bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grouping behaviour, tail‐biting behaviour and sexual dimorphism in the armadillo lizard (Cordylus cataphractus) from South Africa
Authors: Mouton P. le F. N. , Flemming A. F. , Kanga E. M. 
Published: February 2006

AbstractGrouping behaviour, tail‐biting behaviour and sexual dimorphism were investigated in Cordylus cataphractus, a rock‐dwelling lizard from South Africa. Eighty‐five per cent of individuals collected during different seasons occurred in groups of two or more, which shows that grouping behaviour is a year‐round phenomenon in this species. Group size ranged from one to approximately 30. Groups smaller than nine individuals normally included only one adult male, but larger groups often had more than one. Sixty‐eight per cent of lone individuals were adult males. All individuals (n= 134) attempted to bite their tails and roll into a ball on collection. Cordylus cataphractus prefers horizontal crevices with an accompanying ledge on which animals can perch in close proximity to the crevice. Males apparently reach larger asymptotic body sizes than females and also have larger heads and longer tails. The higher incidence of scars among males suggests that sexual dimorphism could result from sexual selection, but sexual differences in scaling of head and tail dimensions, however, suggest that the dimorphism may be the result of differential energy allocation by females. Unlike most other Cordylus species which have female‐biased sex ratios, the ratio is close to one in C. cataphractus.
Identification of newts (Triturus sp.) and their hybrids using molecular methods
Authors: Beebee T. J. C. , Rowe G. , Arntzen J. W. 
Published: February 2006

AbstractIdentification of hybrids is important for the study of introgression between related species, but can be difficult when morphological differences between parental species are small. In the case of the newts Triturus vulgaris and T. helveticus, males are readily identifiable during the breeding season when secondary sexual characters are highly developed, but female dimorphism is always much less. Male hybrids with intermediate characters are therefore more likely to be detected than female ones. RAPD (random amplified polymorphic DNA) analysis of three putative newt hybrids and examples of the two parent species T. vulgaris and T. helveticus confirmed hybrid status in all three cases. The maternal parents of each hybrid were identified by amplification of mitochondrial cytochrome b and ATPase genes, including partial sequencing of the latter. One hybrid had a T. vulgaris mother while the other two had T. helveticus mothers. The PCR‐based methods therefore provided a quick and simple approach for identifying both hybrid status and parentage in crosses between these two urodele species. The RAPD technique should also prove useful for the identification of larvae, which are morphologically indistinguishable in T. vulgaris and T. helveticus.
A phylogeny of the European lizard genus Algyroides (Reptilia: Lacertidae) based on DNA sequences, with comments on the evolution of the group
Authors: Harris D. James , Arnold E. Nicholas , Thomas Richard H. 
Published: February 2006

AbstractThe four species of Algyroides Bibron & Bory, 1833 form part of the relatively plesiomorphic Palaearctic clade of lacertids comprising Lacerta and its allies. An estimate of phylogeny based on DNA sequence from parts of the 12S and 16S rRNA mitochondrial genes confirms the monophyly of the genus already suggested by several morphological features. The molecular data also indicates that relationships within the clade are: (A. nigropunctatus (A. moreoticus (A. fitzingeri, A. marchi))); this agrees with an estimate of phylogeny based on morphology that assumes the taxon ancestral to Alygroides was relatively robust in body form, and not strongly adapted to using crevices. Initial morphological evolution within Algyroides appears to involve adaptation to crypsis in woodland habitats. The most plesiomorphic form (A. nigropunctatus) is likely to have originally climbed extensively on tree boles and branches and there may have been two subsequent independent shifts to increased use of litter and vegetation matrices with related anatomical changes (A. moreoticus, A. fitzingeri), and one to increased use of crevices (A. marchi). Some members of Algyroides are strikingly similar in superficial morphology to particular species of the equatorial African genus Adolfus. This resemblance results from a combination of many shared primitive features plus a few independently acquired derived ones that are likely to give performance advantage in the relatively similar structural niches that these forms occupy. This study provides evidence that: (1) the use of a combination of molecular and morphological data may sometimes allow the estimation of ancestral anatomical features when these are otherwise unknown; (2) process considerations may permit a choice to be made in cases of character evolution where tree topology means that equally parsimonious alternatives exist; such decisions about character evolution may allow ecological shifts to be similarly assessed; (3) parallel evolution in ecological analogues may involve relatively few characters.
Variations in life‐history traits in the common frog Rana temporaria (Amphibia: Anura): a literature review and new data from the French Alps
Authors: Miaud Claude , Guyétant Robert , Elmberg Johan 
Published: February 2006

AbstractLife‐history traits of Rana temporaria were studied in an alpine French population and in the literature. In the living frogs, mean adult body length was greater in females than in males. Sexual dimorphism in body length was 0.109 using Lovich & Gibbon's (1992) formula, but tended to decrease with age. Age of adult frogs was assessed by skeletochronology, and age distribution was not significantly different between the sexes (range 4–15 years in males, 5–12 in females). Adult survival rate was about 0.80 in both sexes. Once maturity was reached, the total expected longevity was 6.1 years in males and 5.5 years in females. Age and body length were positively correlated in both sexes. The growth coefficient (K) was 0.47 in males, and 0.55 in females, mainly reflected as faster female growth between metamorphosis and maturation. Growth rate generally decreased before sexual maturity was reached. On average, females matured 1 year later than males. Newly metamorphosed froglets averaged 16.1 mm. When combined with published data from 12 European populations of R. temporaria, the following general patterns emerge. Mean adult body length is significantly greater in females than in males, and mean body length at maturity shows the same trend. Variation in mean age at maturity and in longevity are considerable among populations, but there is no consistent trend of difference between the sexes. Body length and age are correlated between males and females, i.e. populations with long and old males also have long and old females. Mean adult body length, mean body length at maturity, age at maturity, and longevity all increase with decreasing activity period. Adults exposed to a short activity period grow slower but attain a greater final length. Sexual dimorphism in body length generally increases as activity period gets shorter. Polygons describing norms of reaction for maturation in an age–body length space are similarly oriented in both sexes, but with a wider range in age for females. This is due to an older age at maturity for females in populations with a short activity season. Mean age and length at maturity are significantly correlated in females, but not in males, partly supporting the hypothesis that this species has a flexible pattern of development. Observed patterns are compared with predictions from life‐history theory, paying attention to all life stages and environmental variation.
Small mammal communities and fire in the Brazilian Cerrado
Authors: Vieira Emerson M. 
Published: February 2006

AbstractThe Cerrado biome is a complex of open forests, gallery forests and savanna vegetation that harbours about 60 species of small mammals. Despite the frequent occurrence of fire in this habitat, few studies have analysed its effects on the small mammal communities in the Cerrado. The purpose of this study was to compare small mammal communities of two Cerrado areas with different fire frequencies (2–3 years or more than 18 years since the last fire). Species diversity, species composition, and relative abundance of the most common species of these communities were analysed in both areas before and after fire. One trapping grid was established in each of the two areas. These areas were sampled monthly or bi‐monthly during 1 year before and 1 year after prescribed fires. Both areas had communities with similar species composition, but the protected site had more species, before and after fire (seven and eight, respectively), than the frequently burned site (five and six species, respectively). Both sites showed significant post‐fire changes for a short time period (3 months), but only the area that had been protected against fire for more time showed significant post‐fire changes in relative abundance of the most common species (the murid rodents Bolomys lasiurus, Calomys callosus, C. tener, Oryzomys subflavus, and Thalpomys cerradensis) for the 1 year following fire. Overall diversity tended to be greater in the protected site both before and after fire. Species composition and diversity indices of the small mammal communities were relatively unaffected by the fires. Thalpomys cerradensis, however, appeared to use only areas that burn frequently and C. callosus showed an immediate post‐fire increase in population size in both areas, contrasting with a simultaneous decrease in number of B. lasiurus.
Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica
Authors: Hiruki Lisa M. , Schwartz Michael K. , Boveng Peter L. 
Published: February 2006

AbstractThe hunting behaviour of leopard seals Hydrurga leptonyx was monitored opportunistically at Seal Island, South Shetland Islands, during the austral summers from 1986/87 to 1994/95. Leopard seals used several methods to catch Antarctic fur seal pups Arctocephalus gazella and chinstrap penguins Pygoscelis antarctica, and individuals showed different hunting styles and hunting success. One to two leopard seals per year were responsible for an average of 60% of observed captures of fur seal pups. Leopard seals preyed on penguins throughout the summer, but preyed on fur seal pups only between late December and mid‐February. Hunting behaviour differed significantly between different locations on the island; fur seals were hunted only at one colony, and penguins were hunted in several areas. The relative abundance of prey types, size of prey in relation to predator, and specialization of individual leopard seals to hunt fur seal prey probably influence individual prey preferences among leopard seals. On five occasions, two leopard seals were seen together on Seal Island. Possible interpretations of the relationship between the inter‐acting leopard seals included a mother–offspring relationship, a consorting male–female pair, and an adult leopard seal followed by an unrelated juvenile. In two incidents at Seal Island, two leopard seals were observed interacting while hunting: one seal captured fur seal pups and appeared to release them to the other seal. Observations of leopard seals interacting during hunting sessions were difficult to confirm as co‐operative hunting, but they strongly implied that the two seals were not agonistic toward one another. The hunting success of individual leopard seals pursuing penguins or fur seals is probably high enough for co‐operative hunting not to become a common hunting strategy; however, it may occur infrequently when it increases the hunting productivity of the seals.
Testicular and ovarian development in the harbour porpoise (Phocoena phocoena)
Authors: Karakosta C. V. , Jepson P. D. , Ohira H. , Moore A. , Bennett P. M. , Holt W. V. 
Published: February 2006

AbstractTesticular and ovarian development in neonatal and juvenile harbour porpoises Phocoena phocoena was examined, using tissue from animals (males n= 65 and females n= 10) stranded or caught off the coast of England and Wales. Classification of the animals according to their stage of sexual development was undertaken using characteristics of gonadal morphology. Developmental correlates of the immature testis were increased incidence of prespermatogonia in seminiferous tubules, and the increasing proportion of testicular volume occupied by the seminiferous tubules. Using a low magnification (×200) assessment of testis sections, immature specimens could be grouped into three developmentally distinct classes, based on the relative amounts of interstitial and seminiferous tubule tissue and the frequency of prespermatogonia. Adult testes, showing either active spermatogenesis or seasonal quiescence, could be clearly distinguished from immature testes using histological criteria such as the presence of spermatocytes and spermatids. This classification system was used to determine relationships between testicular development and body size: males were classified as immature when they had body lengths < 135 cm and body weights < 30 kg; mature males always exceeded 140 cm in length and 40 kg in weight; and a transitional group, which was regarded as juvenile, had body lengths between 110 and 140 cm and body weights between 20 and 40 kg. Ovarian morphology was used to distinguish neonatal and juvenile females. Neonates displayed characteristic cords of naked ova which dispersed as development progressed. Neonatal animals had body lengths < 100 cm and body weights < 18 kg; within this group (n= 5) there were significant (P < 0.01) left‐right asymmetries in the number of naked ova present, the left ovary containing nearly twice as many ova as the right. Although this difference was not apparent in females with body lengths > 100 cm and body weights between 19 and 30 kg (juveniles) it could be related to the almost total asymmetry of ovulation from the left ovary in this species (Harrison, Brownwell & Boice, 1972).
Occurrence of the genus Chiasmocleis (Anura: Microhylidae) in the State of Alagoas, north‐eastern Brazil, with a description of a new species
Authors: Cruz C. A. G. , Caramaschi U. , Freire E. M. X. 
Published: February 2006

