Search publications of the members of the Royal Belgian institute of natural Sciences
-
Resistance to water pollution in natural gudgeon (Gobio gobio) populations may be due to genetic adaptation.
- Anthropogenic disturbances cause the environment to change relatively fast. It is reasonable to assume that it is very unlikely for individuals to develop genetic adaptations to their polluted habitats, since adaptation through natural selection is a relatively slow process. Nevertheless, several studies have shown that such adaptations to changing environmental conditions may develop faster than anticipated. This study investigates the impact of historical metal pollution on a natural population of the gudgeon, Gobio gobio. Specimens from a contaminated site and a reference population were subjected to a series of three exposure experiments to cadmium after an acclimation period to reconstituted fresh water of 36 days. First, we performed an acute toxicity test on a sub-sample of both experimental groups to determine times-to-death (TTD) and lethal body burdens (LBB). The remaining individuals were used in a chronic Cd-exposure experiment, after which total Cd-body concentration, as well as Cd-concentrations and metallothionein-like protein (MTLP) levels in liver and gill tissue were determined. From the specimens that were not sacrificed for these measurements, a random subsample was subjected to a second acute toxicity test to evaluate the effect of chronic Cd-exposure (acclimation) on TTD and LBB. Our results show that, particularly after an extra acclimation period to a sublethal Cd-concentration, specimens originating from the contaminated sample area survived the acute exposure experiments better, despite the fact that neither the average Cd-accumulation rate, nor the lethal body concentrations differed between fishes from both groups. We also find that gudgeons from both populations translocated Cd from the gills (and probably also from other compartments) to the liver, where it can be more efficiently detoxified by MTLPs. Indeed, MTLP levels were found to increase faster in liver and gill tissue of specimens from the contaminated site, resulting in significantly higher MTLP-levels in the organs of these fishes. Although this study does not provide direct evidence for a genetic basis of Cd resistance (i.e. at the gene level), our results indicate that the regulation of MTLP-gene expression may involve a genetic component.
-
Response to Comment on “ Origin of the Superflock of Cichlid Fishes from
-
Seit über 100 Jahren im Blickpunkt der Forschung: Die vielvalt der Tanganjikaseefische (translated from English)
-
Shrew trap efficiency: experience from primary forest, secondary forest, old fallow land and old palm plantation in the Congo River basin (Kisangani, Democratic Republic of Congo)
-
Simulating the evolution of neutrally evolving sequences in a population under environmental changes
-
Special study on sediment discharge and its consequences: impact of sedimentation on Biota, a Project funded by UNDP/GEF and executed by the UNOPS
-
Speciation in ancient lake ostracods: Comparative analysis of Baikalian Cytherissa and Tanganyikan Cyprideis
-
Speciation mirrors geomorphology and palaeoclimatic history in African laminate-toothed rats (Muridae: Otomyini) of the Otomys denti and Otomys lacustris species-complexes in the ‘Montane Circle’ of East Africa
- We adopted an integrated systematic approach to delimit evolutionary species and describe phylogeographic, morphometric and ecological relationships in Otomys denti (from the Albertine Rift, Southern Rift in Malawi and the northern Eastern Arc Mountains) and Otomys lacustris (from the Southern Rift in Tanzania and Zambia, and the southern Eastern Arc Mountains). Molecular [cytochrome (cyt) b sequences, 1143 bp, N = 18], craniometric (classical, N = 100 and geometric, N = 60) and ecological (Partial Least Squares regression of shape and ecogeo- graphic variables) approaches show a profound, parallel disjunction between two groups: (1) Eastern Arc and Southern Rift (including the Malawi Rift) (O. lacustris and Otomys denti sungae) and (2) Albertine Rift (Otomys denti denti and Otomys denti kempi) taxa. Within both groups, cyt b sequences or craniometric analysis provided evidence for the differentiation of both southern and northern Eastern Arc from Southern Rift lineages (across the so-called Makambako Gap). Within the Albertine Rift (denti–kempi) lineage, populations from individual mountain ranges differed significantly in skull shape (but not size), but were similar genetically. Over-reliance in the past on very few morphological characters (e.g. number of molar laminae) and a polytypic species concept has obscured phylogenetic relationships and species discrimination in this group. We recognize at least three species in this group, and distinct lineages within two of these species. Each species or lineage was endemic to one of three regions: the Albertine Rift, the Malawi Rift or the Eastern Arc. Our result echo conclusions of recent studies of other mammalian and bird taxa and reflect the geomorphology and palaeoclimatic history of the region.
