Ten years of AFLP in ecology and evolution: why so few animals?
TL;DR: A review of research areas in the study of wild species of animals where the AFLP method should be a very valuable tool to help molecular ecologists to identify when AFLP is likely to be superior to other more established methods, such as microsatellites, SNP (single nucleotide polymorphism) analyses and multigene DNA sequencing.
Abstract: Researchers in the field of molecular ecology and evolution require versatile and low-cost genetic typing methods. The AFLP (amplified fragment length polymorphism) method was introduced 10 years ago and shows many features that fulfil these requirements. With good quality genomic DNA at hand, it is relatively easy to generate anonymous multilocus DNA profiles in most species and the start-up time before data can be generated is often less than a week. Built-in dynamic, yet simple modifications make it possible to find a protocol suitable to the genome size of the species and to screen thousands of loci in hundreds of individuals for a relatively low cost. Until now, the method has primarily been applied in studies of plants, bacteria and fungi, with a strong bias towards economically important cultivated species and their pests. In this review we identify a number of research areas in the study of wild species of animals where the AFLP method, presently very much underused, should be a very valuable tool. These aspects include classical problems such as studies of population genetic structure and phylogenetic reconstructions, and also new challenges such as finding markers for genes governing adaptations in wild populations and modifications of the protocol that makes it possible to measure expression variation of multiple genes (cDNA-AFLP) and the distribution of DNA methylation. We hope this review will help molecular ecologists to identify when AFLP is likely to be superior to other more established methods, such as microsatellites, SNP (single nucleotide polymorphism) analyses and multigene DNA sequencing.
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3,213 citations
TL;DR: It is shown that the inclusion of isolated populations that underwent a strong bottleneck can lead to a high rate of false positives, and it is demonstrated that it is possible to avoid them by carefully choosing the populations that should be included in the analysis.
Abstract: Identifying loci under natural selection from genomic surveys is of great interest in different research areas. Commonly used methods to separate neutral effects from adaptive effects are based on locus-specific population differentiation coefficients to identify outliers. Here we extend such an approach to estimate directly the probability that each locus is subject to selection using a Bayesian method. We also extend it to allow the use of dominant markers like AFLPs. It has been shown that this model is robust to complex demographic scenarios for neutral genetic differentiation. Here we show that the inclusion of isolated populations that underwent a strong bottleneck can lead to a high rate of false positives. Nevertheless, we demonstrate that it is possible to avoid them by carefully choosing the populations that should be included in the analysis. We analyze two previously published data sets: a human data set of codominant markers and a Littorina saxatilis data set of dominant markers. We also perform a detailed sensitivity study to compare the power of the method using amplified fragment length polymorphism (AFLP), SNP, and microsatellite markers. The method has been implemented in a new software available at our website (http://www-leca.ujf-grenoble.fr/logiciels.htm).
2,366 citations
TL;DR: This synthesis presents a multistep screening process to evaluate candidate loci for inclusion in a genetic study that is broadly targeted to both novice and experienced geneticists alike and aims to encourage the use and consistent reporting of thorough marker screening to ensure high quality data.
Abstract: Recent improvements in genetic analysis and genotyping methods have resulted in a rapid expansion of the power of molecular markers to address ecological questions. Microsatellites have emerged as the most popular and versatile marker type for ecological applications. The rise of commercial services that can isolate microsatellites for new study species and genotype samples at reasonable prices presents ecologists with the unprecedented ability to employ genetic approaches without heavy investment in specialized equipment. Nevertheless, the lack of accessible, synthesized information on the practicalities and pitfalls of using genetic tools impedes ecologists ability to make informed decisions on using molecular approaches and creates the risk that some will use microsatellites without understanding the steps needed to evaluate the quality of a genetic data set. The first goal of this synthesis is to provide an overview of the strengths and limitations of microsatellite markers and the risks, cost and time requirements of isolating and using microsatellites with the aid of commercial services. The second goal is to encourage the use and consistent reporting of thorough marker screening to ensure high quality data. To that end, we present a multistep screening process to evaluate candidate loci for inclusion in a genetic study that is broadly targeted to both novice and experienced geneticists alike.
1,601 citations
Cites background from "Ten years of AFLP in ecology and ev..."
...While AFLP markers can be a good alternative choice to microsatellites (Bensch & Akesson 2005)....
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TL;DR: A synthesis of areas of AFLP technique, including comparison to other genotyping methods, assessment of errors, homoplasy, phylogenetic signal and appropriate analysis techniques are provided, with the aim of providing a review that will be applicable to all AFLP-based studies.
631 citations
TL;DR: This review describes the various methods available to handle AFLP data, and investigates the characteristics and limitations of these statistical tools, and appeals for a wider adoption of methodologies borrowed from other research fields, like for example those especially designed to deal with binary data.
Abstract: Recently, the amplified fragment length polymorphism (AFLP) technique has gained a lot of popularity, and is now frequently applied to a wide variety of organisms. Technical specificities of the AFLP procedure have been well documented over the years, but there is on the contrary little or scattered information about the statistical analysis of AFLPs. In this review, we describe the various methods available to handle AFLP data, focusing on four research topics at the population or individual level of analysis: (i) assessment of genetic diversity; (ii) identification of population structure; (iii) identification of hybrid individuals; and (iv) detection of markers associated with phenotypes. Two kinds of analysis methods can be distinguished, depending on whether they are based on the direct study of band presences or absences in AFLP profiles ('band-based' methods), or on allelic frequencies estimated at each locus from these profiles ('allele frequency-based' methods). We investigate the characteristics and limitations of these statistical tools; finally, we appeal for a wider adoption of methodologies borrowed from other research fields, like for example those especially designed to deal with binary data.
563 citations
Cites background or methods from "Ten years of AFLP in ecology and ev..."
...…this review, we aim to address the statistical aspects of AFLP analysis, focusing on four of the important research topics previously identified by Bensch & Akesson (2005): (i) assessment of genetic diversity; (ii) identification of population structure; (iii) identification of hybrid…...
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...…associated with phenotype AFLPs are a tool of choice when it comes to unravel the genetic architecture of complex traits because they are particularly suitable to the screening of basically any genome, at low cost and effort (Blears et al. 1998; Mueller & Wolfenbarger 1999; Bensch & Akesson 2005)....
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...Technical specificities of the AFLP procedure have been well documented over the years (see for example Mueller & Wolfenbarger 1999; Bensch & Akesson 2005; Mba & Tohme 2005; Meudt & Clarke 2007)....
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...As underlined by Bensch & Akesson (2005), ‘The top of the agenda for many molecular ecologists is to study the genetic structure of populations’....
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References
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TL;DR: Pritch et al. as discussed by the authors proposed a model-based clustering method for using multilocus genotype data to infer population structure and assign individuals to populations, which can be applied to most of the commonly used genetic markers, provided that they are not closely linked.
Abstract: We describe a model-based clustering method for using multilocus genotype data to infer population structure and assign individuals to populations. We assume a model in which there are K populations (where K may be unknown), each of which is characterized by a set of allele frequencies at each locus. Individuals in the sample are assigned (probabilistically) to populations, or jointly to two or more populations if their genotypes indicate that they are admixed. Our model does not assume a particular mutation process, and it can be applied to most of the commonly used genetic markers, provided that they are not closely linked. Applications of our method include demonstrating the presence of population structure, assigning individuals to populations, studying hybrid zones, and identifying migrants and admixed individuals. We show that the method can produce highly accurate assignments using modest numbers of loci— e.g. , seven microsatellite loci in an example using genotype data from an endangered bird species. The software used for this article is available from http://www.stats.ox.ac.uk/~pritch/home.html.
27,454 citations
TL;DR: A new DNA polymorphism assay based on the amplification of random DNA segments with single primers of arbitrary nucleotide sequence is described, suggesting that these polymorphisms be called RAPD markers, after Random Amplified Polymorphic DNA.
