bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory-reared larval stages of Dissodactylus mellitae (Decapoda: Braohyura: Pinnotheridae) and developmental patterns within the Dissodactylus species complex
Authors: Marques Fernando , Pohle Gerhard
Published: May 2008

Eggs of Dissodactylus mellitae were incubated for 9–10 days at 28 °C and larval development consisted of three or four zoeal stages and a megalopa. Beginning with the first zoea, the mean duration of successive stages was 5, 3, 4, and 5 days, the first megalopa appearing 10 days after hatching. Among the megalopae obtained, 87% molted from a third zoea, whereas 13% passed through a fourth zoeal stage before metamorphosing to a megalopa. The last zoea is not considered a substage, since it showed no morphological variation, and molting resulted in growth and consistent morphological changes. Compared with other species within the Dissodactylus complex, the development of D. mellitae represents an intermediary level between three and four zoeal stages. The number of zoeal stages of the ancestor of the Dissodactylus species complex cannot presently be inferred. Among larvae of Dissodactylus s.str., D. mellitae zoeae are characterized by a small carapace with relatively long spines and megalopae by a carapace that is as wide as long. The latter can also be distinguished among Atlantic species by the lack of a dactyl on maxilliped 3, by the absence of serrate setae on the chela, and by the blade of the scaphognathite bearing 5 simple setae but lacking a plumodenticulate seta. Within the Dissodactylus species complex significant relationships were determined between egg size and incubation period and between egg size, carapace length, and time to reach the megalopa stage. Another significant relationship was determined between egg size and the duration of the first zoeal stage, but this correlation did not hold for subsequent stages. Differences in survival rates from those of other species may be attributable to differences in diet and the use of antibiotics.
The timing of conflict and cooperation among cofoundresses of the social wasp Polistes fuscatus (Hymenoptera: Vespidae)
Authors: Gamboa George J. , Stump Katherine A.
Published: May 2008

Field observations were made on 37 preworker, multiple-foundress colonies of the social wasp Polistes fuscatus. In total, 401.9 h of behavioural observations of cofoundresses were conducted at three different periods prior to the emergence of workers. Cofoundresses displayed a marked, significant increase in aggression at about the time in the colony cycle when reproductive-destined eggs began to be laid. Both queens and their subordinates became increasingly aggressive at this time. These empirical results support theoretical predictions that conflict among cofoundresses would intensify over the production of reproductive-destined (but not worker-destined) eggs. Cooperation in foraging to minimize nest inattendance as well as synchronicity (temporal overlap) in activity also increased significantly at the onset of the production of reproductive-destined eggs. Thus, conflict and cooperation are not necessarily antagonistic in P. fuscatus. Foundresses minimized the time that nests are unattended at a time in the colony cycle when most conspecific usurpations occur. This suggests that the ecological pressure of conspecific usurpation has favoured increased coordination in foraging to minimize the time nests are unattended. The adaptive significance, if any, of an increase in synchronicity of activity among cofoundresses at the onset of the production of reproductives is not obvious.
Environmental characteristics of North Atlantic right and fin whale habitat in the lower Bay of Fundy, Canada
Authors: Woodley Thomas H. , Gaskin David E.
Published: May 2008

Characteristics of right whale (Eubalaena glacialis) and fin whale (Balaenoptera physalus) habitat in the lower Bay of Fundy were identified by quantifying physical and biological habitat variables and comparing them to the distribution of whales during the summer and autumn of 1989. Right whales were generally distributed over the Grand Manan Basin, where the bottom topography is relatively flat and the water column was stratified. Calanus finmarchicus, the principal prey species of right whales, was the predominant copepod taken in Zooplankton hauls, and the depth-averaged density (mean 1139/m3) was significantly greater where right whales were present. Fin whales were distributed mainly in shallower areas with high topographic variation that were likely well mixed or contained frontal interfaces between mixed and stratified waters. Herring (Clupea harengus) and euphausiids, both known prey of fin whales, were relatively abundant on echosounder traces in areas where fin whales were present. The habitats of both whale species were primarily characterized by high densities of principal prey species and the physical conditions that facilitate the accumulation of these prey.
A new American Stylodrilus species (Lumbriculidae, Oligochaeta)
Authors: Rodriguez Pilar , Coates Kathryn A.
Published: May 2008

Stylodrilus wahkeenensis n.sp. has been reported from three different localities in North America. The distribution of this new species confirms the widespread occurrence of the genus Stylodrilus in the Neartic region, mainly associated with groundwaters. The elongate hairlike setae in dorsal bundles are an interesting character shared with other meiobenthic lumbriculids inhabiting the interstitial milieu.
Differential scaling of home-range area to daily movement distance in two African tortoises
Authors: Hailey Adrian , Coulson Ian M.
Published: May 2008

