bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural hybrids of Papilio (Insecta: Lepidoptera): poor taxonomy or interesting evolutionary problem?
Authors: Sperling Felix A. H.
Published: August 2008

A minimum of 6% of Papilio species hybridize in nature, with most hybrids derived from parents within the same species group. Extensive laboratory hybridization between Papilio species indicates relatively little postzygotic incompatibility and suggests that most barriers to gene flow are prezygotic. In some species, mating behavior appears to be a by-product of selection on ecologically important traits. For example, larval host shifts in P. machaon in western North America may have led to changes in its mating sites and phenology. The extent of these changes can be related to the frequency of hybridization between P. zelicaon and P. machaon. In another species, P. glaucus, gene flow between two distinct subspecies may be decreased by genetic linkage between ecologically important traits on sex chromosomes. Although current information for Papilio species indicates that most species differences developed in allopatry, the observed connection between ecological traits and mating traits suggests the possibility of significant divergence in parapatry or sympatry. The persistent formation of natural hybrids between otherwise distinct species of Papilio supports the view that species are populations primarily maintained by ecological selection.
Natural hybridization in Drosophila, with special reference to species from Hawaii
Authors: Kaneshiro Kenneth Y.
Published: August 2008

The few documented cases of natural hybridization in Drosophila species are reviewed. Evidence for introgression between D. pseudoobscura and D. persimilis and between two pairs of Hawaiian species, D. heteroneura and D. silvestris, and between D. setosimentum and D. ochrobasis, are discussed. Gene flow between D. heteroneura and D. silvestris appears to be unidirectional, based on morphological data. It is suggested that the dynamics of sexual selection plays an important role in permitting occasional hybridization in nature and that this allows limited introgression without destroying the genetic integrity of the species. Also, introgressive hybridization, induced by the dynamics of the sexual selection process, may play an important role in the origin of new genetic material in sympatric populations.
Capture de macromolécules par les cellules péricardiques et rénales de la moule, Mytilus edulis L.
Authors: Marcaillou C. , Martoja M.
Published: August 2008

The uptake of particles (colloidal gold, Thorotrast, ferritin) and hemoprotein tracers (catalase, horseradish peroxidase, microperoxidase) by pericardial glands and kidney was studied in Mytilus edulis L. Molecules smaller than 10 nm are taken up rapidly in large amounts by the pericardial cells from blood and pericardial fluid. These observations suggest that pericardial glands may be involved in ultrafiltration and reabsorption. Molecules of 6 nm are taken up only by the apex of the nephrocytes and their uptake is restricted.
A comparative survey of imposex in northeast Pacific neogastropods (Prosobranchia) related to tributyltin contamination, and choice of a suitable bioindicator
Authors: Bright Doug A. , Ellis Derek V.
Published: August 2008

Imposex, the manifestation of male morphological sex characters in females of functionally dioecious neogastropod taxa, is an abnormal response to tri-n-butyltin (TBT) contamination introduced to the marine environment in antifouling paints. Since the phenomenon has been thoroughly described only in Atlantic species, a comparative survey of field populations from British Columbia was undertaken, and field studies were carried out to assess the relative value as bioindicators of species in the genus Nucella from the Pacific coast. The majority of neogastropods studied to date have demonstrable signs of imposex, although this leads to sterilization of females in only a few species, depending on differences in the development in females of a palliai vas deferens. Within the Nucella species complex, N. lamellosa, N. canaliculata, and N. emarginata show promise as TBT bioindicators. Only the response of N. emarginata, however, was related to TBT bioaccumulation, based on measurements of a limited number of samples. This is attributed to the apparent irreversibility of imposex, the temporal variability of both environmental levels and tissue burdens of TBT, and the considerably shorter life-span of N. emarginata relative to that of N. lamellosa and N. canaliculata. The geographic distribution of imposex in Nucella spp. suggests that water-borne concentrations of TBT sufficiently high to induce imposex occur over large areas within British Columbia where exchange with oceanic water is limited.
Estimation of body condition in harbour porpoises, Phocoena phocoena
Authors: Read Andrew J.
Published: August 2008

I examined the body condition of 220 harbour porpoises (Phocoena phocoena) killed incidentally in commercial fishing operations in the Bay of Fundy between July and September, 1985–1988. Condition was assessed using a direct measure (blubber mass) and two indirect measures (blubber thickness and girth). To compare condition among porpoises of different sizes, each measure was regressed against an appropriate measure of body size, and the residuals of these regressions were used as indices of condition. Mean residuals of blubber mass varied significantly among both reproductive classes and sampling years. Calves and nonlactating mature females had greater mean residual values for blubber mass than immature porpoises and mature males; lactating females possessed intermediate levels. Porpoises sampled in 1987 had greater mean residual blubber mass than porpoises sampled in other years. Although the residuals of girth and blubber thickness demonstrated similar trends to those of blubber mass, they were poorly correlated with the residuals of blubber mass and are not robust indices of condition in harbour porpoises.
History, selection, drift, and gene flow: complex differentiation in checkerspot butterflies
Authors: Baughman John F. , Brussard Peter F. , Ehrlich Paul R. , Murphy Dennis D.
Published: August 2008

The genetic structure of the checkerspot butterfly, Euphydryas editha, was investigated using gel electrophoresis at 19 loci in each of 41 populations from throughout the range of the species. With two exceptions the populations were found to be very similar genetically, despite great differences in morphology and ecology. The low level of population differentiation was attributed to a combination of a historically more continuous range, parallel selection, and gene flow.
Interpopulation variation in male parr maturation of anadromous brown trout (Salmo trutta) in Norway
Authors: L'Abée-Lund Jan Henning , Jensen Arne Johan , Johnsen Bjørn Ove
Published: August 2008

We studied male parr maturation in anadromous brown trout in nine Norwegian rivers. Mean age at maturity increased from 1.5 years in southern populations to 5.2 years in northern populations, but the latitudinal correlation was not significant. Mean age of male parr at maturity was negatively correlated with mean total length of 0- and 1-year-old parr. The proportion of mature male parr varied between 0.06 and 0.6 among populations, and was positively correlated with mean total length of 0- and 1-year-old parr. The proportion of mature male parr decreased significantly with increasing mean smolt age of males. This indicates that in populations with relatively poor growth in fresh water (i.e., high smolt age) males mainly spawn as sea-run migrants, whereas in populations with relatively good growth in fresh water the mature male parr potentially contribute twice to the genetic makeup of the population, further increasing the effective population size.
Host–parasite relationships and geographic distribution of Salmincola corpulentus (Copepoda: Lernaeopodidae) on bloater (Coregonus hoyi) stocks in Lake Huron
Authors: Bowen II Charles A. , Stedman Ralph M.
Published: August 2008

Examination of the branchial cavities of 8347 adult bloaters (Coregonus hoyi) collected from seven locations in Lake Huron for parasitic copepods yielded only the lernaeopodid Salmincola corpulentus; its distribution was limited to bloaters collected in the southern two-thirds of the lake. The infections were highest off Au Sable Point and on Six Fathom Bank, where 12 and 22%, of the bloaters examined were infected, respectively. All copepods seen were sexually mature females. The dorsal anterior portion of the branchial rim was the preferred site of attachment. The prevalence of S. corpulentus increased with length of the bloaters, reaching a maximum of 40% in fish longer than 330 mm; none were seen in bloaters shorter than 182 mm. The mean intensity of S. corpulentus was unusually low (1.0–1.9) for a lernaeopodid copepod and the maximum number of copepods found on a single bloater was five. Prevalences of copepods differed significantly (P < 0.05) between bloaters collected at different geographic locations, suggesting that S. corpulentus may be of value in bloater stock determination.
Observations of large mammals in the Qaidam Basin and its peripheral mountainous areas in the People's Republic of China
Authors: Cai Guiquan , Liu Yongsheng , O'Gara Bart W.
Published: August 2008

During the last 30 years, the human population of the Qaidam Basin in the People's Republic of China increased 27-fold. Much grassland was placed under cultivation, and vegetation on some sandy areas was nearly destroyed and remains in poor condition. Forests in the eastern region of the basin were degraded, and the total forest area was reduced. In addition, the number of domestic animals increased sharply, resulting in overloading of pastures; man-made disturbances, including hunting, increased enormously. For these reasons, the vegetative cover of the basin has been reduced, influencing the survival of wild animals. The senior author surveyed the basin during 1971, and the authors made a second survey in August and September of 1986. Several species of large mammals had apparently become extinct in the basin proper. Although the climate was more severe, there were more species of wild animals and their numbers were greater in the mountainous areas because of fewer disturbances. The authors offer views and suggestions on the protection and utilization of wild mammals of the basin.
Effects of fenitrothion on the arthropod food of tree-foraging forest songbirds
Authors: Millikin Rhonda L.
Published: August 2008

The impact of fenitrothion on the arthropod food of songbirds was measured using white birch (Betula papyrifera Marsh.) and balsam fir (Abies balsamea (L.) Mill.) branch sample and drop trays. Following ground application of fenitrothion at 293 g active ingredient/ha, there was a significant decrease in the biomass of arthropods as determined using branch samples from both tree species, but not until 5 days after the application (29% reduction for balsam fir, 35% for white birch). Samples from drop trays indicated an immediate kill of arthropods not associated with the tree. Most remaining arthropods on treated balsam fir trees were dead. These dead arthropods would not be suitable food for birds that require movement to detect their prey. There was no significant relationship between amount of deposit (treated trees only) and the reduction of arthropods for either tree species.
The haemoproteids of the avian families Corvidae (crows and jays) and Sturnidae (starlings and mynas) (Passeriformes)
Authors: Bishop Madonna A. , Bennett Gordon F.
Published: August 2008

The haemoproteids of the passeriform families Corvidae and Sturnidae are reviewed. Haemoproteus danilewskii Kruse, 1890 and H. picae Coatney and Roudabush, 1937 of the Corvidae and H. pastoris de Mello, 1936 of the Sturnidae have been redescribed and neohapantotypes designated. Halteridium danilewskii (Kruse, 1890) Labbe, 1894 and Haemoproteus corvi Bhatia, 1938 and H. danilewskii var. cairogensis Helmy Mohammed, 1958 are declared synonyms of Haemoproteus danilewskii; H. sturni de Mello, 1936, H. morneti Tendeiro, 1947, and H. morneti orientalis Travassos Santos Dias, 1953 are considered to be synonyms of Haemoproteus pastoris.
Acute temperature and oxygen stress among genotypes of Daphnia pulex and Simocephalus vetulus (Cladocera, Daphniidae) in relation to environmental conditions
Authors: LaBerge S. , Hann B. J.
Published: August 2008

