The Architecture of the Physid Musculature of<i>Physa acuta</i>Draparnaud, 1805 (Gastropoda: Physidae)

Naranjo-García, Edna; Appleton, C.C.

doi:10.5733/afin.050.0101

Cited by 4 publications

(1 citation statement)

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“…They inhabit most freshwater systems, both temporary and permanent, and can be found in drainage ditches, streams, rivers and lakes (DeWitt, ). The family Physidae is distinct among pulmonates in that all members have sinistral coiling shells and a unique group of muscles allowing them to swing their shells in a wide arc (Naranjo‐Garcia & Appleton, ), perhaps as an antipredator device or to discourage unwanted mates (DeWitt, ). Like most pulmonates, individuals are hermaphrodites which, coupled with their rapid growth and development, makes them a popular organism for studying sexual selection and conflict (DeWitt, ; Ohbayashi‐Hodoki et al ., ; Facon et al ., ).…”

Section: Methodsmentioning

confidence: 99%

Why get big in the cold? Size–fecundity relationships explain the temperature‐size rule in a pulmonate snail (Physa)

Arendt

2014

J of Evolutionary Biology

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Most ectotherms follow a pattern of size plasticity known as the temperature-size rule where individuals reared in cold environments are larger at maturation than those reared in warm environments. This pattern seems maladaptive because growth is slower in the cold so it takes longer to reach a large size. However, it may be adaptive if reaching a large size has a greater benefit in a cold than in a warm environment such as when sizedependent mortality or size-dependent fecundity depends on temperature. I present a theoretical model showing how a correlation between temperature and the size-fecundity relationship affects optimal size at maturation. I parameterize the model using data from a freshwater pulmonate snail from the genus Physa. Nine families were reared from hatching in one of three temperature regimes (daytime temperature of 22, 25 or 28°C, night-time temperature of 22°C, under a 12L : 12D light cycle). Eight of the nine families followed the temperature-size rule indicating genetic variation for this plasticity. As predicted, the size-fecundity relationship depended upon temperature; fecundity increases steeply with size in the coldest treatment, less steeply in the intermediate treatment, and shows no relationship with size in the warmest treatment. Thus, following the temperature-size rule is adaptive for this species. Although rarely measured under multiple conditions, size-fecundity relationships seem to be sensitive to a number of environmental conditions in addition to temperature including local productivity, competition and predation. If this form of plasticity is as widespread as it appears to be, this model shows that such plasticity has the potential to greatly modify current life-history theory.

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