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Host-specific phenotypic plasticity of the turtle barnacle Chelonibia testudinaria: a widespread generalist rather than a specialist.

Cheang CC, Tsang LM, Chu KH, Cheng IJ, Chan BK - PLoS ONE (2013)

Bottom Line: Chelonibia testudinaria is specific on marine turtles whereas C. patula is a host generalist, but rarely found on turtles.Based on combined morphological and molecular evidence, we proposed that C. testudinaria and C. patula are conspecific, and the two morphs with contrasting shell morphologies and cirral length found on different host are predominantly shaped by developmental plasticity in response to environmental setting on different hosts.Chelonibia testudinaria is, thus, a successful general epibiotic fouler and the phenotypic responses postulated can increase the fitness of the animals when they attach on hosts with contrasting life-styles.

View Article: PubMed Central - PubMed

Affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.

ABSTRACT
Turtle barnacles are common epibionts on marine organisms. Chelonibia testudinaria is specific on marine turtles whereas C. patula is a host generalist, but rarely found on turtles. It has been questioned why C. patula, being abundant on a variety of live substrata, is almost absent from turtles. We evaluated the genetic (mitochondrial COI, 16S and 12S rRNA, and amplified fragment length polymorphism (AFLP)) and morphological differentiation of C. testudinaia and C. patula from different hosts, to determine the mode of adaptation exhibited by Chelonibia species on different hosts. The two taxa demonstrate clear differences in shell morphology and length of 4-6(th) cirri, but very similar in arthropodal characters. Moreover, we detected no genetic differentiation in mitochondrial DNA and AFLP analyses. Outlier detection infers insignificant selection across loci investigated. Based on combined morphological and molecular evidence, we proposed that C. testudinaria and C. patula are conspecific, and the two morphs with contrasting shell morphologies and cirral length found on different host are predominantly shaped by developmental plasticity in response to environmental setting on different hosts. Chelonibia testudinaria is, thus, a successful general epibiotic fouler and the phenotypic responses postulated can increase the fitness of the animals when they attach on hosts with contrasting life-styles.

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Scanning electron microscopy of mouth parts and cirri of Chelonibia testudinaria.A. Maxilla, B. Serrulate setae on maxilla. C. Maxillule, D. Serrulate setae on maxillule. E. Setae on cutting edge of maxillule. F. Mandibles, G. 3rd –5th teeth and the lower margin of mandible. H. Mandibular palp, showing simple type setae on the inferior margin (I, J) and serrulate setae on superior margin (K). L. Labrum showing enlarged view of teeth on cutting edge (M). N. cirrus I, showing densely pectinated serrulate setae (O) and serrulate setae on rami (P, Q). R. Cirrus II, with serrulate setae (T) and pappose setae (S). U. Cirrus III, with serrulate type setae (V, W) on rami. X. Cirrus VI, showing the intermediate segment (Y).
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pone-0057592-g003: Scanning electron microscopy of mouth parts and cirri of Chelonibia testudinaria.A. Maxilla, B. Serrulate setae on maxilla. C. Maxillule, D. Serrulate setae on maxillule. E. Setae on cutting edge of maxillule. F. Mandibles, G. 3rd –5th teeth and the lower margin of mandible. H. Mandibular palp, showing simple type setae on the inferior margin (I, J) and serrulate setae on superior margin (K). L. Labrum showing enlarged view of teeth on cutting edge (M). N. cirrus I, showing densely pectinated serrulate setae (O) and serrulate setae on rami (P, Q). R. Cirrus II, with serrulate setae (T) and pappose setae (S). U. Cirrus III, with serrulate type setae (V, W) on rami. X. Cirrus VI, showing the intermediate segment (Y).

Mentions: From SEM, the structure of mouth parts and setal types of the cirri were similar between C. patula and C. testudinaria. The maxilla was composed of fine serrulate setae (Figure 3A, B). The maxillule was not notched, with serrulate setae on the cutting edge (Figure 3C, D, E). The mandible consisted of five teeth, with second and third teeth bi-dentate. The lower margin was short and composed of several spines (Figure 3F, G). The mandibular palp consisted of two types of setae, with serrulate setae on the superior margin and simple setae on the inferior margin (Figure 3H, I, J, K). Mandibles were strongly notched, with an array of large sharp teeth (Figure 3L, M). In cirrus I, the posterior rami were longer than the anterior rami, both with densely pectinated serrulate setae (Figure 3N, O, P, Q). In cirrus II, the anterior and posterior rami were similar in length, both with fine serrulate setae (Figure 3R, T) and the basipod with pappose setae (Figure 3S). Both rami of cirrus III were equipped with serrulate type setae (Figure 3U, V, W). Cirri IV to VI were similar in length and morphology, with each segment having two pairs of long serrulate setae and two pairs of short simple setae (Figure 3X, Y).


