Nouveaux travaux

Hypancistrus_spp · Inscrit le: 08 Sep 2001 Messages: 345 Localisation: Suisse

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2 nouveaux travaux à signaler!!

M. C. P. Amorim, J. M. Simões, P. J. Fonseca, G. F. Turner (2008): Species differences in courtship acoustic signals among five Lake Malawi cichlid species (Pseudotropheus spp.)
Journal of Fish Biology 72 (6) , 1355–1368.

Abstract:

Male courtship acoustic signals from five Lake Malawi cichlid fish species of the Pseudotropheus zebra complex were recorded and compared. Sounds made by males of P. zebra, Pseudotropheus callainos and the undescribed species known as Pseudotropheus ‘zebra gold’ from Nkhata Bay, and Pseudotropheus emmiltos and Pseudotropheus faizilberi from Mphanga Rocks, differed significantly in the number of pulses and in pulse period. The largest differences in acoustic variables were found among the sympatric Mphanga Rocks species that, in contrast to the other three species, show relatively minor differences in male colour and pattern. These findings suggest that interspecific mate recognition is mediated by multimodal signals and that the mass of different sensory channels varies among sympatric species groups. This study also showed that sound peak frequency was significantly negatively correlated with male size and that sound production rate increased significantly with courtship rate.

M. Maderbacher, C. Bauer, J. Herler, L. Postl, L. Makasa, C. Sturmbauer (2008): Assessment of traditional versus geometric morphometrics for discriminating populations of the Tropheus moorii species complex (Teleostei: Cichlidae), a Lake Tanganyika model for allopatric speciation
Journal of Zoological Systematics and Evolutionary Research 46 (2) , 153–161.

Abstract:

Lake Tanganyika harbours the oldest and ecologically, morphologically and behaviourally most diverse species flock of cichlid fishes. Its species are excellent subjects for the study of explosive speciation and adaptive radiation. Many species are subdivided into numerous genetically and phenotypically distinct populations, often classified as distinct geographical races or colour morphs, which mostly differ in colour and much less in terms of morphology. This study for the first time quantifies morphological differences among such morphs by studying three populations of Tropheus moorii. We compared ‘traditional morphometrics’ (TM) and ‘geometric morphometrics’ (GM) to explore their potential for discriminating populations. So far species description and population discrimination are almost solely based on TM in the form of standardized measurements, although specialists are aware of their lack of diagnostic power for discrimination of closely related entities. Moreover, comprehensive TM measurements are time consuming and can best be done on dead specimens which have to be preserved in the case re-measuring is necessary. In contrast, GM can also be based on photographs and computer scans of anaesthetized fish, so that the same individual can be repeatedly analysed during its ontogeny. Here, we show that GM is more flexible in data acquisition and more powerful in the discrimination of species and closely related populations. While TM is restricted to distances and ratios of distances, GM not only includes these measurements indirectly, but also allows for body shape analysis using a semi-landmark approach. It can be equally standardized as TM by defining diagnostic landmarks. Data description by canonical variate analysis was most informative using GM data including semi-landmarks, whereas differences between populations were significant (p < 0.05) based on both morphological approaches.

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Yann

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