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C Schlötterer

Publications and source records attributed to C Schlötterer.

At least 19 recordsLinked to original sources
PubMed2001

Haplotype (mtDNA) diversity of brown trout Salmo trutta in tributaries of the Austrian Danube: massive introgression of Atlantic basin fish--by man or nature?

Mitochondrial haplotype diversity in 27 populations of brown trout, Salmo trutta L., in Austria was investigated by sequencing the 5' end of the mitochondrial DNA (mtDNA) control region. Although all populations are within the Danube drainage, 44% of all individuals carried Atlantic basin haplotypes. It is argued that the presence of these haplotypes in Austria primarily reflects introgression stemming from the stocking of hatchery-reared fish. However, several lines of evidence suggest that some natural colonization from Atlantic lineages may have contributed to the present haplotype diversity. Nonetheless, the more diverse Danubian clade is represented by regionally distinct haplotype diversity that should be protected from the continued introduction of domesticated strains of exogenous fish

Animals↗
PubMed2001

Microsatellite variation in natural Drosophila melanogaster populations from New South Wales (Australia) and Tasmania.

Microsatellite variation was studied at 48 microsatellite loci in 10 Drosophila melanogaster populations to investigate the population structure on the Australian east coast. Low, but statistically significant population differentiation was observed among most populations. The populations on the Australian mainland did not show evidence for isolation by distance. We conclude that the population structure of D. melanogaster on the Australian mainland is probably the result of a shared history (recent colonization). The observed differences between local D. melanogaster populations probably reflect variation in effective population sizes rather than patterns of gene flow. Two populations from Tasmania were more differentiated from the Australian mainland than a population from Israel, raising the question whether they are derived from the Australian mainland or colonized from a different source population.

Animals↗
PubMed2001

Three divergent rDNA clusters predate the species divergence in Quercus petraea (Matt.) Liebl. and Quercus robur L.

Quercus petraea and Quercus robur are two closely related oak species that frequently hybridize. We sequenced 70 clones containing the 5.8S and ITS2 regions of ribosomal DNA (rDNA) from these two species and did not detect a species-specific difference. Surprisingly, three divergent (up to 12.6%) rDNA families were identified in both species, indicating that they predate the speciation event. Despite a large between-rDNA-families divergence, rDNA sequences were very similar within families, suggesting ongoing concerted evolution. Expression analysis, relative-rate tests, and mutation spectrum analyses indicated that only a single rDNA family is functional. We propose that past hybridization events, combined with nucleolar dominance, were the evolutionary processes underlying the contemporary rDNA variability in Q. petraea and Q. robur.

Base Sequence↗
PubMed2000

Molecular phylogeny of European muroid rodents based on complete cytochrome b sequences.

Phylogenetic relationships among 18 species of mainly European muroid rodents that belong to three subfamilies were estimated using complete sequences of the mitochondrial cytochrome b gene. The inferred monophyly of the subfamilies Murinae (mice and rats) and Arvicolinae (voles, lemmings, and muskrats) is in agreement with previous studies. Within the Murinae, the morphology-based division of the genus Apodemus into three subgenera is supported by these DNA sequence data. The relationships among the different genera of the Murinae were generally poorly resolved, and the relationships of Micromys and Acomys to the other murine genera remained unresolved. Within the subfamily Arvicolinae, the relations of the genera Arvicola, Clethrionomys, and Microtus remained tentative with our data. However, within the Microtus group, there is a good molecular support for the phylogenetic relationships. These findings suggest that the origin of the different murine and arvicoline lineages was rapid, indicating an adaptive radiation with fast speciation.

Animals↗
PubMed2000

Evolutionary dynamics of microsatellite DNA.

