bluuebunny/crossref_metadata_2025 huggingface dataset:
Handling and stocking-density effects on growth rhythms of brook trout,Salvelinusfontinalis
Authors: Hosn Wafa Aboul , Dutilleul Pierre , Boisclair Daniel
Published: April 2011

We evaluated the effects of handling and stocking density (3 vs. 6 fish/150 L) on the growth-rate rhythms of brook trout, Salvelinus fontinalis. The length of nonhandled fish was estimated with a stereo-video technique and the length and mass of handled fish was measured directly. The main effects of handling and stocking density and their interactions on growth rates were not statistically significant, whereas the main effects of time were significant, as shown by repeated measure analysis. Multifrequential periodogram analysis indicated significant infradian rhythm components of about 8 d in the relative growth rate in length and of about 5 and 11 d in the relative growth rate in mass, regardless of the treatment applied. The characteristics (period, amplitude, and phase) of the rhythms found were not altered, either by handling or by stocking density.
Availability of nest sites does not limit population size of southern flying squirrels
Authors: Brady Matthew J , Risch Thomas S , Dobson F Stephen
Published: April 2011

Among factors that may limit population size, nest site is generally considered important for cavity-nesting species. We tested the hypothesis that nest-site availability limits population size in the southern flying squirrel (Glaucomys volans) by examining the effect of experimentally increasing the number of nest sites. We compared population sizes before and after adding 100 nest boxes (high-quality nests, increasing overall nest density by at least about 65%) on each of three experimental sites on the Savannah River Site in South Carolina. We also compared the experimental populations with three reference (unmanipulated) sites in a paired-block experimental design. All six populations were similarly monitored with livetrapping grids, and flying squirrels readily nested in the supplemental boxes. We predicted that population size would increase where nest sites were added. No increases in population size were observed after nest boxes were added to the three experimental sites, however, nor were populations higher on the experimental sites than on the reference sites. The lack of increase in population size after nest boxes were added demonstrates that the availability of nest sites was not limiting the size of these populations.
Chemosensory discrimination of plant and animal foods by the omnivorous iguanian lizard Pogona vitticeps
Authors: Cooper, Jr. William E
Published: April 2011

Most iguanian lizards are insectivores that do not use chemical cues sampled by tongue-flicking to identify prey before attacking, but the sole iguanian herbivore previously studied did so. To investigate the effects of a partially herbivorous diet on responses to food chemicals, I conducted an experiment to determine whether the omnivorous bearded dragon (Pogona vitticeps) has a similar ability. Chemical stimuli from crickets and carrots, both preferred foods, and alfalfa sprouts, and deionized water (a nonpreferred food and odorless control, respectively) were presented on cotton-tipped applicators. The lizards responded more strongly to both preferred foods than to the controls, performing more tongue flicks and biting the cotton in a greater number of trials. It is hypothesized that lingually mediated food-chemical discrimination is useful to herbivorous and omnivorous lizards for identifying plant and animal foods and for evaluating the quality of plant foods. The insectivorous ambush foragers ancestral to P. vitticeps could not locate prey by tongue-flicking repeatedly at an ambush post and do not exhibit prey-chemical discrimination. Adding plants to the diet altered the selective milieu because plants approached using visual cues can be evaluated using chemical cues, allowing the evolution of the ability to discriminate between plant-food chemicals. The ability to identify animal prey by tongue-flicking may have evolved through correlated evolution with chemosensory identification of plants or specifically for locating or identifying immobile prey.
Reliability of photographic and molecular techniques for sexing northern bottlenose whales (Hyperoodon ampullatus)
Authors: Gowans S , Dalebout M L , Hooker S K , Whitehead H
Published: April 2011

Identifying the sex of living cetaceans can be difficult, even when species are sexually dimorphic. We compare two methods of molecular sexing (ZFY (zinc finger protein gene) and SRY (sex-determining region Y gene)) and evaluate the effectiveness of photographic techniques for identifying sex in northern bottlenose whales, Hyperoodon ampullatus, in the Gully, off Nova Scotia, Canada. Samples from individuals of known sex from historic Norwegian whaling (n = 19) and from recent strandings (n = 3) were used to test the reliability of the molecular techniques. Although both methods gave accurate results, the ZFY method was found to be unsuitable for degraded (historic) samples, owing to the large size of the target DNA fragment. Results from the two molecular-sexing methods were in agreement for biopsy samples taken from bottlenose whales in the Gully (7 males and 13 females). Photographs of the melon profile were used to assign free-swimming animals to the categories female - immature male, subadult male, and mature male. Melon photographs of adult-sized animals taken up to 7 years apart were consistently assigned to the same category. Overall, sex identification from melon photographs was in agreement with results from molecular sexing. However, animals in the category female - immature male were difficult to assign on the basis of morphological features alone.
Early Eocene insects from Quilchena, British Columbia, and their paleoclimatic implications
Authors: Archibald S Bruce , Mathewes Rolf W
Published: April 2011

