Morphological and genetic diversity of two invasive aquatic ampullarids in Peninsular Malaysia

• Main Author: Suganiya, Rama Rao
• Format: Thesis
• Published: 2020
• Subjects: QH Natural history; QL Zoology
• Online Access: http://eprints.sunway.edu.my/2434/

Invasive species are one of the main threats to global biodiversity and impose huge economic costs for their control and eradication. Pomacea canaliculata and P.maculata, from family Ampullariidae are two highly invasive species of apple snailthat have rapidly increased their global range, causing significant economic and ecological impacts mainly on rice and taro agriculture, especially in Asia. To date, studies of Pomacea in Malaysia have been limited to population control in rice fields, but little is known about the genetics of Pomacea’s invasion, adaptive potential and sites of introduction. Thus, we first verified the identity of Pomacea spp. in Peninsular Malaysia using both morphological and genetic criteria, then inferred the geographical distribution and population genetic diversity of Pomacea canaliculata and Pomacea maculata in Peninsular Malaysia. This study is the first to confirm the presence of two invasive species of Pomacea in Peninsular Malaysia using a molecular technique. Two monophyletic taxa, P. canaliculata and P. maculata, occurred in our samples, both quantitative and qualitative morphological characteristics revealed much interspecific overlap and intraspecific variability; hence, species identity cannot be reliably identified based on shell morphology only. Next, the mitochondrial cytochrome c oxidase subunit I (COI) and nuclear ribosomal DNA (rDNA) Internal Transcribed Spacer (ITS) markers were used to assess species identity and population genetic diversity of 184 individuals of P. canaliculata and 91 individuals of P. maculata collected from 25 and 15 localities respectively in Peninsular Malaysia. Eight unique haplotypes were identified with the mitochondrial COI gene and the nuclear ITS marker revealed 45 haplotypes for P. canaliculata; while only one haplotype was obtained for P. maculata using the mitochondrial COI marker, and 30 unique haplotypes based on the nuclear ITS marker. Selangor and north Peninsular Malaysia showed the greatest number of diverse haplotypes suggesting multiple independent introductions and the probable site of the species’ earliest introduction for P. canaliculata whereas southern Peninsular Malaysia had the most nuclear haplotypes suggesting as the probable site of introduction of P. maculata. P. canaliculata is more genetically diverse, abundant and widespread, and may be a more serious pest compared to P. maculata. Besides, genetic admixture through multiple introductions is likely to enhance invasiveness in both species. Now that we have a better understanding on the origin and evolutionary relationships of Pomacea canaliculata and Pomacea maculata in Peninsular Malaysia, it may contribute to future studies such as identifying hybrids, assessing species-specific propensities for invasiveness, and developing effective management strategies at putative sites of introduction which may aid eradication efforts of this serious pest.