Examples of trunk, tail and multiple phenotypes.

<p>(A,B) Compared to the wild-type, the trunk and papillae of <i>chiodino</i> are smaller. (C) Anterior trunk and papillae do not form in <i>mezacapa</i>. (D) An endodermal structure is observed in <i>bermuda</i> that resembles a premature organ rudiment (black arrow). (E,F) The trunk is smaller in the multiple phenotype <i>pigtail</i> and <i>pavese</i> mutations. (G) <i>fuoriditesta</i> (<i>fdt</i>) is another multiple phenotype featuring a shorter tail (not shown) and an externalised sensory vesicle (white arrow). (H) <i>fdt</i> was originally isolated in a double heterozygosity carrier of <i>fdt</i> and <i>omero</i> mutations (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002344#pone-0002344-g001" target="_blank">Figure 1</a>) (dashed line delimits the sensory vesicle in double homozygous mutant larvae). (I) Massive cell death is observed across the body of <i>camus</i> larvae, as shown by the trunk. (J–M) Compared with wild-type larvae, some mutations display tails that are shorter than normal (L). The morphology of the notochord cells in the tails of <i>halftail</i> and <i>streveza</i> homozygous larvae suggests an impaired differentiation (K,M).</p

A schematic representation of sensory organ formation in C. intestinalis.

<p>(A) Otolith differentiation in <i>omero</i> is affected by an early specification problem that is likely to occur during gastrulation. (B) A supranumerary pigment cell in the <i>monkey</i> otolith points to a defect in fate determination at the tailbud stage. (C) Pigment formation in the sensory organs implicates a late differentiation step that becomes obvious at the late-tailbud stage, and is abolished in <i>albus</i>.</p

List of naturally occurring mutations identified during the screening.

<p>Mutation name, population of origin, percentage of F₁ homozygosity, mutation class, short phenotype description and method of validation. Abbreviations: CNS, central nervous system; Nc, notochord; Oc, ocellus; Ot, otolith; SO, sensory organs; SV, sensory vesicle. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002344#s4" target="_blank">Materials and Methods</a> for validation procedures.</p

Genetic characterization based on twelve nuclear microsatellite loci.

*<p><b><i>p</i></b><b><0.05;</b></p>**<p><b><i>p</i></b><b><0.01;</b></p>***<p><b><i>p</i></b><b><0.001</b></p><p>n/tot, number of alleles <i>per</i> locus and <i>per</i> population over the total number of alleles <i>per</i> locus; H_O, observed heterozygosis; H_E, expected heterozygosis; F, fixation index; <i>P</i>, probability level for Hardy-Weinberg equilibrium; n.s., non significant.</p

Genetic distance and gene flow among sites.

<p>Pairwise population comparison based on Nei <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002344#pone.0002344-Shimeld1" target="_blank">[47]</a> genetic distances in lower triangle matrix; Nm (estimated number of migrants) among populations in upper triangle matrix.</p

Homozygous mutant phenotypes with defects in the formation of sensory organs and brain vesicle.

<p>(A,B) Compared to wild-type larvae, no development of melanin is seen in the sensory organs of <i>albus</i> larvae. Scale bar, 100 µm. (C) Few pigment spots are observed in the otolith of <i>tasso</i>. (D) Only one undefined pigmented sensory organ is present in <i>pascoli</i>. (E) In <i>pale</i>, the ocellus is weakly pigmented, while the otolith is normal. (F) Supranumerary pigment cells in the otolith and none in the ocellus are observed in <i>monkey</i>. (G, H) Enlarged ocellus pigmentation and two otolith pigment cells occur in the <i>shiva</i> and <i>miller</i> mutants, respectively. (I) No pigmentation and at least no otolith are observed in <i>omero</i>. (J) The sensory vesicle of <i>divine</i> is not cavitated. White and black arrowheads indicate otolith and ocellus, respectively.</p

Physiological characterization of the curly mutation.

<p>Two graphs showing the effect of CNQX on the frequency of larval swimming. The histograms represent the mean frequency in 10 s bins of spikes before, during and after a light off stimulus.</p

Principal coordinate analysis.

<p>Principal coordinate analysis shows significant differentiation between isolated (FuI) and open-sea (CdS/VC) populations.</p