Fossil insects were examined from the Early Eocene lacustrine shale at Quilchena, British Columbia. Insects of 10 orders (Blattodea, Dermaptera, Orthoptera, Hemiptera, Neuroptera, Coleoptera, Mecoptera, Diptera, Trichoptera, Hymenoptera) were identified, bringing the known number at this site to 11. These were placed in 26 families, 22 of which are new occurrences for this locality. Specimens include early occurrences of bees and ants. Three fossils of leaves with galls were examined. Thirteen of the families are new to British Columbia, and 9 of these (Blaberidae, Haglidae, Cixiidae, Dinidoridae, Cydnidae, Staphylinidae, Panorpidae, Pipunculidae, Halictidae) are new to the region of the Okanagan Highlands. A number of taxa are earliest known occurrences. Several insects in this fauna are larger than their modern relatives and some are larger than their relatives from other Eocene locales. The presence of insects including March flies, diplopterine cockroaches, dinidorid bugs, and seed weevils confirm and perhaps exceed paleobotanical indications that in the Eocene, British Columbia was much warmer than it is today.
Habitat use and survival of northern bobwhite (Colinus virginianus) in cropland and rangeland ecosystems during the hunting season
Authors: Williams Christopher K , Lutz R Scott , Applegate Roger D , Rusch Donald H
Published: April 2011

Many researchers and managers believe that land-use practices are most responsible for declines in northern bobwhite (Colinus virginianus) populations. Additionally, researchers have suggested that the amount of available escape cover in a landscape could alter winter survival of bobwhites. A comparative study of winter bobwhite ecology was conducted on rangeland and cropland ecosystems in east-central Kansas (11 November - 31 January 1993-1996). We considered woody cover type on our study areas to be an escape cover for quail. We used radiotelemetry to investigate survival, movement, and cover-type selection. Over the 3-year period, we monitored 91 individuals on a cropland study area (CSA) and 66 birds on a rangeland study area (RSA). Survival was higher on the CSA (0.46) than on the RSA (0.27) (P = 0.03); the difference was due to increased harvest mortality on the RSA (P = 0.04). Mean daily covey movement was higher on the RSA than on the CSA (P < 0.01). Comparing cover-type selection between study areas, it was found that bobwhites selected cropland more on the RSA than on the CSA (P < 0.01). On the RSA, increased daily movement correlated with decreased selection for woody cover and increased selection for cropland (P < 0.02). On the CSA, increased woody-cover selection decreased natural predation (P = 0.03). On the RSA, decreased movement, increased woody cover, and decreased pasture selection reduced natural predation (P < 0.05). However, increased woody-cover selection increased harvest mortality (P < 0.01). Consequently, we consider the selection for woody cover to be an important variable in bobwhite survival on the RSA. It is suggested that landowners on rangelands could reduce natural mortality by taking advantage of programs available from federal and state governments and nongovernmental organizations, to increase woody cover for bobwhites.
Metabolism and circadian rhythms of the European blind cave salamander Proteus anguinus and a facultative cave dweller, the Pyrenean newt (Euproctus asper)
Authors: Hervant F , Mathieu J , Durand J P
Published: April 2011

Comparisons of circadian rhythmicity, behavior, and metabolism between surface- and cave-dwelling salamanders allow evolutionary trends in these processes to be elucidated. The proteid Proteus anguinus, an obligate cave-dweller, showed no apparent daily rhythm of activity or resting metabolic rate. In contrast, the salamandrid Euproctus asper, a surface-dweller/facultative cave-dweller, had a circadian resting metabolic rate and activity cycle. These circadian rhythms had an endogenous component. The lives of both studied salamanders were characterized by long periods of inactivity punctuated by bouts of foraging or exploratory/predatory behavior. Proteus anguinus had reduced resting metabolic and spontaneous activity rates (considerably lower than those of most surface-dwelling amphibians), and therefore appears to be a good example of a vertebrate as a low-energy system. The low metabolic and activity rates of P. anguinus are interpreted as adaptations to a subterranean environment, where a poor and discontinuous food supply and (or) intermittent hypoxia may be present for long period
Egg size, contents, and quality: maternal-age and -size effects on house fly eggs
Authors: McIntyre G S , Gooding R H
Published: April 2011

Egg size is generally regarded as a good predictor of egg quality. However, in phenotypic studies it is difficult to separate the effects of egg-size variation from the effects of the underlying cause of the differences in egg size. We examined the relationships between the size, shape, hatch rate, and biochemical and energy contents of house fly (Musca domestica L.) eggs using two distinct sources of egg-size variation: maternal age and maternal size. By comparing relationships among egg parameters between manipulations we were able to distinguish some maternal effects from pure egg-size effects. Maternal age was negatively correlated with clutch size, egg volume, hatch rate, and lipid content, but was not correlated with protein, carbohydrate, or energy content. Female size did not affect hatch rate or biochemical and energy contents, but was positively correlated with clutch size and egg volume. Partial correlation analyses revealed that egg-size variation due to maternal-age effects was unrelated to hatch rate, but that egg-size variation due to maternal-size effects was weakly negatively correlated with hatch rate. The results suggest that large and small house fly eggs differ primarily in size and that within size classes there is significant variation in other egg parameters. Size is not a useful predictor of egg quality in this system.
Determining food requirements in marine top predators: a comparison of three independent techniques in Great Cormorants,Phalacrocorax carbocarbo
Authors: Grémillet D , Storch S , Peters G
Published: April 2011