-
Specific limits and emerging diversity patterns in East African populations of laminate-toothed rats, genus Otomys (Muridae: Murinae: Otomyini): Revision of the Otomys typus complex
- We combined evidence from biogeography, craniodental traits, linear and geometric morphometrics (233 skulls), cytoge- netics (karyotypes of 18 individuals) and mitochondrial DNA sequences (44 cytochrome b and 21 12S rRNA sequences) to test species limits within Otomys typus s.l. (Muridae: Murinae: Otomyini), a complex that is patchily distributed across alpine zones of Ethiopia and East Africa. Our results confirm the specific validity of O. dartmouthi, O. jacksoni, O. orest- es, and O. uzungwensis, forms recently removed from synonymy under typus s.l.; support elevation of four other alpine forms to species (O. fortior, O. helleri, O. thomasi, and O. zinki); identify three additional new species (O. cheesmani sp. nov., O. simiensis sp. nov., O. yaldeni sp. nov.); and enable redefinition of O. typus s.s. as a species restricted to certain mountains west of the Great Rift Valley in Ethiopia (Simien and Guna Mountains in the north, extending to the highlands of the western rim of the Rift Valley). Phylogenetic interpretation of the cytochrome b data clearly demonstrates that the alpine morphotype once united under O. typus s.l. has originated independently at high elevations on several mountain ranges in eastern and northeastern Africa; although generally adapted to high-elevation vegetation, such alpine species are ecologically segregated from one another. Patterns of morphometric, genetic, and ecological differentiation among popu- lations once misassigned to nominal O. tropicalis and O. typus more parsimoniously reflect regional cladogenesis along elevational gradients, rather than multiple, successive colonization by different ancestral forms from southern Africa as earlier supposed. Although incomplete and preliminary, information gathered for O. tropicalis indicates that it too is a spe- cies composite; several lines of research are discussed to redress its polyphyletic content. Our results, together with other recent taxonomic studies of Otomys, appreciably elevate the level of endemism within eastern Africa and underscore the significance of Africa's eastern highlands to the continental diversification of Otomyini.
-
Subtle population structure and male-biased dispersal in two Copadichromis species (Teleostei, Cichlidae) from Lake Malawi, East Africa
-
Systematics of African lowland rainforest Praomys (Rodentia, Muridae) based on molecular and craniometrical data
-
Taxonomy and biogeography of the African Pygmy mice , Subgenus Nannomys ( Rodentia , Murinae , Mus ) in Ivory Coast and Guinea ( West Africa )
-
Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity
-
Temperature and pH effects on the total white muscle LDH of i Oreochromis niloticus/i(Pisces: Cichlidae)
-
Terrestrial Small Mammals as Reservoirs of Mycobacterium ulcerans
-
The application of molecular techniques to the study of ostracods
-
The brush-furred rats of Angola and southern Congo : description of a new taxon of the Lophuromys sikapusi species complex
-
The characterization of the Kilimanjaro Lophuromys aquilus TRUE 1892 population and the description of five new Lophuromys species ( Rodentia , Muridae )
-
The eye lens proteins of haplochromine cichlids from lake Victoria studied by isoelectric focusing
-
The eye-lens protein pattern of eight Lake Tanganyika cichlids studied by isoelectric focussing
