title: Towards understanding the genetic basis of mouth asymmetry in the scale-eating cichlid Perissodus microlepis.
abstract: How polymorphisms consisting in left-right asymmetries are produced and maintained in natural populations is a tantalizing question, which remains largely unanswered. The scale-eating cichlid fish Perissodus microlepis is a remarkable example of extreme ecological specialization achieved by morphological and behavioural laterality. Its asymmetric mouth is accompanied by a pronounced lateralized foraging behaviour, where a left-bending morph preferentially feeds on the scales of the right side of its prey, while the opposite is true for the right morph. This striking asymmetry made this fish a textbook example of the astounding degree of ecological specialization and negative frequency-dependent selection. Yet, the genetic basis underlying this spectacular laterality remains unknown. We addressed this question through analyses of wild-caught fish using high-throughput DNA sequencing data. A novel array of SNP markers was developed by ddRAD sequencing (ddRADseq) and the use of pooled DNA samples (PoolSeq). We obtained more than 155 000 SNPs using ddRADseq and 3 900 000 SNPs with PoolSeq. Among these, we identified one (ddRAD) SNP, and 38 or 378 (PoolSeq) windows that are differentiated between the left and right morphs accounting for spurious associations due to geographic structuring. This allowed us to uncover candidate genomic regions that potentially contain genes for this trait. Then, this interesting trait has a genetic basis that is likely to be influenced by multiple loci. This result contributes to a greater understanding of the genetic bases of left-right asymmetry and, ultimately, the evolutionary processes governing the maintenance of this striking case of laterality.
authors.affiliation: Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany.|International Max Planck Research School (IMPRS) for Organismal Biology, Max-Planck-Institut für Ornithologie, Am Obstberg 1, 78315, Radolfzell, Germany.
authors.forename: Francesca
authors.initials: F
authors.lastname: Raffini
authors.affiliation: Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Fruciano
authors.affiliation: Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany.
authors.forename: Paolo
authors.initials: P
authors.lastname: Franchini
authors.affiliation: Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany.|International Max Planck Research School (IMPRS) for Organismal Biology, Max-Planck-Institut für Ornithologie, Am Obstberg 1, 78315, Radolfzell, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Meyer
mesh_terms: D000818:Animals; D005075:Biological Evolution; D023681:Cichlids / Q000033:anatomy & histology* / Q000235:genetics*; D005247:Feeding Behavior; D009055:Mouth / Q000033:anatomy & histology*; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA
keywords: 
  Perissodus microlepis
  ; PoolSeq; RADseq; bilateral asymmetry; quantitative trait; scale-eating cichlid fish