Assessment of food requirements is a key feature in the evaluation of the ecological status of the marine megafauna. However, this remains technically difficult because prey intake by marine top predators occurs mainly under water, out of sight. In this paper, we compare three independent methods currently available for use in quantitative dietary studies: (1) time-energy budget; (2) stomach-temperature measurements; and (3) automatic weighing. To this end, concurrent measurements were performed on Great Cormorants (Phalacrocorax carbo carbo) breeding in Normandy. According to the time-energy budget method, breeding males required 690 g of fish while incubating, 1050 g when rearing small chicks, and 1350 g when rearing large chicks; corresponding values for breeding females were 500, 760, and 970 g. These measurements are similar to estimates derived from automatic weighing data, which gave a mean food intake of 540 and 390 g for incubating males and females, 1150 and 830 g for those tending small chicks, and 1410 and 1010 g for those tending large ones, respectively. Stomach-temperature measurements, which can only be performed for birds raising small chicks, were lower (640 g fish in males and 450 g in females) than those obtained using the other two methods. We compare these results with former estimates obtained at the same study site and for other Great Cormorant subspecies and discuss the relative accuracies of the three techniques. Finally, we stress that better assessment of the ecological status of marine top predators requires further technical improvements and additional investigations outside of the reproductive phase.
Levels of compatibility in a new host-parasite association: Apis mellifera/Varroa jacobsoni
Authors: Vandame Rémy , Colin Marc-E. , Morand Serge , Otero-Colina Gabriel
Published: April 2011

We investigated the relationships between the honey bee, Apis mellifera, and the parasitic mite Varroa jacobsoni in Mexico. In an 18-month survey of European honey bees (EHB) and Africanized honey bees (AHB), we showed that EHB were highly compatible with V. jacobsoni, while AHB were not as compatible. Furthermore, mite infertility ("parasite infectivity" factor), suspected to be the main factor of low AHB/V. jacobsoni compatibility in Brazil, was not observed in Mexico. The "intrinsic rate of natural increase" of mites did not differ significantly between host subspecies, indicating that the cause of low compatibility appears only at high parasite densities. The "carrying capacity" was twice as high in EHB as in AHB, indicating that the cause of low compatibility is possibly linked to honey bees' behavior. We hypothesize that the reason why V. jacobsoni is highly fertile on Mexican AHB (whereas it has low fertility on Brazilian AHB) may be that different strains of V. jacobsoni exist in the two countries.
Bipedal locomotion in birds: the importance of functional parameters in terrestrial adaptation in Anatidae
Authors: Abourachid Anick
Published: April 2011

The kinematic characteristics of a bird's walk vary according to whether the species is cursorial or not. To increase their speed, running birds increase the frequency of their movements, whereas non-running birds preferentially increase the amplitude. Previous studies have shown that these differences are accompanied by differences in posture; however, the observations were carried out on different species. Do these differences correspond to morphological differences linked to the history of the particular species, or do they reflect more effective solutions from a mechanical point of view? Two breeds of the duck Anas platyrhynchos platyrhynchos, the mallard and the Indian runner, which have different locomotor behaviours, are compared. The mallard is a dabbling duck with the typical horizontal duck posture, while the Indian runner is a terrestrial duck that carries its trunk very erect. The kinematic characteristics of the walks of both breeds were studied. The observed differences in posture between the mallard and the Indian runner have repercussions in the kinematic features of locomotion. The strategies used to increase speed differ in the two breeds: the mallard increases the amplitude of its movements, like other non-running birds, while the Indian runner increases the frequency of its movements, as cursorial birds do. Thus, behavioural adaptation to terrestrial locomotion is associated with functional adaptation (upright posture) that permits a more effective mechanical solution without requiring obvious morphological modifications.
Incidence of dart shooting, sperm delivery, and sperm storage in natural populations of the simultaneously hermaphroditic land snailArianta arbustorum
Authors: Baminger Helmut , Locher Rolf , Baur Bruno
Published: April 2011

In several families of terrestrial pulmonates, simultaneously hermaphroditic animals form a sharp, hard, calcified or chitinous structure (the so-called love dart) in the female part of their reproductive organs. The dart is used to pierce the body of the mating partner during courtship. The adaptive significance of this peculiar behaviour is still little understood. We examined dart shooting, autosperm delivery, and allosperm storage in three natural populations of the simultaneously hermaphroditic land snail Arianta arbustorum in the Austrian Alps. Twenty-six (30.2%) of 86 copulating snails used their dart. The frequency of dart shooting tended to vary among populations. There was no reciprocity in dart shooting: individuals shot their dart independently of the behaviour of the mating partner. The number of spermatozoa delivered ranged from 522 000 to 4 238 000 (mean 1 706 000). The occurrence of dart shooting was related to neither the number of sperm delivered nor the number received from the partner. The occurrence of dart shooting was not influenced by the amount of allosperm from previous matings stored in the spermatheca of the dart shooters in two populations. In the third population, however, dart shooters had stored more allosperm in their spermatheca than non-shooters. The number of sperm received was not correlated with the size of the donor or the size of the recipient, indicating that snails do not allocate more sperm to larger partners. Experimental results showed that snails which mated under laboratory conditions did not differ in dart-shooting frequency from snails which mated in the wild.
Indications of two genetically different subpopulations of Atlantic walruses (Odobenus rosmarus rosmarus) in west and northwest Greenland
Authors: Andersen L W , Born E W
Published: April 2011

Analyses of nuclear and mitochondrial DNA in walruses from northwestern Greenland (76°30'-78°30'N; i.e., in the area of the North Water polynya of northern Baffin Bay and Smith Sound) and west-central Greenland ( 67°-68°N) revealed two genetically distinct subpopulations. The studied sample consisted of tissues from 91 Atlantic walruses (Odobenus rosmarus rosmarus) from northwestern Greenland (1989-1990) and 33 Atlantic walruses from western Greenland (1988-1997). The analyses were based upon 12 nuclear microsatellite loci and restriction length polymorphisms observed in the ND1, ND2, and ND3/4 segments of mtDNA. Evolutionary factors creating the observed genetic differences were mainly drift and gene flow, even though a more pronounced mutational effect was observed at the mitochondrial level. Hence, there appears to be some male-mediated gene flow between the two subpopulations, whereas female-mediated gene flow apparently has been restricted for a considerable time. No temporal variation in population structure was detected in the sample from northwestern Greenland. Females collected in the summer season in this area were shown to be philopatric, meaning that closely related females stay and (or) travel together with a mean relatedness value close to the expected relatedness value for half siblings.
Long-term fluctuations of a caribou population revealed by tree-ring data
Authors: Morneau Claude , Payette Serge
Published: April 2011

We used a dendroecological approach that involved examination of debarking lesions (trampling scars) produced by caribou (Rangifer tarandus) hooves on surficial roots and low branches of conifers to assess caribou activity in the summer range of the Rivière George caribou herd in northeastern Quebec-Labrador over the last 100 years. We deduced changes in caribou activity from the age-frequency distributions of trampling scars in three widely spaced (>100 km) old-growth conifer stands in the Rivière George area. We used the fluctuating patterns in age distributions, described by residuals of the log-linear regression, as an index of the number of trampling scars with time. This index indicated that caribou activity at the three sites followed a general decreasing trend from the turn of the last century to around 1950. There were two stages of rapid decline, around 1905-1915 and 1940, separated by a minor increase in the 1920-1930s. A sustained increase occurred from the 1950s to the 1980s. A comparison with survey and historical data for caribou suggested that these fluctuations in this common signal of activity at the three sites resulted mainly from fluctuations in caribou abundance that occurred throughout the 20th century in northeastern Quebec-Labrador. The increase in caribou activity during the 1920-1930s suggested by the frequency of trampling scars is not reported in the historical record. Caribou trampling scars on conifers may offer a new opportunity to assess large-scale spatial and temporal population trends of caribou in subarctic and boreal zones.
Winter activity patterns of northern flying squirrels in sub-boreal forests
Authors: Cotton C Laine , Parker Katherine L
Published: April 2011

We described autumn-winter activity patterns of northern flying squirrels (Glaucomys sabrinus) in northwestern British Columbia during 1996-1997 and 1997-1998. Nineteen flying squirrels (12 males and 7 females) were fitted with temperature-sensitive radio collars. We located animals in 82 daytime nests using radiotelemetry techniques and monitored 268 nights of activity using data-logging receivers placed at the base of nest trees. The average temperature of the animals, as determined by the collar sensors while the animals were in nests, was 39.2 ± 0.1°C, with no significant differences among animals, tree species, or tree sizes. Activity periods in a mild field season followed a dusk- and dawn-activity pattern, but activities in harsh winter conditions shifted towards a shorter single activity bout or two very short activity bouts in the middle of the night. No long activity bouts (>1.9 h) were observed at temperatures below -20°C. This reduction in time spent active and adjustment of the timing of activity during extremely low temperatures likely serve as an energy-conservation strategy.
Ejaculate-storage patterns and the site of fertilization in female snow crabs (Chionoecetes opilio; Brachyura, Majidae)
Authors: Sainte-Marie Guy , Sainte-Marie Bernard , Sévigny Jean-Marie
Published: April 2011

A light-microscopy study of mated female snow crabs (Chionoecetes opilio) was conducted to investigate the site of fertilization and to resolve how multiple ejaculates are stored in the spermathecae. In its basic configuration, an ejaculate consisted of a layer or patch of spermatophores enclosing mature spermatids that was capped by a relatively large volume of amorphous matter, which in turn could include a patch of spermatophores containing immature spermatids. Up to 10-12 ejaculates were stored in the spermathecae with the largest loads. An ejaculate was initially deposited in the intermediate chamber and ventral part of the spermatheca, and was displaced toward the dorsal part of the spermatheca when a new ejaculate was inserted. Ejaculates were neatly stratified along the ventrodorsal axis of spermathecae with small to moderate loads, but they were disrupted and the storage pattern was disorderly in spermathecae with large loads. Ejaculate stratification favors last-male sperm precedence and single-male paternity. However, multiple-male paternity might occur in females with large spermathecal loads, in part because several ejaculates can co-occur close to the oviduct opening. Mixing of male and female gametes in preparation for oviposition, and probably also fertilization, occurs to some degree in the ovaries.
Inbreeding avoidance and mate choice in the mandarin vole (Microtus mandarinus)
Authors: Fadao Tai , Tingzheng Wang , Yajun Zhao
Published: April 2011

Five experiments were conducted to test the performance of adult mandarin voles (Microtus mandarinus) in discriminating and preferring siblings versus nonsiblings raised in different conditions. The results indicate that adult males and estrous females displayed a significant preference for individuals raised by other parents over those raised by the same parent, regardless of genetic relatedness. The effect appears to depend on the presence of siblings during development. This shows that familiarity through association before weaning plays an important role in kin recognition. The preference of reproductively active mandarin voles for unfamiliar voles is interpreted as inbreeding avoidance. Although Wilcoxon's matched-pair tests showed no significant preferences of adult mandarin voles for siblings over nonsiblings raised by the same parents or by other parents, mean durations of visiting, mounting, and lying near nonsiblings were higher than those for siblings. This implies that genetic relatedness may have some effect on kin recognition, although familiarity is the main mechanism.
Vocalizations of eastern Australian Risso's dolphins, Grampus griseus
Authors: Corkeron Peter J , Van Parijs Sofie M
Published: April 2011

Recordings were made from a group of Risso's dolphins (Grampus griseus) off the coast of Newcastle, Australia, between 30 Hz and 22 kHz. Risso's dolphins exhibited seven separate vocalisation types: broadband clicks, barks, buzzes, grunts, chirps, whistles, and simultaneous whistle + burst-pulse sounds. Broadband clicks were highly variable in duration, with a frequency range of 6 to >22 kHz. Bark vocalisations consisted of highly variable burst pulses, with durations ranging from 0.2 to 7.4 s and a frequency range of 2-20 kHz. Buzz vocalisations were clearly stereotyped, consisting of a short burst pulse of around 2 s and a frequency range of 2.1 to >22 kHz. Low frequency narrowband grunt vocalisations (0.40.8 kHz) were short in duration. Chirp vocalisations were slightly higher in frequency than the grunt vocalisations, ranging in frequency from 2 to 4 kHz. There were at least five different whistle types, ranging in frequency from 4 to 22 kHz. We recorded a combined tonal and burst-pulse vocalisation. The rising whistles ranged from 6 to 18 kHz, while the burst-pulse sounds ranged between 3 and 21 kHz. This combined whistle + burst pulse sound appears to be unique to Risso's dolphins.
Spatial and temporal variation in abundance of Diplostomum spp. in walleye (Stizostedion vitreum) and white suckers (Catostomus commersoni) from the St. Lawrence River
Authors: Marcogliese David J , Dumont Pierre , Gendron Andrée D , Mailhot Yves , Bergeron Emmanuelle , McLaughlin J Daniel
Published: April 2011

Abundances of eye flukes (Diplostomum spp.) were compared between walleye (Stizostedion vitreum) and white suckers (Catostomus commersoni) collected in late summer 1997 from Lake St. Louis and Lake St. Pierre, two expansions of the St. Lawrence River in Quebec, Canada. The white sucker, a benthic consumer, was more heavily infected than the walleye, a pelagic piscivore, in both lakes. Infection levels increased significantly with host age and size. For both species, abundance of Diplostomum spp. within each age group and length class was higher in fish from Lake St. Louis than in those from Lake St. Pierre. Walleye of all ages and white suckers [Formula: see text]7 years old from Lake St. Louis were also larger at age than those of corresponding age from Lake St. Pierre. Therefore, walleye and white suckers from Lake St. Louis are probably different populations from those in Lake St. Pierre. The higher infection levels in Lake St. Louis are most likely due to the larger number of ring-billed gulls (Larus delawarensis), an important definitive host of Diplostomum spp., in colonies in close proximity to that lake; there are >75 000 pairs within 40 km of Lake St. Louis and 16 000 pairs within 40 km of Lake St. Pierre. No detrimental effects of infection with Diplostomum spp. could be detected on fish fork length, body mass, condition index, or gonadosomatic index. Walleye from shallow lentic waters in Lake St. Louis were larger and possessed heavier infections of Diplostomum spp. than those from deeper lotic waters. Walleye collected from a fixed trap near Quebec City in July 1997 were smaller but more heavily infected with Diplostomum spp. than those collected in October, which implies that different populations of fish may be present seasonally at this location. A visual index developed to measure the degree of opacity of the lens of fishes does not appear to be a reliable indicator of levels of infection with eye flukes. Experimental infection of laboratory-raised juvenile ring-billed gulls with metacercariae from the lenses of various fish species collected in the St. Lawrence River demonstrated that metacercariae were primarily Diplostomum indistinctum (8492%), the remainder being Diplostomum huronense, and this pattern is consistent across host species and localities.
Regeneration neurohormones and growth factors in echinoderms
Authors: Thorndyke M C , Carnevali MD Candia
Published: April 2011