Movements of the tortoises Geochelone pardalis (mean body mass 4.0 kg) and Kinixys spekii (0.62 kg) were studied by thread-trailing. The mean daily movement distance of G. pardalis was 435 m, and the short-term home-range area was 26 ha. The values for K. spekii were 172 m and 1.9 ha, respectively. The area used by G. pardalis was significantly larger than would be produced by scaling up the movements of K. spekii in the same geometric pattern. Home-range areas were about the same size (K. spekii) or several times as large (G. pardalis) as those predicted for mammals of equal body mass. Ingestion of soil for sodium may be a factor determining the large home range of the purely herbivorous G. pardalis. These tortoises frequented a small area of strongly sodic soil from which they dispersed over long distances.
Chromosome-banding study of the Alaska blackfish, Dallia pectoralis (Euteleostei: Esocae), with implications for karyotype evolution and relationship of esocoid fishes
Authors: Crossman E. J. , Ráb P.
Published: May 2008

Chromosomes of Dallia pectoralis from two widely separated locations in Alaska (Yukon River system and Colville River) were analyzed by Giemsa staining, C-banding, and Chromomycin A3 fluorescence. The karyotype was redescribed more precisely. The diploid number 2n = 78 was found, but a significant number of cells with 74–77 chromosomes in individuals from the Yukon River indicate chromosomal polymorphism in the species. The diploid chromosome number of individuals from Colville River was constant (2n = 74). Colville River individuals had one more pair of metacentrics than Yukon River individuals with 2n = 76. The distribution of heterochromatin was nearly the same, and the number and location of nucleolar organizer regions (NORs) was identical. The variation (71–79) may be attributable to the association of NOR-bearing chromosomes or to chromosomal distinction between populations in the two rivers. The results suggest close relationships among all the species of Umbra, a closer relationship between Novumbra and Dallia than either bears to Umbra, and a possible closer relationship between Umbra and Esox than between Esox and Novumbra plus Dallia.
Genetic adaptation and founder effect in laboratory populations of the entomopathogenic nematode Steinernema glaseri
Authors: Stuart Robin J. , Gaugler Randy
Published: May 2008

Laboratory culture can have detrimental effects on populations through adverse environmental conditions such as poor nutrition or disease, or through genetic effects such as inbreeding depression, founder effect, genetic drift, or laboratory adaptation. We tested for laboratory effects on the entomopathogenic nematode Steinernema glaseri (Steiner) by forming a genetically diverse base population from a series of field isolates and rearing several independent lines through 12 cycles of laboratory culture, using larvae of the greater wax moth, Galleria mellonella (L.), or the Japanese beetle, Popillia japonica Newman, as hosts. Laboratory bioassays based on G. mellonella indicated that lines maintained with large breeding populations did not deteriorate but often showed significant increases in infectivity (15.3–48.0%), proportion of males (12.2–36.1%), and reproductive potential (39.0–160.4%). Lines reared on P. japonica larvae responded similarly to lines reared on G. mellonella but showed higher levels of reproductive potential. Two of three lines subjected to initial genetic bottlenecks to test for founder effects differed from other lines by showing very high infectivity but little change in sex ratio or reproductive potential. These results demonstrate that laboratory adaptation can produce dramatic changes in important biological attributes of these nematodes, but that a lack of genetic variation associated with founder effects can impede this process. Laboratory adaptation should be considered a potent factor when designing, interpreting, and comparing studies of this important group of biological control organisms.
Mitochondrial DNA and the phylogeography of Newfoundland black bears
Authors: Paetkau David , Strobeck Curtis
Published: May 2008

The degree of genetic differentiation separating Newfoundland black bears (Ursus americanus hamiltoni) from continental Canadian black bears (U. a. americanus and U. a. cinnamomum) was assessed using sequence data from part of the mitochondrial DNA molecule. All of the individuals from insular Newfoundland, New Brunswick, and Quebec, and most of the individuals from Alberta, had very closely related haplotypes. Haplotypes from Newfoundland animals were more similar to those in eastern Canada than the eastern Canadian lineages were to related lineages in Alberta black bears. Given the previous observation of reduced genetic diversity in Newfoundland black bears, this subspecies likely arose through rapid genetic drift associated with a founder effect during postglacial colonization of the island, and not through long periods of isolation in a glacial refugium.
Reaction of rodlet cells to a myxosporean infection in kidney of the bluegill, Lepomis macrochirus
Authors: Leino Richard L.
Published: May 2008

Bluegills, Lepomis macrochirus, netted soon after ice-out from two Minnesota lakes exhibited the early stages of a myxosporean infection involving the kidney tubules and glomeruli. When secretory rodlet cells were present in the tubule epithelium, parasites were absent or damaged. Tubules without secretory rodlet cells contained healthy-appearing parasites. Rodlet cell secretions appeared to contribute to the elimination of myxosporean parasites from bluegill kidney tubules. These findings support the author's hypothesis that rodlet cells react to the presence of ectoparasites on epithelial surfaces and that rodlet cell secretions are antibiotic in nature.
Do olfactory cues mediate interactions between rodents on northern shortgrass prairie?
Authors: Stapp Paul , Horne Beatrice Van
Published: May 2008

