GLORIA — GEOMAR Library Ocean Research Information Access

1

Digitale Medien

A molecular approach to detect hybridisation between crucian carp (Carassius carassius) and non-indigenous carp species (Carassius spp. and Cyprinus carpio) (2005)

HÄNFLING, B. ; BOLTON, P. ; HARLEY, M. ; [weitere]

Oxford, UK : Blackwell Science Ltd

Freshwater biology 50 (2005), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 1. Releases of non-native fish into the wild is an increasing problem posing considerable ecological and genetic threats through direct competition and hybridisation.2. We employed six microsatellite markers to identify first generation hybrids and backcrosses between native crucian carp (Carassius carassius) and introduced goldfish (C. auratus) and common carp (Cyprinus carpio) in the U.K. We also investigated the genetic characteristics of the taxonomically controversial gibel carp (Carassius spp.) from sites across Europe.3. Natural hybridisation between goldfish and crucian carp occurs frequently, although hybrids between all other species pairs were observed. Only 62% of British crucian carp populations (n = 21) consisted exclusively of pure crucian carp. In some populations hybrids were so frequent, that no pure crucian carp were caught, indicating a high competitive ability of hybrids.4. Most hybrids belonged to the F1 generation but backcrossing was evident at a low frequency in goldfish × crucian carp hybrids and goldfish × common carp hybrids. Furthermore, some local populations had high frequencies of backcrosses, raising the opportunity for introgression.5. Gibel carp from Germany and Italy belonged to two triploid clonal lineages that were genetically closely related to goldfish, whereas all individuals identified from British populations proved to be crucian carp × goldfish hybrids.6. Our study suggests that the release of closely related exotic cyprinids not only poses a threat to the genetic integrity and associated local adaptations of native species, but may also contribute to shifts in community structure through competitive interactions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01330.x

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2

Digitale Medien

Molecular genetic analysis of Daphnia in the English Lake District: species identity, hybridisation and resting egg banks (2000)

Reid, V. A. ; Carvalho, G. R. ; George, D. G.

Oxford, UK : Blackwell Science Ltd

Freshwater biology 44 (2000), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 〈list style="custom"〉1Taxonomic issues in many Daphnia species complexes are often confused by a high degree of phenotypic plasticity and by interspecific hybridisation. Here, we employ molecular genetic tools to confirm the species composition and incidence of hybridisation in extant and resting egg populations of Daphnia from Windermere and Esthwaite Water in the English Lake District.2A combination of species-diagnostic allozymes and mtDNA, confirms that contemporary populations are dominated by a single species, D. galeata.3We present the first account of genetic characterisation of dated ‘resting’ eggs using microsatellites and mtDNA, employing PCR-based DNA recovery, thus providing a temporal dimension to taxonomic patterns. Thirty years ago, two species were present in Esthwaite, D. galeata and D. hyalina, but Windermere populations were dominated by D. galeata only.4The use of PCR-based mtDNA RFLP analysis as a species-diagnostic tool, and microsatellites to monitor clonal diversity, provide a valuable approach for long-term studies, especially in populations free from the complicating effect of frequent hybridisation. The detailed limnological records available for many large lakes, and associated changes in land-use, pollutants and climate, combined with long-term ephippial molecular genetic data, provide opportunities for exploring natural and anthropogenic impacts on genetic and community structure.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00561.x

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3

Digitale Medien

Comparative demographic impacts of `info-chemicals' and exploitative competition: an empirical test using Daphnia magna (2002)

MITCHELL, S. E. ; CARVALHO, G. R.

Oxford UK : Blackwell Science Ltd.

Freshwater biology 47 (2002), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: 1. Crowding `info-chemicals', metabolites released into the environment that act as signals to conspecifics as well as other organisms, have often been shown to cause phenotypic plasticity in cladoceran life-history traits including morphology, reproductive strategy and sex induction. Effects on population demography and diversity, however, have not been examined directly.2. Replicate laboratory populations of the zooplankter, Daphnia magna, were started with 250 juveniles and allowed to develop for 8 weeks in 10 L flow-through aquaria with food levels of 1 mg CL–1. Two crowded water treatments from different clonal sources were compared with untreated water as a control.3. The presence of crowding chemicals affected initial population structure, through reduction in parthenogenetic female body lengths, brood sizes and juvenile densities. However, the timing of population density maxima and subsequent population structure, clonal composition and diversity were similar among all treatments.4. Clonal richness remained slightly higher in untreated populations because of increased prevalence of rare clones.5. Exploitation competition had greater impact on population structure than the relative concentration of crowding chemicals, indicating that density dependent effects were mediated primarily by competition for common resources.6. Crowding info-chemicals may play a greater role in community structure than in single species population structure because of taxonomic diversity in species' response that may be unrelated to the source species density.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-2427.2002.00816.x