There has been much recent interest in the presence and biological functions of growth regulators in invertebrates. In spite of the different distribution patterns of these molecules in different phyla (from molluscs, insects, and annelids to echinoderms and tunicates), they seem always to be extensively involved in developmental processes, both embryonic and regenerative. Echinoderms are well known for their striking regenerative potential and many can completely regenerate arms that, for example, are lost following self-induced or traumatic amputation. Thus, they provide a valuable experimental model for the study of regenerative processes from the macroscopic to the molecular level. In crinoids as well as probably all ophiuroids, regeneration is rapid and occurs by means of a mechanism that involves blastema formation, known as epimorphosis, where the new tissues arise from undifferentiated cells. In asteroids, morphallaxis is the mechanism employed, replacement cells being derived from existing tissues following differentiation and (or) transdifferentiation. This paper focuses on the possible contribution of neurohormones and growth factors during both repair and regenerative processes. Three different classes of regulatory molecules are proposed as plausible candidates for growth-promoting factors in regeneration: neurotransmitters (monoamines), neuropeptides (substance P, SALMFamides 1 and 2), and growth-factor-like molecules (TGF-β (transforming growth factor β), NGF (nerve growth factor), RGF-2 (basic fibroblast growth factor)).
Function of eponymous structures in echinoderms: a review
Authors: Lawrence John M
Published: April 2011

Eponymous structures in echinoderms include Aristotle's lantern, Cuvierian tubules, Gregory's diverticulum, Hoffmann's organ, Lange's and Ludwig's nerves, Polian vesicles, Prouho's membrane, Reichensperger's organ, Simroth's organs, Stewart's organs, and Tiedemann's bodies and pouches. They are of particular interest because they are unique to echinoderms. Descriptive anatomical studies have provided the basis for most interpretations of their function, but many questions remain. Experimental physiological studies are necessary for a complete understanding of their roles. Systematically comparative studies are essential to establish their phylogeny.
Response of American kestrels and gray-tailed voles to vegetation height and supplemental perches
Authors: Sheffield Lisa M , Crait Jamie R , Edge W Daniel , Wang Guiming
Published: April 2011

We tested the behavioral and demographic responses of American kestrels, Falco sparverius, and gray-tailed voles, Microtus canicaudus, to vegetation height and addition of perches. We conducted our experiment in sixteen 0.2-ha rodent enclosures with four replicates assigned to each of the following treatments: tall vegetation without perches, tall vegetation with perches, short vegetation without perches, and short vegetation with perches. The enclosures were stocked with 20 gray-tailed voles in early November 1998. Before perches were erected during the 12th week of the experiment, kestrels showed a preference for short-vegetation enclosures (P < 0.05). After perches were erected, kestrels used enclosures with perches, showing the greatest preference for short-vegetation enclosures with a perch. Vole populations and recruitment rates were higher in tall-vegetation enclosures than in short-vegetation enclosures, but supplemental perches did not affect vole populations or recruitment. In many agricultural areas where perches are not available, providing supplemental perches may increase accessibility to prey species that cause crop damage. Facilitating predation by raptors may reduce vole populations and reduce the need to use potentially harmful chemicals in pest population management.
Estimating the mortality rate of humpback whale calves in the central North Pacific Ocean
Authors: Gabriele Christine M , Straley Janice M , Mizroch Sally A , Baker C Scott , Craig Alison S , Herman Louis M , Glockner-Ferrari Debbie , Ferrari Mark J , Cerchio Salvatore , Ziegesar Olga von , Darling Jim , McSweeney Dan , Quinn II Terrance J , Jacobsen Jeff K
Published: April 2011

