The paper – to which I had the pleasure to contribute to – deals with the question of what allow a given lineage readily speciate in sympatry where other lineages do not.
The paper focuses on sympatrically-speciating Midas cichlid fish and compares them to a closely-related lineage (Archocentrus centrarchus) which lives in the same lakes as Midas cichlids but do not speciate in sympatry (see Fruciano et al. 2016 – Ecology and Evolution). See also the page on sympatric speciation on this website for a very short summary of the study system. The question we studied is, then: what makes Midas cichlids “special”?
This study comprises a vast array of data types and analyses, including: two de novo genomes, population-level whole genome sequencing (WGS) for both lineages, QTL mapping, population genomic scans, transposable element dynamics, gene family expansion, major chromosomal rearrangements, and analyses of genes under positive selection.
In addition to testing for various genome-scale factors as potential determinants of the propensity to produce adaptive radiations, this study confirms using WGS previous results based on lower-resolution genetic data (Fruciano et al. 2016 – Ecology and Evolution; Franchini et al. 2017 – Molecular Ecology) showing that priority effects cannot be invoked to explain the difference in propensity to speciate. That is, Midas cichlids did not speciate in sympatry because they colonized the new environment first, as all our studies show that A. centrarchus arrived either first or at approximately the same time as Midas cichlids.
Photo associated to this news item: Seiichi Hamada – originally used as article photo for Fruciano et al 2016 – Ecology and Evolution; also used as cover picture for the issue of Ecology and Evolution where the paper was published.
Banner image from Fruciano et al. 2019 – Genome Biology and Evolution