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Phenotypic Buffering in a Monogenean: Canalization and Developmental Stability in Shape and Size of the Haptoral Anchors of Ligophorus cephali (Monogenea: Dactylogyridae).

Llopis-Belenguer C, Balbuena JA, Galván-Femenía I, Rodríguez-González A - PLoS ONE (2015)

Bottom Line: Phenotypic variation results from the balance between sources of variation and counteracting regulatory mechanisms.Canalization and developmental stability are two such mechanisms, acting at two different levels of regulation.Geometric morphometrics can be readily applied to other host-monogenean models, affording not only to disentangle the effects of canalization and developmental stability, as shown herein, but to further partition the environmental and genetic components of the former.

View Article: PubMed Central - PubMed

Affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.

ABSTRACT
Phenotypic variation results from the balance between sources of variation and counteracting regulatory mechanisms. Canalization and developmental stability are two such mechanisms, acting at two different levels of regulation. The issue of whether or not they act concurrently as a common developmental buffering capacity has been subject to debate. We used geometric morphometrics to quantify the mechanisms that guarantee phenotypic constancy in the haptoral anchors of Ligophorus cephali. Canalization and developmental stability were appraised by estimating inter- and intra-individual variation, respectively, in size and shape of dorsal and ventral anchors. The latter variation was estimated as fluctuating asymmetry (FA) between anchor pairs. The general-buffering-capacity hypothesis was tested by two different methods based on correlations and Principal Components Analyses of the different components of size and shape variation. Evidence for FA in the dorsal and ventral anchors in both shape and size was found. Our analyses supported the hypothesis of a general developmental buffering capacity. The evidence was more compelling for shape than for size and, particularly, for the ventral anchors than for the dorsal ones. These results are in line with previous studies of dactylogyrids suggesting that ventral anchors secure a firmer, more permanent attachment, whereas dorsal anchors are more mobile. Because fixation to the host is crucial for survival in ectoparasites, we suggest that homeostatic development of the ventral anchors has been promoted to ensure the morphological constancy required for efficient attachment. Geometric morphometrics can be readily applied to other host-monogenean models, affording not only to disentangle the effects of canalization and developmental stability, as shown herein, but to further partition the environmental and genetic components of the former.

No MeSH data available.


Lollipops graphs of Principal Component Analysis of the dorsal anchors.(A) Inter- and (B) intra-individual variation (Fluctuating asymmetry, FA). Graphs display the landmarks displacements for the first three principal components (PCs) of Principal component analyses of factors in the Procrustes ANOVA. (C) Percentage of shape variation explained by each PC in the different analyses.
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pone.0142365.g005: Lollipops graphs of Principal Component Analysis of the dorsal anchors.(A) Inter- and (B) intra-individual variation (Fluctuating asymmetry, FA). Graphs display the landmarks displacements for the first three principal components (PCs) of Principal component analyses of factors in the Procrustes ANOVA. (C) Percentage of shape variation explained by each PC in the different analyses.

Mentions: The landmark displacements are graphically represented as lollipop graphs (Figs 5 and 6). Broadly, most shape variation affected the root lengths and, in some dimensions, the point orientation. In the dorsal anchors (Fig 5), the first three PCs explained 74.0% of the total variance for inter-individual variation; 70.1% for intra-individual variation; and 58.0% for measurement error. In the ventral anchors (Fig 6), the first three PCs accounted for 63.8%, 77.0% and 48.3% of the total variance for inter-individual, intra-individual variation and measurement error, respectively. The angular tests revealed that patterns of morphological variation in anchor shape were in general coherent, because angle between PCs were significantly smaller than angles between pairs of random vectors. These results were obtained for both comparisons between inter- (individual variation) and intra-individual (FA) variation, and between dorsal and ventral anchors (Table 4). When the angular analysis is significant, coordinate landmark displacement between PCs can be compared by the visual inspection of lollipop graphs (Figs 5 and 6).