AbstractThe range of the genus Chiasmocleis found in the south‐eastern and southern parts of the Atlantic rainforest of eastern Brazil, is expanded to the north‐eastern region. Chiasmocleis alagoanus sp. nov. is described from two localities in the State of Alagoas. It is characterized by: medium size (snout–vent length 25.5–27.8 mm in females, 22.7–23.4 mm in males); snout short, tip truncate in dorsal and rounded in lateral profile; hand and foot not webbed; fingers and toes without lateral dermal spines; dorsal and ventral surfaces of body and limbs smooth, without dermal spines; colour on dorsum uniformly dark brown; venter roughly marbled in dark brown and pale cream.
Trends in the numbers and mortality patterns of sparrowhawks (Accipiter nisus) and kestrels (Falco tinnunculus) in Britain, as revealed by carcass analyses
Authors: Newton I. , Wyllie I. , Dale L. 
Published: February 2006

AbstractThe numbers of sparrowhawks Accipiter nisus received for study at Monks Wood Research Station increased greatly between 1963 and 1992, then declined by 50% in 1992–97. The long‐term increase reflected the national population recovery over this period and followed the reduction in the use of organochlorine pesticides. It was most marked in the eastern parts of Britain where the earlier population decline was greatest. The numbers of kestrels Falco tinnunculus received for study fluctuated greatly from year to year, and showed only a slight net increase over the study period. There was a marked increase in the late 1970s in eastern districts, the only areas where kestrels had obviously declined during the peak years of organochlorine use. The sparrowhawk carcasses revealed two peaks in recorded mortality: August–September, affecting mainly recently independent juveniles; March–April, affecting similar numbers of adults and juveniles. Kestrels showed no obvious seasonal peak in recorded mortality, but fewest carcasses were received in the early breeding season April–May. Among sparrowhawk carcasses, the sex ratio was significantly biased towards females (0.8 male to 1.0 female), but among kestrel carcasses the sex ratio was close to unity. Overall, 64% of sparrowhawks and 69% of kestrels were juvenile (= first year) birds, implying a mean first‐year mortality in the two species of 64% and 69%. The proportion of juveniles among sparrowhawk carcasses increased during the study period (probably reflecting improved breeding success), but the proportion of juveniles among kestrel carcasses showed no long‐term trend. The most important causes of recorded deaths in both species were collisions (65% for sparrowhawk and 35% for kestrel) and starvation (18% for sparrowhawk and 40% for kestrel). The frequencies of different mortality causes recorded among carcasses found were unlikely to reflect their frequencies in the population at large, but they did reveal changes over time. During 1962–97, deaths attributed to organochlorine poisoning and shooting declined in frequency, while accidental deaths increased in frequency, especially collisions with road vehicles in kestrels and with windows in sparrowhawks.
Compliant walking in primates
Authors: Schmitt Daniel 
Published: February 2006

AbstractIt is now well recognized that terrestrial mammals can maintain equivalent bone stresses despite dramatic differences in body size through the adoption of extended limb positions during locomotion. However, this dynamic solution is not available to all mammals. Medium‐ and large‐bodied arboreal mammals, such as anthropoid primates, must maintain relatively gracile and mobile limbs in order to manoeuvre in a discontinuous arboreal environment. But they must also use flexed (i.e. crouched) limb positions in order to maintain balance on arboreal substrates, thus subjecting their gracile limbs to relatively high loads. To determine how primates resolve this conflict between their kinematics and their morphology, five species of Old World monkeys were videotaped with lateral, frontal, and overhead cameras while they walked at a range of natural speeds along a runway and raised horizontal poles instrumented with a force platform. Kinematic and kinetic data on the forelimb show that during arboreal quadrupedalism, Old World monkeys do crouch when travelling on arboreal supports compared to the ground. Simultaneously, they lower vertical peak reaction forces and thereby reduce and reorient the peak resultant substrate reaction force, so that moment arms and moments are roughly equivalent on poles and the ground. This is accomplished through the adoption of a compliant walking gait characterized by high degrees of forelimb protraction, substantial elbow yield, low vertical oscillations of the body, and long contact times. The use of a compliant walking gait appears to be extremely rare among mammals and is most likely related to an initial primate adaptation to quadrupedal locomotion on terminal branches. This gait represents a previously unrecognized dynamic postural mechanism for maintenance of similar bone stresses and safety factors in both arboreal and terrestrial environments.
Regulation of reproduction in female common mole‐rats (Cryptomys hottentotus hottentotus): the effects of breeding season and reproductive status
Authors: Spinks A. C. , Bennett N. C. , Jarvis J. U. M. 
Published: February 2006