We counted captures of free-ranging deer mice (Peromyscus maniculatus) in odor-baited traps to determine whether deer mice use olfactory cues to detect and evade grasshopper mice (Onychomys leucogaster), a predator and possible competitor on northern shortgrass prairie. Avoidance was measured using the frequency of captures in traps containing grasshopper mouse odors compared with that in traps containing odors of an innocuous rodent (Reithrodontomys megalotis) and in clean traps. We predicted that deer mice would be most deterred by odors in areas where grasshopper mice were common, and during winter, when alternative prey for grasshopper mice are less abundant. We also expected reproductive females to show greater avoidance because of the vulnerability of litters in burrows. Surprisingly, deer mice showed no evidence of avoidance in any experiments. These results are consistent with trapping records from capture–recapture studies on our site. We assert that the presence of grasshopper mice may affect the surface activity of deer mice, but that deer mice apparently do not use olfactory cues to avoid grasshopper mice. Taken with other studies noting the lack of avoidance of predator odors by deer mice and similar species, our results suggest that the response of rodents to predator odors is more variable than was previously appreciated.
A taxonomic revision of the Allolobophora caliginosa complex (Oligochaeta, Lumbricidae): a preliminary study
Authors: Briones M. J. I.
Published: May 2008

The Allolobophora caliginosa complex includes a number of nominal taxa: A. caliginosa (Savigny, 1826), A. trapezoides (Dugès, 1828), A. tuberculata Eisen, 1874, A. turgida Eisen, 1873, and A. nocturna Evans, 1946. There is wide disagreement as to the validity and rank of these taxa, and existing descriptions are generally inconsistent. In view of this confusion, about 4000 specimens of A. caliginosa s.l. collected from four regions of northern Spain and material in the collections of the Natural History Museum in London and the Canadian Museum of Nature in Ottawa were examined. Gross morphology was studied and the seminal vesicles were examined to determine whether sperm were present. I suggest that only a single species, A. caliginosa, should be maintained, with two subspecies, A. c. caliginosa and A. c. trapezoides. Allolobophora turgida and A. tuberculata are synonyms of A. caliginosa. Allolobophora nocturna-type specimens were not found in my sampling program and are very infrequent in museum collections, making it difficult to clarify the status of this taxon; it seems likely, however, that it is an ecotype with a localized distribution.
Bet-hedging theory and eigenelasticity: a comparison of the life histories of loggerhead sea turtles (Caretta caretta) and snapping turtles (Chelydra serpentina)
Authors: Cunnington David C. , Brooks Ronald J.
Published: May 2008

The life table for snapping turtles (Chelydra serpentina) generated from a 16-year study in Algonquin Park, Ontario, suggests that the population is declining. We use a stage-based matrix model based on this life table to simulate population management options. In addition we analyze the demographic sensitivities of the Algonquin Park population life table and a life table recently published for a population of snapping turtles at the E.S. George Reserve in Michigan. The results are compared with a similar study of loggerhead sea turtles (Caretta caretta). We use these inter- and intra-specific comparisons to test bet-hedging life-history theory. Bet-hedging theory predicts that the long lives and low annual reproductive effort of turtles reduces the effect of low, stochastic juvenile survival on an individual's reproductive success. We test this prediction using proportional sensitivity of the intrinsic rate of increase to variation in life-table parameters (eigenelasticity) to compare the two populations of snapping turtles with each other and with loggerhead sea turtles. Annual adult survival is shown to be the variable most predictive of sensitivity to variation in first-year survival.
The development of sexual dimorphism: seasonal and lifetime mass changes in bighorn sheep
Authors: Festa-Bianchet Marco , King Wendy J. , Jorgenson Jon T. , Smith Kirby G. , Wishart William D.
Published: May 2008

Individually marked bighorn sheep (Ovis canadensis) were monitored to determine how seasonal and lifetime changes in mass affected the development of sexual dimorphism, and to what extent mass at a given age could predict mass of the same sheep at a later age. We trapped sheep from late May to early October each year from 1971 to 1985 in a population artificially kept at low density. Lambs and yearlings gained mass linearly from June to September, while absolute mass gain of older sheep was faster in June–July than in August–September. Males gained more mass than females each summer up to at least 3 years of age. Relative summer mass gain, calculated as a proportion of body mass at the beginning of June, was the same for male and female lambs but was greater for male than for female yearlings and 2-year-olds. With the exception of lambs, all age-classes lost mass during winter. Mass loss between September 15 and June 5 was greater for females than for males, possibly because ewes lost mass through parturition in late May. For both sexes, asymptotic mass was not reached until at least 7 years of age. Mass at 4 and 12 months of age was correlated with mass at 4 years. For all sex–age classes, mass on June 5 was negatively correlated with summer mass gain. For lambs and yearlings, winter mass loss was positively correlated with mass on September 15. Our results suggest that at low population density, sheep optimize rather than maximize summer mass accumulation. Most sexual dimorphism develops after weaning, through faster mass gain by males than by females at 1 and 2 years of age and possibly a longer season of mass gain each year for males than for females after females reach puberty.
New taxa of Rhagidiidae (Acari: Prostigmata) from North America. Part IV. Genus Foveacheles Zacharda, with a key to world species
Authors: Zacharda Miloslav
Published: May 2008

