Interpopulation variation in life-history traits of Pomacea canaliculata (Gastropoda : Ampullariidae) in southwestern Buenos Aires Province, Argentina
Martin PR, Estebenet AL
Univ Nacl Sur, Dept Biol Bioquim & Farm, RA-8000 Bahia Blanca, Buenos Aires, Argentina
The Argentinean apple snail Pomacea canaliculata is a freshwater gastropod with a high interpopulation variation in shell shape, size and thickness. Previous experimental studies have shown that many life-history traits are highly dependent on rearing conditions. Three natural populations located in one same drainage basin and climatic regime showed marked differences in birth, maturity and maximum sizes. Most of this variation disappeared when newborns from each population were reared under homogeneous conditions in the laboratory, indicating its ecophenotypic origin. However, a significant variation in reproductive, growth and survival patterns attributable to genetic differences among the source populations was still discernible among laboratory cohorts. The three sites studied represent a marked gradient in stability and food availability. Females from the most unstable and poorer site showed a faster prematurity growth and a higher oviposition rate than those from the most stable and productive site. This higher oviposition rate was associated with bigger clutches and a higher mortality rate. The different patterns of survival and somatic and reproductive allocation in the three populations, being heritable and adaptively correlated to different environmental conditions, could be considered as parts of different life-history strategies. Since the 1980s, P. canaliculata has become a serious pest of paddy fields in most Southeast Asian countries. Nearby and recently isolated populations of P. canaliculata from the same basin showed genetically different life-history strategies, so that different populations of this pest could require different control programs.
Malacologia 44 (1): 153-163 2002