Taxon-restricted genes at the origin of a novel trait allowing access to a new environment

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Science  20 Oct 2017:
Vol. 358, Issue 6361, pp. 386-390
DOI: 10.1126/science.aan2748
  • Fig. 1 Morphology, habitat correlation, and nymphal development of the Rhagovelia fan.

    (A) Midleg morphology comparison between R. antilleana and the outgroup species S. tersa. Rhagovelia tarsi have longer and wider claws and are forked to host the fan, which can be deployed and retracted following leg movements (movie S2). (B) Habitat and behavior of Rhagovelia (left) and Stridulivelia (right). (C) Nymph developmental series, showing an increase in fan size and in the number of branches across molting stages.

  • Fig. 2 Fan expression profiling and protein alignment of gsha and mogsha.

    (A) In situ hybridization showing the expression of all five genes at the tips of the midleg (leg 2, L2). Scale bar, 100 μm. (B) Protein alignment of c68581_g1 (mogsha) and c67063_g1 (gsha), with divergent amino acids highlighted in color (nucleotide alignment in fig. S4). Single-letter abbreviations for the amino acid residues are as follows: A, Ala; C, Cys; D, Asp; E, Glu; F, Phe; G, Gly; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn; P, Pro; Q, Gln; R, Arg; S, Ser; T, Thr; V, Val; W, Trp; and Y, Tyr.

  • Fig. 3 Sequence evolution, expression, and functional characterization of gsha and mogsha.

    (A) Bayesian phylogenetic reconstruction showing that mogsha is more similar to the taxon-restricted unduplicated copy (gray box), whereas gsha is a Rhagovelia-specific duplicate that has evolved at a higher rate (red box; note the branch length). Node values represent the posterior probability, and the scale bar indicates the genetic distance between sequences. (B) Gene-specific quantitative PCR showing gsha and mogsha expression in the midleg (leg 2; n = 3) of fourth instar nymphs. Error bars, SEM. (C) gsha/mogsha RNAi-mediated knockdown resulted in a severe reduction of the fan (n = 27), but the claws (arrows) and leg morphology (figs. S7 and S8) were unaffected.

  • Fig. 4 Comparative analysis of locomotion parameters.

    (A and B) Boxplots for the still water setup, comparing (A) mean speed and (B) stroke frequency among S. tersa (green; n = 10), R. antilleana (blue; n = 7), R. antilleana with ablated fans (gray; n = 4), and gsha/mogsha-RNAi R. antilleana (yellow; n = 9). The range of severity of gsha/mogsha-RNAi phenotypes can be found in fig. S7. (C) Scheme of the stream setup (top) (movie S3), with the percentage of individuals succeeding in rowing against the current, together with their corresponding arrival time, shown below. Error bars, SEM. (D and E) Boxplots for the stream setup, comparing (D) mean speed and (E) stroke frequency among R. antilleana (blue; n = 10), R. antilleana with ablated fans (gray; n = 8) and gsha/mogsha-RNAi R. antilleana (yellow; n = 8). (F) Angles of R. antilleana turns in still water (R. antilleana, n = 8; gsha/mogsha-RNAi, n = 8; R. antilleana with fan ablated, n = 8). Each boxplot spans the minimum and maximum values (whiskers), with medians shown by the horizontal lines and first and third quartiles delineated by the box. Student’s t test or the Mann-Whitney test was performed for each pairwise comparison. P values are shown next to asterisks. ns, not significant.

Supplementary Materials

  • Taxon-restricted genes at the origin of a novel trait allowing access to a new environment

    M. Emília Santos, Augustin Le Bouquin, Antonin J. J. Crumière, Abderrahman Khila

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S11
    • Tables S2 to S12
    • Caption for Table S1
    • Captions for Movies S1 to S3
    • References
    Table S1
    Item 3 Cited in text as: [Movie S1] Filename: [] Filetype: []Caption:

    Images, Video, and Other Media

    Movie S1
    Locomotion habits and niche preference of Rhagovelia and Stridulivelia
    Movie S2
    Comparison of fan deployment between untreated and gsha/mogsha RNAi-treated Rhagovelia. Note that despite the reduction of the fan in RNAi-treated individuals, the remnants of the fan are still deployed and retracted just like in normal individuals.
    Movie S3
    Stream set up showing the condition for the ascension test against current and the performance of untreated compared to gsha/mogsha RNAi-treated individuals.

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