Two new species of rhagidiid mites from the Nearctic region, Foveacheles pribilovi n.sp. and F. mexicana n.sp., are described. A detailed description of F. arenaria (Willmann) based on Canadian material is given. A key to adults of the known subgenera and 31 species of the genus Foveacheles Zacharda for the world is presented.
Growth and age of Alberta long-toed salamanders (Ambystoma macrodactylum krausei): a comparison of two methods of estimation
Authors: Russell Anthony P. , Powell G. Lawrence , Hall Dean R.
Published: May 2008

Both skeletochronology and a somatic growth model based upon mark–recapture data were used to estimate life-span and the relationship between size and age in two populations of long-toed salamanders (Ambystoma macrodactylum krausei) in the upper Bow Valley of southwestern Alberta. Skeletochronologically aged salamanders (n = 170) displayed a sigmoidal relationship between snout–vent length and age, with a great deal of variation in snout–vent length within each year class. The modified logistic-by-mass somatic growth model (based upon 47 recaptures) predicted sexual maturity at 3 years of age and adult size at 6 years, with asymptotic length approached at 15 years of age. These predictions were falsified by skeletochronology, which indicated that a snout–vent length characteristic of sexual maturity could be reached by 2 years and adult size by 3 years of age, and that the maximum life-span attained was 10 years, with most individuals living 6 years at most. Considerable variation in growth, evidently due to factors other than simple age, is displayed among individuals in these populations. Their demographic characteristics suggest that the skeletochronologically determined maximum age is real and not due to a cessation of growth, and thus of bone deposition, in these salamanders.
Foraging efficiency: energy expenditure versus energy gain in free-ranging black-tailed deer
Authors: Parker Katherine L. , Gillingham Michael P. , Hanley Thomas A. , Robbins Charles T.
Published: May 2008

Foraging efficiency (metabolizable energy intake/energy expenditure when foraging) was determined over a 2-year period in nine free-ranging Sitka black-tailed deer (Odocoileus hemionus sitkensis) in Alaska, and related to foraging-bout duration, distances travelled, and average speeds of travel. We calculated the energy-intake component from seasonal dry matter and energy content, dry matter digestibility, and a metabolizable energy coefficient for each plant species ingested. We estimated energy expenditures when foraging as the sum of energy costs of standing, horizontal and vertical locomotion, sinking depths in snow, and supplementary expenditures associated with temperatures outside thermoneutrality. Energy intake per minute averaged 4.0 times more in summer than winter; energy expenditure was 1.2 times greater in summer. Animals obtained higher amounts of metabolizable energy with higher amounts of energy invested. Energy intake during foraging bouts in summer was 2.5 times the energy invested; in contrast, energy intake during winter was only 0.7 times the energy expended. Changes in body mass of deer throughout the year increased asymptotically with foraging efficiency, driven primarily by the rate of metabolizable energy intake. Within a season, summer intake rates and winter rates of energy expediture had the greatest effects on the relation between foraging efficiency and mass status. Seasonal changes in foraging efficiency result in seasonal cycles in body mass and condition in black-tailed deer. Body reserves accumulated during summer, however, are essential for over-winter survival of north-temperate ungulates because energy demands cannot be met by foraging alone.
Species differences in activity patterns during oestrus
Authors: Cushing Bruce S. , Cawthorn J. Michelle
Published: May 2008

The onset of oestrus in females has been associated with an increase in locomotor activity; however, we predicted that there would be species in which the females would not increase their activity during oestrus. We tested this in the laboratory, using running wheels, with white-footed mice (Peromyscus leucopus) and California mice (Peromyscus californicus), which were predicted to increase activity, and hispid cotton rats (Sigmodon hispidus), which were predicted to show no change in activity level. The results supported our predictions, as cotton rats showed no change, while both Peromyscus species increased activity during oestrus. Based upon laboratory activity patterns we conducted a field study to examine the relative levels of activity of two species, white-footed mice and prairie voles (Microtus ochrogaster). We predicted that significantly more white-footed mice than prairie voles would be caught during oestrus. Before trapping we generated a model to predict the probability of capturing oestrous females. Live-trapping results supported our prediction, as significantly more oestrous female white-footed mice were captured than prairie voles (48.8 vs. 7.5%), and capture of oestrous white-footed mice deviated significantly from the model's prediction. The capture of oestrous prairie voles fit within the lower limits of the model's predictions. The results are discussed in terms of mating strategies, how oestrus is achieved, and predation risk.
The ontogeny of resource allocation in giant transgenic rat growth hormone mice
Authors: Kajiura Lovaye J. , Rollo C. David
Published: May 2008

Dry mass budgets were conducted on transgenic metallothionein-1 rat growth hormone mice and normal Mus musculus to assess ontogenic changes in growth, feeding, and resource allocation. Younger mice had higher rates and efficiencies of growth than older mice. Young transgenic mice and normal controls were relatively similar for most features but became progressively dissimilar with time. The rate of growth of transgenics was never faster than the most rapid growth observed in normal mice, but they grew larger by maintaining a higher growth rate to a later age. On a mass-specfic basis, transgenic animals consumed less food than normal ones. Reduced feeding was not simply a reflection of the allometric scaling of food intake with larger body size, as younger transgenic mice ate less food than normal ones of equivalent size, even on an absolute basis. Transgenic mice achieved increased growth via superior production efficiency and ontogenically by maintaining greater efficiency to a later age. Differences in feeding and efficiency were detectable even before the mice diverged much in size. A single relationship relating production efficiencies and growth rates for older mice was confirmed, but younger transgenic mice and normal controls displayed fundamentally different relationships between efficiencies and rates of growth. Insights into growth regulation, feeding, life-history trade-offs, and allometric theory are discussed.
The phylogeny of cockroach families: a cladistic appraisal of morpho-anatomical data
Authors: Grandcolas Philippe
Published: May 2008

