摘要:

A multivariate analysis using canonical variates and theD2test show that five taxa of Palaearctic gazelles examined are distinct. Several forms of gazelles of dubious taxonomic position were also compared on the canonical axes, with conclusions not dissimilar to those of recent workers on the Arabian gazelles, viz. that there are three distinct species in the Arabian peninsula;Gazella dorcas saudiya, Gazella gazella arabicaandGazella subgutturosa marica. Gazella dorcaspopulations in Somalia have a local form inG. dorcas pelzelnidistinct in horns but not in skull measurements fromGazella spekeiin the nearby highlands.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1972.tb00687.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

A multivariate statistical analysis, using both discriminatory procedures on canonical axes and factor analysis was used to determine if there was any separation into different morphological types corresponding to the ostensible species of the Scottish antiarchPterichthyodes.These analyses indicated that, although there were two definite types of pectoral appendage, those differences which were apparent in body shape, were part of a continuous variation exhibited by the whole population, and were but extreme forms of a continuum. The distinction in pectoral appendage types is attributed to sexual dimorphism.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1972.tb00688.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Chromosomes obtained from bone‐marrow, spleen and testes were studied in samples from five populations ofSpalacopus cyanusof Central Chile. Animals of four low‐land coastal localities and animals of a high Andean valley showed a karyotype of2n =58 chromosomes, with almost no variation, either in number or in structure, both within each population or among the various populations. This karyotype was found to be very similar to that ofOctodon degus, but very different to those in species ofCtenomys.The evolutionary and systematic significance of these results is discussed. The lack of karyotypic variation found inSpalacopusis correlated with its taxonomic uniformity, and both could be the result of the high vagility of the populations of this rodent, suggested by previous studies. This high capacity of dispersal is supposed to have enhanced gene flow, and therewith chromosome uniformity and low taxonomic diversification. The occurrence of a case of dimorphism for the presence of a secondary constriction in one of the autosome pairs is reported and discus

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1972.tb00689.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Consideration of the possibilities and difficulties of detecting character displacement leads to a re‐definition of the phenomenon; character displacement is the process by which a morphological character state of a species changes under Natural Selection arising from the presence, in the same environment, of one or more species similar to it ecologically and/or reproductively. This incorporates the principal ideas in the original definition given by Brown&Wilson (1956), but eliminates the restriction of making comparisons of the character states of a species in sympatry and allopatry.The evidence for the ecological (competitive) aspect of character displacement is assessed by analyzing in detail the best documented and well publicized examples in the literature. Some of the examples either do not exhibit displaced characters or, if they do, the “displacement” can be interpreted in other and perhaps simpler ways; this applies to the so‐called classical case of character displacement,Sitta tephronotaandS. neumayerin Iran. Other examples, involving lizards and birds, constitute better evidence for character displacement, but in no single study is it entirely satisfactory. It is concluded that the evidence for the ecological aspect of character displacement

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1972.tb00690.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1972.tb00687a.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY