Project description:In the eastern United States the buckeye butterfly, Junonia coenia, shows a seasonal wing color polyphenism where adults emerging in the spring are pale brown, while those emerging in the autumn are dark red. This variation can be artificially induced in laboratory colonies, thus making J. coenia a useful model system to examine the developmental basis of phenotypic plasticity. We used RNA-seq to generate the first set of assembled transcripts for this species while simultaneously quantifying relative gene expression associated with development of alternative seasonal color morphs. The assembled consolidated wing transcriptome was 77.55 Mb. 16,251 contigs of over 1000bp in length were assembled, of which 3,145 were differentially expressed between stages and/or color morphs. Depending on the developmental stage, between 547 and 1420 transcripts were significantly differentially expressed between brown and red wing morphs. These extensive differences in gene expression stand in stark contrast to the much smaller numbers found in previous studies on genetic wing pattern variation, and suggest that environmentally induced phenotypic shifts may arise from very broad systemic processes. Overall gene ontology (GO) analyses revealed that genes associated with structural constituents of ribosomes and oxygen transport were significantly upregulated in the pale brown morph, while genes associated with peptidase activity were very significantly upregulated in the dark red morph. Focused analyses of candidate endocrine and pigmentation pathways revealed a number of notable genes upregulated in the red morph, including several ecdysone-related genes and cinnabar, an ommochrome pigment gene implicated in color pattern variation in other butterflies. Surprisingly, we found numerous melanin-related transcripts, including tan and yellow-family genes, strongly upregulated in the red morph, leading us to speculate that red pigmentation in autumn J. coenia may include red or brown melanins in addition to ommochromes. While we identified several endocrine and pigmentation genes as obvious candidates for color morph differentiation, we speculate that the majority of gene expression differences we observed were due to thermal stress response. The buckeye transcriptome provides a basis for further developmental studies of phenotypic plasticity.

Project description:In the eastern United States the buckeye butterfly, Junonia coenia, shows a seasonal wing color polyphenism where adults emerging in the spring are pale brown, while those emerging in the autumn are dark red. This variation can be artificially induced in laboratory colonies, thus making J. coenia a useful model system to examine the developmental basis of phenotypic plasticity. We used RNA-seq to generate the first set of assembled transcripts for this species while simultaneously quantifying relative gene expression associated with development of alternative seasonal color morphs. The assembled consolidated wing transcriptome was 77.55 Mb. 16,251 contigs of over 1000bp in length were assembled, of which 3,145 were differentially expressed between stages and/or color morphs. Depending on the developmental stage, between 547 and 1420 transcripts were significantly differentially expressed between brown and red wing morphs. These extensive differences in gene expression stand in stark contrast to the much smaller numbers found in previous studies on genetic wing pattern variation, and suggest that environmentally induced phenotypic shifts may arise from very broad systemic processes. Overall gene ontology (GO) analyses revealed that genes associated with structural constituents of ribosomes and oxygen transport were significantly upregulated in the pale brown morph, while genes associated with peptidase activity were very significantly upregulated in the dark red morph. Focused analyses of candidate endocrine and pigmentation pathways revealed a number of notable genes upregulated in the red morph, including several ecdysone-related genes and cinnabar, an ommochrome pigment gene implicated in color pattern variation in other butterflies. Surprisingly, we found numerous melanin-related transcripts, including tan and yellow-family genes, strongly upregulated in the red morph, leading us to speculate that red pigmentation in autumn J. coenia may include red or brown melanins in addition to ommochromes. While we identified several endocrine and pigmentation genes as obvious candidates for color morph differentiation, we speculate that the majority of gene expression differences we observed were due to thermal stress response. The buckeye transcriptome provides a basis for further developmental studies of phenotypic plasticity. mRNA profiling of hind wings from 4 developmental stages of two color morphs (Rosa and Linea) of the buckeye butterfly (J. coenia), generated by deep sequencing, in triplicate, using Illumina GAII or HiSeq 2000.

Project description:Wing polymorphism is a powerful model for examining many aspects of adaptation. The wing dimorphic cricket species, Gryllus firmus, consists of a long-winged morph with functional flight muscles that is capable of flight, and two flightless morphs. One (obligately) flightless morph emerges as an adult with vestigial wings and vestigial flight muscles. The other (plastic) flightless morph emerges with fully-developed wings but later in adulthood histolyzes its flight muscles. Importantly both flightless morphs have substantially increased reproductive output relative to the flight-capable morph. Much is known about the physiological and biochemical differences between the morphs with respect to adaptations for flight versus reproduction. In contrast, little is known about the molecular genetic basis of these morph-specific adaptations. To address this issue, we assembled a de novo transcriptome of G. firmus using 141.5 million Illumina reads generated from flight muscles and fat body, two organs that play key roles in flight and reproduction. We used the resulting 34,411 transcripts as a reference transcriptome for differential gene expression analyses. A comparison of gene expression profiles from functional flight muscles in the flight-capable morph versus histolyzed flight muscles in the plastic flight incapable morph identified a suite of genes involved in respiration that were highly expressed in pink (functional) flight muscles and genes involved in proteolysis highly expressed in the white (histolyzed) flight muscles. A comparison of fat body transcripts from the obligately flightless versus the flight-capable morphs revealed differential expression of genes involved in triglyceride biosynthesis, lipid transport, immune function and reproduction. These data provide a valuable resource for future molecular genetics research in this and related species and provide insight on the role of gene expression in morph-specific adaptations for flight versus reproduction.

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Morph-specific transcriptome

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