Seventy-two morpho-anatomical characters were examined in 221 genera belonging to the families Blattidae, Polyphagidae, Blattellidae, and Blaberidae. They were cladistically analyzed and polarized using two mantids and two termites. As no autapomorphies of the family Blattellidae were found, the constituent subfamilies were used as terminal taxa together with other families. Three trees were found (CI = 0.81 and RI = 0.88, without autapomorphies) that differed only by the position of Nyctiborinae relative to Blattellinae and Ectobiinae. The strict consensus tree was [Blattidae [Polyphagidae [Anaplectinae [[Pseudophyllodromiidae, Blaberidae] [Nyctiborinae, Blattellinae, Ectobiinae]]]]]. The main discrepancies with McKittrick's tree were the monophyly of Polyphagidae (instead of paraphyly) and that the Blaberidae is the sister-group of Pseudophyllodromiinae (instead of the sister-group of Blattellinae, Ectobiinae, and Nyctiborinae). These results made it necessary to elevate the Anaplectinae and Pseudophyllodromiinae to familial status, and to give a new sense to the family Blattellidae, which includes only the subfamilies Blattellinae, Ectobiinae, and Nyctiborinae. This phylogeny was used to test current evolutionary hypotheses concerning sociality and reproductive behaviour; many traits were assumed to be ancestral to all cockroaches (protozoan symbionts and familial life habits) or preadaptive (progressing from advanced oviparity in Blattellidae to ovoviviparity in Blaberidae) that must actually be considered homoplasic.
Spatial distribution in the bushy-tailed wood rat (Neotoma cinerea) and its implications for the mating system
Authors: Topping Michael G. , Millar John S.
Published: May 2008

We examined the spatial distribution of reproductively active bushy-tailed wood rats (Neotoma cinerea) over three breeding seasons (1992–1994), using radiotelemetry. An index value was calculated for each animal to describe the degree of intersexual and intrasexual overlap. We tested the prediction that our pattern of spatial distribution would resemble that of a polygynous mating system, which has been suggested for this species. Over the three seasons of study, no significant differences were observed between the degrees of intersexual and intrasexual overlap of males. Females exhibited either similar degrees of intersexual and intrasexual overlap (1992 and 1993) or a greater degree of intersexual than intrasexual overlap (1994). Such a pattern of spatial overlap does not support the predictions of a polygynous mating system. We suggest that bushy-tailed wood rats display a pattern of spatial organization that is consistent with a promiscuous mating system.
An assessment of burbot (Lota lota) weight–length data from North American popuplations
Authors: Fisher Shannon J. , Willis David W. , Pope Kevin L.
Published: May 2008

Declining burbot (Lota lota) abundance across some portions of North America has prompted a search for additional evaluation tools, including a measure of condition. Weight–length data were compiled for 10 293 burbot from 79 North American populations. These data were used to develop a 75th percentile standard weight (Ws) equation using the regression-line-percentile technique. The proposed equation is log10Ws = −4.868 + 2.898 log10 TL, where Ws is the standard weight in grams, and TL is the maximum total length in millimetres. The equation is valid for burbot ≥ 20 cm and will allow calculation of relative weights (Wr) for this species. Based on the length of the longest burbot in our data set (104.3 cm), we propose minimum standardized length categories of 20, 38, 53, 67, and 82 cm for stock, quality, preferred, memorable, and trophy length, respectively. The standard length categories will allow determination of mean Wr by length group, as well as calculation of stock density indices. Differences in Wr values were present between lentic and lotic burbot populations, suggesting variation in body shape and a need for establishment of different Wr objective ranges.
Reproductive response to photoperiod affects corticosterone and immunoglobulin G concentrations in prairie voles (Microtus ochrogaster)
Authors: Nelson Randy J. , Asfaw Benjamin , DeVries A. Courtney , Demas Gregory E.
Published: May 2008

Nontropical rodent species display prominent breeding seasons mediated by photoperiod. Nonreproductive functions also exhibit seasonal changes; for example, fluctuations in adrenal activities may affect immune function and, ultimately, drive seasonal fluctuations in survival rates. The effects of photoperiod on adrenal and splenic masses and serum concentrations of corticosterone and immunoglobulin G (IgG) were evaluated in male prairie voles (Microtus ochrogaster). In one experiment, photoperiodic effects on adrenal and splenic masses and serum corticosterone and IgG levels were assessed in males that maintained "summer-like" reproductive systems after 8 weeks of short-day exposure. In a second experiment, the same parameters were examined in males in which testicular regression occurred after 8 weeks on short days. Voles that maintained reproductive organ size on short days failed to display other photoperiod-mediated differences in body, splenic, or adrenal masses or in serum corticosterone or IgG concentrations. In contrast, voles that underwent reproductive regression in response to short days decreased absolute adrenal mass and body mass compared with long-day animals, and also increased serum corticosterone concentrations and decreased IgG levels compared with their long-day counterparts. Taken together, these data indicate that reproductive responsiveness to day length may be linked to seasonal fluctuations in nonreproductive adaptations.
Energy constraint exerted by the parasite Schistosoma mansoni on the locomotion of its snail host, Biomphalaria glabrata
Authors: Gérard Claudia
Published: May 2008