Host-specific phenotypic plasticity of the turtle barnacle Chelonibia testudinaria: a widespread generalist rather than a specialist.

Cheang CC, Tsang LM, Chu KH, Cheng IJ, Chan BK - PLoS ONE (2013)

Scanning electron microscopy of mouth parts and cirri of Chelonibia testudinaria.A. Maxilla, B. Serrulate setae on maxilla. C. Maxillule, D. Serrulate setae on maxillule. E. Setae on cutting edge of maxillule. F. Mandibles, G. 3rd –5th teeth and the lower margin of mandible. H. Mandibular palp, showing simple type setae on the inferior margin (I, J) and serrulate setae on superior margin (K). L. Labrum showing enlarged view of teeth on cutting edge (M). N. cirrus I, showing densely pectinated serrulate setae (O) and serrulate setae on rami (P, Q). R. Cirrus II, with serrulate setae (T) and pappose setae (S). U. Cirrus III, with serrulate type setae (V, W) on rami. X. Cirrus VI, showing the intermediate segment (Y).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585910&req=5

pone-0057592-g003: Scanning electron microscopy of mouth parts and cirri of Chelonibia testudinaria.A. Maxilla, B. Serrulate setae on maxilla. C. Maxillule, D. Serrulate setae on maxillule. E. Setae on cutting edge of maxillule. F. Mandibles, G. 3rd –5th teeth and the lower margin of mandible. H. Mandibular palp, showing simple type setae on the inferior margin (I, J) and serrulate setae on superior margin (K). L. Labrum showing enlarged view of teeth on cutting edge (M). N. cirrus I, showing densely pectinated serrulate setae (O) and serrulate setae on rami (P, Q). R. Cirrus II, with serrulate setae (T) and pappose setae (S). U. Cirrus III, with serrulate type setae (V, W) on rami. X. Cirrus VI, showing the intermediate segment (Y).
Mentions: From SEM, the structure of mouth parts and setal types of the cirri were similar between C. patula and C. testudinaria. The maxilla was composed of fine serrulate setae (Figure 3A, B). The maxillule was not notched, with serrulate setae on the cutting edge (Figure 3C, D, E). The mandible consisted of five teeth, with second and third teeth bi-dentate. The lower margin was short and composed of several spines (Figure 3F, G). The mandibular palp consisted of two types of setae, with serrulate setae on the superior margin and simple setae on the inferior margin (Figure 3H, I, J, K). Mandibles were strongly notched, with an array of large sharp teeth (Figure 3L, M). In cirrus I, the posterior rami were longer than the anterior rami, both with densely pectinated serrulate setae (Figure 3N, O, P, Q). In cirrus II, the anterior and posterior rami were similar in length, both with fine serrulate setae (Figure 3R, T) and the basipod with pappose setae (Figure 3S). Both rami of cirrus III were equipped with serrulate type setae (Figure 3U, V, W). Cirri IV to VI were similar in length and morphology, with each segment having two pairs of long serrulate setae and two pairs of short simple setae (Figure 3X, Y).

Bottom Line: Chelonibia testudinaria is specific on marine turtles whereas C. patula is a host generalist, but rarely found on turtles.Based on combined morphological and molecular evidence, we proposed that C. testudinaria and C. patula are conspecific, and the two morphs with contrasting shell morphologies and cirral length found on different host are predominantly shaped by developmental plasticity in response to environmental setting on different hosts.Chelonibia testudinaria is, thus, a successful general epibiotic fouler and the phenotypic responses postulated can increase the fitness of the animals when they attach on hosts with contrasting life-styles.

View Article: PubMed Central - PubMed

Affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.

ABSTRACT
Turtle barnacles are common epibionts on marine organisms. Chelonibia testudinaria is specific on marine turtles whereas C. patula is a host generalist, but rarely found on turtles. It has been questioned why C. patula, being abundant on a variety of live substrata, is almost absent from turtles. We evaluated the genetic (mitochondrial COI, 16S and 12S rRNA, and amplified fragment length polymorphism (AFLP)) and morphological differentiation of C. testudinaia and C. patula from different hosts, to determine the mode of adaptation exhibited by Chelonibia species on different hosts. The two taxa demonstrate clear differences in shell morphology and length of 4-6(th) cirri, but very similar in arthropodal characters. Moreover, we detected no genetic differentiation in mitochondrial DNA and AFLP analyses. Outlier detection infers insignificant selection across loci investigated. Based on combined morphological and molecular evidence, we proposed that C. testudinaria and C. patula are conspecific, and the two morphs with contrasting shell morphologies and cirral length found on different host are predominantly shaped by developmental plasticity in response to environmental setting on different hosts. Chelonibia testudinaria is, thus, a successful general epibiotic fouler and the phenotypic responses postulated can increase the fitness of the animals when they attach on hosts with contrasting life-styles.

Show MeSH