The interactions among the genetics, physiology, and ecology of Daphnia pulex and Simocephalus vetulus inhabiting an ephemeral pond were studied. Electrophoretic analysis of four loci revealed high genetic diversity and genotypic coexistence within each species. In a total of 227 D. pulex individuals, 92 unique genotypes were found, and for 112 S. vetulus individuals, there were 18 unique genotypes. Daphnis pulex inhabited the pond early in the summer, but later there was a shift to S. vetulus as the primary cladoceran inhabitant. Biweekly sampling through the open water period allowed us to monitor environmental parameters such as water temperature and oxygen saturation, as well as the condition of the animals under study by assessing egg number, lipid content and ovary development, carapace length, and haemoglobin content. In laboratory experiments, S. vetulus was found to be more tolerant of both high temperature and low oxygen saturation than D. pulex. In addition to these interspecific tolerance differences, there were genotypic differences within each species in temperature tolerance. We have related these laboratory-determined genetic and physiological differences within and between species to the temporal variation in environmental conditions experienced directly in the pond. Thus, the rapid changes in pond conditions appear to play a large role in determining the species and genotypes able to exist in such an unpredictable environment.
The genetic relationship between Bombus moderatus Cresson and the Bombus lucorum auct. species complex (Hymenoptera: Apidae)
Authors: Scholl A. , Obrecht E. , Owen R. E.
Published: August 2008

The relationship between the North American bumble bee species Bombus moderatus Cresson and the European and Asian species in the subgenus Bombus sensu stricto has long been in question. Bombus moderatus has either been regarded as a distinct species or has been synonymized with B. lucorum (L.). We surveyed 10 Bombus s.str. species at 26 enzyme loci, using horizontal and vertical starch-gel electrophoresis. We found that B. moderatus differs from B. lucorum at three loci but is identical in these and all other loci surveyed with B. cryptarum (Fabricius) and B. magnus Vogt. The present distribution of B. moderatus, together with the observation that its closest relatives are the European B. cryptarum and B. magnus and the Asian B. hypocrita Pérez, suggests that differentiation occurred after dispersal to North America via Beringia.
Size selection of common mussels, Mytilus edulis, by common eiders, Somateria mollissima: energy maximization or shell weight minimization?
Authors: Bustnes Jan Ove , Erikstad Kjell Einar
Published: August 2008

Prey size selection by common eiders, Somateria mollissima, preying on common mussels, Mytilus edulis, in northern Norway is described. The mean length (± 1 SD) of mussels preyed upon was 13.9 ± 5.7 mm (range 3.5–38.1 mm). The dry flesh weight as a percentage of the total dry weight ranged from 4.2 to 8.6% in different body-length categories and was greatest in the mussels most frequently fed upon. There was a close negative correlation between the size of mussels fed upon and the estimated total shell weight that birds had to ingest to obtain their daily requirement of food (rs = −0.86). A hypothesis is proposed that common eiders select mussels of certain size classes to minimize the daily shell weight intake.
Winter condition and proximate composition of anadromous arctic charr (Salvelinus alpinus) in eastern Ungava Bay, Quebec
Authors: Boivin Thomas G. , Power G.
Published: August 2008

Arctic charr (Salvelinus alpinus) were sampled during the winter of 1985–1986 in the Kangiqsualujjuaq area of northern Quebec to examine feeding patterns and temporal variation in condition. No feeding was observed at any time during the winter, and examination of gallbladder coloration indicated that feeding had not occurred for a long period of time. Proximate composition analysis of nonreproductive charr from Koroc River indicated that liver and muscle lipid and liver protein reserves changed during the winter fast, and this was most pronounced in early winter. Spent charr sampled at Lake Tasikallak had lower liver lipid and condition factor values and were more depleted than nonreproductive charr. Despite a reduction in lipids and protein during winter, the general condition of nonreproductive charr renders them suitable for commercial sale at any time of the year.
Keratella armadura (Rotifera: Brachionidae), a new rotifer from a Michigan bog lake
Authors: Stemberger Richard S.
Published: August 2008

The rotifer Keratella armadura n.sp. is described from a shallow alkaline bog lake from Michigan's lower peninsula. The facet pattern of the dorsal plate is similar to that of the common North American phenotype of Keratella cochlearis and K. taurocephala. The rigid, thickened lorica, long recurving posterior spine, and constriction of the body near the base of the anterior spines is distinctive from known congenors. The species was abundant (> 300 individuals/L) within a well-defined habitat, and appears to have a narrow geographic range. Keratella armadura occurred in spring and summer months and was absent from fall and winter collections. This restricted distribution, if common among rotifers, suggests that many undescribed species still exist in Michigan and in North America.
A new milliped of the genus Metaxycheir from the Pacific coast of Canada (Polydesmida: Xystodesmidae), with remarks on the tribe Chonaphini and the western Canadian and Alaskan diplopod fauna
Authors: Shelley Rowland M.
Published: August 2008