Within the past decade microsatellites have developed into one of the most popular genetic markers. Despite the widespread use of microsatellite analysis, an integral picture of the mutational dynamics of microsatellite DNA is just beginning to emerge. Here, I review both generally agreed and controversial results about the mutational dynamics of microsatellite DNA. Microsatellites are short DNA sequence stretches in which a motif of one to six bases is tandemly repeated. It has been known for some time that these sequences can differ in repeat number among individuals. With the advent of polymerase chain reaction (PCR) technology this property of microsatellite DNA was converted into a highly versatile genetic marker (Litt and Luty 1989; Tautz 1989; Weber and May 1989). Polymerase chain reaction products of different length can be amplified with primers flanking the variable microsatellite region. Due to the availability of high-throughput capillary sequencers or mass spectrography the sizing of alleles is no longer a bottleneck in microsatellite analysis. The almost random distribution of microsatellites and their high level of polymorphism greatly facilitated the construction of genetic maps (Dietrich et al. 1994; Dib et al. 1996) and enabled subsequent positional cloning of several genes. Almost at the same time, microsatellites were established as the marker of choice for the identification of individuals and paternity testing. The high sensitivity of PCR-based microsatellite analysis was not only of great benefit for forensics, but opened completely new research areas, such as the analysis of samples with limited DNA amounts (e.g., many social insects) or degraded DNA (e.g., feces, museum material) (Schlötterer and Pemberton 1998). More recently, microsatellite analysis has also been employed in population genetics (Goldstein and Schlötterer 1999). Compared with allozymes, microsatellites offer the advantage that, in principle, several thousand potentially polymorphic markers are available. Nevertheless, the application of microsatellites to population genetic questions requires a more detailed understanding of the mutation processes of microsatellite DNA as the evolutionary time frames covered in population genetics are often too long to allow novel microsatellite mutations to be ignored. Additional interest in the evolution of microsatellite DNA comes from the discovery that trinucleotide repeats, a special class of microsatellites, are involved in human neurodegenerative diseases (e.g., fragile X and Huntington's disease). A detailed understanding of the processes underlying microsatellite instability is therefore an important contribution toward a better understanding of these human neurodegenerative diseases.

Animals↗
PubMed2000

Microsatellite analysis reveals substantial genetic differentiation between contemporary New World and Old World Holstein Friesian populations.

Genotypic data from 39 microsatellite loci typed in 211 animals were used to assess the genetic differentiation between Old World and New World Holstein Friesian cattle populations. Gene diversities were similar in all five Holstein Friesian populations surveyed, ranging from 0.43 to 0.48. A tree of individuals based on the proportion of shared alleles indicated a clear distinction between Old World and New World Holstein Friesian populations. Similarly, genetic differentiation between populations, as measured by FST, was highly significant. Using the split decomposition method, we were able to visualize the significant introgression of New World Holstein Friesian into European Holstein Friesian populations.

Alleles↗
PubMed2000

Microsatellite analysis indicates genetic differentiation of the neo-sex chromosomes in Drosophila americana americana.

The neo-sex chromosomes of Drosophila americana americana were formed by a centric fusion between the autosomal element B and the X chromosome. Previous work has shown that the neo-Y chromosome is not degenerated genetically and that there is no evidence for genetic differentiation between neo-X and neo-Y chromosomes at the sequence level. To further address the genetic differentiation between the neo-sex chromosomes, microsatellites mapping to the neo-sex chromosome of D. a. americana were isolated. Microsatellite analysis indicated a highly significant differentiation between D. a. americana and D. a. texana as well as between the neo-X and neo-Y chromosomes in D. a. americana. Nevertheless, levels of variability were similar among the neo-sex chromosomes, indicating a very recent origin.

Animals↗
PubMed2000

Mitochondrial haplotype diversity among Portuguese brown trout Salmo trutta L. populations: relevance to the post-pleistocene recolonization of northern Europe.

Mitochondrial haplotype diversity in seven Portuguese populations of brown trout, Salmo trutta L., was investigated by sequencing the 5' end of the mitochondrial DNA (mtDNA) control region. Five new haplotypes were described for this species, each two to three mutational steps distant from the common north Atlantic haplotype. Significant population subdivision of mtDNA haplotypes was also apparent. Based on these results, as well as on published data describing the distribution of both mtDNA haplotypes and allozyme alleles throughout Europe, the postglacial recolonization of northern Europe was re-evaluated. It is argued that the available data do not support the contribution of two major glacial refugia (southwest Atlantic and Ponto-Caspian Basin) to this postglacial recolonization, as proposed in a recently published model. The unique genetic architecture of Portuguese brown trout within the Atlantic-basin clade of this species represents a highly valuable genetic resource that should be protected from introgression with nonendemic strains of hatchery fish.

Animals↗
PubMed2000

Long microsatellite alleles in Drosophila melanogaster have a downward mutation bias and short persistence times, which cause their genome-wide underrepresentation.

Microsatellites are short tandemly repeated DNA sequence motifs that are highly variable in most organisms. In contrast to mammals, long microsatellites (>15 repeats) are extremely rare in the Drosophila melanogaster genome. To investigate this paucity of long microsatellites in Drosophila, we studied 19 loci with exceptionally long microsatellite alleles. Inter- and intraspecific analysis showed that long microsatellite alleles arose in D. melanogaster only very recently. This lack of old alleles with many repeats indicated that long microsatellite alleles have short persistence times. The size distribution of microsatellite mutations in mutation-accumulation lines suggests that long alleles have a mutation bias toward a reduction in the number of repeat units. This bias causes the short persistence times of long microsatellite alleles. We propose that species-specific, size-dependent mutation spectra of microsatellite alleles may provide a general mechanism to account for the observed differences in microsatellite length between species.

Alleles↗
PubMed2000

Drosophila virilis has long and highly polymorphic microsatellites.

Comparative genomics is a powerful approach to inference of the dynamics of genome evolution. Most information about the evolution of microsatellites in the genus Drosophila has been obtained from Drosophila melanogaster. For comparison, we collected microsatellite data for the distantly related species Drosophila virilis. Screening about 0.5 Mb of nonredundant genomic sequence from GenBank, we identified 239 dinucleotide microsatellites. On average, D. virilis dinucleotides were significantly longer than D. melanogaster microsatellites (7.69 repeats vs. 6.75 repeats). Similarly, direct cloning of microsatellites resulted in a higher mean repeat number in D. virilis than in D. melanogaster (12.7 repeats vs. 12.2 repeats). Characterization of 11 microsatellite loci mapping to division 40-49 on the fourth chromosome of D. virilis indicated that D. virilis microsatellites are more variable than those of D. melanogaster.

Animals↗
PubMed2000

Removal of microsatellite interruptions by DNA replication slippage: phylogenetic evidence from Drosophila.

Microsatellites are tandem repetitions of short (1-6 bp) motifs. It is widely assumed that microsatellites degenerate through the accumulation of base substitutions in the repeat array. Using a phylogenetic framework, we studied the evolutionary dynamics of interruptions in three Drosophila microsatellite loci. For all three loci, we show that the interruptions in a microsatellite can be lost, resulting in a longer uninterrupted microsatellite stretch. These results indicate that mutations in the microsatellite array do not necessarily lead to decay but may represent only a transition state during the evolution of a microsatellite. Most likely, this purification of interrupted microsatellites is caused by DNA replication slippage.

Animals↗
PubMed2000

Microsatellite variability differs between dinucleotide repeat motifs-evidence from Drosophila melanogaster.

