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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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FST value for each of the AFLP loci and their associated posterior odds (PO).Solid vertical line represents the threshold value (false discovery rate of 0.05) of PO; loci with PO larger than the threshold regarded as outliers. Note that PO is equivalent to Bayes Factors when the prior odds are set to 1 (refer to text for details).
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pone-0057592-g006: FST value for each of the AFLP loci and their associated posterior odds (PO).Solid vertical line represents the threshold value (false discovery rate of 0.05) of PO; loci with PO larger than the threshold regarded as outliers. Note that PO is equivalent to Bayes Factors when the prior odds are set to 1 (refer to text for details).

Mentions: While 120 AFLP bands on average (<200 bands) were scored for each primer combination in the present study, the biases on the outlier identification introduced by size homoplasy of AFLP was assumed to be small (see [30]). A total of 340 polymorphic loci were detected from the AFLP pattern generated. The number of polymorphic loci for C. testudinaria and C. patula was 321 (94.4%) and 308 (90.6%) respectively. The Nei’s genetic distance (expected heterozygosity) estimate based on AFLP ranged from 0.33 to 0.37 (Table 2). There was no significant difference between the two species in terms of both Nei’s genetic diversity (unpaired t test; P>0.05) and pairwise distance calculated based on allelic frequency (permutation test in AFLPsurv; FST = 0.0012, p (high) >0.05; nMDS ordination Figure 2C). The results of AMOVA from the AFLP analysis were similar to those from the mitochondrial markers, showing a majority of “within population” variance (Table 3). One locus (201 bp of combination E_ACC/M_CTT) out of 340 loci (0.29%) was identified to possess a FST value significantly higher than that across all loci (FST = 0.06, Alpha = 0.66, Log10(PO) = 0.31), when the FDR was set at 0.05 (Figure 6). This locus was inferred to be under selection pressure.


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)

FST value for each of the AFLP loci and their associated posterior odds (PO).Solid vertical line represents the threshold value (false discovery rate of 0.05) of PO; loci with PO larger than the threshold regarded as outliers. Note that PO is equivalent to Bayes Factors when the prior odds are set to 1 (refer to text for details).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585910&req=5

pone-0057592-g006: FST value for each of the AFLP loci and their associated posterior odds (PO).Solid vertical line represents the threshold value (false discovery rate of 0.05) of PO; loci with PO larger than the threshold regarded as outliers. Note that PO is equivalent to Bayes Factors when the prior odds are set to 1 (refer to text for details).
Mentions: While 120 AFLP bands on average (<200 bands) were scored for each primer combination in the present study, the biases on the outlier identification introduced by size homoplasy of AFLP was assumed to be small (see [30]). A total of 340 polymorphic loci were detected from the AFLP pattern generated. The number of polymorphic loci for C. testudinaria and C. patula was 321 (94.4%) and 308 (90.6%) respectively. The Nei’s genetic distance (expected heterozygosity) estimate based on AFLP ranged from 0.33 to 0.37 (Table 2). There was no significant difference between the two species in terms of both Nei’s genetic diversity (unpaired t test; P>0.05) and pairwise distance calculated based on allelic frequency (permutation test in AFLPsurv; FST = 0.0012, p (high) >0.05; nMDS ordination Figure 2C). The results of AMOVA from the AFLP analysis were similar to those from the mitochondrial markers, showing a majority of “within population” variance (Table 3). One locus (201 bp of combination E_ACC/M_CTT) out of 340 loci (0.29%) was identified to possess a FST value significantly higher than that across all loci (FST = 0.06, Alpha = 0.66, Log10(PO) = 0.31), when the FDR was set at 0.05 (Figure 6). This locus was inferred to be under selection pressure.

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