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4

Digitale Medien

Population differentiation in Trinidadian guppies (Poecilia reticulata): patterns and problems (1991)

Shaw, P. W. ; Carvalho, G. R. ; Magurran, A. E. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 39 (1991), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Populations of the guppy, Poecilia reficulata, in N. Trinidad exhibit marked population differentiation in allozyme frequencies. Here we investigate six further populations electrophoretically at 25 enzyme-coding loci to examine patterns in geographical structuring, genotypic distributions and genetic diversity. With one exception, possibly related to an experimental introduction, populations divided broadly (dendrogram of Nei's mean genetic identity, Ī) in accordance with proposed ancestral colonization. Most populations were in Hardy Weinberg equilibrium, though some significant deficits in heterozygotes were detected. Incorporating information from published data, markedly hjgher levels of genetic diversity (mean observed heterozygosity, H̄o) were recorded in lowland [H̄o= 0.0382 ± k0406 (s.e.), n= 9] compared with upstream populations [H̄o= 0.0112 ± 00034 (S.E.), n = 9]. Patterns are discussed in relation to historical and present-day evolutionary forces.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1991.tb05084.x

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5

Digitale Medien

Genetic population structure in the Lake Tanganyika sardine Limnothrissa miodon (1998)

Hauser, L. ; Carvalho, G. R. ; Pitcher, T. J.

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 53 (1998), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: There was significant morphological differentiation among samples of Tanganyika sardine Limnothrissa miodon, indicating non-random association of fish. Individuals within schools appeared to be unrelated as high mtDNA haplotype diversity demonstrated the presence of many maternal lineages in each school. Nevertheless, there was evidence from allozyme analysis for genetic differentiation on a very small geographical scale, possibly even among individual schools, without any clear geographical boundaries among populations. Similar microgeographical differentiation at the allozyme level was found in several marine pelagic species, suggesting a general pattern of random genetic structure in pelagic schooling fish. Such genetic patchiness may arise from biased reproductive success in localized spawning events and long-term stability of schools, resulting in genetic differentiation among schools. While the present results are preliminary, the far-reaching implications both for fisheries management and for evolutionary processes in pelagic species warrant further research on microgeographical genetic patterns using more sensitive markers.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1998.tb01040.x

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6

Digitale Medien

Morphological and genetic differentiation of the African clupeid Limnothrissa miodon 34 years after its introduction to Lake Kivu (1995)

Hauser, L. ; Carvalho, G. R. ; Pitcher, T. J.

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 47 (1995), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: The evolutionary consequences of an artificial introduction of the clupeid Limnothrissa miodon from Lake Tanganyika into Lake Kivu, East Africa were examined. In 1959, 57 400 fry (mixture of Limnothrissa and the related clupeid, Stolothrissa tanganicae), were released into Lake Kivu to boost fisheries production. Comparisons were made between respective source and transplant populations 34 years later (1993) using morphometrics (‘truss’ method), allozymes (29 enzyme-coding loci) and mitochondrial (mt) DNA variation (RFLP analysis of PCR-amplified ND5/6 genes). Significant morphological and genetic differentiation between source and transplant samples was detected, with a distinct clustering of Kivu Limnothrissa on respective dendrograms, especially at the morphometric and mtDNA levels. Differentiation within Lake Tanganyika was, however, consistently higher than that between lakes. Allozymic diversity was similar in samples from both lakes (Lake Tanganyika: heterozygosity = 0.0658, mean number of alleles=1.44; Lake Kivu: heterozygosity = 0.0655; mean number of alleles = 1.48), however, a significantly lower mtDNA haplotype diversity was detected in Lake Kivu (Lake Tanganyika: 0.905; Lake Kivu: 0.755). Data suggest that high post-introduction mortality and various demographic factors reduced the effective population size of the introduced population to tens rather than thousands of individuals, resulting in a reduction in genetic diversity and founder effect.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb06049.x

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7

Digitale Medien

Evolutionary aspects of fish distribution: genetic variability and adaptation (1993)

Carvalho, G. R.

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 43 (1993), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Many species of freshwater and anadromous fish are fragmented into local populations, some of which display adaptive traits that enhance survival and reproduction in particular environments. This paper focuses on the genetic component of response to heterogeneous environments, with emphasis on how the levels and distribution of genetic diversity may influence the distribution of conspecific populations. It addresses three aspects of genetic variability and adaptation: (1) the significance of genetic variability in relation to adaptation; (2) the adaptive significance of population differentiation; (3) the effects of stocking on local adaptation. In addition to considering local adaptation in salmonids, especially in relation to the genetic consequences of stocking, examples are chosen across fish taxa, with emphasis on recent studies in the guppy, Poecilia reticulata. The significance of within-population genotypic variance in fitness traits, genetic load and outbreeding depression is discussed in relation to adaptation. Evidence for local adaptation is drawn from molecular investigations, genotypic selection experiments, and integrated breeding and field studies. The fragility and uniqueness of locally adapted gene pools is emphasized. Threats arise from direct interactions between native and introduced fish through stocking and escapees of cultured fish. Conservation of genetic resources must not only include practices that maximize levels of genetic diversity, but also measures to preserve the associated genotypic variance in ecologically-significant traits. The integration of descriptive population genetic studies with empirical demonstrations of adaptive traits is encouraged.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1993.tb01179.x

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8

Digitale Medien

The genetic structure and microdistribution of shoals of Phoxinus phoxinus, the European minnow (1993)

Naish, K.-A. ; Carvalho, G. R. ; Pitcher, T. J.

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 43 (1993), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Efficient foraging and a reduction in predation risk have been proposed as reasons for shoal formation. Some behaviours in cyprinid shoals are at first sight altruistic (e.g. predator inspection behaviour, reactions to alarm substance), such that kin selection may have been involved in their evolution. If shoaling behaviour does evolve through kin selection, then genetic differentiation is expected to be greater between shoals than within shoals. Such a hypothesis was tested here by examining shoal integrity and the relatedness of individuals within and between shoals in the European minnow, Phoxinus phoxinus, using nuclear and mitochondrial DNA markers. The breeding structure of 13 minnow shoals collected from Dorset and North Wales, U.K., was examined using allozymes. Genetic affinity within and between shoals was tested using mitochondrial DNA and multi-locus DNA fingerprinting. Shoals consisted of a random assortment of allozyme genotypes, shoal members did not share the same maternal mtDNA lineages and DNA fingerprint profiles were as varied within shoals as between them. The data indicate that it is unlikely that kin selection occurs in P. phoxinus and there is no apparent relationship between shoaling behaviour and genotype distribution in this species.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1993.tb01180.x

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9

Digitale Medien

Schooling preferences for familiar fish in the guppy, Poecilia reticulata (1994)

Magurran, A. E. ; Seghers, B. H. ; Shaw, P. W. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 45 (1994), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Although schooling behaviour is an important antipredator response of guppies (Poecilia reticulata) in Trinidad it is not known whether fish elect to school with particular individuals. Familiarity is a simple mechanism that could lead to non-random associations within schools. In this paper we test the idea that prior experience of particular individuals influences the choice of partners during schooling. We show (in a laboratory study) that female guppies prefer to associate with familiar individuals. However, we are unable to detect any schooling preference for unfamiliar females from the same population.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1994.tb01322.x

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10

Digitale Medien

Factors affecting the distribution of genetic variability in the guppy, Poecilia reticulata (1994)

Shaw, P. W. ; Carvalho, G. R. ; Magurran, A. E. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 45 (1994), S. 0

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ISSN: 1095-8649

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Previous studies on Trinidadian guppies have shown an apparent association of genetic variability, expressed as mean heterozygosity (Ho) at allozyme loci, with river order: fish from lowland sites exhibit higher mean Ho than their upland counterparts. Detailed genetic and behavioural observations were undertaken in the present study by repeated sampling throughout two river courses to examine population heterogeneity. Results show that the predation regime mediated mating behaviour of upland and lowland populations in the wild is not as divergent as previous laboratory observations have suggested. Furthermore, genetic variation at the eight loci variable in Trinidadian populations (p100=0·13–O·88, H0=O·03–0·23) appears to bear little association with predation regime, but is related to sub-structuring of populations by habitat features and geographic isolation. We therefore conclude that the observed patterns of genetic variability arise primarily as a consequence of stochastic as opposed to deterministic factors.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1095-8649.1994.tb00951.x

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