bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth dynamics in the American alligator (Alligator mississippiensis)
Authors: Jacobsen T. , Kushlan J. A. 
Published: March 2009

The growth dynamics of the American alligator (Alligator mississippiensis) were studied in the subtropical Florida Everglades using extensive mark‐recapture data from over 2000 recaptures of known‐aged and unknown‐aged animals. A model based on the power curve best describes growth of Everglades alligators. The nonasymptotic character of this curve leads to rejection of the hypothesis that alligator growth is determinate. A model consisting of piece‐wise linear equations better described growth in the first year, and suggested a period of arrested growth occurred in the first winter. A comparison of predictions from growth models derived from several populations indicated that Everglades alligators grew more slowly than did those in more temperate areas, leading to the rejection of the hypothesis that growth rates in subtropical Florida would be elevated because of the long growing season. We attribute this result to a combination of increased maintenance costs and a limited resource base in the Everglades.Analyses considered the extent to which growth model evaluation and use can be affected by data selection. Mathematical constraints posed by negative growth data can be alleviated by including growth records over combined recapture intervals to achieve a positive growth increment. However, periods of no to negative growth may be real, and such deviations are obscured by fitting growth data to monotonically increasing models.
The effects of acid water and aluminium on the embryonic development of the common frog, Rana temporaria
Authors: Tyler‐Jones R. , Beattie R. C. , Aston R. J. 
Published: March 2009

A decline in recent decades in the status of Rana temporaria in the British Isles has been attributed to a number of factors, mostly relating to increased urbanization. Acidification has recently been suggested as a factor which could affect R. temporaria populations in certain areas.The effects of acid water and aluminium on the embryonic development of R. temporaria were investigated using eggs obtained by artificial fertilization from frogs caught in two widely separated areas; an upland area (acidic ponds) and a lowland area (circumneutral ponds). The eggs were kept in artificial soft water at either pH 4.5 or pH 6.0 and with aluminium concentrations covering the range measured in water from the acidic ponds.The survival of embryos to normal free‐swimming larvae was not affected by water pH in the absence of aluminium. Increasing aluminium concentrations reduced the survival of lowland embryos in circumneutral water, but upland embryos were unaffected. However, in acidic water the survival of embryos from both areas decreased with increasing aluminium concentrations. Embryos which did not survive either died early in development, or developed gross abnormalities, or were constricted in the perivitelline membrane and failed to hatch. The body length of surviving larvae was decreased by both increasing aluminium concentrations and low pH, probably owing to a reduction in growth rate rather than development rate. The body length of larvae from upland ponds was decreased less than that of lowland larvae in acidic water, suggesting a greater acid tolerance in embryos from acidic ponds.Reduced embryo survival, sublethal effects, such as reductions in embryonic growth rate, and indirect ecological effects may affect recruitment to the adult population in acid ponds. It is not possible to predict from the present data what effects these results of acidification may have on regional population because the acid tolerance of embryos varies widely within regions.
Two new species of the genus Tyrophagus (Acari: Acaridae)
Authors: Lynch Corinne A. 
Published: March 2009

Two new species of Tyrophagus Oudemans, 1924, are described. One species, T. Savasi, has been discovered in several habitats of economic importance. It closely resembles T putrescentiae (Schrank) and T. neiswander Johnston & Bruce. The second, T. rebertsonae, has so far been discovered in only two, soil and tree bark. It differs from other species of Tyrophagus by a number of character. Both new species have pigmented ‘eyespots’ on the prodorsal shield. A new character used to differentiate these species is the shape of the sclerotized neck of receptaculum semins.The position of the new species in three commonly used keys to adults of the genus Tyrophagus is indicated
Explaining the scaling of transport costs: the role of stride frequency and stride length
Authors: Strang K. T. , Steudel Karen 
Published: March 2009

The mechanisms which enable large animals to transport a unit of body mass through a unit distance at a lower metabolic cost than smaller animals have been the subject of numerous studies. Recent investigations have concluded that stride frequency is a main determinant. We examine the role of both stride frequency and stride length in determining the scaling of the cost of transport.Slopes for regressions between stride frequency and speed and stride length and speed were determined in four species of rodents. These data were pooled with literature values for the slopes of stride frequency, stride length and cost of locomotion (all vs. speed) for a total of 17 species ranging in size from 30 g to 250 kg. Interspecific equations were calculated for each of these slopes versus body mass, and residuals from these allometric lines were calculated. Residuals were compared to see if variation in the rate of cost increase at a given size is related to variation in the rates of stride frequency and/or stride length increase.The residual analysis revealed that the variation in transport cost is explicable only in terms of the interaction of stride frequency and stride length slopes. The product of the scaling exponents for stride frequency slope and stride length slope is not significantly different from the scaling exponent for the cost of transport. A model seeking to explain the scaling of the cost of transport must therefore consider the influence of both stride length and stride frequency.We propose that absolutely longer limbs allow large animals to minimize the rate of increase of stride frequency and stride length with speed, and that this allows utilization of muscles with lower intrinsic rates of contraction, which in turn results in a lower mass‐specific cost of transport.
Morphometric analysis of embryonic development in Alligator mississippiensis, Crocodylus johnstoni and Crocodylus porosus
Authors: Deeming D. C. , Ferguson M. W. J. 
Published: March 2009

The size of embryos at various stages of development was determined in three species of crocodilian (Alligator mississippiensis, Crocodylus johnstoni and C. porosus). Various morphometric measurements were taken of embryos throughout development and were described for each stage of development. Increase in size from stage to stage was faster in A. mississippiensis than in C. porosus and C. johnstoni. Hatchlings of A. mississippiensis were large in length but light in mass compared with the hatchlings of C. johnstoni and C. porosus which were heavier per unit length. These morphometric parameters can be used to determine the stage of embryonic development by size. The use of principle component analysis improves this technique further by dampening any anomalous data points.The rate of embryonic growth in A. mississippiensis appeared to be under greater genetic control than in the two species of Crocodylus. The evolutionary advantages of this phenomenon probably relate to the biology of A. mississippiensis. Due to the northerly range of this species it is advantageous for alligators to hatch as soon as possible, as large as possible, to maximize the period prior to winter hibernation and reduce predation. Tropical crocodiles have fewer selection pressures for rapid development and have slower rates of embryonic growth. Genetic aspects of crocodilian embryonic development have been largely ignored but may help explain some aspects of crocodilian growth under farming conditions.
A classification of pythons (Serpentes, Pythoninae)
Authors: Underwood G. , Stimson A. F. 
Published: March 2009

The Central American Loxocemus and the pythons are assigned to sister subfamilies Loxoceminae and Pythoninae, within the weakly characterized family Boidae. They share the character of the left cerebral artery foramen being larger than the right. Within the Henophidia, paired subcaudal scales associate these subfamilies with Xenopeltis and the Uropeltidae.Twenty‐nine discrete variables were coded as 52 binary characters. Nine continuous (meristic) variables were examined. A method is described by which 18 binary characters were selected from seven of these variables, for inclusion in the data set. With Loxocemus and Xenopeltis as outgroups, the data were analysed by a compatibility method. The Pythoninae are resolved into tribes Pythonini and Moreliini on the basis of complementary synapomorphies. The Pythonini have only the genus Python, for the African and Asiatic species, including reticulatus and timoriensis. The Moreliini have all of the Australasian species, in two genera: Aspidites and Morelia.A phylogenetic analysis of the two tribes is presented, with incomplete resolution of the Moreliini. The two tribes overlap in the areas of the Moluccas and Timor. It is postulated that: Loxocemus plus Pythoninae represent a Laurasian stock; south‐east Asia was the primary centre of radiation of the Pythoninae; by the Miocene dispersal to Australasia had occurred, where there was a second radiation.
Seasonal variation in gut morphology in wild rabbits (Oryctolagus cuniculus)
Authors: Sibly R. M. , Monk K. A. , Johnson I. K. , Trout R. C. 
Published: March 2009

It is shown experimentally that diet composition affected the sizes of several digestive organs in juvenile rabbits collected from the wild. Stomach weight, small intestine volume and colon length were larger in rabbits reared on diets higher in fibre. Small intestine weight, however, was lower.Analysis of natural variation in wild adult rabbits showed that all digestive organs (except for the appendix) were larger in rabbits living on chalk soils than in those living on sand or clay. Seasonal variation was more marked in males than in females, probably because of the sexes' different breeding requirements. Thus most male digestive organs were smaller between December and June than at other times of year. Female digestive organs did not show this pattern, and were largest in May/June, when the demands of pregnancy and lactation are highest. However, food quality may have been important too. Food quality is probably highest in April, and most digestive organs were then smallest (both sexes). The dry weights of stomach and small intestine did not fit these patterns. Stomach weight increased with the presence of the nematode parasite Graphidium strigosum and small intestine and caecal volumes with the presence of cestodes. Numbers of nematodes (Trichostrongylus retortaeformis and Passalurus ambiguus) in the caecum or colon, however, had no effects on organ sizes.Data are presented on variation in intensity and prevalence of these helminth parasites with season and soil type.
Seasonal and spatial differences in food selection by otters (Lutra lutra) in Shetland
Authors: Kruuk H. , Moorhouse A. 
Published: March 2009

Otters Lutra lutra in Shetland feed almost exclusively in the sea. Their diet was assessed from direct observations of 13, 313 dives, of which 27% were successful, and 2028 prey could be identified. The results are compared with published data on the availability offish for different seasons, time of day, state of tide, and different types of coast. The most frequently taken prey was eelpout Zoarces viviparus (34%), but they were relatively small, and rocklings Ciliata mustela dominated the diet in terms of biomass (18%, against eelpout 15%). Small eel‐shaped, bottom‐living species dominated in the diet at all times, but of those, otters took the larger fishes in the populations (median weight of prey 28 g). The size and species composition of prey of males was the same as that of females with cubs, but females without cubs took smaller fish.In spring, prey was smaller than at other times, and otters were least successful when diving. Diving success and mean prey weight was highest in winter, although prey availability was highest in summer.Eelpout were caught mostly along sheltered coasts, rocklings in more exposed areas. It is argued that for optimal exploitation of the seasonal availability of different species of prey, otters need to use different types of coast, and the size of their ranges would be related to the spacing of coastal types.Most fishes were caught in daytime, and around high tide otters fed less than at other times; hunting therefore took place during periods of inactivity of prey. For the main prey species, Ciliata mustela, it was estimated that otters took a substantial part of the total population.
Morphological adaptations to an unusual defensive strategy in the mantid Orthoderella ornata (Insecta: Mantidae)
Authors: Brunner Dani , Gandolfo Daniel 
Published: March 2009

The behaviour of Orthoderella ornata Giglio Tos, 1897, a cryptically coloured mantid, is described with reference to some morphological adaptations that conceal the typical insect outline.The modification of the typical morphology of the head in mantids is analysed with special mention of the internal structure, the tentorium, and by comparison with the disposition of two other species with a different defensive strategy.The hypothesis that O. ornata has short legs in correlation with its resting position is supported by a morphometric comparison with five other species of mantids which show different behaviour and positions in their cryptic strategy.
Skeletal growth and function in the California gull (Larus californicus)
Authors: Carrier David , Leon Lisa R. 
Published: March 2009