Sighting histories of individually identified female humpback whales (Megaptera novaeangliae) in their winter and summer ranges were used to investigate mortality of North Pacific humpback whale calves. We compiled records collected between 1979 and 1995 by eight independent research groups, which yielded 29 cases where 25 different mothers sighted in Hawai'i were identified later the same year in Alaska. In 7 of 29 cases, a calf sighted with its mother in Hawai'i was missing from its mother's Alaska sighting(s). After investigating many factors, we determined that the largest potential bias would occur in late-autumn observations, when calf absences might indicate weaning or temporary mothercalf separation rather than calf mortality. Our minimal and most robust estimate excluded all mortalities and survivals based on sightings of the mother after October 31; 3 of 20 cases or 0.150 (95% confidence intervals (CI) = 0.032, 0.378). The maximal calf mortality rate, derived from all the available data, was 7 of 29 cases or 0.241 (95% CI = 0.103, 0.434). An intermediate estimate that excluded all cases based on single Alaska sightings and omitted late-season sightings (2 of 11 cases or 0.182; 95% CI = 0.023, 0.518) is perhaps closest to the actual first-year mortality rate for humpback whale calves, although it is compromised by its small sample size. Our results demonstrate both the value and the limitations of using longitudinal data to determine the life-history parameters that are essential for documenting the recovery of endangered populations.
Seed preferences and foraging by granivores at raccoon latrines in the transmission dynamics of the raccoon roundworm (Baylisascaris procyonis)
Authors: Page L Kristen , Swihart Robert K , Kazacos Kevin R
Published: April 2011

Raccoons (Procyon lotor) habitually defecate at preferred sites (latrines). Feces at latrines often harbor eggs of the roundworm Baylisascaris procyonis, a parasite of raccoons that is pathogenic to numerous species of small vertebrates. Undigested seeds are also commonly found in raccoon feces, the composition varying with availability of seed types. Thus, feces at latrines may serve as a source of food and pose a mortality risk for small granivores. To examine this interaction, we manipulated the seed composition in feces at simulated raccoon latrines and tested for differences in vertebrate visitation rates as a function of seed type. Treatments involved placing seeds, including corn, cherry ( Prunus virginiana), dogwood (Cornus racemosa), and a combination of the three types, at simulated raccoon latrines. Using TrailmasterTM camera systems we documented 2406 vertebrate visits by 16 mammal and 11 bird species during 455 camera-nights. Small granivorous mammals, including white-footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus), were the most common visitors. Visitation by white-footed mice was significantly greater when corn, the most preferred seed type, was present in raccoon feces. Visitation by eastern chipmunks and other vertebrate species did not vary with seed type. Active foraging was documented for five vertebrate species and accounted for 10% of all recorded events. We conclude that raccoon latrines are routinely visited by a variety of vertebrate species, especially small granivores. Active foraging for seeds in raccoon feces is an important risk factor for transmission of B. procyonis to small vertebrates, and white-footed mice may suffer elevated rates of infection when corn is present in raccoon feces.
Body size and segmentation patterns in free-living and parasitic polychaetes
Authors: Poulin Robert
Published: April 2011

Taxa that include both free-living and parasitic lineages present opportunities to examine if and how the life-history traits of parasitic organisms have diverged from those of their free-living relatives. In a comparative analysis the body sizes and numbers of body segments of parasitic polychaetes of the family Oenonidae were compared with those of free-living polychaetes from closely related families. There was no difference in body length between oenonids and free-living polychaetes. However, the parasitic oenonids attain, on average, a much higher number of body segments than their free-living counterparts. The number of segments per unit body length is also much higher in oenonids than in related free-living polychaetes. This suggests that new segments are produced at a higher rate or for longer periods in oenonids than in free-living polychaetes, in which the proliferation of new segments slows down over time to allow for the segments to grow in size. Given that each segment can produce gametes late in the life of the worm, the proliferation of segments in oenonids may be an adaptation to their parasitic life-style.
Myrmecophagy by Yellowstone grizzly bears
Authors: Mattson David J
Published: April 2011

I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging <5% of fecal volume at peak consumption), ants may have been an important source of protein during midsummer and were heavily consumed during some years. Myrmecophagy was most common annually when known high-quality foods were scarce, as well as during the warmest months of the study, when regional average temperatures exceeded 1215°C. Bears tended to select large ants (>8 mm long) nested in logs over small ants ([Formula: see text]6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 45 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.
Physical variability and fluctuating asymmetry in heterozygous and homozygous populations ofRivulusmarmoratus
Authors: Taylor D Scott
Published: April 2011

