Genetic variation of Macrobrachium lanchesteri (De Man, 1911) in Northeastern Thailand

Abstract

The freshwater prawn Macrobrachium lanchesteri is one of the most economically important and widely distributed species in Northeastern Thailand. However, few studies have investigated the genetic variation of these crustaceans. Water quality, morphometrics and genetic variation were determined for 1,219 individuals of M. lanchesteri from 11 provinces in Northeastern Thailand. Water quality analysis showed water temperature, pH, water hardness and dissolved oxygen as 25 to 33ºC, 6 to 9, 64 to 101 ml l⁻¹ and 4 to 7.5 ml l⁻¹ respectively. Water quality indicated that aquatic animals could live. Morphological characters showed total length as 1.5to 4.5 cm with M. lanchesteri mean length of females higher than males in all 11 provinces. M. lanchesteri from Nong Khai presented the largest size with Buri Ram mostly comprising the smallest. Genetic variation was determined using the PCR-RFLP technique with five restriction enzymes as Dde I, Alu I, Hinf I, Bgl II and Hae III. Results showed one composite haplotype when samples were digested with Dde I, Alu I, Hinf I, Bgl II and Hae III, respectively, as AAAAA. A total of 9 haplotypes were detected. Nucleotide sequencing analysis found low genetic variation in populations of M. lanchesteri in Northeastern Thailand ranged from 0 to 0.035. Phylogenetic tree (UPGMA) construction determined that the M. lanchesteri population constituted two clades which all populations closely related apart from one separate population. This study can be used as a guideline for selection of commercial cultures by shrimp breeders and may also be useful for shrimp conservation.