AbstractThe effects of breeding season and reproductive status on female reproduction were investigated in the common mole‐rat, Cryptomys hottentotus hottentotus, a co‐operatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive tract morphometrics, ovarian histology and plasma testosterone concentrations were studied in 80 females from 42 wild‐caught colonies. Although the birth of offspring is restricted to the summer, qualitative analysis of ovarian histology revealed that females retained reproductive function during the winter non‐breeding period. Seasonal differences were found in ovarian morphometrics and testosterone concentrations and are probably associated with the occurrence of pregnancy in reproductive females during the breeding period. The continuance of reproductive function during the non‐breeding period in female common mole‐rats parallels the situation in males, and is believed to be important in dispersal in C. h. hottentotus. The non‐breeding period coincides with the period of maximal dispersal opportunities in the winter rainfall areas inhabited by the common mole‐rat. Reproductive activation in dispersing animals may aid intersexual recognition, assist pair‐bond formation and thereby facilitate independent reproduction. Reproductive and non‐reproductive females exhibited a similar degree of reproductive function, and as for season, the only clear‐cut status‐related differences were associated with the occurrence of pregnancy in reproductive females. This absence of a physiologically well‐defined suppression of reproduction in female common mole‐rats is similar to the situation in males. Incest taboos between philopatric siblings may negate the need for a rigorous suppression of reproduction in subordinate colony members of this obligate outbreeder.
The comparative biomechanics of an ophidian defensive behaviour: head triangulation in hognose snake (Heterodon) and an egg‐eating snake (Dasypeltis)
Authors: Young B. A. , Lalor J. , Solomon J. 
Published: February 2006

AbstractHead triangulation is a regular component of the defensive behaviour of both Heterodon and Dasypeltis. In Heterodon platyrhinos, the triangulation is achieved primarily through rotation of the quadrate in the transverse plane with the distal end of the quadrate moving dorsad. The quadrate is pulled by the m. cervicomandibularis acting in conjunction with one of the jaw adductors. Head triangulation in Dasypeltis scabra is produced by rotation of the quadrate mainly in the frontal plane with the distal end of the quadrate moving craniad. Experimental analysis documents that contraction of the m. adductor mandibulae externus superficialis is temporally linked to this displacement of the quadrate. The presence of two different mechanical bases for head triangulation in these distantly related colubrids suggests that this behavioural display has evolved independently in these ophidian lineages.
Thyone herberti, a new dendrochirotid species from the east coast of South Africa (Echinodermata: Holothuroidea)
Authors: Thandar Ahmed S. , Rajpal Vish 
Published: February 2006

AbstractA new species of a dendrochirotid holothuroid, Thyone herberti, is described from the deep waters of Matigulu, KwaZulu‐Natal, South Africa. The new species is distinct from other species of the genus in the form of its calcareous ring, in which the radial plates are prolonged posteriorly before bifurcating, and in the presence of non‐rosette‐like perforated rods and plates in the tentacles and the introvert. The new species increases to eight the number of southern African species currently classified in the genus Thyone.