Abstract
BackgroundTelmatochromis temporalis is a cichlid fish endemic to Lake Tanganyika. The normal and dwarf morphs of this fish are a clear example of ongoing ecological speciation, and body size plays an important role in this speciation event as a magic trait. However, the genetic basis underlying this trait has not been studied.ResultsBased on double-digested restriction-site associated DNA (ddRAD) sequencing of a hybrid cross between the morphs that includes F0 male, F0 female, and 206 F2 individuals, we obtained a linkage map consisting of 708 ddRAD markers in 22 linkage groups, which corresponded to the previously reported Oreochromis niloticus chromosomes, and identified one significant and five suggestive quantitative trait loci (QTL) for body size. From the body-size distribution pattern, the significant and three of the five suggestive QTL are possibly associated with genes responsible for the difference in body size between the morphs.ConclusionsThe QTL analysis presented here suggests that multiple genes, rather than a single gene, control morph-specific body size. The present results provide further insights about the genes underlying the morph specific body size and evolution of the magic trait during ecological speciation.
Highlights
Telmatochromis temporalis is a cichlid fish endemic to Lake Tanganyika
The number of digested restriction-site associated DNA (ddRAD) sequence pairs per sample ranged from 2.7 × to 7.0 × (1.9 × 106 on average) [DNA Data Bank of Japan (DDBJ) accession no
We identified 1,409 single nucleotide polymorphisms (SNPs) that did not share alleles between the parents
Summary
Telmatochromis temporalis is a cichlid fish endemic to Lake Tanganyika. The normal and dwarf morphs of this fish are a clear example of ongoing ecological speciation, and body size plays an important role in this speciation event as a magic trait. Body size is a life-history trait that has a serious impact on individuals’ fitness through natural or sexual selection [4,5,6]. This suggests that body size could be a candidate magic trait. Body size is thought to be a ‘classic’ magic trait, in that body size evolved under divergent selection and acted on mating cues, there are few conclusive examples [3]. A clear example of such size-mediated automatic magic traits is reported for Telmatochromis temporalis from Lake Tanganyika
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