bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acanthocephala in fish from the Bothnian Bay, Finland
Authors: Valtonen E. Tellervo , Crompton D. W. T. 
Published: March 2009

A sample of 7266 fish from 31 species was obtained from the north‐eastern Bothnian Bay, Baltic Sea, from 1975 to 1982. Twenty‐six fish species were found to be infected with seven acanthocephalan species identified as Echinorhynchus salmonis, E. bothniensis, E. borealis, E. gadi, Acanthocephalus anguillae, A. lucii and Neoechinorhynchus rutili. Acanthocephalus lucii was the only acanthocephalan not to attain sexual maturity in at least one species of fish. Fourteen new host records were found for E. bothniensis. A total of 1576 acanthocephalan infections was found; in most cases these were single species infections, but in 108 cases infections of two, and in two cases of three species were observed.The most prominent host‐parasite relationship involved E. salmonis and Coregonus widegreni, where the total of 11 505 worms taken from 1164 fish was roughly ten times the number of any of the other acanthocephalan parasites taken from all its hosts. Echinorhynchus gadi was encountered only in Gadus morhua. The fish of the Bothnian Bay were not considered to offer an important environment for E. gadi, E. borealis or A. lucii. Acanthocephalus anguillae was common only in Leuciscus idus while the range of hosts for N. rutili was found to be broad with 15 of 18 infected fish species being genuine definitive hosts.Larger host fish tended to be more frequently and heavily infected than smaller ones with all acanthocephalan species except for N. rutili. Female fish were usually more heavily infected than males and the frequency distributions of numbers of acanthocephalans per fish were often observed to be overdispersed. The occurrence of non‐acanthocephalan species of helminth in the alimentary tracts of 23 species of fish was recorded during the survey. On the basis of estimates of Berger‐Parker indices, acanthocephalans were considered to be dominant in seven species of fish, cestodes in 12, digeneans in three and nematodes in one host species. Observations were also made on acanthocephalans in lampreys. The relevance of some of the findings for acanthocephalan transmission and adaptation to new environments is discussed briefly.
Zooplankton associations in Zimbabwe
Authors: GREEN J. 
Published: March 2009

The specific composition and diversity of the zooplankton in 18 impoundments in Zimbabwe were analysed on the basis of samples taken in July and August 1983. All the lakes lay at altitudes over 1200 m, with the highest at 2270 m.Thirty species of Rotifera and 20 species of Crustacea were identified, but the mean numbers of species per lake were 5·7 rotifers and 4·5 crustaceans. Some records represent considerable extensions of known ranges. Daphnia laevis was the most widespread and frequently dominant crustacean, while among the rotifers Keratella cochlearis was most frequently dominant, particularly in the lakes at the upper part of the altitudinal range.Ordination and cluster analysis of the associations revealed a group of lakes with closely interrelated similarities which could be attributed to their lying on tributaries of the same river system and receiving trout from the same hatchery. These analyses also picked out the lowest locality as the most divergent and the one showing the most typically tropical zooplankton association. Although all the lakes were well within the tropics, their altitudes seem to have excluded some of the widespread tropical African zooplankters.The possibility that these associations could be formed by random colonization is discussed and dismissed.The momentary species composition of these Zimbabwean zooplankton associations was similar to that given by Pennak (1957) for the world average, although the mean number of species of Copepoda was significantly lower than the world average. Comparisons with data from Brazil and Lake Maggiore indicate the need for a further geographical analysis.A comparative study of the species diversity in impoundments of different sizes indicates that, over several orders of magnitude of area, the number of species of Ciadocera and Copepoda shows a small increase, but the number of species of Rotifera shows a much larger and more variable increase.
Incubation of eggs of tuatara, Sphenodon punctatus
Authors: THOMPSON MICHAEL B. 
Published: March 2009