Recently, the use of microsatellites as genetic markers has become very popular. While their evolutionary dynamics are not yet fully understood, the emerging picture is that several factors are influencing microsatellite mutation rates. Recent experiments demonstrated a significant effect of repeat motif length on microsatellite mutation rates. Here, we studied the influence of the base composition of the microsatellite. Forty-two microsatellite loci on the second chromosome with the three most abundant dinucleotide repeat motifs (TC/AG, AT/TA, GT/CA) were characterized for six different Drosophila melanogaster populations. Applying ANOVA to the variance in repeat number, we found a significant influence of repeat motif on microsatellite variability. Calculating relative mutation rates, GT/CA appears to have the highest mutation rate, and AT/TA appears to have the lowest. Similar differences in mutation rates were obtained by an alternative method which estimates microsatellite mutation rates from their genomic length distribution.

Alleles↗
PubMed1999

Distribution of dinucleotide microsatellites in the Drosophila melanogaster genome.

Microsatellites, a special class of repetitive DNA, have become one of the most popular genetic markers. The progress of various genome projects has made it possible to study the genomic distribution of microsatellites and to evaluate the potential influence of several parameters on their genesis. We report the distribution of dinucleotide microsatellites in the genome of Drosophila melanogaster. When considering only microsatellites with five or more repeat units, the average length of dinucleotide repeats in D. melanogaster is 6.7 repeats. We tested a wide range of parameters which could potentially influence microsatellite density, and we did not detect a significant influence of recombination rate, number of exons, or total length of coding sequence. In concordance with the neutral expectation for the origin of microsatellites, a significant positive correlation between AT content and (AT/TA)n microsatellite density was detected. While this pattern may indicate that microsatellite genesis is a random process, we also found evidence for a nonrandom distribution of microsatellites. Average microsatellite density was higher on the X chromosome, but extreme heterogeneity was observed between different genomic regions. Such a clumping of microsatellites was also evident on a more local scale, as 38.9% of the contiguous sequences analyzed showed a deviation from a random distribution of microsatellites.

Animals↗
PubMed1998

A microsatellite-based multilocus phylogeny of the Drosophila melanogaster species complex.

Uncovering the genealogy of closely related species remains a major challenge for phylogenetic reconstruction. It is unlikely that the phylogeny of a single gene will represent the phylogeny of a species as a whole [1], but DNA sequence data across a large number of loci can be combined in order to obtain a consensus tree [2]. Long sequences are needed, however, to minimize the effect of (infrequent) base substitutions, and sufficient individuals must be sequenced per species to account for intraspecific polymorphisms, an overwhelming task using current DNA sequencing technology. By contrast, microsatellites are easy to type [3], allowing the analysis of many loci in multiple individuals. Despite their successful use in mapping [4,5], behavioural ecology [6] and population genetics [7], their usefulness for the phylogenetic reconstruction of closely related taxa has never been demonstrated, even though microsatellites are often conserved across species [8-10]. One drawback to microsatellite use is their high mutation rate (10(-4)-10(-2)), combined with an incomplete understanding of their mutation patterns. Many microsatellites are available for Drosophila melanogaster, and they are distributed throughout the genome [11]. Most can be amplified in the D. melanogaster species complex [12,13] and have low mutation rates [14, 15]. We show that microsatellite-specific distance measurements [16] correlate with other multilocus distances, such as those obtained from DNA-DNA hybridization data. Thus microsatellites may provide an ideal tool for building multilocus phylogenies. Our phylogenetic reconstruction of the D. melanogaster complex provides strong evidence that D. sechellia arose first, followed by a split between D. simulans and D. mauritiana.

Animals↗
PubMed1998

Multiple mating in wild Drosophila melanogaster revisited by microsatellite analysis.

The occurrence of multiple mating in Drosophila melanogaster is of particular interest to evolutionary biologists, as seminal fluid has some toxic effects for females. Thus, it has been predicted that the number of matings per females should be low. We have tested this prediction with seven highly polymorphic microsatellite loci in inseminated females from a Viennese D. melanogaster population. In contrast to the predicted low number of matings and previous studies in natural populations, we identified the genotypes of four to six different males fertilizing the offspring of each female tested. Potential causes and consequences are discussed.

Animals↗