Phenotypic Buffering in a Monogenean: Canalization and Developmental Stability in Shape and Size of the Haptoral Anchors of Ligophorus cephali (Monogenea: Dactylogyridae).

Llopis-Belenguer C, Balbuena JA, Galván-Femenía I, Rodríguez-González A - PLoS ONE (2015)

Lollipops graphs of Principal Component Analysis of the dorsal anchors.(A) Inter- and (B) intra-individual variation (Fluctuating asymmetry, FA). Graphs display the landmarks displacements for the first three principal components (PCs) of Principal component analyses of factors in the Procrustes ANOVA. (C) Percentage of shape variation explained by each PC in the different analyses.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4636253&req=5

pone.0142365.g005: Lollipops graphs of Principal Component Analysis of the dorsal anchors.(A) Inter- and (B) intra-individual variation (Fluctuating asymmetry, FA). Graphs display the landmarks displacements for the first three principal components (PCs) of Principal component analyses of factors in the Procrustes ANOVA. (C) Percentage of shape variation explained by each PC in the different analyses.
Mentions: The landmark displacements are graphically represented as lollipop graphs (Figs 5 and 6). Broadly, most shape variation affected the root lengths and, in some dimensions, the point orientation. In the dorsal anchors (Fig 5), the first three PCs explained 74.0% of the total variance for inter-individual variation; 70.1% for intra-individual variation; and 58.0% for measurement error. In the ventral anchors (Fig 6), the first three PCs accounted for 63.8%, 77.0% and 48.3% of the total variance for inter-individual, intra-individual variation and measurement error, respectively. The angular tests revealed that patterns of morphological variation in anchor shape were in general coherent, because angle between PCs were significantly smaller than angles between pairs of random vectors. These results were obtained for both comparisons between inter- (individual variation) and intra-individual (FA) variation, and between dorsal and ventral anchors (Table 4). When the angular analysis is significant, coordinate landmark displacement between PCs can be compared by the visual inspection of lollipop graphs (Figs 5 and 6).

Bottom Line: Phenotypic variation results from the balance between sources of variation and counteracting regulatory mechanisms.Canalization and developmental stability are two such mechanisms, acting at two different levels of regulation.Geometric morphometrics can be readily applied to other host-monogenean models, affording not only to disentangle the effects of canalization and developmental stability, as shown herein, but to further partition the environmental and genetic components of the former.

View Article: PubMed Central - PubMed

Affiliation: Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain.

ABSTRACT
Phenotypic variation results from the balance between sources of variation and counteracting regulatory mechanisms. Canalization and developmental stability are two such mechanisms, acting at two different levels of regulation. The issue of whether or not they act concurrently as a common developmental buffering capacity has been subject to debate. We used geometric morphometrics to quantify the mechanisms that guarantee phenotypic constancy in the haptoral anchors of Ligophorus cephali. Canalization and developmental stability were appraised by estimating inter- and intra-individual variation, respectively, in size and shape of dorsal and ventral anchors. The latter variation was estimated as fluctuating asymmetry (FA) between anchor pairs. The general-buffering-capacity hypothesis was tested by two different methods based on correlations and Principal Components Analyses of the different components of size and shape variation. Evidence for FA in the dorsal and ventral anchors in both shape and size was found. Our analyses supported the hypothesis of a general developmental buffering capacity. The evidence was more compelling for shape than for size and, particularly, for the ventral anchors than for the dorsal ones. These results are in line with previous studies of dactylogyrids suggesting that ventral anchors secure a firmer, more permanent attachment, whereas dorsal anchors are more mobile. Because fixation to the host is crucial for survival in ectoparasites, we suggest that homeostatic development of the ventral anchors has been promoted to ensure the morphological constancy required for efficient attachment. Geometric morphometrics can be readily applied to other host-monogenean models, affording not only to disentangle the effects of canalization and developmental stability, as shown herein, but to further partition the environmental and genetic components of the former.

No MeSH data available.