PT  - JOURNAL ARTICLE
AU  - Catherine R. Linnen
AU  - Claire T. O’Quin
AU  - Taylor Shackleford
AU  - Connor R. Sears
AU  - Carita Lindstedt
TI  - Genetic architectures of larval pigmentation and color pattern in the redheaded pine sawfly (<em>Neodiprion lecontei</em>)
AID  - 10.1101/183996
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 183996
4099  - http://biorxiv.org/content/early/2017/09/03/183996.short
4100  - http://biorxiv.org/content/early/2017/09/03/183996.full
AB  - Evolutionary biologists have long debated the contribution of large-effect mutations to phenotypic evolution. Although theoretical work suggests that developmental, demographic, and ecological contexts can have profound and predictable impacts on trait genetic architectures, there are few empirical tests of these predictions. Here, we test the hypothesis that, due to differences in pleiotropy in the underlying genetic pathways, the genetic architecture of overall body color (pigmentation) is predictably simpler (i.e., large-effect mutations explain proportionally more of the phenotypic variance) than that of color patterning. To test this prediction, we crossed divergent populations of the redheaded pine sawfly (Neodiprion lecontei) that differ in larval body color and melanic spotting pattern and measured these traits in their recombinant haploid male progeny. Using a combination of interval mapping and polygenic association mapping, we identified large-effect QTL for both traits. Consistent with the pigmentation/patterning hypothesis, we found that compared to spotting pattern, body color had a larger percentage of genetic variance attributable to large-effect loci. Additionally, by combining mapping results with a linkage group-anchored genome assembly for N. lecontei, we identified several promising candidate genes for both carotenoid-based yellow pigmentation and melanin-based spotting pattern. Because few studies have investigated the genetic basis of naturally occurring variation in larval color and carotenoid-based pigmentation, our study helps fill a void in the invertebrate pigmentation literature. Finally, we argue that when leveraged to test explicit a priori hypotheses regarding trait genetic architectures, polygenic association mapping has the potential to shed new light on the 150-year-old micromutationist-macromutationist debate.