The Heritability of Shell Morphometrics in the Freshwater Pulmonate Gastropod Physa

Abstract

The cosmopolitan freshwater pulmonate snail Physa acuta hybridizes readily with Physa carolinae in the laboratory, although their F1 progeny are sterile. The two species differ qualitatively in shell shape, the former bearing a more globose shell and the latter more fusiform. We performed a hybridization experiment, measuring a set of 14 traditional (linear) and landmark-based shell morphological variables on even-aged parents and their offspring from both hybrids and purebred control lines. Parent-offspring regression yielded a strikingly high heritability estimate for score on the first relative warp axis, h2 = 0.819 ± 0.073, a result that would seem to confirm the value of geometric morphometrics as a tool for retrieving evolutionary relationships from gastropod shell form. Score on the second relative warp axis was also significantly heritable (h2 = 0.312 ± 0.123), although more moderate, as were scores on second principal components extracted from traditional measurements (correlation h2 = 0.308 ± 0.069, covariance h2 = 0.314 ± 0.050). Although score on the first relative warp axis was significantly correlated with centroid size (p < 0.001), scores on none of the three second axes were so correlated. This result suggests that second axis score might prove especially useful for estimating genetic divergence among mixed-age populations of gastropods sampled from the field.

Offspring reaction norms shaped by parental environment: interaction between within- and trans-generational plasticity of inducible defenses

“…The persistent effect of family on every measured traits indicated that both genetic variation and/or maternal effects occured. Furthermore, Dillon & Jacquemin (2015) [ 68 ] showed a high heritability of shell morphological traits in Physa . An intensive knowledge is available on maternal effects and transmission of various factors in ovocytes [ 4 , 5 ].…”

Conchology Variations in Species Identification of Pachychilidae (Mollusca, Gastropoda, Cerithiodea) through Multivariate Analysis

“…However, Köhler and Glaubrecht (2006) study was further supported by molecular work, thus make distinction among species more concrete. Most of the previous studies on gastropod shell morphometrics used at least four to thirteen shell characteristics ( Dillon Jr. & Jacquemin 2015 ; Ismail & Elkarmi 2006 ; Köhler & Glaubrecht 2006 ; Chiu et al 2002 ).…”

“…Other delineation studies are a combination of shell morphometrics with reproductive morphology ( Köhler & Glaubrecht 2003 ), nervous system, radula, or alimentary system ( Köhler & Glaubrecht 2006 ). Dillon and Jacquemin (2015) categorised shell morphometrics into two groups, traditional morphometrics and geometric morphometrics. The current study is categorised under traditional morphometrics which is based on linear measurement.…”

Volatility in the effective size of a freshwater gastropod population

“…In recent years, the freshwater basommatophoran pulmonate snail Physa acuta has found widespread use as a model organism for a variety of evolutionary studies (Figure 1). Populations of P. acuta in both field and laboratory settings have played important roles in studies of mating behavior (Janicke, Vellnow, Lamy, Chapuis, & David, 2014;Janicke, Vellnow, Sarda, & David, 2013;Wethington & Dillon, 1996), sex allocation (Janicke & Chapuis, 2016;Wethington & Dillon, 1993), inbreeding depression (Jarne, Perdieu, Pernot, Delay, & David, 2000;Noel et al, 2016), reproductive isolation (Dillon, Robinson, & Wethington, 2007), gene flow (Bousset, Henry, Sourrouille, & Jarne, 2004;Van Leeuwen et al, 2013), speciation (Dillon, Wethington, & Lydeard, 2011), and ecophenotypic plasticity (Auld & Relyea, 2011;Dillon & Jacquemin, 2015;Gustafson, Kensinger, Bolek, & Luttbeg, 2014).…”