The consequences of the constraint caused by the parasite Schistosoma mansoni on the locomotory activity of its snail host, Biomphalaria glabrata, were studied during the patent period. Rates of locomotion were determined 6 times per 24-h period for juvenile and adult snails with single-miracidium infections, then compared with those of healthy snails of the same age. The locomotory activity of infected snails was the same during the day and at night, whereas control snails moved less at night than during the day. The locomotion of snails infected when immature was similar to that of the controls during the day and superior at night. The locomotion of snails infected when mature decreased regularly during patency and clearly decreased in comparison with that of healthy snails. The results are interpreted in terms of energy constraint on the mode of resource allocation of the host due to the parasite.
Energy savings from vocal regulation of ambient temperature by 3-day-old domestic chicks
Authors: Espira Anton , Evans Roger M.
Published: May 2008

Precocial domestic chicks (Gallus domesticus) become endothermic at or soon after hatching, but when chilled still vocalize to solicit heat from a parent or surrogate. In this study, we examined the potential energy savings resulting from vocal solicitation of heat by comparing the oxygen consumption of 3-day-old chicks facing a cold challenge of 20 °C with and without the option of regulating ambient temperature by vocally soliciting 2-min periods of rewarming at 35 °C from a surrogate parent in the laboratory. Body temperature was unaffected by vocal regulation, but the thermal gradient between body and ambient temperature was reduced by 5.0 ± 0.4 °C (mean ± SE). Mass-specific oxygen consumption [Formula: see text] increased by 62.5% to a near steady state mean of 3.64 mL∙g−1∙h−1 during constant chilling at 20 °C, but increased by only 48.1%, to 3.08 mL∙g−1∙h−1, during vocal regulation. Relative to chilled controls, vocally regulating chicks had a mean net energy saving of 15.4% during the final, stable 15 min of testing. Vocal solicitation of heat from a brooding parent seems likely to be an important means of saving energy expended in thermoregulation in some precocial species when young chicks are exposed to low ambient temperatures under natural conditions.
A taxonomic reevaluation of North American Daphnia (Crustacea: Cladocera). II. New species in the Daphnia pulex group from the south-central United States and Mexico
Authors: Hebert Paul D. N. , Finston Terrie L.
Published: May 2008

Although the establishment of species boundaries in the genus Daphnia is complicated by the prevalence of interspecific hybrids and by phenotypic plasticity, genetic studies can resolve these complexities. This investigation employed allozyme analyses to critically assess species boundaries in members of the Daphnia pulex group from the south-central United States and Mexico. These studies demonstrated the occurrence of three common Nearctic species (obtusa, pulex, pulicaria), but also revealed the occurrence of three previously unrecognized taxa (cheraphila, pileata, prolata). All of these newly described species have their distributional centroid in this region of North America and are restricted to clay-water habitats. F1 hybrids were detected between three pairs of species (cheraphila × prolata, obtusa × pileata, pulex × pulicaria), but only the latter hybrids were common. The discovery of daphniid taxa endemic to this region of North America contrasts with the results of a broader survey of sites in Canada, and suggests that additional species await description from other unglaciated regions of North America.
Microdistributions of filter-feeding caddisflies (Insecta: Trichoptera) in a regulated Rocky Mountain river
Authors: Voelz Neal J. , Ward J. V.
Published: May 2008

A year-round study was conducted in the Blue River, Colorado, U.S.A., to examine microdistributions of the filter-feeding caddisflies Arctopsyche grandis and Brachycentrus occidentalis along a regulated stream environmental gradient. There was a well-defined longitudinal species replacement, with A. grandis reaching maximum densities 2.3 km below the impoundment and declining downstream as B. occidentalis increased. Arctopsyche grandis was often the only caddisfly found near the dam. The two species co-occurred at two downstream sites, with A. grandis numerically dominant 5.2 km below the impoundment and B. occidentalis at the farthest downstream site (11 km). Near the dam, where densities of filter-feeders were highest, there were significant relationships between individual rock surface area and the number of larvae during most sampling periods. Contrary to our predictions of selection of current-exposed microhabitats, both species occurred primarily on the bottom and lower lateral sides of rocks at all sites. Clumped distribution patterns in the absence of spatial segregation by size class suggests common microhabitat preferenda for species and instars. This use of similar spaces indicates that competitive displacement may occur, partially explaining the longitudinal distribution patterns. At a macroscale the reservoir-induced environmental alterations clearly limit the distribution of organisms, especially at sites directly below the impoundment. As the stream regains its preimpoundment character farther downstream, factors at a microscale may play a more important role in producing the distinct longitudinal distribution patterns.
Reproduction and persistence of Vancouver Island marmots (Marmota vancouverensis) in natural and logged habitats
Authors: Bryant Andrew A.
Published: May 2008

