Mapping of quantitative trait loci underlying a magic trait in ongoing ecological speciation

Area of Science:

• Evolutionary Biology
• Genetics
• Ichthyology

Background:

• Telmatochromis temporalis, a cichlid fish from Lake Tanganyika, exhibits distinct normal and dwarf morphs.
• These morphs serve as a model for ecological speciation, with body size acting as a key trait.
• The genetic underpinnings of this body size variation remain largely unexplored.

Purpose of the Study:

• To identify the genetic factors contributing to the body size differences between T. temporalis morphs.
• To investigate the role of body size as a magic trait in the ongoing ecological speciation of this species.

Main Methods:

• Employed double-digested restriction-site associated DNA (ddRAD) sequencing on a hybrid cross.
• Generated a linkage map with 708 ddRAD markers across 22 linkage groups.
• Performed quantitative trait loci (QTL) analysis to identify genetic loci associated with body size.

Main Results:

• A linkage map was constructed, aligning with Oreochromis niloticus chromosomes.
• One significant and five suggestive QTL for body size were identified.
• Evidence suggests these QTL are linked to genes responsible for the observed body size dimorphism between morphs.

Conclusions:

• Morph-specific body size in T. temporalis is controlled by multiple genes, not a single locus.
• These findings enhance understanding of the genetic architecture of a magic trait during ecological speciation.