Although the bones of rapidly growing animals are composed of weak tissue, they often must function in locomotor activity. We address the conflict between development and skeletal function by analysing the ontogeny of skeletal strength in the California gull, Larus californicus. Changes in shape and mechanical properties of the femur, tibia, tarsometatarsus, humerus, ulna and carpometacarpus were analysed in a complete post‐hatching growth series. During post‐hatching growth, strength and stiffness of the skeletal tissue increases six‐ to ten‐fold. At hatching, long bones of the wing are relatively weak and they remain so throughout the major portion of the growth period. However, in the hind limb, relatively thick bones in juveniles compensate for the weak tissue such that the force required to break the bones remains constant relative to body mass. This difference between hind limb and wing parallels the development of locomotor function; young gulls begin to walk within a day or two of hatching, but they do not fly until they are fully grown. Thus, in the bones of the hind limb, the conflict between rapid growth and skeletal function is solved by negative allometry of bone thickness.After young gulls reach adult size, the breaking strength of the wing bones increases three‐ to four‐fold, the mass of the pectoralis muscle triples and the surface area of the wing doubles. The one aspect of wing development that is not delayed until shortly before fledging is linear growth of the bones. Bones of the wing increase in length at a rapid and relatively constant rate from the time of hatching to the attainment of adult size. Relatively early initiation of linear growth of the wing bones suggests that the rate at which bones grow in length may be the rate limiting factor in wing development.
The distribution, density and biomass of terrestrial reptiles in Dominica, West Indies
Authors: Bullock D. J. , Evans P. G. H. 
Published: March 2009

Fourteen species of reptiles have been recorded from the island of Dominica, Lesser Antilles. As part of a larger study of the ecology of Dominica's forests, the distribution, density and biomass of three widespread lizard species (Anolis oculatus, Ameiva fuscata and Mabuya mabouya) were estimated in all major vegetation types. No consistent differences between seasons occurred for any of the three species, and at no site was a definite breeding season detected. Densities, estimated mainly by plot counts, were highest in coastal woodlands where mean densities reached 2148 Anolis per hectare, 379 Ameiva per hectare, and 751 Mabuya per hectare. Densities in rain forest sites were often very low. Combined biomass for the three species also reached a maximum in coastal woodlands of 44.7 kg/ha. This value is amongst the highest recorded for terrestrial reptile assemblages, and suggests that Dominica's coastal woodlands are unusually favourable habitats for reptiles.Previous studies of Caribbean lizards have suggested that either competition or predation from birds may influence lizard densities. The present study, however, found no such relationships, and it was concluded that lizard density was independent of bird density.
Selection of gastropod prey by a tropical freshwater crab
Authors: Dudgeon David , Catherine Cheung Pui Shan 
Published: March 2009

Prey selection by Somaniathelphusa sinensis (Parathelphusidae) among five gastropod species (two prosobranchs, three pulmonates) was associated with two snail attributes. First, the degree of defence of the tissues by the shell, approximated by shell weight (SW)/tissue dry weight (M). Snails with the heaviest shells (Sinotaia quadrata: Viviparidae) could not be attacked successfully by any crabs, and those with somewhat lighter shells (Melanoides tuberculata: Thiaridae) were protected from small crabs. Secondly, among those light‐shelled snails which could be attacked successfully, prey value (M/handling time, Ht) determined rank order of preference. Biomphalaria straminea (Planorbidae), with the highest M/Ht, was the species most readily eaten. When presented with a single snail species, crabs selected among different‐sized B. straminea in a way which maximized M/Ht. This preference was most strongly exhibited by small crabs. A lack of size selection for Radix plicatulus (Lymnaeidae) prey was in agreement with an absence of a clear influence of size on Ht for this species. Manipulation of M/Ht by attaching plastic discs to B. straminea shells (thereby increasing Ht) resulted in patterns of prey selection in accordance with the hypothesis that foraging S. sinensis maximized M/H1.Partial consumption of R. plicatulus, and to a lesser degree Physella acuta (Physidae), was common when groups of snails were presented to individual crabs, and occurred more frequently when large snails were offered. Partial consumption and subsequent rejection of large snails may have masked selection for small prey which were rarely abandoned before being completely eaten.The implications of patterns of prey selection were discussed with reference to the influence of crab predation on snail distribution and abundance in Hong Kong fresh waters.
Behaviour and social organization in a colony of the Damaraland mole‐rat Cryptomys damarensis
Authors: Bennett N. C. 
Published: March 2009