Metaxycheir pacifica, a new chonaphine xystodesmid milliped from Vancouver Island, British Columbia, inhabits decidous spots in the forests along the Pacific Ocean from Bamfield to China Beach Provincial Park. It displays a subcylindrical body, imparted by reduced paranota caudal to segment 4; an acropodite in the form of a broad, open loop; and an acicular prefemoral process with minute subapical barbules. It is segregated from the type species, M. prolata Buckett and Gardner, in northern Idaho, by over 600 km, and is the second western Canadian xystodesmid. The tribe Chonaphini occupies five areas of allopatric populations: that of M. pacifica; from central Oregon to western Montana; and three areas in the north central and eastern states. The Pacific coastal region harbors the most diverse fauna of western Canada, and a second center of diversity lies around Mount Revelstoke and Glacier national parks. The diplopod fauna of Alaska and western Canada consists of at least 5 orders, 13 families, 22 genera, and 24 species; of these, 5, 10, 16, and 17 are indigenous forms and 2, 4, 6, and 7 are introductions, respectively. The chordeumatoid family Rhiscosomididae and the genus Rhiscosomides are new to Canada; five allochthonus species, Cylindroiulus caeruleocinctus (Wood), Ophyiulus pilosus (Newport), Oxidus gracilis (C. L. Koch), Brachydesmus superus Latzel, and Polydesmus inconstans Latzel, are new to the western provinces; and the Polyxenidae (Polyxenida) and Caseyidae (Chordeumatida) are new to Alaska.
A review of the North American species of Aptilotus, with descriptions of new species from North America and Nepal (Diptera: Sphaeroceridae)
Authors: Marshall S. A. , Smith Ian P.
Published: August 2008

All macropterous species of Aptilotus Mik are keyed, with descriptions of two new macropterous North American species, Aptilotus pogophallus and A. nigriphallus. New distributional records are given for other North American species, and brachyptery is noted for the first time in A. luctuosus (Spuler). Four new macropterous species of Aptilotus (glabrifrons, spinistylus, rufiscapus, and binotatus are described from Nepal. The relationships between the North American and Nepalese species are discussed. Minocellina Papp is synonomized with Aptilotus, and the two species formerly in Minocellina, A. thaii (Papp) and A. besucheti (Papp), are thus given as new combinations. Limosina carbonicolor Richards, from Ethiopia, is redescribed and transferred to Aptilotus.
A hermaphroditic Sphaerosyllis (Polychaeta: Syllidae) with epitokous genital chaetae from intertidal sands of the Island of Phuket (Thailand)
Authors: Westheide Wilfried
Published: August 2008

The small interstitial Sphaerosyllis hermaphrodita n.sp. from sand beaches of Phuket (Thailand) is unique within the genus in being a simultaneous hermaphrodite. Chaetigers 8, 9, and 10 are male and the following three segments contain oocytes. Investigation of about 90 specimens of various sizes revealed that during maturation chaetiger 9 alters its shape and loses most of its normal chaetae. They are replaced by a strong chaeta with sawlike subdistal teeth, which is assumed to be a genital structure used during the process of sperm transfer.
Forest cover, snow conditions, and black-tailed deer sinking depths
Authors: Bunnell Fred L. , Hovey Fred W. , McNay R. Scott , Parker Kathy L.
Published: August 2008

Sinking depths of black-tailed deer (Odocoileus hemionus columbianus) and associated snow characteristics were recorded in old-growth, second-growth, and recently clearcut forests. Erratic deer movement in a 20-year-old stand prohibited measurements of deer sinking depth there, but a surrogate measure (human sinking depth) and associated snow characteristics were recorded. Both daily weather conditions and forest cover influenced deer sinking depths and associated snow conditions (p < 0.001). The two oldest stands had more shallow snowpacks with denser snow in the upper layers and greater mean hardness values than did the clearcut. As a result, mean deer sinking depths were lower in those stands. For all but 1 day (n = 9), forested habitats showed consistent rankings relative to the potential for deer movement: clearcut (worst) < 20-year-old < old growth and 80-year-old (about equal and best).
Aquatic thermoregulation of captive and free-ranging beavers (Castor canadensis)
Authors: MacArthur Robert A. , Dyck Alvin P.
Published: August 2008

Abdominal cooling occurred in 91% of all aquatic excursions documented in free-ranging beavers during fall and winter. Kits aged 4–7 months cooled faster and spent less time foraging in 1–12 °C water than did animals > 1 year old. All beavers tested in the laboratory displayed abdominal cooling in 2–20 °C water, with maximal cooling rates recorded in a 5- to 7-week-old kit. Immersion in cold water induced strong peripheral cooling, though skin temperatures beneath the pelage remained within 4–5 °C of abdominal measurements. The resting metabolic rate of beavers > 1 year old was independent of water temperature between 19 and 31 °C, but increased proportionately at lower temperatures. Whole-body conductance of resting animals was on average 1.6–3.0 times higher in water than in air. Maximum testing metabolic rates in water varied from 1.8 to 2.4 times the mean resting thermoneutral rate in air. Our results suggest that beavers mitigate the thermogenic effort required in water by adopting a thermoregulatory strategy which combines avoidance of prolonged immersion with a tolerance to passive cooling.
Glutamate-like immunoreactivity in the cestode Hymenolepis diminuta
Authors: Eklove Harley , Webb Rodney A.
Published: August 2008

