Abstract
Allometry involves the study of the relationship between size and shape of an individual, and in particular, the manner in which shape depends on size. Animals with multi-element skeletons may have differing growth allometries in different parts of the body. Chitons, for example, have eight overlapping shell plates or valves of three distinct types: head (one plate), intermediate (six plates), and tail (one plate). The overall chiton body is ellipsoidal and different species differ in their eccentricity. The aim of this study was to examine overall allometry in size and shape over adult ontogeny, and how these patterns vary among four closely related species of intertidal chitons from Southeastern Pacific Ocean. For each specimen (n = 407), measurements were taken of total body length and the exposed anterio-posterior lengths of the eight shell plates. Multivariate allometry was evaluated by means of a principal component analysis for each species separately, and for the total. The results showed differential allometric growth of specific skeletal elements, which varied among species; however, there was no clear evidence for specific differentiable growth stages. The overall trend among the combined species was for weakly positive allometry of shell plate widths, but isometric growth of total length and width; thus, the lateral proportion of the animal occupied by shell increases over growth and conversely “thinner looking” girdles may be generally indicative of older animals.
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References
Araya JF, Araya ME (2015) The shallow-water chitons (Mollusca, Polyplacophora) of Caldera, Region of Atacama, northern Chile. Zoosyst Evol 91:45–58
Avaca MS, Narvarte M, Martín P, van der Molen S (2013) Shell shape variation in the Nassariid Buccinanops globulosus in northern Patagonia. Helgol Mar Res 67:567–577
Avila-Poveda OH, Abadia-Chanona QY (2013) Emergence, development, and maturity of the gonad of two species of chitons ‘‘sea cockroach’’ (Mollusca: Polyplacophora) through the early life stages. PLoS One 8:e69785
Barnes DW (1824) Descriptions of five species of Chiton. Am J Sci Art 7:69–71
Baxter JM (1982) Allometric and morphological variations of whole animal and valve dimensions in the chiton Lepidochitona cinereus (L.) (Mollusca: Polyplacophora). J Molluscan Stud 48:275–282
Baxter JM, Jones AM (1986) Allometric and morphological characteristics of Tonicella marmorea (Fabricius, 1780) populations (Mollusca: Polyplacophora: Ischnochitonidae). Zool J Linn Soc 88:167–177
Bookstein FL (1991) Morphometric tools for landmark data. Cambridge University Press, Cambridge, p 435
Brito MJ (2017). Ecología reproductiva en tres especies de Chiton Linnaeus, 1758 (Mollusca: Polyplacophora) en Coquimbo, Chile. Master Degree Thesis. Universidad Católica de la Santísima Concepción, Chile, pp 76
Conde-Padín P, Grahame JW, Rolán-Alvarez E (2007) Detecting shape differences in species of the Littorina saxatilis complex by morphometric analysis. J Molluscan Stud 73:147–154
Connors MJ, Ehrlich H, Hog M, Godeffroy C, Araya S, Kallai I, Gazit D, Boyce M, Ortiz C (2012) Three-dimensional structure of the shell plate assembly of the chiton Tonicella marmorea and its biomechanical consequences. J Struct Biol 177:314–328
Dryden IL, Mardia KV (1998) Statistical shape analysis. Wiley, New York, p 347
Economo EP, Kerkhoff AJ, Enquist BJ (2005) Allometric growth, life-history invariants and population energetic. Ecol Lett 8:353–360
Eernisse DJ (2007) Chitons. In: Denny MW, Gaines SD (eds) Encyclopedia of tidepools and rocky shores. University of California Press, Berkeley, pp 127–133
Emam WM, Ismail NS (1993) Intraspecific variation in the morphometrics of Acanthopleura haddoni (Mollusca: Polyplacophora) from the Arabian Gulf and Gulf of Oman. Zool Middle East 8:45–52
Flores-Campaña LM, Arzola-González JF, De León-Herrera R (2012) Body size structure, biometric relationships and density of Chiton albolineatus (Mollusca: Polyplacophora) on the intertidal rocky zone of three islands of Mazatlan Bay, SE of the Gulf of California. Rev Biol Mar Oceanogr 47:203–211
Frembly J (1827) A description of several new species of chitones, found on the coast of Chili, in 1825; with a few remarks on the method of taking and preserving them. Zool J 3:193–205
Gayon J (2000) History of the concept of allometry. Am Zool 40:748–758
Gould SJ (2002) The structure of evolutionary theory. Harvard University Press, London, p 1433
Hollander J, Adams DC, Johannesson K (2006) Evolution of adaptation through allometric shifts in a marine snail. Evolution 60:2490–2497
Huxley JS (1932) Problems of relative growth. Methuen, Co. LTD., London, p 276
Kemp P, Bertness M (1984) Snail shape and growth rates: Evidence for plastic shell allometry in Littorina littorea. Proc Natl Acad Sci USA 81:811–813
Klingenberg CP (1996) Multivariate allometry. In: Marcus LF, Corti M, Loy A, Naylor GJP, Slice DE (eds) Advances in morphometrics. Plenum Press, New York, pp 23–49
Klingenberg CP (1998) Heterochrony and allometry: the analysis of evolutionary change in ontogeny. Biol Rev 73:79–123
Klingenberg CP (2010) Evolution and development of shape: integrating quantitative approaches. Nat Rev Genet 11:623–635
Mosimann JE (1970) Size allometry: size and shape variables with characterizations of the lognormal and generalized gamma distributions. J Am Stat Assoc 65:930–945
Nikolioudakis N, Koumoundouros G, Kiparissis S, Somarakis S (2010) Defining length-at-metamorphosis in fishes: a multi-character approach. Mar Biol 157:991–1001
Otaíza RD, Santelices B (1985) Vertical distribution of chitons (Mollusca: Polyplacophora) in the rocky intertidal zone of central Chile. J Exp Mar Biol Ecol 86:229–240
R Core Team (2014) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.R-project.org/. Accessed 11 June 2014
Rolán E, Guerra-Varela J, Colson I, Hughes RN, Rolán-Alvarez E (2004) Morphological and genetic analysis of two sympatric morphs of the dogwhelk Nucella lapillus (Gastropoda: Muricidae) from Galicia (Northwestern Spain). J Molluscan Stud 70:179–185
Saad AEA (1997) Morphometric studies on the rock chiton Acanthopleura spiniger (Mollusca: Polyplacophora) from the northwestern region of the Red Sea. Indian J Mar Sci 26:49–52
Schwabe E (2010) Illustrated summary of chiton terminology (Mollusca, Polyplacophora). Spixiana 33:171–194
Sepúlveda RD, Ibáñez CM (2012) Clinal variation in the shell morphology of intertidal snail Acanthina monodon in the Southeastern Pacific Ocean. Mar Biol Res 8:363–372
Shea BT (1985) Bivariate and multivariate growth allometry: statistical and biological considerations. J Zool Lond 206:367–390
Sigwart JD (2009) Morphological cladistic analysis as a model for character evaluation in primitive living chitons (Polyplacophora, Lepidopleurina). Am Malacol Bull 27:95–104
Sigwart JD, Green PA, Crofts SB (2015) Functional morphology in chitons (Mollusca, Polyplacophora): influences of environment and ocean acidification. Mar Biol 162:2257–2264
Sirenko B (2006) A new outlook on the system of chitons (Mollusca: Polyplacophora). Venus 65:27–49
Sotil GE (2004) Variación estacional de la madurez gonadal y oogénesis de Chiton cumingsii Frembly, 1827 de Bahía Ancón, Lima Perú. Biology Thesis. Universidad Nacional Mayor de San Marcos. Lima, Perú, pp 63
Vélez-Arellano N, Shibayama M, Ortiz-Ordóñez E, Silva-Olivares A, Arellano-Martínez M, García-Domínguez F (2014) Histological description of oogenesis in Chiton virgulatus (Mollusca: Polyplacophora). Int J Morphol 32:608–613
Acknowledgements
This study was financially supported by FONDECYT #1130266 Grant “Evolutionary biogeography of the Southeastern Pacific polyplacophorans” to C.M. Ibáñez. We are grateful to F. Alfonso, A. Cifuentes, S. Curaz, A. Fabres, A. Navarrete, M.C. Pardo-Gandarillas, V. Sanhueza, J. Salazar, C. Tobar and G. Torretti for their assistance in field and laboratory work.
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This research was approved by the Universidad Andres Bello ethical committee and the Chilean government through FONDECYT. The manuscript has not been submitted to more than one journal for simultaneous consideration nor has it been published previously.
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Ibáñez, C.M., Sepúlveda, R.D. & Sigwart, J.D. Comparative allometric variation in intertidal chitons (Polyplacophora: Chitonidae). Zoomorphology 137, 249–256 (2018). https://doi.org/10.1007/s00435-017-0387-2
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DOI: https://doi.org/10.1007/s00435-017-0387-2