salmon, perhaps for nutritional reasons or parasite avoidance. Preying on salmon may be adaptive, as this nutritious and spatially constrained resource imposes lower risks of injury compared with hunting large mammals. We infer from capture rates and efficiencies, as well as stereotypical hunting and feeding behaviour, a history of salmon predation by wolves and, as a corollary, a broad distribution of this foraging ecology where wolves and salmon still co-exist.
Temperature acclimation influences temperature-related behaviour as well as oxygen-transport physiology and biochemistry in the water fleaDaphnia magna
Authors: Lamkemeyer Tobias , Zeis Bettina , Paul Rüdiger J
Published: June 2003

To evaluate the role of temperature in oxygen transport in the water flea Daphnia magna, temperature-related behaviour as well as oxygen-transport physiology and biochemistry were investigated in animals long-term acclimated to moderate temperatures: 10, 20, or 30°C (normoxia) or 20°C (hypoxia). Study of the behaviour of animal groups within a normoxic thermal gradient showed their preferred temperatures and distribution patterns to be connected with acclimation conditions; for example, cold-acclimated individuals, with their relatively high metabolic rates and low oxygen-transport capacities, crowded at low temperatures where the oxygen concentration was high. One key to explaining these data is to assume a strategy of avoiding oxygen shortage. Both temperature and hypoxia acclimation also modified oxygen-transport variables such as oxygen consumption, ventilation and circulation rates, or the concentration and oxygen affinity of haemoglobin. Characteristic features of cold-acclimated D. magna were relatively high oxygen-consumption and heart rates and a low concentration and oxygen affinity of haemoglobin. Hypoxia-acclimated D. magna showed relatively low convective rates (frequency of thoracic-limb movements, heart rate) but a high concentration and oxygen affinity of haemoglobin. Additional experiments showed that independently of each other, temperature and ambient oxygen concentration modify haemoglobin quantity and quality, the former possibly acting via a temperature-induced hypoxia. The varying oxygen affinity is probably due to alterations of haemoglobin subunit composition, with the particular participation of subunits A, E, and G as revealed by two-dimensional gel electrophoresis.
Changes in ventilation, metabolism, and behaviour, but not bradycardia, contribute to hypoxia survival in two species of Amazonian armoured catfish
Authors: MacCormack T J , McKinley R S , Roubach R , Almeida-Val V M.F , Val A L , Driedzic W R
Published: June 2003

Amazonian armoured catfishes exhibit substantial cardiac hypoxia tolerance, but little is known concerning organismal cardiorespiratory, metabolic, and behavioural responses to low oxygen levels. This study assessed the general mechanisms used by two species of armoured catfish, Glyptoperichthyes gibbceps and Liposarcus pardalis, to survive the frequent periods of hypoxia encountered in the Amazon River. The gill ventilation rate (fv) and heart rate (fh) were studied under controlled hypoxia in aquaria and under natural hypoxia in a simulated pond. Glyptoperichthyes gibbceps were fitted with radiotelemetry tags and held in field cages to study their habits of depth selection and air breathing. When denied aerial respiration under hypoxia in aquaria, G. gibbceps increased fv, but neither they nor L. pardalis exhibited alterations in fh. An increase in fvwas initially observed in G. gibbceps during pond hypoxia before aerial respiration was initiated and fvdeclined. Glyptoperichthyes gibbceps were hyperglycaemic under normoxia, and extremely large increases in plasma glucose and lactate concentrations were observed under hypoxia. Field studies confirmed their nocturnal behaviour and showed that air breathing increased at night, regardless of dissolved oxygen concentration. Our results show that armoured catfishes preferentially up-regulate fvand anaerobic metabolism and exhibit no bradycardia during hypoxia.
Life at the interface: ecology ofPrionodactylus oshaughnessyiin the western Amazon and comparisons withP. argulusandP. eigenmanni
Authors: Vitt Laurie J , Avila-Pires Teresa Cristina S. , Zani Peter A , Espósito Maria Cristina , Sartorius Shawn S
Published: June 2003

The gymnophthalmid lizard Prionodactylus oshaughnessyi was studied at two Amazonian rain-forest sites. These lizards live at the interface of the terrestrial habitat and arboreal habitat, are active throughout the day at relatively low body temperatures, and maintain body temperatures (29.0 ± 0.34°C) slightly higher than ambient temperatures. Grasshoppers and crickets, roaches, insect larvae, and spiders dominate their carnivorous diet. Sexual size dimorphism is not apparent but differences in coloration and relative head size exist, with males having brighter and more vivid coloration and a relatively larger head. Differences in activity time, prey type, prey size, and microhabitat use exist between populations. A comparison of three species of Prionodactylus from Amazonian rain forest revealed some ecological similarity. However, differences in microhabitat use and diet exist. Differences in Baupläne were consistent with differences in microhabitat use. Dietary overlaps were relatively low; nevertheless, diets of the Prionodactylus species were more similar to each other than expected, based on a null model analysis in which a sampling of all diets was used for comparison.
Prey capture in a mantid (Gonatista grisea): does geotropy promote success?
Authors: Ladau J
Published: June 2003