I tagged and monitored Vancouver Island marmots (Marmota vancouverensis) to investigate demographic trends among colonies inhabiting natural subalpine meadows and recently logged habitats. Marmota vancouverensis exhibits low reproductive rates, with litter sizes of 2–5 ([Formula: see text], SD = 0.83, n = 36). Females are capable of breeding at age 3, but most animals did not breed until age 4 ([Formula: see text] years, SD = 0.82 years, n = 13), and displayed a nonreproductive interval of at least 1 year between litters ([Formula: see text] years, SD = 0.76 years, n = 6). Persistence of marmots was higher at natural sites than in logged areas (65 versus 48%). Maximum female age was 9 years in natural habitats and 5 years in clearcuts. No adult female inhabiting a clearcut (n = 14) produced more than a single litter, while 5 of 14 females in natural habitats produced 11 litters. The net reproductive value of colonies in clearcut habitats was less than half that of natural colonies (0.25 versus 0.72). Recently logged habitats may act as a demographic "sink" by consuming more dispersers than they produce, and therefore impede the recolonization of distant natural habitats.
Glycine transport by the red cells of channel catfish
Authors: Angermeier S. M. , Shepard M. D. , Tunnicliff G.
Published: May 2008

In humans, glycine enters the red cell via four distinct plasma membrane carrier systems. The purpose of the present experiments was to measure the mode of transport of glycine by channel catfish (Ictalurus punctatus) red cells. About 54% of the glycine was transported by system L, while 16.1% of the glycine was transported by system Gly. A further 15.6% of transport was via system ASC and system asc together. An unidentified Na+-independent system was responsible for the transport of 7.2% of the glycine. No solute appeared to be carried into the cell by band 3. The remainder of the glycine entered the cell by diffusion. The Na+-independent system exhibited a Ktvalue of 57 ± 12 (mean ± standard deviation) μM and Vmaxof 142 ± 27 nmol∙g hemoglobin−1∙min−1(this compares with system L, which exhibited a Ktvalue of 65 ± 21 μM and Vmaxof 516 ± 117 nmol∙g hemoglobin−1∙min−1). These results demonstrate that channel catfish red cells are capable of transporting glycine by three of the four transporters involved in human red cells, although the relative contributions differ markedly, and by an additional unidentified transport system not requiring Na+. The differences in glycine transport between human and catfish red cell membranes can be attributed to evolutionary influences.
Female antennal sensilla ofEpidinocarsis lopeziandLeptomastix dactylopii(Hymenoptera: Encyrtidae), parasitoids of pseudococcid mealybugs
Authors: Baaren Joan van , Barbier Roger , Nénon Jean-Pierre
Published: May 2008

Antennal sensilla were compared in females of two encyrtid Hymenoptera, Epidinocarsis lopezi and Leptomastix dactylopii, parasitoids of adults and larvae of Pseudococcidae. The external morphology of these sensilla was studied using scanning electron microscopy and their ultrastructure observed under transmission electron microscopy using ultrathin sections. Female antennae have seven different types of sensilla, morphologically very similar in the two species: trichoid sensilla, which are putative mechanosensilla, sensilla chaetica types 1 and 2, which are presumably contact chemosensilla, and sensilla chaetica types 3 and 4, basiconic sensilla, and placoid sensilla, which are all presumed to be olfactory sensilla. Sensilla chaetica types 2 and 4 are thought to be directly involved in host discrimination. The only differences between the two species are in the number and distribution of some types of sensilla. These differences might be related to the varied tritrophic ecological context of the two species rather than to their similar biology.
Spool-and-line studies on the behavioural ecology of rats (Rattus spp.) in the Galápagos Islands
Authors: Key Gillian E. , Woods Richard D.
Published: May 2008

The spool-and-line technique has been neglected in the study of the behavioural ecology of mammals. It has advantages over the more widely used method of radio tracking in terms of cost and depth of detail in the data obtained, despite its limitations. A spool and line was used to study habitat use of two species of Rattus on Santa Cruz Island, Galápagos, in areas of sympatry and allopatry. Significantly longer total spool lines were collected from R. rattus than R. norvegicus, and R. rattus also climbed trees significantly more. Significantly longer spool lines were collected from female than male R. rattus, and rats caught in the morning spent significantly more time on the ground than those caught at night. The method of handling and the occasion of capture (first, second, or third) had no significant effect on either the total length of spool line collected or the proportion of time spent on the ground. Arboreality in R. rattus was compared with that in R. norvegicus between areas of sympatry and allopatry, and a significant difference was found between sites in terms of both the total length of spool line collected and the proportion of time spent on the ground. Rattus rattus was least arboreal at site D, an area of allopatry, and most arboreal at site B, where the fewest trees occurred, suggesting that factors other than vegetation structure influence arboreality. The use of spool-and-line devices in the study of behavioural ecology is discussed.
Genetic relationships among North American bison populations
Authors: Polziehn Renee O. , Strobeck Curtis , Beech Robin , Sheraton Jane
Published: May 2008

