摘要:

This study investigated the phylogenetic relationships and biogeographic history of West Indian geckos belonging to the genusSphaerodactylusthrough an analysis of protein variation. Two techniques were used: sequential starch gel electrophoresis of 15 slow‐evolving loci and microcomplement fixation of albumin. The relationships obtained were used to revise the classification of this genus. Two major groups (subsections) occur in the West Indies. Thesputatorsubsection, centred in the Greater Antilles, is composed of three series:cinereus, sputatorandargus. Thefantasticussubsection, restricted to the Lesser Antilles, includes only thefantasticusseries.Three antibodies (argus, asterulusandcopei) were used to investigate albumin evolution and estimate times of divergence withinSphaerodactylus. Using the albumin clock calibration derived from other groups, the West IndianSphaerodactylushad diverged from other sphaerodactylines by approximately 27 million years before present (mybp). Therefore, fragmentation of the Proto‐Antilles (60 mybp) apparently did not play a role in the group's evolution. The present distribution of West IndianSphaerodactylusresulted from dispersal. Hispaniola probably was the centre ofSphaerodactylusdiversity and the source of colonists for other islands. Certain features ofSphaerodactylusecology and physiology make them likely candidates for dispersal. In contrast to the West Indian species ofAnolisandEleutherodactylus, few exampies of morphological convergence are found inSphaerodactylus. Allopatric speciation, perhaps due to climatic changes in the Pliocene and Pleistocene, is suggested as the primary mechanism of species formation in West IndianSphaerodacty

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04323.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

I report previously undocumented encounters between avian scavengers and desert bighorn sheep (Ovis canadensis nelsoni). These encounters are of interest because they occurred only during the nursery season when lamb mortality was high. Desert bighorn sheep responded to the presence of avian scavengers with typical anti‐predator behaviours, which may indicate that avian scavengers are potential predatorsorthat desert bighorn sheep are unable to distinguish between avian scavengers and avian predator

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04324.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Food intake and digestion were investigated at four stages in the first 218 days of lactation in tammar wallabies (Macropus eugenii) carrying litters of one, and in non‐lactating females as a control. This period of lactation in tammars, which includes the phase of exponential growth of the young, is comparable to gestation plus early lactation in ruminant placentals. Food and energy intakes by mothers remained at the non‐lactating level while rate of growth of young was slow (up to Day 105 of lactation) but then rose as the growth rate of young increased, keeping pace with the predicted requirements for milk synthesis and export. There was no indication of the energy deficit seen in late gestation and early lactation in many herbivorous placental mammals. The gross efficiency of utilization of ME for growth of offspring was estimated as 13–15%, which is at least as high as values for placentals during gestation. The mean intake of metabolizable energy (ME) at 218 days was 603 kJ.kg‐0.75.d‐1, which represented 136% of ME intake by nonlactating females, or an increment of 159 kJ.kg‐0.75.d‐1. It was estimated that ME intake may rise to 773 kJ.kg‐0.75.d‐1at peak lactation, which would be 174% of the non‐lactating level or an increment of 329 kJ.kg‐0.75. d‐1. This allometrically‐scaled increment is similar to values for some ruminants that use body reserves extensively to offset peak lactational food requirements. These and previously‐reported trends suggest that ecologically comparable herbivorous marsupials and placentals utilize different physiological strategies to minimize demands on food resources during reproduction, but that both daily and ove

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04325.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Middle ear ontogeny inMonodelphis domesticais investigated to understand better both the immediate consequences for suckling in a neonate marsupial and the epigenetic factors that constrain morphogenesis. Neonates ofMonodelphispossess neither mammalian (dentarysquamosal) nor reptilian (quadrate‐articular) jaw articulations, nor does the contact between the incus and crista parotica offer a joint surface (contraMaier, 1987). Elasticity in Meckel's cartilage allows minimal deflection of the lower jaw. Observation of the developmental rate of the individual elements reveals that mandibular arch derivatives (malleus, incus and tensor tympani) are on a slightly faster ontogenetic schedule than hyoid arch derivatives (stapes and m. stapedius

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04326.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The occurrence of detachable nodal structures in the downy barbules of many birds was studied with light‐ and scanning electron microscopy. Anuli are the only type of nodal structure that may break loose and slide along the barbules to form dual or multiple nodes. Considerable variation exists in the occurrence of this feature. Multiple nodes are more frequently present in tail‐coverts than in breast feathers. This is the first report of the presence of detachable anuli in feathers of Cracidae, Numididae and Musophagidae. The suggestion by earlier workers that these structures are characteristic for all galliforms is not confirmed, since megapodes never show detached nodes. The downy barbules ofAfropavoresemble those of other phasianids in all respects, while those ofOpisthocomusare strikingly different from both galliforms and cuckoos. Outgroup comparison indicates that multiple nodes may be synapomorphic for Tinamidae, Cracidae, Tetraonidae, Phasianidae, Numididae, Meleagridae and Musophagidae together, but, considering the incongruence of this hypothesis with recently proposed phylogenies, alternative explanations for the structural similarities between the downy barbules of tinamous, turacos and galliforms are discus

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04327.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Burrows of the northern hairy‐nosed wombat were arranged in loose clusters, each of which was used in common by a group of up to 10 wombats. However, individual wombats rarely used the same burrows on the same days and feeding ranges tended to be separate within each sex. The incidence of breeding dispersal among females was quite high (at least 50%); dispersal distances ranged up to almost the full extent of the population's range. Dispersal by adult males was rare, and no juvenile males were observed to dispers

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04328.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

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 freq

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04329.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The dasyurid marsupialAntechinus 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 specie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04330.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

In a study of morphological directional asymmetry (DA) on the population level, four characters were bilaterally examined in geckos (museum specimens, totalnPtyodactylus puiseuxi,P. guttatusandP. hasselquistii, from Israel and Sinai. Significant DA occurred in adults in five or six out of 12 character‐taxon‐combinations (CTCs): number of supralabilia inP. puiseuxiandguttatus, length of ear aperture inpuiseuxiandhasselquistii; number of subdigital lamellae inguttatus; and width of the digital pad inhasselquistii. The average magnitude of DA per CTC ranged from 1.5 to 5% of organ size, without correlation to organ size. Side dominance varied, mostly witin characters between taxa. No sexual differences in DA were significant, although for two CTCs DA was significant only in one sex. Presumably neutral or pleiotropically‐adaptive DA is a potential base for the evolution of functional DA. One practical conclusion is that in comparative biometrical studies, bilateral characters should not be examined consistently on only one

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04331.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb04332.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY