摘要:

Kinematic characteristics of the fore‐ and hindlimb displacements during terrestrial and aquatic locomotions in juvenile marine turtlesDermochelys coriaceaare compared. Modulations of the spatial displacements of the limbs and durations of the stance and swing phases are analysed in relationship with the constraints of the aquatic and terrestrial environments. The stance and swing phases used for describing the aquatic locomotion are re‐evaluated in the light of the spatial displacements of the forelimbs during complete beating cyc

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02689.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

A total of 121 European fallow deer does, being either parous (n= 15) or nulliparous (n= 106), were treated with intravaginal progesterone impregnated controlled internal drug release (CIDR) devices for 14 days. The does were divided into three treatment groups and inseminated in utero by laparoscopy, at approximately 65 hours after CIDR device removal, with 25 × 106fresh Mesopotamian (n= 40), 25–35 × 106frozen‐thawed Mesopotamian (n= 41) or 30–32.5 × 106frozen‐thawed European (n= 40) fallow deer spermatozoa. The semen used had been collected, from two Mesopotamian and two European fallow deer bucks, by electroejaculation under general anaesthesia. Pregnancy was diagnosed by rectal ultrasonogrdphy on Day 50 after insemination.There were no apparent differences in the quality of ejaculates between the two subspecies of fallow deer. The volume of semen and the total number of spermatozoa ranged between 0.6–1.2 ml and 2.11–4.95 × 109per ml of semen, respectively. Evaluation of frozen‐thawed spermatozoa revealed post‐thaw motility rates between 50–70%. The overall conception rate was 65.3%. A higher conception rate was observed following insemination with European than Mesopotamian frozen‐thawed spermatozoa (75% vs. 53.7%, respectively,P<0.05). Insemination with fresh Mesopotamian spermatozoa increased the conception rate to a level not significantly different from that observed following insemination with European frozen‐thawed spermatozoa (67.5% vs. 75%, for fresh Mesopotamian and frozen‐thawed Eu

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02690.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

We studied echolocation call structure, flight morphology and feeding behaviour of three hipposiderid bats (Asellia tridens, Hipposideros cafferandH. ruber: Chiroptera: Hipposideridae) in The Gambia during the wet season (July‐August). All three species emitted brief CF/FM echolocation calls. InA. tridensCF (constant frequency) frequencies between 108 and 122 kHz were recorded. This variation was caused mainly by sex and age difference in call frequencies: juveniles used lower frequencies than did adults, and males were lower in frequency than females. Among adults, CF frequency was related to forearm length in a polynomial manner.Asellia tridensis unusual for a microchiropteran in that males are larger than females: nevertheless this species follows the typical trend for bats using CF components in their calls in that males call at lower frequencies than do females. The spread in frequencies noted forA. tridensin group flight was not caused primarily by individual shifting their frequencies when flying in a group compared with when flying alone. Three bats were flown separately and then together in a small room. The hypothesis that bats shift emitted frequencies in group flight to minimize confusing their own echoes with those from conspecifies was not supported. Rather, we suggest each bat has a personal CF frequency determined by sex, age and size, and that the variation created by these factors reduces confusion with other bats' echoes during group flight. Bats of the genusHipposideroswere separated into two groups by discriminant analysis on flight morphology. The two groups showed little overlap of CF frequencies used in echolocation. Bats identified asH. rubercalled with CF resting frequencies between 121 and 136 kHz, whileH. cafferused 128–153 kHz. Our results support the classification of these bats into two sibling species. We compared the flight performance ofA. tridensandH. ruberby flying bats through obstacle courses:H. ruberhad a lower wing loading and was able to negotiate more complex arrays of obstacles than couldA. tridens. In the wild,H. ruberfed in more cluttered situations than didA. tridens. Both species were feeding mainly on Coleoptera during the study period, and inH. ruberindividuals with higher aspect ratios and longer wingspans tended to eat more months than did bats with broader and shorter wi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02691.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The distribution of smooth newts,Triturus vulgaris, and palmate newts,Triturus helveticus, in north‐west Europe is related to geology and water quality. This study compared the development of the eggs and larvae of the two species under sublethal acidic and neutral conditions. Newt embryos raised under low pH hatched at an earlier stage of development, at a smaller size, and before those raised under neutral conditions.T. vulgarishatched at a smaller size thanT. helveticus, but pH did not affect the species differentially. Larvae of both species grew to a larger size under neutral than under acid conditions. Larvae raised in heterospecific pairs grew at least as well as those raised in conspecific pairs. Feeding was depressed under acid conditions, and reduced growth may therefore be associated with changes in the behaviour of newt larvae and their pre