Gonatista grisea (Fabricius) is one of many arboreal arthropods and reptiles that orient downwards to ambush prey. To investigate if orienting downwards increases hunting success, a 2 × 2 factorial experiment was performed using mantid orientation (upwards, downwards) and direction of prey approach (posterior, anterior) as factors and prey capture success as the response variable. The results indicated that the mantid captures prey equally well when oriented upwards or downwards but that it is less effective when the prey approaches posteriorly. Because prey likely climb upwards more frequently than downwards, these findings suggest that G. grisea increases its hunting success with its downwards orientation.
Mammal population cycles: evidence for intrinsic differences during snowshoe hare cycles
Authors: Sinclair A R.E , Chitty Dennis , Stefan Carol I , Krebs Charles J
Published: June 2003

Some mammals in high northern latitudes show regular population cycles. In snowshoe hares (Lepus americanus), these occur every 910 years. One hypothesis proposes extrinsic causes such as food shortage or predation. The other proposes intrinsic causes through different morphs that alternate between different phases of the cycle. The morphs should differ in behaviour or physiology. This hypothesis predicts that animal lineages bred from high and low phases of the population cycle should differ in reproduction and survivorship. In a 16-year breeding program, lineages of purebred high-phase female hares had reduced reproductive rates relative to those of purebred low-phase females, resulting in extinction of high-phase lineages. Reproductive output declined with age in high- but not low-phase animals. These lineages also differed in longevity and senescence. These results are consistent with the intrinsic hypothesis and suggest a mechanism for alternating population densities that could work synergistically with extrinsic causes like predation and food shortage.
Venom injection by rattlesnakes (Crotalus atrox): peripheral resistance and the pressure-balance hypothesis
Authors: Young Bruce A , Phelan Molly , Morain Malinda , Ommundsen Melissa , Kurt Robert
Published: June 2003

Differential venom injection by snakes, between two size classes of prey for example, has typically been explained within the rubric of the venom-metering hypothesis, which claims that snakes decide how much venom to inject in a given strike. Recently, an alternative, the pressure-balance hypothesis, was advanced, which attributes differential venom flow to the balance of internal forces acting at the venom gland and venom chambers and external forces acting at the exit orifice of the fang. This study tests these competing hypotheses. High-speed digital videos of predatory and defensive strikes by western diamondback rattlesnakes, Crotalus atrox, revealed considerable variation in the trajectory of the fang relative to the target, which would yield wounds with potentially different levels of peripheral resistance. The importance of peripheral resistance was also suggested by the expulsion of venom from the fang after withdrawal from the target (in 7% of strikes) and by the forceful ejection of fluid from the target around the embedded fang (in 2.8% of strikes). Experimental milking chambers were constructed that exposed the right and left venom-delivery systems to different levels of peripheral resistance; with increased peripheral resistance significantly less venom was injected into the chamber and significantly more venom was released on the chamber's surface.
Maternal attendance patterns of Steller sea lions (Eumetopias jubatus) from stable and declining populations in Alaska
Authors: Milette Linda L , Trites Andrew W
Published: June 2003

Maternal attendance patterns of Alaskan Steller sea lions (Eumetopias jubatus) were compared during the summer breeding seasons in 1994 and 1995 at Sugarloaf Island (a declining population) and Lowrie Island (a stable population). Our goal was to determine whether there were differences in maternal attendance between the two populations that were consistent with the hypothesis that lactating Steller sea lions in the area of decline were food-limited during summer. Our a priori expectations were based on well-documented behavioural responses of otariids to reduced prey availability. We found that foraging trips were significantly shorter in the area of population decline, counter to initial predictions. The mean length of foraging trips in the declining area was 19.5 h compared with 24.9 h in the stable area. In contrast, the mean perinatal period (time between parturition and first feeding trip) was significantly longer in the area of decline (9.9 versus 7.9 days), again countering initial predictions. The mean length of shore visits for the declining population was also significantly longer (27.0 h compared with 22.6 h where the population was stable). For both populations, the mean time that mothers foraged increased as pups grew older, whereas the time that they spent on shore with their pups became shorter. Behavioural observations of maternal attendance patterns are inconsistent with the hypothesis that lactating Steller sea lions from the declining population had difficulty obtaining prey during summer.
Interdemic variation in the African cyprinidBarbus neumayeri: correlations among hypoxia, morphology, and feeding performance
Authors: Schaack Sarah , Chapman Lauren J
Published: June 2003