Glutamate-like immunoreactivity in the cestode Hymenolepis diminuta was investigated at the light-microscopic level by immunohistochemistry with an antiglutamate antibody. Immunoreactivity was seen in the basal region of the suckers, in the rostellum, subtegumental regions, central nervous system, and longitudinal nerve cords, and in eggs. In the scolex the cerebral ganglia were diffusely immunoreactive, and immunoreactive tracts, passing from the cerebral ganglia to the suckers, were observed. The longitudinal nerve cords contained large groups of intensely stained cell bodies and processes throughout the length of the strobila. Immunoreactive tracts from the longitudinal nerve cords formed junctions with the deep longitudinal muscles only in the lateral regions of the proglottids. However, neuron-like varicose swellings were seen in the subtegumental area of the mature region. The localization of glutamate-like immunoreactivity in various parts of the nervous system and tissues of Hymenolepis diminuta provides further support for the role of glutamate as an excitatory neuromuscular transmitter in the platyhelminths.
Eimeria hermani Farr, 1953 of the Canada goose, Branta canadensis: endogenous development, including intranuclear schizogony, in the domestic goose (Anser anser domesticus)
Authors: Skene R. C. , Fernando M. A.
Published: August 2008

All endogenous stages of Eimeria hermani were found throughout the small intestine of experimentally infected domestic goslings. At least two generations of schizogony were seen to occur prior to gamogony, and mature schizonts were seen from 36 to 84 h postinfection. Developing gamonts were seen between 96 and 120 h postinfection and oocysts were seen in histological sections by 132 h. All schizogonic stages occurred within the nuclei of epithelial cells whereas the sexual stages were found within the cytoplasm of epithelial cells. Infected nuclei appeared close to the brush border of epithelial cells, in contrast to the basal position occupied by uninfected nuclei. The schizonts and the resulting merozoites lay within a parasitophorous vacuole bounded by a vacuolar membrane. In infected nuclei a dissociation of the granular and fibrillar portions of the nucleolus was apparent and the heterochromatin was concentrated near the nuclear membrane. The ultrastructure of the merozoites is described and the intranuclear development of the asexual stages of E. hermani is discussed in relation to previously described intranuclear coccidian parasites.
Reduction in oocyte production and gonadotrope activity, and plasma levels of estrogens and vitellogenin, in brook trout exposed to low environmental pH
Authors: Tam W. H. , Fryer J. N. , Valentine B. , Roy R. J. J.
Published: August 2008

Maturing brook trout were exposed to pH 4.5 at the beginning of the rapid oocyte development phase in mid-June. The number of atretic follicles containing vitellogenic oocytes in acid-treated trout gradually increased with time, to exceed that of control fish on day 30, reaching a maximum (22–24% of all vitellogenic oocytes) between days 45 and 60 of acid exposure, before declining on day 73. Follicular atresia reduced the number of healthy vitellogenic oocytes in the acid-stressed fish to 59% of controls by day 60. Plasma vitellogenin and estrogen levels were not consistently affected by acid exposure. During the first 45 days of acid exposure, the mean weight of the healthy vitellogenic oocytes and the plasma levels of estrogen in the acid-exposed fish were at times significantly higher than those of control trout, but after day 45 these differences were no longer observed. Ultrastructural morphometry showed that secretory activity of the gonadotropes in the female acid-stressed brook trout was suppressed. Throughout the experimental period, the acid-exposed trout showed various symptoms characteristic of acid stress, such as elevated ACTH and cortisol secretion, hyperglycemia, acidosis, and hyponatremia. Food intake was reduced to 14% of the control value. These results suggest that the disruptive physiological changes and (or) reduced nutritional status associated with acid stress are responsible for the reduction in activity of the gonadotropes and oocyte atresia.
Spermatogenesis in photostimulated Red-winged Blackbirds (Agelaius phoeniceus) chronically treated with a potent gonadotropin releasing hormone analogue
Authors: Lacombe Diane , Cyr André , Matton Pierre
Published: August 2008

To study the effect of a gonadotropin releasing hormone analogue (GnRH-A) on male Red-winged Blackbirds, birds received 13 (experiment 1) or 14 (experiment 2) consecutive daily injections of saline (control group) or GnRH-A during photoperiodically induced testicular growth. GnRH-A did not modify the diameter of the seminiferous tubules in treated groups compared with saline-injected controls. However, the thickness of the germinal epithelium was significantly reduced in groups receiving 0.1, 1.0, 10.0, or 20.0 μg of GnRH-A. Redwings showing disturbed spermatogenesis were significantly more frequent in the GnRH-A treated groups than in the control group. Moreover, there was a dose–response effect, since the proportion of redwings showing disturbed spermatogenesis increased with increasing doses of GnRH-A. Hyperplasia of the interstitial cells was frequent in GnRH-A treated birds compared with control birds, except for the group which received 0.01 μg of GnRH-A. These experiments show that chronic treatment with GnRH-A impairs spermatogenesis in Red-winged Blackbirds treated during testicular growth.
Nutrient reserves of breeding Ring-necked Ducks (Aythya collaris)
Authors: Alisauskas Ray T. , Eberhardt Robert T. , Ankney C. Davison
Published: August 2008