This paper reports qualitative and quantitative behavioural studies of the social mole‐rat C. damarensis. The behaviours were subdivided into four major categories: nest, maintenance, interactive and auto‐behaviours. Social interactions and behavioural types were analysed by sex, age category and caste. The nest area is a focal point in the burrow system with individuals spending more than 70% of the day there. Many of the interactive behaviours occurred there and the mole‐rats showed definite preferences with regard to which individuals they rested next to or avoided.The Damaraland mole‐rat colonies show some division of labour, into frequent and infrequent worker groups; these castes differed significantly in the amount of both digging and soil movement undertaken.
Population variables and causes of mortality in a hedgehog (Erinaceous europaeus) population in southern Sweden
Authors: Kristiansson Hans 
Published: March 2009

A hedgehog population in southern Sweden was studied by capture‐mark‐recapture during 1972–1979. Each animal was weighed, sexed and marked with one numbered clip in each ear.The number of subadult and adult hedgehogs was about 20 in the first two years, 1972–1973. Numbers then increased and approximately doubled and the population peaked in 1978. A decrease came in 1979.The estimated number of juveniles produced varied between years with the lowest figure (15 juv.) in 1974 when the population was low and the highest in 1977 (39 juv.) when the population was high. As no captured subadult female had suckled young, estimates of recruitment rate assumed that females did not reproduce until they were adult. The average number of juveniles per adult female was 2.8. Recruitment rate did not show any correlation with non‐juvenile population densities.For both juveniles and non‐juveniles the annual mortality varied greatly between years. Average yearly mortality was 47% for non‐juveniles and 34% for juveniles.For non‐juveniles, most of the total mortality occurred during winter, ranging between 26% and 43% (average 33%), and increased with increasing densities of non juveniles. Juvenile winter mortality varied between 6% and 94%, averaging 33%.Summer mortality of non‐juveniles averaged 15%, ranging between 3% and 22%. Traffic kills were the predominant cause of death. Only a few juveniles were found dead during summer and autumn.There were no statistical differences in age‐specific survival rate between males and females and, generally, no differences in survival rate between the age categories within each sex. It is argued that the population size appears to be more influenced by environmental factors, such as food availability, winter nest sites and winter climate, than by density‐dependent factors.
The relative age structure and body masses of complete wild‐captured colonies of two social mole‐rats, the common mole‐rat, Cryptomys hottentotus hottentotus and the Damaraland mole‐rat, Cryptomys damarensis
Authors: Bennett N. C. , Jarvis J. U. M. , Wallace D. B. 
Published: March 2009

The relative ages of individuals in a complete wild‐captured colony of 13 Cryptomys hottentotus hottentotus and a complete wild‐captured colony of 25 Cryptomys damarensis were determined by means of tooth wear and eruption patterns and through the degree of ossification of their skeletons.From sequential tooth wear and eruption patterns four relative age classes were discerned in C. h. hottentotus and five in C. damarensis. These relative age class allocations were supported by the studies on the ossification of the skeletons.In C. damarensis, older animals are not necessarily the larger‐sized individuals. In C. h. hottentotus, however, older animals are usually the larger‐sized individuals. The reproductive pair in each of the Cryptomys species are the oldest or amongst the oldest individuals in the colony.Individuals in a second colony of C. damarensis kept under laboratory conditions for three years maintained greatly disparate body masses which were correlated with the role of the individual within the colony and not, where it was known, with the age of the animal.An analysis of 13 body and skull measurements performed on a complete colony of 13 C. h. hottentotus and a complete colony of 25 C damarensis revealed that only C. damarensis showed sexual dimorphism. This dimorphism was apparent from an early age but became more pronounced in older animals.