Adaptive change in one character may affect associated, but functionally unrelated, characters in adaptive or nonadaptive ways. For example, adaptive change in gill size (i.e., larger gills in hypoxic habitats) may alter adjacent feeding structures and therefore have indirect effects on feeding behavior. This study examines whether differences in total gill filament length among populations of the African cyprinid Barbus neumayeri correlate with variation in trophic structures and feeding performance. Morphological measurements revealed larger total gill filament length in populations from low-oxygen habitats. Differences in external and internal morphology of the trophic apparatus correlated with those found in gills and suggest a reduction in food capture and processing ability in fish with larger respiratory apparatus. In paired feeding trials on a novel prey type, large-gilled fish spent more time feeding than small-gilled fish of the same body size without ingesting more food. This suggests less efficient food uptake in large-gilled fish from hypoxic habitats. We suggest that variation in gill size facilitates the broad habitat distribution of B. neumayeri but may limit the success of phenotypes crossing physicochemical gradients.
The nature and consequences of motherdaughter associations in naturally and forcibly weaned bison
Authors: Brookshier Jennifer S , Fairbanks W Sue
Published: June 2003

Bison (Bos bison) mothers and daughters have a stable association that may persist beyond weaning, whereas no such extended relationship exists between mothers and sons. The practice of forced weaning of bison in Antelope Island State Park, Utah, provided the opportunity to experimentally investigate the nature and consequences of postweaning motherdaughter associations. Forced weaning changes the early social environment of calves and may disrupt social organization by eliminating motherdaughter associations. We compared the motherdaughter associations of forcibly weaned female yearlings, following release back into the population, with those of naturally weaned female yearlings. Yearlings that had been forcibly weaned as calves did not reassociate with their mothers following winter separation. Forcibly weaned yearlings spent no more time with their mothers than with randomly chosen adult females. Naturally weaned yearlings had a significantly stronger association with their mothers, were displaced less often by other herd members, and spent more time in the centre of groups than forcibly weaned yearlings. We were unable to detect benefits to naturally weaned daughters in terms of growth and age at first reproduction. Mothers of naturally weaned yearlings did not differ from mothers of forcibly weaned yearlings in subsequent mass change or reproduction.
Vigilance and foraging patterns of American elk during the rut in habitats with and without predators
Authors: Wolff Jerry O , Horn Toni Van
Published: June 2003

Animal behavior is often optimized as a trade-off between survival and reproduction. During the breeding season, mammals tend to maximize their reproductive effort within the constraints of predation pressure. When predation pressure is reduced, greater effort can be allocated to reproductive behavior and less to vigilance and predator avoidance. The objective of this study was to test the hypothesis that elk, Cervus elaphus, in Yellowstone National Park (YNP), with predators, would spend more time in vigilance and risk-avoidance behavior than would elk in Rocky Mountain National Park (RMNP), a predator-free environment. We further predicted that elk at Mammoth Hot Springs (MAM) in YNP would behave similarly to those at RMNP because predators were absent in that area of the park. Cow elk in YNP spent more time in vigilance and less in foraging during activity periods than did cows in RMNP or MAM. Also, elk in YNP retreated to forest cover during the midday inactive period, whereas elk in RMNP and MAM remained in open habitat. Vigilance was not correlated with group size at either site. Cows with calves spent more time in vigilance and less in foraging than did cows without calves in RMNP and YNP. Bull elk spent most of their time in courtship at all sites, but foraged more at RMNP than in YNP or MAM. Mean harem sizes were similar among the three sites: 17.0 in RMNP, 15.7 in YNP, and 19.0 in MAM. The proportion of cows with calves was significantly lower in the area with predators, YNP (0.10), than in the predator-free areas (0.24 in RMNP and 0.37 in MAM), probably because of greater calf mortality in YNP. Elk in YNP behaved in accordance with a predation risk, whereas those in RMNP and MAM showed less vigilance behavior.
Effect of starvation on the accumulation of CfDAP and CfDAP-like proteins in post-diapause Choristoneura fumiferana and diapause-free Choristoneura occidentalis
Authors: Han Er-Ning , Béliveau Catherine , Bauce Éric , Cusson Michel
Published: June 2003