We studied carcass composition of Ring-necked Ducks, Aythya collaris, collected on breeding areas in Beltrami County, Minnesota. Females collected before they had commenced rapid growth of ovarian follicles apparently stored body lipid and body protein. For every gram of egg lipid produced, somatic lipid stores declined by 0.48 g at all stages of rapid follicle growth, irrespective of the daily rate of egg lipid production. A decline in body protein coincided with increased daily requirements for clutch proteins. However, females increased their protein reserves from mid to late rapid follicle growth, resulting in no difference between reserves of females starting and terminating rapid follicle growth. We suggest that observed patterns of lipid storage by Ring-necked Ducks, and possibly by other species of temperate-nesting ducks, have evolved to allow supply of clutch lipids at a rate in line with the ease with which we suspect that breeding hens are able to procure dietary protein; the high daily protein requirements to meet protein demands of clutch formation are possible to meet because ducks typically nest near wetlands in which there is a large seasonal flush of invertebrates.
Host and geographic distribution of Skrjabinoclava spp. (Nematoda: Acuarioidea) in Nearctic shorebirds (Aves: Charadriiformes), and evidence for transmission in marine habitats in staging and wintering areas
Authors: Wong P. L. , Anderson R. C.
Published: August 2008

Twelve species of shorebirds belonging to the families Charadriidae (N = 3) and Scolopacidae (N = 9) were infected with 11 species of Skrjabinoclava and there was little overlap of parasites between these two families of birds. Most Skrjabinoclava spp. are transmitted apparently in marine staging and (or) wintering areas of their hosts, as indicated by the presence of larval stages of six species. There was no evidence that transmission occurs on the breeding grounds in freshwater habitats. Skrjabinoclava tupacincai, found predominantly in sanderlings (Calidris alba (Pallas)), is transmitted on the Pacific (Washington, California, Chile) and Atlantic coasts (New Jersey) in winter and the Gulf of Mexico (Florida and Texas) in winter and spring. Skrjabinoclava myersi was found, with a single exception, only in sanderlings, and transmission is apparently restricted to coastal Washington and California in winter. Skrjabinoclava bakeri, found predominantly in western sandpipers (Calidris mauri Cabanis), is transmitted on the Pacific coast (California) and in the Gulf of Mexico in winter. Skrjabinoclava morrisoni and Skrjabinoclava pusillae were found mainly in semipalmated sandpipers (Calidrispusilla (L.)). Both parasites are transmitted in the Gulf of Mexico in spring, but S. morrisoni is also transmitted in the Bay of Fundy in fall. Skrjabinoclava inornatae, found mainly in willets (Catoptrophorus semipalmatus (Gmelin)), is transmitted in Louisiana, Texas, and Peru in winter. Skrjabinoclava kritscheri was found only in marbled godwits (Limosafedoa (L.)), and it is suggested that infected birds collected in southern Alberta in spring acquired their infections while wintering along the Pacific coast of the United States. Skrjabinoclava hartwichi, found in black turnstones (Arenaria melanocephala (Vigors)) wintering in California and ruddy turnstones (Arenaria interpres (L.)) wintering in Peru, is transmitted along the Pacific coast of North America. Skrjabinoclava semipalmatae was found in semipalmated plovers (Charadrius semipalmatus Bonaparte) wintering in California. Skrjabinoclava wilsoniae was found in Wilson's plover (Charadrius wilsonia Ord) wintering in Texas and in a black-bellied plover (Pluvialis squatarola (L.)) migrating through southern Alberta in spring. Skrjabinoclava bartlettae was found in black-bellied plovers collected in southern Alberta in spring and Louisiana in winter.
The lungworm Protostrongylus boughtoni (Nematoda, Metastrongyloidea) in gastropod intermediate hosts and the snowshoe hare, Lepus americanus
Authors: Kralka Robert A. , Samuel W. M.
Published: August 2008

Natural infections of Protostrongylus boughtoni in intermediate and definitive hosts were examined in Boreal Forest habitats of north central Alberta. Vertigo gouldi was the major intermediate host. Prevalence and intensity of P. boughtoni larvae in V. gouldi were similar among habitats, among size classes of V. gouldi, and temporally. Prevalence of P. boughtoni in adult snowshoe hares was 100%; mean intensity varied monthly at relatively low levels. Juvenile snowshoe hares became infected within a month of birth; intensities increased to relatively high within 3 months and then declined, indicating development of an immune response or decreased exposure to infected snails. No evidence was found for transplacental transmission. Relative rates of flow of P. boughtoni were calculated to determine the importance of snail species and habitat types in transmission of the parasite. Vertigo gouldi accounted for nearly all flow from snails to hares, and most of the flow from snails to hares occurred in dry coniferous and mixed wood habitats.
A review of the taxonomy of five Ontario genera of freshwater cyclopoid Copepoda (Crustacea)
Authors: Dussart B. H. , Fernando C. H.
Published: August 2008

Examination of material of five cyclopoid copepod genera found in Ontario fresh waters and a comparison with species of these genera from other parts of the world closely related to Ontario species has given some very interesting results. The widespread Ectocyclops phaleratus was the species previously recorded from Ontario. However, the Ontario material fits the description of E. polyspinosus Harada, 1931, known from Taiwan. There is considerable confusion in the nomenclature of North American species of Eucyclops. In Ontario Eucyclops serrulatus is found. This widespread and variable species needs revision on the basis of worldwide material. Hence, only a provisional identification can be made now. The species previously called E. speratus in Ontario is a hitherto underscribed species, E. neomacruroides, closely related to, but we think distinct from, E. macruroides and E. speratus. The third species is Eucyclops macruroides denticulatus and the fourth is the very distinctive E. prionophorus. In the genus Tropocyclops, besides the widely occurring Tropocyclops prasinus prasinus, T. extensus was found. This latter species has been consistently identified as T. prasinus mexicanus since 1959. Four species of the genus Acanthocyclops occur in Ontario. Acanthocyclops robustus is very common; A. vernalis is rare and so are A. venustoides and A. carolinianus. We are unable to resolve the status of A. venustoides bispinosus, as only late copepodid stages of this species, and no mature adults, are available. Mesocyclops americanus, long called M. leuckarti, is now a well-documented species, much rarer than the somewhat atypical (for the genus) M. edax, well known in North America. Our proposed designations for North American species are summarized. There is a need to collect material year round from all available biotopes to document the species composition of Ontario Copepoda. Our work is also a first step in clarifying the status of North American Copepoda, comparing material from North America and elsewhere.
Manipulating external Ca2+ inhibits particle capture by planktotrophic echinoderm larvae
Authors: Hart Michael W.
Published: August 2008

Planktotrophic larvae of echinoderms feed by filtering suspended particles from seawater using a ciliary reversal mechanism. The control of ciliary beat depends on calcium ion flux across the membranes of ciliated cells in many organisms. In an earlier study, T. H. J. Gilmour (1985. Can. J. Zool. 63: 1354–1359) observed that the calcium channel blocker verapamil failed to prevent particle capture by echinoid larvae, and he interpreted this result as indicating that ciliary reversals are not important in particle capture by these larvae. I have also found that echinoid and asteroid larvae feed normally (and have high rates of clearance) in concentrated solutions of verapamil in seawater, but particle captures by these larvae are qualitatively identical to those by the same larvae before exposure to verapamil and they appear to occur by ciliary reversal. Clearance rates are greatly depressed, however, for larvae in Ca2+-free artificial seawater and for larvae in artificial seawater containing 9 mM Co2+. Most particle captures under these conditions do not appear to occur by the reversal of ciliary beat. These observations suggest that verapamil fails to block calcium channels in the membranes of ciliated cells of echinoderm larvae, but that other methods of preventing transmembrane Ca2+ flux do interfere with ciliary reversals and particle capture.
Song and plumage phenotypes in a contact zone between subspecies of the White-crowned Sparrow (Zonotrichia leucophrys)
Authors: Lein M. Ross , Corbin Kendall W.
Published: August 2008

We examined the transitions in a plumage character (lore color) and a learned behavioral character (song pattern) across a 400 -km intergrade zone between two subspecies of the White-crowned Sparrow (Zonotrichia leucophrys) in southwestern Alberta. The proportion of birds with black lores, characteristic of Z. l. oriantha, shifted gradually from over 80% in southernmost localities to less than 20% at the northern end of the zone, where most individuals had grey lores, characteristic of Z. l. gambelii. The song pattern of males also showed a complete transition across the zone, but the change was significantly more abrupt than for lore color, occurring over 50–100 km in the center of the intergrade zone. We suggest that this apparent difference in degree of introgression between the two characters may result either from differential dispersal of males and females or from switches in the song patterns of young males that immigrate into populations in which a different song type predominates. Our findings indicate that male song pattern may not be an accurate indicator of the genetic history of populations in this species.
The effects of social status on life-history variation in juvenile salmon
Authors: Metcalfe Neil B. , Huntingford Felicity A. , Thorpe John E. , Adams Colin E.
Published: August 2008