Abstract: Molecular genetic maps are commonly constructed by analyzing the segregation of restriction fragment length polymorphisms (RFLPs) among the progeny of a sexual cross. Here we describe a new DNA polymorphism assay based on the amplification of random DNA segments with single primers of arbitrary nucleotide sequence. These polymorphisms, simply detected as DNA segments which amplify from one parent but not the other, are inherited in a Mendelian fashion and can be used to construct genetic maps in a variety of species. We suggest that these polymorphisms be called RAPD markers, after Random Amplified Polymorphic DNA.
13,764 citations
TL;DR: The AFLP technique provides a novel and very powerful DNA fingerprinting technique for DNAs of any origin or complexity that allows the specific co-amplification of high numbers of restriction fragments.
Abstract: A novel DNA fingerprinting technique called AFLP is described. The AFLP technique is based on the selective PCR amplification of restriction fragments from a total digest of genomic DNA. The technique involves three steps: (i) restriction of the DNA and ligation of oligonucleotide adapters, (ii) selective amplification of sets of restriction fragments, and (iii) gel analysis of the amplified fragments. PCR amplification of restriction fragments is achieved by using the adapter and restriction site sequence as target sites for primer annealing. The selective amplification is achieved by the use of primers that extend into the restriction fragments, amplifying only those fragments in which the primer extensions match the nucleotides flanking the restriction sites. Using this method, sets of restriction fragments may be visualized by PCR without knowledge of nucleotide sequence. The method allows the specific co-amplification of high numbers of restriction fragments. The number of fragments that can be analyzed simultaneously, however, is dependent on the resolution of the detection system. Typically 50-100 restriction fragments are amplified and detected on denaturing polyacrylamide gels. The AFLP technique provides a novel and very powerful DNA fingerprinting technique for DNAs of any origin or complexity.
12,960 citations
"Ten years of AFLP in ecology and ev..." refers methods in this paper
...They all include the production of preamplified adapterligated restriction fragments as described in Vos et al. (1995) but the selective amplification is modified by the use of a primer anchoring to a simple sequence repeat (SSR) or two different adjoining SSRs (Witsenboer et al. 1997)....
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Journal Article•
TL;DR: It is reported that specific human (dC-dA)n.(dG-dT)n blocks are polymorphic in length among individuals and therefore represent a vast new pool of potential genetic markers.
Abstract: Interspersed DNA elements of the form (dC-dA)n.(dG-dT)n constitute one of the most abundant human repetitive DNA families. We report that specific human (dC-dA)n.(dG-dT)n blocks are polymorphic in length among individuals and therefore represent a vast new pool of potential genetic markers. Comparison of sequences from the literature for (dC-dA)n.(dG-dT)n blocks cloned two or more times revealed length polymorphisms in seven of eight cases. Variations in the lengths of 10 (dC-dA)n.(dG-dT)n blocks were directly demonstrated by amplifying the DNA within and immediately flanking the repeat blocks by using the polymerase chain reaction and then resolving the amplified DNA on polyacrylamide DNA sequencing gels. Use of the polymerase chain reaction to detect DNA polymorphisms offers improved sensitivity and speed compared with standard blotting and hybridization.
3,457 citations
"Ten years of AFLP in ecology and ev..." refers methods in this paper
...Similar to many molecular methods used in molecular ecology, the microsatellite technology was first developed for studies of human genetics (Litt & Luty 1989; Weber & May 1989)....
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TL;DR: In this paper, the use of isolation by distance models as a basis for the estimation of demographic parameters from measures of population subdivision was re-examined, and the results for values of F-statistics in one-dimensional models and coalescence times in 2D models were provided.
Abstract: I reexamine the use of isolation by distance models as a basis for the estimation of demographic parameters from measures of population subdivision. To that aim, I first provide results for values of F-statistics in one-dimensional models and coalescence times in two-dimensional models, and make more precise earlier results for F-statistics in two-dimensional models and coalescence times in one-dimensional models. Based on these results, I propose a method of data analysis involving the regression of F(ST)/(1 - F(ST)) estimates for pairs of subpopulations on geographic distance for populations along linear habitats or logarithm of distance for populations in two-dimensional habitats. This regression provides in principle an estimate of the product of population density and second moment of parental axial distance. In two cases where comparison to direct estimates is possible, the method proposed here is more satisfactory than previous indirect methods.
3,331 citations