Temperature-dependent interaction between an invasive and a native freshwater gastropod: a competitive edge for the invader?

Abstract Multiple studies have focused on the environmental damage done by invasive species and highlighted them as a major threat to biodiversity. Invasive species can completely eliminate some native species. On the other hand, the invasion potential of alien species is strongly influenced by abiotic factors. Taking these factors into consideration, the present study has focused on the competitive interaction between an invasive freshwater pulmonate snail Physella acuta Draparnaud, 1805 (Gastropoda: Physidae) and sympatrically occurring Racesina luteola Lamarck, 1822 (Gastropoda: Lymnaeidae) in India. Competitive superiority of the exotic species was assessed by comparing the reproductive output of the invasive and indigenous species subjected to interactions observed in a community. To investigate the role of temperature as a driving force of the competitive superiority of the invasive snail, 4 temperatures were considered. At all temperatures, the invasive snail P. acuta deposited more egg clutches per individual than the native snail R. luteola did, irrespective of the interaction types. The reproductive output of both species increased with the gradual increase in temperature up to 30°C. At 35°C, the production of egg capsules (clutches) per individual and eggs per individual again decreased for both species. Their reproductive output was the highest at 30°C, while at 20°C, R. luteola laid lower numbers of egg clutches and eggs per individual when kept with P. acuta than when living with conspecifics only. This study shows that temperature can strongly affect the outcome of competition between invasive and indigenous species.