North American bison are presently divided into two subspecies: wood bison (Bison bison athabascae) and plains bison (B. b. bison). A survey was undertaken to determine the distribution of mitochondrial DNA haplotypes among subspecies and populations. Twelve haplotypes were identified with sequence data from the control region of mitochondrial DNA from 32 bison. Mitochondrial haplotypes for 269 bison from nine populations were then determined using the polymerase chain reaction and analyzed for restriction fragment length polymorphisms. Haplotype frequencies suggest genetic distances among bison populations from 0.0715 to 0.362. The extent of differentiation varies considerably. Based on the composition and phylogeny of haplotypes in the bison herds, plains bison form a paraphyletic group and wood bison form a polyphyletic group. Because neither subspecies of bison is derived from one lineage, neither is a well-defined taxon.
Spiralling of particles by suspension feeders in a small lake-outlet stream
Authors: Wotton Roger S. , Joicey Constantine P. , Malmqvist Björn
Published: May 2008

Suspension feeders in streams trap particles from the water column and their egesta can be captured by other individuals downstream. The resultant retention and cycling of organic matter has been termed spiralling. We investigated its significance in a lake-outlet stream that had dense aggregations of suspension-feeding black fly and midge larvae in a thin film of water. We examined the abundance of dye particles, added as a pulse, in larval guts at six sites along the outlet stream (0.15–6.94 m from the top of the dam). Samples were taken 15 min, 60 min, and 24 h after the dye had been added. From samples taken after 15 min we estimated the average spiralling length to be 5.6 m. After 24 h very few particles remained, but there were significantly more in both black fly and midge larvae at sites downstream than in those upstream.
How hot is a hibernaculum? A review of the temperatures at which bats hibernate
Authors: Webb Peter I. , Speakman John R. , Racey Paul A.
Published: May 2008

We review records of the temperature at which bats (Chiroptera) have been found torpid within hibernacula in the wild. Temperatures ranged from −10 to 21 °C, with a mode of 6 °C for Vespertilionidae (n = 29 species) and 11 °C for Rhinolophidae (n = 5 species). Both the mean minimum temperature and the mean median temperature at which species were found were significantly higher for rhinolophids (6.26 and 10.05 °C, respectively) than for vespertilionids (−0.17 and 5.68 °C, respectively).
Foraging ecology of coyotes (Canis latrans): the influence of extrinsic factors and a dominance hierarchy
Authors: Gese Eric M. , Ruff Robert L. , Crabtree Robert L.
Published: May 2008

We examined the influence of intrinsic (age, sex, and social status) and extrinsic (snow depth, snowpack hardness, temperature, available ungulate carcass biomass) factors in relation to time–activity budgets of coyotes (Canis latrans) in Yellowstone National Park, Wyoming. We observed 54 coyotes (49 residents from 5 packs, plus 5 transients) for 2507 h from January 1991 to June 1993. Snow depth, ungulate carcass biomass, and habitat type influenced the amount of time coyotes rested, travelled, hunted small mammals, and fed on carcasses. Coyotes decreased travelling and hunting and increased resting and feeding on carcasses as snow depth and available carcass biomass increased. Age and social status of the coyote influenced activity budgets. During times of deep snow and high carcass biomass, pups fed less on carcasses and hunted small mammals more than alpha and beta coyotes. Pups apparently were restricted by older pack members from feeding on a carcass. Thus, pups adopted a different foraging strategy by spending more time hunting small mammals. Coyotes spent most of their time hunting small mammals in mesic meadows and shrub–meadows, where prey densities were highest. Prey-detection rates and prey-capture rates explained 78 and 84%, respectively, of the variation in the amount of time coyotes spent hunting small mammals in each habitat in each winter. Our findings strongly suggested that resource partitioning, as mediated by defense by older coyotes, occurred among coyote pack members in Yellowstone National Park.
Comparative morphology of spermathecae in solitary and primitively eusocial bees (Hymenoptera; Apoidea)
Authors: Pabalan Noel , Davey K. G. , Packer Laurence
Published: May 2008

Spermathecae of solitary and primitively eusocial bees from five major families were compared according to their chamber size, epithelial cell height (wall thickness), number and shape of glands, number of sperm pumps, and diameter of the duct, using whole mounts and serial sections. A thick spermathecal wall with a small chamber in our exemplar colletid, megachilid, and andrenid bees, a large chamber with a thick wall in social Apidae, and a thin wall with a large chamber in social halictids indicate that a big chamber may be associated with increased colony size. A thin epithelium in the receptacle of halictid bees suggests relegation of spermathecal secretion to the spermathecal gland. A relatively thick spermathecal wall in the Apinae indicates the potential importance of both the epithelial cell layer of the receptacle and the enlarged spermathecal gland in maintaining large numbers of stored sperm. There was one sperm pump in all taxa surveyed except the representative Halictidae, in which this structure was paired. Elongated spermathecal glands may typify the spermathecae of eusocial bees.