The debate over the influence of heterozygosity and homozygosity on developmental stability is ongoing, and rarely is an animal model found that represents these two genetic states in naturally occurring populations. Rivulus marmoratus (Pisces: Aplocheilidae), a small cyprinodontid fish indigenous to mangrove marshes of the western tropical Atlantic coast, may be an appropriate model. This species is well known as the only self-fertilizing hermaphroditic vertebrate, and populations normally consist of genetically diverse groups of homozygous clones. However, male fish are known from a few populations, and outcrossing has been documented from one area (Belize in Central America) where heterozygosity is the norm. Are there differences in developmental stability, as represented by fluctuating asymmetry (FA) and physical variability, between naturally occurring homozygous and heterozygous populations? Thirty-one meristic and morphometric characters in 180 fish from 10 populations were examined to determine physical variability. In addition, FA and the presence of physical anomalies were analyzed. Belize fish (heterozygous) were compared with eight other (homozygous) populations. To control for possible environmental effects, offspring of two populations (Belize and Florida) were reared at 25°C and similarly analyzed. The FA analyses and variability comparisons revealed no differences between heterozygous and homozygous populations, and the same was true for fish reared at a constant temperature. However, some populations (e.g., Brazil) were more variable than others. These results indicate that coadapted gene complexes may be more important than heterozygosity in canalizing developmental stability in this animal.
Distinct seawater and freshwater types of chloride cells in killifish,Fundulus heteroclitus
Authors: Katoh Fumi , Hasegawa Sanae , Kita Jun , Takagi Yasuaki , Kaneko Toyoji
Published: April 2011

Physiological and morphological differences between killifish adapted to seawater (SW) and fresh water (FW) were examined with special reference to chloride cells. There was no difference in plasma osmolality between SW- and FW-adapted fish, reflecting their euryhalinity. A rich population of chloride cells was detected in whole-mount preparations of the gills and opercular membrane from SW- and FW-adapted fish. There was no difference between SW- and FW-adapted fish in gill Na+,K+-ATPase activity or oxygen-consumption rates. The gill chloride cells were located mostly in a flat region of the afferent-vascular edge of the filaments. In both tissues, the cells were larger in FW- than in SW-adapted fish. The apical membrane of chloride cells was invaginated to form a pit in SW-adapted fish, whereas it was flat or showed projections and was equipped with microvilli in FW-adapted fish. Chloride cells often interdigitated with neighboring accessory cells in SW-adapted fish, forming multicellular complexes. In FW-adapted fish, on the other hand, a pair of chloride cells that were similar in size was occasionally associated to form "twin cells." Thus, distinct SW and FW types of chloride cells were defined. Our findings suggest that SW- and FW-type chloride cells are equally active in the two environments, but exhibit different ion-transporting functions.
Mark-recapture estimates of daily survival rates of two damselflies (Coenagrion puella and Ischnura elegans)
Authors: Anholt Bradley R , Vorburger Christoph , Knaus Peter
Published: April 2011

Male-biased operational sex ratios are very common in sexually mature dragonflies. These may be due to differential survival or differences in time spent at the breeding site by the sexes. Because most studies are carried out at the breeding site, these two processes can be measured as survival rates or recapture rates using modern capturemarkrecapture methods. We marked 66 female and 233 male Coenagrion puella, and 137 female and 347 male Ischnura elegans during three capture periods spread over 18 days. Each time an animal was recaptured it was re-marked so that the capture history of any captured animal could be readily identified. We recaptured 131 C. puella and 55 I. elegans at least once. We used the CormackJollySeber model to estimate the daily probability of survival and recapture. The probability of recapture was, on average, more than three times higher for male C. puella (0.489) than females (0.133) with significant day to day variation. The daily probability of survival did not differ significantly between the sexes (0.860), with no significant variation among days. In contrast, in I. elegans the probability of recapture did not differ between the sexes (0.139 for the first 5 days; between 0.032 and 0.287 for the final 3 days), but the daily probability of surviving was much higher for males (0.812) than for females (0.579). Assuming that the sex ratio was unity at sexual maturity, the recapture and survival rates predicted well the sex ratio of the sample of C. puella but predicted more males than were observed in the sample of I. elegans. This suggests that male I. elegans may suffer higher mortality than females in the immature stage.
Effects of population reduction on home ranges of female white-tailed deer at high densities
Authors: Kilpatrick Howard J , Spohr Shelley M , Lima Kelly K
Published: April 2011

The relationship between deer density and home range size is important in assessing the effectiveness of deer reduction programs and predicting the effects of deer on habitat. We quantified annual home range and core area size and spatial configuration of adult female white-tailed deer (Odocoileus virginianus) exposed to a population reduction program and a control group exposed to no population reduction program over a 4-year period (19941997). Deer were removed from Bluff Point during a 9-day shotgun hunt in 1996 and a 4-day removal program in 1997. Annual home range size during high deer densities (8891 deer/km2) were larger than during periods of moderate (20 deer/km2) and low deer densities (11 deer/km2). We found a positive relationship between deer density and home range size. Annual home range size for the control group of deer did not differ among years. There were no significant shifts in the spatial arrangement of deer home ranges as deer densities were reduced. Significant improvements in deer herd health and reductions in deer browsing were documented during the 2-year deer reduction program. Population reduction programs at our study area did not cause the resident deer population to expand home range size or shift into adjacent habitat. We believe that localized deer reduction programs can be effective tools to manage problem deer herds. Deer removal efforts initiated to reduce deer damage to vegetation, particularly in urban areas, may have an added effect of reducing foraging range of the remaining resident deer.