摘要:

Two distinct chromosomal polymorphisms, among others, characterize the short (p) and long (qh) arms of chromosome number 1 of theSpalax ehrenbergicomplex in Israel. We have studied the geographic distributions of these two polymorphisms in 60 animals belonging to four chromosomal species (2n= 52, 54, 58 and 60). These comprised 15 populations: 12 from continuously distributed populations, two from semi‐isolates, and one isolate in the northern Negev Desert.Our results indicate that: (i) the two polymorphisms are widespread not only within populations and species but most strikingly between different bone marrow cells within an individual; this may reflect a diversity generating mechanism; (ii) the two polymorphisms of p and qh, primarily of p, are correlated with climatic factors of water availability and temperature, as well as geographical distances; these correlations are significantly above those expected by chance, (iii) The semi‐isolates and the isolate display high levels of polymorphism in both p and qh, but particularly in qh, despite the small size population effects.We suggest that at least the polymorphism in p is involved in the adaptive radiation of mole rats into diverse climatic regimes. Furthermore, we speculate that the forces generating chromosomal polymorphisms relevant to speciation (i.e. Robertsonian mutations), coupled with the evolutionary forces operating in small peripherally isolated populations, may be appropriate for the origin of new chromosomal species through peripatric speciat

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00447.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Outstanding progress in understanding segmentation of tracheate arthropods (Atelocerata), i.e. Chilopoda, Diplopoda, Pauropoda, Symphyla and Insecta, has been gained through experimental studies carried out on a single, very derivative organism, i.e.Drosophila.We stress the need for a broader comparative approach. We have studied the segmental structure of the trunk in geophilomorph centipedes, where we can identify morphogenetic units of two, four, eight or 16 segments. Accordingly, we sketch an improved model for arthropod segmentation, with the following initial steps: (a) biochemical marking of a very few repetitive units (eosegments); (b) iterative duplications of this first periodicity, until the embryo acquires an array of biochemical markings matching the whole number of segments of the future larva or juvenile specimen; (c) transpatterning, stabilization and interpretation of this ‘segmental’ arrangement; (d) possible repatterning, to give a final repetitive pattern we define as metasegmental. Finally, we express some doubt about the homology between annelid and arthropod segmentat

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00448.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The colour patterns ofHeliconiusbutterflies are composed from a relatively simple set of pattern elements whose homologues are recognizable throughout the genus. AlthoughHeliconiuscolour patterns look quite different from those of most nymphalids, these pattern elements are seen to derive from the generalized nymphalid groundplan. The differences arise primarily from the loss or positional shift of certain pattern elements, a high degree of fusion between individual pattern elements, and, in the forewing, asymmetries of the pattern elements relative to the wing‐cell midline. The scheme of homologies we present is consistent with what is currently known about the comparative morphology and developmental physiology of colour pattern formation in Lepidoptera, and provides a framework for the interpretation of developmental, evolutionary and genetic studies inHeliconiu

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00449.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Making and analysing groups in systematics can be performed by jointly using normal and cladistically‐modulated homogeneity as the test for clustering. This method is robust under a variety of data conditions and appears to be an efficient computer image of classical methods. Phenetic groups are sought by a homogeneity test instead of by similarity. For quantitative data, information‐rich, continuous property coding is used which can express any degree of development. There is full provision for other kinds of data. In the cladistic test for grouping, those properties which show gradual evolutionary trends from plesiomorphic to more apomorphic states can influence clustering through a range of intensities of synapomorphy. This cladistic effect is further controlled by a factor based on the certainty of any property's trend evidence. Supporting systems for this approach include extracting overall size to expose proportional relationships, de‐weighting based on close resemblance between property descriptors, allowing intra‐item variation to affect clustering, and controlling lumping and splitting by altering the intensity of clustering. Results obtained from a computer program called Bolaid are di

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00450.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Only large bats can take large prey but size alone does not identify ‘carnivorous bats’ (those including small terrestrial vertebrates in their diets). Morphological data, including body mass, aspect ratio and relative wing loading, along with information about orientation and foraging strategies can be used to characterize a suite of features which identifies carnivorous bats. We use the available data to make predictions about which large Microchiroptera will be found to be carnivorous. A combination of morphological features including body mass (^0.017 kg), low aspect ratio (<6.3), and low relative wing loading (<36) significantly identifies carnivorous species from among other animal‐eating forms. Some carnivorous species use short, low intensity, high frequency, broadband echolocation cells but rely on prey generated cues to locate their targets. Other carnivorous species are facultative echolocators. The available data lead to the prediction thatPhyllostomus hastatusandHipposideros diademaare not regularly carnivorous, whileOtonycteris hemprichimay be. Large species with echolocation calls adapted for flutter detection (rhinolophids and hipposiderids) or those with long narrowband calls and high aspect ratio wings with high relative wing loading (for example molossids, some emballonurids and some vespertilionids) chase airborne prey in the open; neither of these approaches involves prey other than arthr

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00451.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Colour polymorphisms in prey could be maintained if predators concentrate on common morphs and confer a selective advantage on rare morphs. We describe experiments to test whether wild birds feed on pastry‐stuffed shells ofCepaea hortensisin a manner that might lead to such apostatic selection. The birds were first given a ‘pre‐training’ choice test of a shell population with equal numbers of yellow unbandeds and yellow five‐bandeds; they were then trained on one morph alone, given a second choice test, trained on the other morph and, finally, given a third choice test. The birds preferred five‐bandeds in five of the six pre‐training tests. In all six experiments the first training session increased the birds' preferences for the morph that was familiar. The results were less clear‐cut when selection during pre‐training was compared with selection after the second training session. However, a comparison between selection after each of the two training sessions showed that in all six experiments the results were in the direction predicted from the hypothesis that familiar morphs are preferred. This set of experiments is one of the few in which behaviour which could lead to apostatic selection has been tested with morphs that differ inpattern.The findings support the idea that polymorphism inCepaeacould be maintained by ap

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00452.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb00453.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY