Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 110108
Title The small barbs Barbus humilis and B. trispilopleura of Lake Tana (Ethiopia): Are they ecotypes of the same species?
Author(s) Dejen, E.; Rutjes, H.A.; Graaf, M. de; Nagelkerke, L.A.J.; Osse, J.W.M.; Sibbing, F.A.
Source Environmental Biology of Fishes 65 (2002). - ISSN 0378-1909 - p. 373 - 386.
Department(s) Experimental Zoology
Publication type Refereed Article in a scientific journal
Publication year 2002
Abstract Four species of ‘small barbs’ (Barbus, subgenus Enteromius Cope, 1869) are known from Lake Tana, isolated in the Ethiopian highlands: B. humilis, B. trispilopleura, B. pleurogramma (all Boulenger, 1902) and B. tanapelagius de Graaf, 2000. However, only three species appear valid from cluster analysis using 32 morphometric characters and taking specimens from different locations in the southern Gulf of Lake Tana during August–October 1999. B. humilis and B. trispilopleura significantly differ from B. tanapelagius and B. pleurogramma in up to 36 characters. However, B. humilis and B. trispilopleura cannot be distinguished from each other by morphometric analysis or by gut contents. Specimens from clear, shallow rocky areas with vegetation have a darker back, will be more susceptible to birds, have significantly higher infection by cestodes, smaller size at first reproduction, lower fecundity, and correspond most to the B. trispilopleura phenotype. Specimens in turbid deeper water without vegetation are most similar to the B. humilis phenotype. We conclude that both species actually are extremes (ecotypes) of a continuum, belonging to a single biological species. The observed variation may well be induced by habitat-dependent predation pressure by birds. The high frequency (57€of spot numbers intermediate between Boulenger’s number for B. trispilopleura (3) and for B. humilis (0) demonstrates the continuum best. Pigment spots and colour change in response to aquarium conditions and are in this case no valid taxonomic characters. Both characters may reduce the risk of predation. It is concluded that B. trispilopleura is a synonym of B. humilis. For future research we recommend to use the most appropriate name, B. humilis, for both types.
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