In 1998, Palli et al. found that in the eastern spruce budworm, Choristoneura fumiferana, two hexameric proteins termed CfDAP1 and CfDAP2 are expressed abundantly before and during diapause. To determine whether the accumulation of these proteins in early instars is a direct consequence of the diapause phenomenon, we assessed the abundance of CfDAP-like proteins in first (L1), second (L2), and third (L3) instars of a diapause-free strain of the closely related western spruce budworm, Choristoneura occidentalis. Using sodium dodecyl sulfate  polyacrylamide gel electrophoresis and Western-blot analyses of L2 whole-body proteins, a CfDAP-specific antiserum reacted with two C. occidentalis proteins displaying apparent molecular masses identical with those of CfDAP1 and CfDAP2. Among the three larval stadia examined, CfDAP-like proteins accumulated to significant levels only in the first two, with enhanced accumulation observed in L2s starved from the time of hatching. Accumulation of CfDAP1 and CfDAP2 in post-diapause C. fumiferana L2s was affected similarly by food availability. Thus, the data presented here, combined with those of Palli et al., suggest that expression of CfDAP and CfDAP-like proteins in early larval life is more or less limited to L1 and L2, and is associated with starvation stress imposed either experimentally or by elements of the life cycle (i.e., diapause).
The metabolic cost of amplexus in the grey tree frog (Hyla versicolor): assessing the energetics of male mating success
Authors: McLister James D
Published: June 2003

The metabolic cost of amplexus was calculated for 37 pairs of grey tree frogs, Hyla versicolor, by measuring the rate of O2consumption of each amplexed pair and the combined resting rates of O2consumption of the two individuals of each pair, and calculating the difference. The mean cost of amplexus was 1.20 mL O2·h1for each pair. The cost of amplexus was correlated with the mass of the males but not the mass of the females, and amplexus with artificial males did not have a significant effect on female metabolic rate. Therefore, the cost of amplexus appears to be incurred entirely by the male. Reproductively successful males spend less time calling per evening than reproductively unsuccessful males, leaving the chorus early to enter into amplexus. The mass-specific cost of amplexus (0.158 mL O2·g1·h1) is approximately 1/10 the mass-specific cost of call production (1.620 mL O2·g1·h1), and net energy consumption per evening is less for reproductively successful male H. versicolor than it is for reproductively unsuccessful males. The probability of future reproductive success is enhanced if reproductive success is energetically less expensive than reproductive failure.
The Harderian gland of two species of snakes: Pseudonaja textilis (Elapidae) and Thamnophis sirtalis (Colubridae)
Authors: Rehorek Susan J , Halpern Mimi , Firth Bruce T , Hutchinson Mark N
Published: June 2003

The reptilian Harderian gland is a poorly understood cephalic structure. Despite the recent assertion that in snakes it may function as part of the vomeronasal system, the Harderian gland has been described in few snake species. In this study we examined the gross anatomy, histology, and ultrastructure of the Harderian gland of two different advanced snake species (Colubroidea): Pseudonaja textilis (Elapidae) and Thamnophis sirtalis (Colubridae). In both species the Harderian gland is a large serous gland whose secretions pass directly into the vomeronasal organ via the nasolacrimal duct. Contrary to previous publications, the Harderian gland in both species studied possesses a specific duct system lined by mucous cells. However, the Harderian glands of these two species differ in shape, the histochemical nature of these mucous secretions, and the ultrastructure of the serous granules. In conclusion, though the Harderian glands of snakes are remarkably conserved morphologically, there is some interspecific variation.
Timing and patterns of mating in a free-ranging population of Lycosa tarantula (Araneae, Lycosidae) from central Spain
Authors: Fernández-Montraveta Carmen , Cuadrado Mariano
Published: June 2003

We analysed the timing and patterns of mating in a free-ranging population of the wolf spider Lycosa tarantula (Araneae, Lycosidae) in central Spain monitored during a whole reproductive period. The population showed a polygamous mating system. However, the frequency of multiple mating was relatively low. Reproductive success of males was highly skewed, as a few males monopolized most of the copulations recorded. Males matured slightly before females but male and female maturation largely overlapped. Mortality of subadult spiders was independent of their sex, and the operational sex ratio was 1:1. Early maturation of females resulted in a larger number of visiting males but not higher mating success, indicating the possibility of female mate choice in this species.
Experimental transmission of Pharurus pallasii (Nematoda: Metastrongyloidea), a lungworm of the cranial sinuses of the beluga whale (Delphinapterus leucas), to fish
Authors: Houde Magali , Measures Lena N , Huot Jean
Published: June 2003

Transmission of lungworms (Metastrongyloidea: Pseudaliidae) in the marine environment has been poorly studied. This experimental study is the first conducted on a pseudaliid, Pharurus pallasii, a lungworm of the cranial sinuses of the beluga whale (Delphinapterus leucas). First-stage larvae removed from uteri of gravid female P. pallasii from a freshly dead beluga were experimentally exposed to various marine organisms (fish, crustaceans, molluscs). First-stage larvae failed to develop in experimentally exposed invertebrates. The first moult occurred in the intestinal wall of American plaice (Hippoglossoides platessoides) and Arctic sculpins (Myoxocephalus scorpioides) 45 and 78 days post exposure, respectively. The third larval stage, which is infectious to the final host, was not observed in fish during the 14 months of the experiment. No cellular inflammatory reaction to or encapsulation of larvae was observed in histological sections of the intestinal wall of American plaice 268 days post exposure. Survival and development of P. pallasii larvae to the second stage in fish suggest that fish are likely suitable intermediate hosts in the life cycle of P. pallasii. Invertebrates may still play a role as transport (paratenic) hosts. The morphology of the first and second larval stages of P. pallasii is described for the first time.
Comment on "Predator classification by the sea penPtilosarcus gurneyi(Cnidaria): role of waterborne chemical cues and physical contact with predatory sea stars"
Authors: Dalby Jr James E , Elliott Joel K
Published: June 2003

In their study of behavioural responses of pennatulaceans to physical contact with asteroids in 2002, Weightman and Arsenault claim to be the first to demonstrate that cnidarians have the ability to distinguish predators from nonpredators. In fact, it has been known since at least the 1960s that cnidarians are capable of predator recognition. We briefly describe some of the abundant literature on this topic, especially studies on anthozoans.
Reply to the comment by Dalby and Elliott on "Predator classification by the sea pen Ptilosarcus gurneyi (Cnidaria): role of waterborne chemical cues and physical contact with predatory sea stars"
Authors: Weightman Janice O , Arsenault David J
Published: June 2003

The comment of Dalby and Elliott was triggered by a statement we made in a research note to the effect that our study provided the first experimental evidence of predator-classification abilities in cnidarians. Based on an extensive literature search and the appreciation of our manuscript by the reviewers, at the time of publication we believed that this statement was correct. After reviewing the research articles highlighted by Dalby and Elliott, we concur that the statement is incorrect. We discuss some possible reasons why the articles cited by the authors were not found during our literature search, including the use of technical "jargon". In formulating their comment, the authors make several incorrect assumptions, including (i) that our literature search was limited to a single broad review paper and (ii) that we overlooked key information in at least two of the papers we cited. Also, the authors appear to confound predator recognition and predator classification, as some of the articles they cite do not examine predator-classification abilities. Finally, they give the impression that predator-classification abilities are ubiquitous in cnidarians. This appears to be an overstatement, since a number of published studies clearly indicate high variability in the ability of cnidarians to (i) recognize predators and (ii) respond "correctly" according to the relative threat they represent.
Quantifying an anti-bat flight response by eared moths
Authors: Fullard J H , Muma K E , Dawson J W
Published: June 2003

Using near-infrared videotaping we measured the nocturnal flight times of six species of eared moths (Amphipyra pyramidoides Guenée, Caenurgina erechtea (Cramer), Feltia jaculifera (Guenée), Phlogophora periculosa Guenée, Lymantria dispar (Linné), and Ennomos magnaria Guenée) in cages in which they flew, under randomized conditions, for 3 h in the absence and 3 h in the presence of simulated bat-attack sounds. When exposed to the ultrasound, four of the six species exhibited significant reductions in total flight time ranging from 38 to 98%. We suggest that this quantified measurement of flight time will be useful for fundamental studies on the evolution and ecology of moth hearing as well as applied studies on acoustic methods of controlling moth pests.
Physiological effects of immune challenge in captive greenfinches (Carduelis chloris)
Authors: Hõrak Peeter , Saks Lauri , Ots Indrek , Kullissaar Tiiu , Kollist Hannes , Zilmer Mihkel
Published: June 2003

It is expected that the costs of exploiting an organism's immune system form the basis of many life-history trade-offs. However, the processes responsible for generating these costs have rarely been quantified in terms of energy expenditures and physiological rearrangements in the organism during the immune response. To determine the physiological changes caused by the immune response, we recorded various condition indices of male captive greenfinches (Carduelis chloris) 1, 4, and 8 days after immune challenge with a nonpathological antigen (sheep red blood cells; SRBC). Measured variables included estimates of total and differential leukocyte counts, serum protein concentrations and profile, serum triglyceride concentration, basal metabolic rate, body mass, spontaneous locomotory activity, and serum total antioxidant capacity. On days 4 and 8 post injection, immune-challenged greenfinches significantly reduced their spontaneous locomotory activity, which suggests a switch to energy conservation. Fourteen hours after injection of SRBC, a transient increase in serum beta-globulin concentration was recorded, indicating an acute-phase response to the antigen. None of the other condition indices was affected by the treatment, which suggests that when birds maintained on an affluent feeding regimen in captivity mounted an immune response against SRBC, they did not incur any serious physiological impact.
Functional morphology of sexually selected gentalia in the water strider Aquarius remigis
Authors: Fairbairn Daphne J , Vermette Richard , Kapoor Narinder N , Zahiri Nayer
Published: June 2003

In the water strider Aquarius remigis (Say), sexual selection favours males with longer genitalia. We used video analysis plus light and scanning electron microscopy to examine the structure, movement, and articulation of the genitalia as a first step in determining the functional basis of this selection. Male A. remigis are characterized by long, robust genital segments; a marked ventral median notch in the posterior margin of the pregenital segment; an enlarged phallus tipped with a uniquely prolonged sclerotized plate; and a large, spine-covered, membranous lobe that inflates within the female's reproductive tract. Detailed examinations of genital interactions prior to and during copulation allow us to deduce the functional significance of these distinguishing traits. We postulate that by increasing the length, mobility, strength, and rigidity of the phallus, the first three traits increase the ability of males to achieve intromission in spite of active female resistance, and to maintain intromission during the prolonged copulations characteristic of this species. Inflation of the large, spinous lobe probably contributes to the latter function, and may also directly affect fertilization success by displacing or damaging sperm from previous males. We discuss these interpretations in the context of current theories of genitalic coevolution and sexual conflict in the Gerridae.
Using patch and landscape variables to model bird abundance in a naturally heterogeneous landscape
Authors: Crozier Gaea E , Niemi Gerald J
Published: June 2003

Regression models were developed to predict relative bird abundance in a naturally heterogeneous landscape using patch and landscape spatial scales. Breeding birds were surveyed with point counts on 140 study sites in 1997 and 1998. Aerial photographs were digitized to obtain habitat patch information, such as area, shape, and edge contrast. Classified remote-sensing data were gathered to provide information on landscape composition and configuration within a 1-km2 area around the study sites. Stepwise multiple linear regression was used to develop 40 species-specific models within specific habitat types using patch and landscape characteristics. In 38 out of the 40 models, area of the habitat patch was first selected as the most important predictor of relative bird abundance. Variables related to the landscape were retained in 6 of the 40 models. In this naturally heterogeneous region, the landscape surrounding the patch contributed little to explaining relative bird abundance. The models were evaluated by examining how well they predicted relative bird abundance in a test set not included in the original analyses. The results of the test data were reasonable: >79% of the test observations were within the prediction intervals established by the training data.
Sex divergence in space utilisation in the steppe tortoise (Testudo horsfieldi)
Authors: Lagarde Frédéric , Bonnet Xavier , Henen Brian , Legrand Arnaud , Corbin Johanna , Nagy Ken , Naulleau Guy
Published: June 2003

In animal species without parental care, the fitness of males should increase with the number of females encountered, court, and fertilise, and the fitness of females depends strongly on the quantity and quality of resources acquired. This should translate into a marked sex differences in the patterns of space utilisation. We analysed the sex divergences in home range and movements pattern in the steppe tortoise (Testudo horsfieldi) in Uzbekistan. From the radio-tracking data of 36 individuals throughout the active season, the home range of the male steppe tortoise was estimated to be smaller than that of the female (24 vs. 57 ha), even when the analysis focused on the mating season only. During the mating season, males intensively patrolled a small area, going back and forth within their territory, thereby covering greater distances than females. The females movements were more unidirectional, resulting in large loops over a very extended home range. We proposed several nonexclusive hypothesis for such a pattern.
Malacological insights into the marine ecology and changing climate of the late Pleistocene  early Holocene Queen Charlotte Islands archipelago, western Canada, and implications for early peoples
Authors: Hetherington Renée , Reid Robert G.B
Published: June 2003

The first intertidal species to colonize the Queen Charlotte Islands archipelago along the northeastern Pacific margin of Canada after the last glacial maximum (LGM) was Macoma nasuta at 13 210 ± 80 14C years BP. Prior to this time, molluscs were likely excluded where grounded ice extended from the 2 km thick Cordilleran ice sheet on mainland British Columbia. Low water temperatures, high sedimentation rates, high turbidity, dilution, and low primary productivity limited invertebrate colonization subsequent to the LGM, a period of rapid sea-level and climate change. As an adult, M. nasuta is a facultative deposit-suspension feeder that tolerates high turbidity and lowered salinity, and its pediveligers and early juveniles must also have been able to survive these conditions. Subsequently, in addition to M. nasuta, Macoma irus (inquinata), Saxidomus giganteus, Protothaca staminea, Protothaca tenerrima, Hiatella pholadis, Clinocardium nuttallii, and Mytilus trossulus constituted a typical intertidal bivalve assemblage. These findings are explained in terms of the physiology, feeding mechanisms, development, and sediment preferences of living molluscs. The disappearance of most bivalve species between ~11 000 and 10 000 14C years BP indicates the onset of a short interval of low sea-surface temperatures coincident with the Younger Dryas cooling event. Some cold-hardy species persisted, including Clinocardium californiense, Mya truncata, and Serripes groenlandicus. Bivalve species not previously reported as Pleistocene fossils were collected in sediments dating older than 10 000 14C years BP. They include Macoma incongrua, Musculus taylori, Mytilimeria nuttallii, and Tellina nuculoides. Fossil assemblages of intertidal molluscs are used to map ancient shorelines and indicate which species were available as a subsistence resource for early peoples from at least 13 210 ± 80 14C years BP. Intertidal food biomass densities may have reached present commercially harvested levels on southern Moresby Island by 8800 ± 70 14C years BP and on northern Graham Island by 8990 ± 50 14C years BP. When early peoples might have been migrating along the littoral zone, the molluscan productivity of the outer coast was much higher than it is at present.
Sex and age differences in distribution, abundance, and habitat preferences of wintering Harlequin Ducks: implications for conservation and estimating recruitment rates
Authors: Rodway Michael S , Regehr Heidi M , Cooke Fred
Published: June 2003

We determined the sex- and age-specific distribution, abundance, and habitat preferences of wintering Harlequin Ducks (Histrionicus histrionicus) and evaluated potential biases in measuring ratios of immature males to adult males to estimate recruitment rates. A comparison of the occurrence of birds with habitat availability at the 1-km scale indicated a preference for wide intertidal habitat with cobblegravel or bedrockboulder substrate, small offshore islets and shoreline with attached or nearby reefs and islets, areas without streams, and areas with a greater historical abundance of herring spawn. Where the substrate was bedrockboulder, birds preferred areas with tidal rapids. Densities of birds were highest along linear and complex shorelines with reefs or islets where intertidal habitat was >100 m wide and substrate was cobblegravel or bedrockboulder. Patterns of habitat use among sex and age classes were the same at the 1-km scale but differed at smaller scales, with adult and immature males occurring farther offshore than females. Age ratios varied among areas and were biased by survey method and misidentification of distant birds. Correcting for detected biases gave an estimated male age ratio of 9.8%. Calculated estimates of female recruitment suggest a declining population, but it is necessary to incorporate emigration in estimates of adult survival before demographic trends can be confidently inferred.
Experimental analysis of the mating system of the white pine weevil,Pissodes strobi(Peck) (Coleoptera: Curculionidae)
Authors: Liewlaksaneeyanawin Cherdsak , Ritland Kermit , Ritland Carol , El-Kassaby Yousry A
Published: June 2003

The white pine weevil, Pissodes strobi, severely restricts the growth and range of Sitka spruce (Picea sitchensis) in British Columbia. Knowledge of the patterns of male and female mating success is important for designing biocontrol programs and for understanding the reproductive potential of this weevil. To examine patterns of male and female reproductive success, we performed experiments in which the numbers of competing mates were varied, and used microsatellite markers to assay for mating success. Matings were conducted under four regimes: two males competing for a female, four males competing for a female, two females competing for a male, and four females competing for a male. We assayed 1869 progeny among several replicates for four marker loci. We found considerable multiple paternity, and the variance of reproductive success was higher in males than in females. The normalized variance of male success was higher among four competing males than between two competing males, which is consistent with last-male sperm precedence, while the normalized variance of female success was independent of female number for a constant male number, indicating that sperm quantity was not a limiting factor for reproduction at these mate densities.
Temporal patterns of foraging activities of northern gannets,Morus bassanus, in the northwest Atlantic Ocean
Authors: Garthe Stefan , Benvenuti Silvano , Montevecchi William A
Published: June 2003

We investigated time allocation and diel rhythms in foraging northern gannets (Morus bassanus). Chick-rearing adults on Funk Island, Newfoundland, Canada, were equipped with different types of data loggers. We found no effects of the devices on the birds' behaviour or breeding success. A total of 25 foraging trips were recorded from 16 birds. Foraging- trip durations (median 13.5 h, range 3.039.2 h) showed a bimodal distribution, coinciding with a partitioning of foraging trips into 1- and 2-day trips. Some individuals were consistent in performing either 1- or 2-day trips. During foraging trips, gannets were flying, on average, 44% of the time. Foraging activities exhibited a clear diel rhythm. Flight and diving activity was concentrated during early morning and late afternoon, with reduced activity during midday. Gannets were inactive at night. Flight time between the terminal dive of a foraging trip and arrival at the colony was significantly longer during 2-day trips (94 ± 22 min; mean ± SD) than during 1-day trips (51 ± 22 min). Water masses visited differed between 1- and 2-day trips. We could find no evidence for a clear dual foraging strategy, although birds were exploiting more distant waters during 2-day trips, as has been found for many procellariform species.
Fine-scale habitat selection by coastal bottlenose dolphins: application of a new land-based video-montage technique
Authors: Hastie Gordon D , Wilson Ben , Thompson Paul M
Published: June 2003

Cetacean distribution and underwater topography are frequently correlated. These patterns are commonly studied on large spatial scales, over tens of kilometres, but very rarely on a fine scale. Sightings of bottlenose dolphins, Tursiops truncatus, within the Moray Firth, Scotland, were previously found to be concentrated within deep, narrow channels. To understand why such areas were selected, more-detailed information on the distribution of dolphins was required. This study describes the development of a video technique to study the spatial distribution and relative abundance of bottlenose dolphins. We then used the methodology to investigate whether water depth and seabed gradient influence the dolphins' distribution patterns. Furthermore, temporal patterns of use were examined with respect to seasonal, tidal, and diurnal cycles. The distribution of dolphins was significantly related to topography: dolphins were sighted most frequently in the deepest regions with the steepest seabed gradients. There was a clear temporal pattern in the use of the area, with sightings peaking during July. However, the presence of dolphins was not significantly related to tidal or diurnal cycles. The topography of the area appears to be a significant influence on its intensive use by dolphins, and patterns of use indicate that topography may facilitate foraging during seasonal migrations of fish.
Genetic structure and phylogeography of the takin (Budorcas taxicolor) as inferred from mitochondrial DNA sequences
Authors: Li Ming , Wei Fuwen , Groves Pamela , Feng Zoujian , Hu Jinchu
Published: June 2003

To investigate the genetic structure within the takin (Budorcas taxicolor), a little-studied and threatened species, portions of the mitochondrial DNA control region and cytochrome b gene were sequenced from 40 takins from three subspecies and 10 separate geographical locations in China. Overall variation among individuals was low. Both neighbor-joining and parsimony analyses did separate animals into three distinct clades reflecting the subspecific definitions, with only one locality grouping with a clade distinct from its purported subspecies. Animals within each clade were genetically similar to each other, which we hypothesize is due to the mobility of the animals leading to significant gene flow within each region until recent habitat alteration limited movements. We also suggest that genetic bottlenecks survived by the species since the end of the Pleistocene may have contributed to overall low levels of variability within the species.
Genetic variation and population structure of moose (Alces alces) at neutral and functional DNA loci
Authors: Wilson Paul J , Grewal Sonya , Rodgers Art , Rempel Rob , Saquet Jacques , Hristienko Hank , Burrows Frank , Peterson Rolf , White Bradley N
Published: June 2003

Genetic variation was examined for moose (Alces alces) from Riding Mountain, Isle Royale, and Pukaskwa national parks; northwestern, Nipigon, northeastern, and central Ontario; New Brunswick; and Newfoundland. The national parks were identified as maintaining potentially different local selection pressures due to the absence of hunting and the presence or absence of the parasite Parelaphostrongylus tenuis. Genetic variation was estimated using neutral DNA markers, assessed by multilocus DNA fingerprinting and five microsatellite loci, and the functional antigen binding region (ARS) (exon 2) of the major histocompatibility complex (MHC) gene DRB. There was discordance in the allelic diversity observed at the neutral loci compared with the MHC DRB locus in a number of populations. Ontario populations demonstrated higher levels of variability at the neutral loci and relatively low levels at the DRB locus. Conversely, the Isle Royale population has the lowest genetic variability, consistent with a historic small founding event, at the neutral DNA markers and relatively high variability at the MHC gene. Relatively high levels of genetic variation at the DRB locus were observed in protected park populations concomitant with the absence of white-tailed deer (Odocoileus virginianus) or the parasite P. tenuis and an absence of hunting. Gene flow was observed among the neighboring geographic regions within Ontario, including Pukaskwa National Park, with evidence of isolation-by-distance among more distant regions within Ontario. The discordant patterns between DNA markers suggest that neutral DNA markers may not accurately reflect adaptive variation present at functional loci.