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02692.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The mechanical properties of the tissues of the tusk of a narwhalMonodon monoceros, their histological arrangement, and the gross anatomy of the tusk were examined. The histology of the tusk shows various toughening mechanisms. The tusk tissues are of low stiffness, but are very tough, suiting the tusks for loading on impact, but not for longitudinal loading. These mechanical properties suggest the possible functions of the tusk, namely to be long in order to be sexually attractive, while being tough in order to withstand ‘testing’ blows from other ma

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02693.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The fine structure of a cell type in the epidermis of brown trout,Salmo truttaL., is described. Its cytological features are compared with those of other sacciform cells reported in several species of teleost fish. This cell type also has a highly electron‐dense cytoplasm with numerous Golgi systems and extensive rough endoplasmic reticulum. However, surrounding the large central vacuole there are no peripheral vesicles—‘bubbles’—which are characteristic features in non‐salmonid teleosts. Instead of these, in the vacuole there are cytoplasmic intrusions of circular cross‐sections forming a mesh in the cortical zone. Inside these intrusions there are granules which are interpreted as ribosomes trapped by fusion of the vacuole and reticulum membranes. The way in which the secretion is released into the lumen of the central vacuole is discussed. It is suggested that this proteinaceous material does not pass through the Golgi system, but flows directly from endoplasmic cisternae t

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02694.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Mechanical properties of the pigeon humerus are significantly influenced by internal bony trabeculae. Experimental testing of braced (intact trabeculae) and unbraced (trabeculae experimentally removed) humerus pairs extracted from the same individuals demonstrates that the flexural rigidity, strength and toughness (work of fracture) of the pigeon humerus are all augmented by an intact framework of trabeculae. Measured differences in mechanical properties in braced/unbraced comparisons generally exceed discrepancies attributable to random variation in construction and thus cannot be ascribed to inherent skeletal asymmetry. The structural contribution of bony trabeculae is apparently greater in subadult birds, possibly due to thickening of cortical bone and/or increasing mineralization of bone tissue with age.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02695.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Between 1988 and 1991 grey seal (Halichoerus grypus) pups at various developmental stages were sampled at Sable Is., NS, and blubber samples were analysed for lipid content and organochlorine (OC) residue concentrations. Blubber lipid content increased significantly between birth and 12 d, and then stayed relatively constant. Blubber OC residue concentrations were fairly constant during the first 12–16 d of life. From weaning (approx. 16 d) until four months, the pups are learning to feed but are relying on blubber fat reserves; thus, during this period blubber weight declined to minimum levels, and OC residue concentrations in blubber lipid increased significantly. Blubber lipid OC concentrations then declined slightly as the pups gained weight, until at the end of one year they were about twice those immediately post‐weaning. Blubber lipid residueburdenscalculated from these data showed that at weaning, about 98% of the seal's residues were accumulated from maternal milk. After weaning, there were no significant changes in the burdens of any residue until the end of the first year of the pup's life, and the organochlorine concentration changes reflected a fairly constant organochlorine burden around which lipid contents varied. These data suggest that the capacity of the seal to degrade the residue inherited from its mother is very limited. Furthermore, the absence of any significant accumulation of organochlorines during the second six months of the seal's life suggests that the juvenile seal must feed at a low trophic level which is not highly contaminated with organochlori

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02696.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The rock lizardLacerta monticolais a climatic relict confined to three mountain ranges and one coastal region of the Iberian peninsula. Scalation was studied in specimens from localities encompassing all major parts of its range. Population differentiation was analysed using analyses of variance, z‐transformations of within‐locality character‐correlations, canonical variate analyses, principal components analysis, and matrix association tests. Substantial differentiation was found between Pyrenees specimens and those from other localities, supporting a recent study which indicated that the Pyrenees populations could represent a different species. Considerable geographic variation is also found among populations from the remaining parts of its range, the pattern of which is not compatible with existing racial categories designated for this sp

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02697.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Ovarian development in sexual and parthenogenetic geckos of theHeteronotia binoeicomplex was analysed quantitatively by gross and histological examination. Females were classified into one of four stages of the reproductive cycle: non‐reproductive, preovulatory, postovulatory and postoviposition. Parthenogens had significantly more developing follicles present in the ovaries than sexual females in non‐reproductive, preovulatory and postovulatory stages of the reproductive cycle. The larger number of developing follicles in parthenogeneticHeteronotiawas correlated with the significantly larger body size of the parthenogenetic females at the localities examined. Maximum follicular size and rates of follicular atresia were not significantly different between sexual and parthenogenetic females. These findings raise the possibility that the reproductive output of the parthenogenetic females may be higher than that of sympatric sexual females at these localities due to an increase in follicular recruitment. Based on this evidence, we predict that at these localities parthenogenetic females produce more clutches of two eggs than sexual females. If viability is equal, this would enhance the reproductive advantage of parthenogens over the two‐fold level already present. In all other respects, the morphology of the ovaries appeared very similar between parthenogenetic and sexual females and was typical of g

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02698.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY