Restricted Genetic Variation in Populations of <i>Achatina</i> (<i>Lissachatina</i>) <i>fulica</i> outside of East Africa and the Indian Ocean Islands Points to the Indian Ocean Islands as the Earliest Known Common Source

<div><p>The Giant African Land Snail, <i>Achatina</i> ( = <i>Lissachatina</i>) <i>fulica</i> Bowdich, 1822, is a tropical crop pest species with a widespread distribution across East Africa, the Indian subcontinent, Southeast Asia, the Pacific, the Caribbean, and North and South America. Its current distribution is attributed primarily to the introduction of the snail to new areas by Man within the last 200 years. This study determined the extent of genetic diversity in global <i>A. fulica</i> populations using the mitochondrial 16S ribosomal RNA gene. A total of 560 individuals were evaluated from 39 global populations obtained from 26 territories. Results reveal 18 distinct <i>A. fulica</i> haplotypes; 14 are found in East Africa and the Indian Ocean islands, but only two haplotypes from the Indian Ocean islands emerged from this region, the C haplotype, now distributed across the tropics, and the D haplotype in Ecuador and Bolivia. Haplotype E from the Philippines, F from New Caledonia and Barbados, O from India and Q from Ecuador are variants of the emergent C haplotype. For the non-native populations, the lack of genetic variation points to founder effects due to the lack of multiple introductions from the native range. Our current data could only point with certainty to the Indian Ocean islands as the earliest known common source of <i>A. fulica</i> across the globe, which necessitates further sampling in East Africa to determine the source populations of the emergent haplotypes.</p></div

Median-joining network of the 18 <i>Achatina fulica</i> 16S haplotypes.

<p>Each mutation between haplotypes is represented by a bar. Unsampled putative haplotypes are represented by black dots.</p

Distribution map of the <i>Achatina fulica</i> populations and their 16S rRNA haplotypes.

<p>Distribution map of the <i>Achatina fulica</i> populations and their 16S rRNA haplotypes.</p

Twenty variable sites across the 18 haplotypes based on the 293-bp 16S rRNA fragment.

<p>A dot represents an identical nucleotide with respect to the reference haplotype <i>A</i>. <i>N</i> represents the number of individuals sampled for each haplotype.</p><p>Twenty variable sites across the 18 haplotypes based on the 293-bp 16S rRNA fragment.</p