Eggs of the tuatara, Sphenodon punctatus, were incubated either buried or half buried in vermiculite at constant temperatures of 15, 18, 20, 22 and 25 °C and constant water potentials between —90 and —400 kPa. Many clutches failed completely, possibly because they had been taken from females prior to proper shell development. Failed eggs were significantly smaller than successful eggs. Incubation is unsuccessful at 15 °C. Hatching success is high between 18 and 22 °C but low at 25 °C, but equally successful between 18 and 22°C. Incubation is strongly influenced by temperature, with mean incubation periods of 328 days at 18 °C, 259 days at 20 °C, 169 days at 22 °C and 150 days at 25 °C. Water potential generally has little influence on incubation time at a given temperature. Buried eggs hatch sooner than partially buried eggs at 20 °C but the large range makes significance dubious.Eggs on the driest substrata at 18 and 20 °C lose water initially but then gain water through the rest of incubation. Eggs in all other conditions gain water throughout incubation, with the rate of i water absorption being maintained or increasing late in incubation. The suggestion that increasing rate of water absorption late in incubation facilitates explosive hatching is not supported. Egg mass at the time of hatching varies from 132 to 398% of initial values, depending on incubation conditions. Final egg mass is not affected significantly by incubation temperature. Hence, rates of absorption increase with temperature.Water potential has no influence on hatchling size. However, hatchlings from buried eggs generally are significantly larger than those from partially buried eggs.
Hind limb movements of the American alligator (Alligator mississippiensis) and postural grades
Authors: Gatesy Stephen M. 
Published: March 2009

The hind limb kinematics of American alligators (Alligator mississippiensis) executing the high walk were analysed using cineradiography. The stance phase is characterized by hip extension of 60–80d̀, knee extension of 30–40d̀ and a flexion (30–40d̀)—extension (80–90d̀) sequence of the ankle. At initial foot contact with the substratum, the femur is positioned 20–25d̀ from the sagittal plane of the sacrum. During retraction the femur is abducted to a maximum angle of 40–50d̀ near foot lift‐off. A slight medial rotation about the femoral axis takes place to maintain the orientation of the femoral condyles. The sacral region undergoes rotation about a vertical axis of 20–30d̀ and transverse roll of 10–12d̀ with each stride. One individual used an atypical limb posture in which the femur was adducted to 20d̀ rather than abducted during the stance phase.Although the crocodilian high walk appears to be a good example of a ‘semi‐erect’ posture that is intermediate between ‘sprawling’ and ‘fully erect’, the current system of postural grades hampers our understanding of locomotor variability and diversity. Grades must be considered categorical abstractions until enough data can be acquired to demonstrate that postural divisions are based on well‐defined kinematic parameters and functional mechanisms. The indiscriminate use of postural grades, particularly in fossil taxa, blurs differences between members of each grade and artificially broadens distinctions between members of different grades.
Clines revisited: The timing of pupping in the harbour seal (Phoca vitulina)
Authors: Temte J. L. , Bigg M. A. , Wiig Ø. 
Published: March 2009

The regional variation in the pupping season of the harbour seal (Phoca vitulina) was reviewed using the birth periods reported for 65 colony sites distributed over a range from 30.4d̀ to 78.5d̀ North latitude. The birth timing ofP. v. vitulinawas not related to latitude, but birthing inP. v. concoloralong eastern North America exhibited a latitudinal cline. The timing of birth inP. v. richardsivaried in three distinct patterns: (1) a significant unidirectional latitudinal cline extending between Baja California and the west coast of Washington; (2) a cluster comprised of Puget Sound, Washington and Vancouver Island, British Columbia colonies in which birthing occurred an average of 65 days later than on the Washington coast; and (3) a cluster from northern British Columbia and Alaska which did not demonstrate a latitudinal cline. Insufficient data were available for the analysis ofP. v. mellonaeorP. v. stejnegeri.We found great regional variation in the timing of birth among all colonies, with mean birth dates occurring as early as 15 March and as late as 3 September. Little variation existed north of 50d̀. To the south of 50d̀, however, most of the variation could be attributed to correlation with latitude or to affiliation with the Puget Sound, Washington‐Vancouver Island, British Columbia geographic area.Clinal variation in pupping could result from: (1) geographic variations in a selective factor with perhaps gene exchange between contiguous populations playing a role in smoothing the variation; or (2) for populations between Mexico and the west coast of Washington, regional variation in a non‐selective environmental variable, such as photoperiod.
New perspectives on protozoa
Authors: Coombs Professor G. H. , Finlay B. J. , Patterson D. J. 
Published: March 2009

The interest of the British research community in protozoa has in the past emphasized the parasitic organisms‐especially those causing diseases of economic importance in Africa. The last 20 years have witnessed dramatic changes in protozoology, and the purpose of this meeting was to indicate the nature and significance of these changes.Three areas were discussed. The first was our present understanding of protozoan diversity and the evolution of protozoa (by David Patterson), the second (by Bland Finlay) presented some novel and ecological important symbiotic relationships between protozoa and other microorganisms), and finally Graham Coombs discussed the problems still being posed by parasitic protozoa and the application of new technologies to those problems.
Breeding pond fidelity in the common toad, Bufo bufo
Authors: Reading C. J. , Loman J. , Madsen T. 
Published: March 2009

Two independent studies of adult common toad, Bufo bufo, movements between different spawning ponds/populations both within and between years were made in England and Sweden during the spring breeding periods of1987–1990. The results of the two studies were subsequently combined since they were found to be complementary. In addition, in England during 1984 and 1985, large numbers of ‘toadlets’ were marked so that they could be identified if recaptured as breeding adults.The degree of relocation between ponds was negatively correlated to the distance between ponds. The proportion of both males and females that moved between ponds within a particular year was significantly less than the proportion relocating between years. In any year, between 79% and 96% of adults that survived to breed the following year, returned to the original pond. Similarly, of the toadlets marked during1984–85, 81% of the males that subsequently returned as breeding adults were captured in their pond of origin.Isolation, in relation to both population dynamics and population genetics, is defined and its implications for the management of common toad populatins discussed.
Minimum summer populations and densities of bats in N.E. Scotland, near the northern borders of their distributions
Authors: Speakman J. R. , Racey P. A. , Catto C. M. C. , Webb P. I. , Swift S. M. , Burnett A. M. 
Published: March 2009

The contemporary summer populations of three species of bats, the common pipistrelle (Pipistrellus pipistrellus), the brown long‐eared bat (Plecorus auritus) and Daubenton's bat (Myotis daubentonii) in an area of 3200 km2. in N.E. Scotland (57°N), near to the northern borders of their distributions, were assessed by surveying nursery roosts. A total of 184 roosts were discovered between 1973 and 1989, and the species in occupation was identified at 147 of these. Of the roosts with identified occupants. 109 were occupied by pipistrelles. Most pipistrelle roosts were located close to the major rivers. The mean roost size in early summer for pipistrelles was 117 individuals. The larger roosts were predominantly (98.8%) female (n= 165). Captured bats foraging on the rivers were only 67%) female (n= 102) which indicated there was also a large population ofmales which the roost survey did not detect. The minimum density of females in the occupied habitat was estimated at 18.2 bats per km2. This contemporary population in the study area is much greater than was indicated in historical records from the 19th century. There was no evidence that the populations of pipistrelles, near to the northern border of their distribution. was reduced when compared with populations further south.Thirty‐four of the roosts were occupied by brown long‐eared bats. These roosts were located predominantly along a short(25 km). well wooded section of the River Dee. The mean roost size in early summer for brown long‐eared bats was 16.8 individuals. On average, these roosts were predominantly female(69.6%, n = 273), but contained a variable proportion of immature and occasionally mature males. The density of brown long‐eared bats in the occupied habitat was 1.66 bats per km2, less than a tenth the density of pipistrelles. Historically, this bat was more widespread and abundant in the area.There were only four identified roosts of Daubenton's bats, containing in total about 300 individuals. In all these cases, the roosts were located immediately adjacent to the major rivers, and in two of the cases were also close to areas of open water. A survey of 72 bridges in the area revealed only two individual Daubenton's bats. The density of Daubenton's bats in the occupied habitat was around2–4 bats per km2. There has been a substantial reduction in the population of this bat in the area over historical times. At the turn of the century it was the commonest bat in the area, but currently it is the rarest. The causes of the decline are uncertain but are unlikely to reflect draining of areas of open water or the activities of anglers.
The population ecology of house mice (Mus domesticus) on the Isle of May, Scotland
Authors: Triggs G. S. 
Published: March 2009

The colonizing ability, catholic habitat utilization and wide distribution of house mice (Mus domesticus, Rutty) are indicators of their ecological resilience. Numerous studies have been made of commensal, caged and free‐living mouse populations though few have assessed the relative importance of physiological and genetical components of adaptability in a simple ecosystem. This paper reports such findings, derived from live‐trapping which formed part of an inter‐disciplinary study of adaptability in a feral population of house mice living on a small Scottish island (57 ha).The population size ranged from450–3250 animals. A high proportion of mice showed homerange tenacity, though15–20% shifted their range during winter. This ‘churning’ of the population is consistent with the island population forming an effectively panmictic unit rather than fragmented demes. The breeding season, survival of individuals and change in population size related to patterns of gross climatic variation (temperature and rainfall) so that rates of reproduction and survival were lowest in cold, wet conditions. Thermoregulatory adjustment of the mice to lowered ambient temperatures and its contribution to overwinter survival are discussed. Genetical monomorphism of May Island mice is discussed in relation to their biological performance compared with other populations, especially that of the ecologically comparable Skokholm Island (Wales).
Hybridization and gene flow in house mice introduced into an existing population on an island
Authors: Berry R. J. , Triggs G. S. , King P. , Nash H. R. , Noble L. R. 
Published: March 2009

Seventy‐seven house mice (Mus domesticus) from the Orkney island of Eday were released on the Isle of May, Firth of Forth in April 1982. The May had a long‐established mouse population, which was effectively homozygous at 71 allozymic loci scored; the Eday population had a heterozygosity at allozymic loci of 5% (80 loci scored) and was homozygous for three pairs of Robertsonian fusions. Introduced alleles at six loci expressed in blood were scored in animals trapped on the May at the beginning and end of the breeding season each year from 1982 to 1988. Hybrids between native and introduced animals were found in all parts of the island six months after the original release. All the introduced alleles survived and increased in frequency, albeit to different extents. There was no clear evidence of natural selection from differential survival of individuals or seasonal fluctuation of allele frequencies, but the change and apparent stabilization of frequencies after about three years (at different levels to both the parental Eday population and in the animals released) implies that some controlling factors must have acted.These results were wholly unexpected. House mouse populations are divided into small demes, apparently with very restricted gene flow between them. The introduced mice on the May may have been successful because the native population had a low variability, but the latter had persisted successfully for over a century and certainly had a normal social structure. The spread of the Eday alleles to stability in the May population destroys the myth that population division inevitably restricts gene flow in house mice, and draws attention to the importance of coadaptation (or ‘genetic architecture’) in maintaining variation and affecting allele frequencies.
Phase delay of the natural photoperiod alters reproductive timing in the marsupial Antechinus stuartii
Authors: McAllan B. M. , Joss J. M. P. , Firth B. T. 
Published: March 2009

