摘要:

Size variation of body and skull of five species of Australian mammals (echidna,Tachyglossus aculeatus; brush‐tail possum,Trichosurus vulpecula; eastern grey kangaroo,Macropus giganteus; western grey kangaroo,M. fuliginosus; red kangaroo,M. rufus), is related to climatic factors. All five species show trends in body size that conform with Bergmann's rule, individuals from colder environments being larger than those from warmer areas. The western and eastern grey kangaroos also conform with Allen's rule, the relative size of their extremities being large in warmer areas. In four of the five species (not the red kangaroo) body size is also correlated with indices of biomass productivity. However, since biomass productivity and ambient temperature are related to some extent, it is difficult to separate the effects of these factor

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb00278.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The structure of copulatory organs is used very widely in systematics, both for differentiating species and for working out relationships. Differences between taxa may arise from a variety of sources, including non‐homology, differences in other parts of the animal, direct selection on copulatory organs, development of physical isolating mechanisms and pleiotropic events. Physical isolating mechanisms seem likely to account for the abrupt differences, involving size, asymmetry and simplifications, that are useful in distinguishing very similar lacertid species. Although these differences usually seem to arise at the end of a speciation event they can simultaneously be the initiating mechanism in a second one. Copulatory organs appear to have high inherent stability, probably resulting from frequent location in strongly homoeostatic environments, single function, insensitivity to niche shift and inertia due to the need to conform to the genitalia of the opposite sex. This stability may be overridden at times by direct selection on the organs themselves or pleiotropic events. Such changes tend to be retained because efficiency in copulation depends not on any absolute genital architecture but on close conformity of the organs. It is the combination of relative stability and tangible input of varied change, which tends to be retained, that so often makes these structures good indicators of relationshi

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb00279.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Glycine argyrea(Fabaceae), a perennial wild relative of soybean, has a dual flowering strategy of both self‐fertilized cleistogamous flowers and chasmogamous flowers on the same plant. Using allozyme polymorphisms the frequency and pattern of outcrossing was determined. The genotypes of seeds from each of several fruit (legumes) per plant were analysed by starch gel electrophoresis, and the maternal genotype inferred. The maximum likelihood estimates of outcrossing rate for the chasmogamous flowers averaged 0.38. The observed level of heterozygosity in the adult population (h = 0.25) compared with the level expected under random mating (h = 0.32) indicated that partial outcrossing was typical of this population. To analyse the mating pattern further, the pollen genotypes of several seeds per legume for pairs of legumes from the same plant were determined. About 35% of fruit from chasmogamous flowers had no genetically detectable outcross progeny, presumably because they were not cross‐pollinated effectively. The majority of the remaining fruit had seed which were of mixed origin (both self‐fertilized and outcrossed), suggesting that insect pollination does not preclude self‐fertilization. As might be expected from this entomophilous pollination system, the pollen of outcrossed seed within one fruit usually (85% of cross‐pollinated legumes) came from one male source. Evidence of pollen carry‐over was found in the other legumes. The joint distribution of male sources among the pairs of legumes (paired fruit analysis) showed that non‐self sources were shared in 30% of pairs. The probability that two outcrossed seeds from the same fruit would be half‐sibs was estimated as 0.15, and for two seeds from different fruit on the same plant as 0.42. There is a hierarchy of genetic identity within and among legumes on the same plant, and on different plants, providing scope for the operation of selection at d

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb00280.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The rate of heating and the temperature attained after 10 and 20 min have been examined for shells of the yellow, dark and orange morphs of the mangrove leaf snailLittoraria pallescens.Under the experimental conditions used, heating from 20 to 40d̀C took 5–10 min and thereafter the temperature remained roughly constant for up to 20 min. This represents temperature conditions which the animals are likely to experience in the wild. Large shells heat more slowly than small ones and reach lower temperatures. At around 40d̀C yellows are on average 1.5d̀C cooler than the dark morph, and orange individuals lie between. This difference could account for the observed difference between morphs in their choice of preferred leaf surface. Besides differing in colour, yellows are thinner and less heavy than dark shells, which probably contributes to the fact that they arc less ro

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb00281.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

A survey was made to determine the shape of the chromosomal cline, between two races of the alpine grasshopperPodisma pedestris, in an area distant from previous detailed studies. The new section was in an isolated mountain block at the western end of the Alpes Maritimes. The past changes in the grasshoppers' distribution can be deduced from a consideration of the history of climatic fluctuations. These distribution changes imply that the hybrid zone has persisted on the isolated mountain block since before the last climatic optimum. The stability of the zone's location can be explained if there are persistent, wide gradients inPodismadensity. An assessment ofPodismadensity revealed suitable gradients. Whilst the cline was generally the same width as in other areas, it was more abrupt where it crossed an inhospitable area, and less well defined in marginal populations. This suggested other interactions between the population density and the dynamics of the racial mixing. The implications of these interactions are discussed. It is suggested that population structure is important in the spread of co‐adapted genomes, as well as in their establishmen

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb00282.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Four species of philomycid slugs were collected at 13 sites in Tennessee and one site in Virginia. A total of 361 individuals were examined electrophoretically at 11 allozyme loci. Outcrossing was the primary breeding in all populations of all four species. Genetic similarities among demes, among species and among genera are similar to values obtained in studies of other animals with similar vagility and demography and are in good agreement with systematics based on morphological characters. In the species examined in greatest detail,Philomycus carolinianus, there was substantial genetic differentiation among demes. This differentiation appears to result from genetic drift and restricted gene flow. Genetic similarity betweenP. carolinianusdemes did not correlate with the geographic distance between demes and hierarchical F‐statistic analysis showed more than half of the differentiation among demes to result from differentiation at the smallest geographic scale. The Tennessee River system also appears to be a major barrier to gene flow among theP. carolinianusdemes sample

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb00283.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY