The distribution of terrestrial pest gastropods and their damage to agricultural crops in Kandy and Nuwara Eliya districts in Sri Lanka

An island wide survey from 1999 to 2002 in Sri Lanka highlighted the presence of 18 species of exotic snails and slugs, of which most were identified as pests of agriculture crops. However, since this survey, no studies on pest gastropods have been carried out in the country. Hence, the present study was carried out in Kandy and Nuwara Eliya districts in approximately 15 hectares of agricultural land to determine the current status of these gastropods. During the study, a total of 14 terrestrial gastropod species were recorded from agricultural lands of which eight species were recognized as exotic pest gastropods. They were Deroceras reticulatum, Laevicaulis altae, Mariaella dussumieri, Milax gagates, Lissachatina fulica, Bradybaena similaris, Allopeas gracile and Subulina octona. The damage from pest gastropods was observed in many crops and especially in the seedling or nursery stage plants. The highest damage to crops in Nuwara Eliya and Kandy districts were caused by D. reticulatum and Lissachatina fulica respectively. The study indicated that the distribution range of many of these pest gastropods, especially Laevicaulis altae and Lissachatina fulica has increased during the past fifteen years. Elevation is a key environmental factor that affects their distribution in these districts

863 genomes reveal the origin and domestication of chicken

Despite the substantial role that chickens have played in human societies across the world, both the geographic and temporal origins of their domestication remain controversial. To address this issue, we analyzed 863 genomes from a worldwide sampling of chickens and representatives of all four species of wild jungle fowl and each of the five subspecies of red jungle fowl (RJF). Our study suggests that domestic chickens were initially derived from the RJF subspecies Gallus gallus spadiceus whose present-day distribution is predominantly in southwestern China, northern Thailand and Myanmar. Following their domestication, chickens were translocated across Southeast and South Asia where they interbred locally with both RJF subspecies and other jungle fowl species. In addition, our results show that the White Leghorn chicken breed possesses a mosaic of divergent ancestries inherited from other subspecies of RJF. Despite the strong episodic gene flow from geographically divergent lineages of jungle fowls, our analyses show that domestic chickens undergo genetic adaptations that underlie their unique behavioral, morphological and reproductive traits. Our study provides novel insights into the evolutionary history of domestic chickens and a valuable resource to facilitate ongoing genetic and functional investigations of the world’s most numerous domestic animal