The dasyurid marsupial Antechinus stuartii (20–40 g) has a brief, highly synchronized mating period in spring followed by complete male mortality. Analysis of breeding times in nature suggests that the rate of change of photoperiod is the main Zeitgeber for reproductive timing in this species. To test this hypothesis the natural photoperiod was phase delayed by two months, one experiment beginning in late summer, and the other in the autumn, before the spring breeding period.The reproductive cycle of males and females exposed to the delay in summer was synchronously delayed by two months, coincident with the exact duration of the delay. Animals exposed to the two month phase delay in autumn also exhibited a delay in reproductive timing, but it was less synchronized than either the control or the other experimental group. Reproduction in control animals exposed to natural photoperiod was synchronous with that of a wild population monitored simultaneously. It is therefore likely that the rate of change of photoperiod is the dominant Zeitgeber for the reproductive cycle in this species.
The effect of seasonal food restriction on activity, metabolism and torpor in the South African hedgehog (Atelerix frontalis)
Authors: Gillies A. C. , Ellison G. T. H. , Skinner J. D. 
Published: March 2009

Twelve South African hedgehogs (Atelerix frontalis) were subjected to nine‐week experimental protocol comprising four weeks of simulated summer conditions (14L: 10D and 25 °C), and transition week followed by four weeks of simulated winter conditions (10L: 14D and 15 °C).Six control hedgehogs, with access to food ad libitum throughout the experiment, did not increase their energy intake during winter yet retained stable body mass. Six experimental hedgehogs, of similar body size, experienced restricted diet during the last three weeks of each season. These hedgehogs displayed significantly lower energy intake than controls during food restriction and lost approximately 7% of their body weight in both seasons, although this weight loss was not significant.Both groups displayed lower digestive efficiencies in winter, together with decline in activity. However, there remained no significant effect of food restriction on these parameters.Neither control nor experimental hedgehogs displayed torpor during summer and, whilst both groups became torpid in winter, the duration of torpor was significantly longer in experimental hedgehogs following food restriction.Analysis of fluctuations in body mass suggest that experimental hedgehogs supplemented their restricted diet with energy derived from body reserves during both seasons. However, the ability of this species to modify the duration of torpor in response to additional energetic stress indicates that A. frontalis can control its energetic expenditure in order to limit the depletion of body reserves.
Do the Bivalvia demonstrate environment‐specific sexual strategies? A Hong Kong model
Authors: Morton Brian 
Published: March 2009

The expression of sexuality, overall sex ratio and variation in sex ratio with age of 14 southern Chinese freshwater, brackish and marine bivalves have been investigated.Freshwater species are often hermaphroditic and brooding, e.g. Musculium and Pisidium (Pisidiidae), while Corbicula fluminea (Corbiculidae) demonstrates wide intraspecific variability in sexual expression, but also broods. Anodontu woodiunu (Unionidae) and Limnoperna fortunei (Mytilidae) are dioecious, with low incidence of hermaphrodites in the former, but both have strong female‐biased overall sex ratio which does not change with age. Juvenile age classes of Corbicula cf. fluminalis have female‐biased sex ratio. A pronounced female bias is means to optimize reproductive success, by maximizing resource allocation into more energy‐demanding oogenesis, in temporally and spatially heterogeneous lacustrine habitats. In such habitats, moreover, there are probably diminishing returns to producing sons.Mangrove and brackish water species are all dioecious (except Succostrea cuculluta) with slight male‐biased sex ratio overall, but are strongly male‐biased as juveniles. This strategy similarly optimizes success in fluctuating intertidal environment, where high rates of juvenile mortality may be expected possibly, for example, through enhanced predation. In such case, therefore, the greater investment in sons is prerequisite to an overall balanced sex ratio. The marine intertidal species, Perna ciridis (Mytilidae) and Donax semigranosus (Donacidae) have stable I:I sex ratio, notvvarying with age, and are representative of the ‘typical’ dioecious condition recorded for most marine bivalves.Thus, although intraspecific variations in life history tactics and sexual strategies equip all species for variable environment, it is postulated that permutations of the ‘dioecious’ condition, mediated through variations in the sex ratio either overall or with age, broadly equip the Bivalvia for the total range of aquatic habitats.