Under good growing conditions, juvenile Atlantic salmon metamorphose into the migratory smolt stage at 1+ or 2+ years of age. The life-history decision on whether or not to migrate at 1+ years is made in July–August of the previous year. After this time, populations develop a bimodal size distribution, the larger fish (upper modal group) being the 1+ smolts and the lower modal group being fish that will smolt at 2+. Fish of high social status are more likely to become 1+ smolts. We examined the causal nature of this relationship by manipulating status within a laboratory population of sibling fish. The absolute status of individual fish was estimated within 2 weeks of first feeding. Relative status was then manipulated by dividing the population into two, half containing the fish with the highest absolute status (high ranking) and the remaining half of fish of lowest absolute status (low ranking). The status of individually marked fish was then determined within each of the two groups. Individual growth rates were monitored until smolting strategies were apparent. There was a complete overlap in the sizes of subsequent upper and lower modal group parr in early June, but from late June onwards fish in the upper modal group grew faster. The high- and low-ranking groups did not differ either in mean growth rates or in the proportions of fish adopting the alternative smolting strategies. However, they differed in the factors that influenced an individual's developmental strategy: within the high-ranking group, relative social status in June was a significant predictor of whether a fish would smolt aged 1+, whereas length at that time was not. In contrast, no relationship between status and smolting strategy was found in the low-ranking group, where differences in status were less clear-cut and had less influence on growth. Instead, age of smolting could be predicted from early growth rate. These results demonstrate that the influence of status on smolting depends on the extent to which fish of high status suppress the growth of those lower in the hierarchy.
The centipede Theatops posticus (Say) (Scolopendromorpha: Cryptopidae) in the southwestern United States and Mexico
Authors: Shelley Rowland M.
Published: August 2008

The common eastern Nearctic centipede Theatops posticus (Say), previously reported once each from Arizona and southern Utah and therefore considered rare in southwestern North America, is widespread in Arizona and newly recorded from southern Nevada, southwestern New Mexico, southern California, and northwestern Mexico (Baja California Norte, Sonora, and Chihuahua); it is even known from Santa Cruz Island in the Pacific Ocean off the southern California coast. The species therefore exhibits a continental distribution pattern, with eastern and western populations segregated by some 1200 km (750 mi) in Texas and New Mexico. Some southwestern individuals exhibit small ventral spurs on the ultimate pre femora and (or) femora, and coxopleurae with slightly elevated, caudally produced medial borders, conditions that are intermediate between those displayed by the eastern population and the congener in California and southern Oregon. Since these variants are also geographically intermediate, they prove that the latter's phenotypic resemblance to Theatops erythrocephalus (C. L. Koch) in southern Europe represents convergence. Consequently, this name is not applicable to the Pacific species, and californiensis Chamberlin is available as its correct specific name.
Early-winter diet of woodland caribou in relation to snow accumulation, Selkirk Mountains, British Columbia, Canada
Authors: Rominger Eric M. , Oldemeyer John L.
Published: August 2008

Woodland caribou (Rangifer tarandus caribou) in the southern Selkirk Mountains of British Columbia shift from a diet of primarily vascular taxa during snow-free months to an arboreal lichen – conifer diet during late winter. We present evidence that caribou diets, during the early-winter transition period, are influenced by snow accumulation rates. Caribou shift to an arboreal lichen – conifer diet earlier during winters of rapid snow accumulation and forage extensively on myrtle boxwood (Pachistima myrsinites), an evergreen shrub, and other vascular plants during years of slower snow accumulation. The role of coniferous forage in early-winter food habits is examined. Forest management strategies can be developed to provide habitat that will enable caribou to forage in response to varying snow accumulation rates.
Courtship and use of mating areas by grizzly bears in the Front Ranges of Banff National Park, Alberta
Authors: Hamer David , Herrero Stephen
Published: August 2008

In five of six observations of courting grizzly (brown) bears (Ursus arctos), pairs were isolated on a summit or upper-elevation ridge where the male repeatedly blocked the female's descent. These observations substantiate an earlier single observation of this mating behaviour. Similar isolation of mating grizzly bears on summits or ridges has not been reported elsewhere in North America. The habitat of the mating areas is described. The areas were not grizzly bear feeding habitat. Food intake evidently was reduced during the period of isolation. These observations are interpreted as male sequestering of an oestrus female and female testing of male vigour.
Blue whales feeding on high concentrations of euphausiids around Monterey Submarine Canyon
Authors: Schoenherr Jill R.
Published: August 2008

An unusually high concentration of blue whales, Balaenoptera musculus, fed on euphausiids that were concentrated in deep scattering layers and daytime surface swarms in Monterey Bay, California, during the fall of 1986. Blue whales were closely associated with deep scattering layers that were elongated along the southeast edge of the Monterey Submarine Canyon throughout most of November 1986. These scattering layers contained euphausiids, primarily Thysanoessa spinifera, which accounted for 45.4% of the total biomass of zooplankton tows taken through deep scattering layers. Tows taken above or outside the layers consisted of only 4.0% euphausiids. The greatest concentrations of blue whales were observed in areas of thick scattering layers that contained high krill biomass. In addition, surface-lunging blue whales fed on daytime surface swarms of Thysanoessa spinifera near the head of Monterey Submarine Canyon on 11 and 12 November 1986. Surface tows taken in whale feeding areas were dominated by T. spinifera, which accounted for 64.4% of the total zooplankton biomass, while surface tows taken outside whale areas consisted of only 0.3% euphausiids. Euphausiid densities in surface swarms were slightly higher and more variable than in deep layers. Thysanoessa spinifera size frequency distributions showed that surface swarms may be similar to the deep layer in some areas, but they may contain larger, sexually mature individuals in other areas. Blue whale fecal samples confirmed that the whales were feeding on euphausiids. The disappearance of the blue whales from Monterey Bay was accompanied by a decline in krill biomass along the southeast edge of the submarine canyon. This coincided with the cessation of a prolonged upwelling period that persisted in Monterey Bay throughout November 1986.