Abstract
Identifying the basis of phenotypic variation is a key objective of genetics. This work has been mostly limited to model systems with a plethora of genetic manipulation and functional characterization tools. With the development of high-throughput sequencing and new computational tools, it is possible to identify candidate genes related to phenotypic variation in non-model organisms. Fireflies are excellent for studying phenotypic variation because of their diverse and well-characterized behaviors. Most adult fireflies emit a single mating flash pattern and do not eat. In contrast, adult females of many species in the genus Photuris employ multiple flash patterns and prey upon mate-seeking males of other firefly species. To investigate the genetic basis for this variation, we used comparative transcriptomics to identify positively selected genes between a predatory firefly, Photuris sp., and a non-predatory relative, Photuris frontalis, controlling for genes generally under selection in fireflies by comparing to a Photinus firefly. Nine gene families were identified under positive selection in the predatory versus non-predatory Photuris comparison, including genes involved in digestion, detoxification, vision, reproduction, and neural processes. These results generate intriguing hypotheses about the genetic basis for insect behavior and highlight the utility of comparative transcriptomic tools to investigate complex behaviors in non-model systems.
Highlights
The extent to which phenotypes are a result of genetic versus environmental factors is a longstanding question in genetics
Other approaches have utilized genetic crosses to map quantitative traits to genomic regions, or leverage natural variation and genome sequence data to investigate the genetic basis of quantitative traits
Locus mapping and Genome Wide Association studies, reviewed in [4]). While these techniques are powerful, they may require a combination of genomic data, genetic manipulation tools, large sample sizes, and extensive crosses, limiting them to model systems
Summary
The extent to which phenotypes are a result of genetic versus environmental factors is a longstanding question in genetics. This behavior likely has a genetic basis as there is no parental care in fireflies, and lab-reared Photuris offspring exhibit the behavior [25] Because these predatory behaviors are highly dependent on vision, recognition and production of prey species flash patterns, and the ability to digest and process toxins, genes involved in these processes may contribute to the complex femme fatale phenotype and are predicted to be under positive selection between predatory and non-predatory species. Weusing used an established computational pipeline to Using identify this gene approach, families under positive selection for in pairwise comparisons among theand taxa.Pt. we investigated we generated improved assemblies two species, Pt. frontalis sp., and identified 29 gene the potential identity and functions of these gene families using sequence homology search strategies. We are interested in the genes involved in predatory behavior, which are in the Photuris frontalis and Photuris sp. comparison, represented by a star
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