Length - weight relationship and molecular phylogenetic analysis to infer status of Uroteuthis duvaucelii (d’Orbigny 1835) population in the southern coastal region of Sri Lanka

Abstract

Population status of Indian squid: Uroteuthis (Photololigo) duvaucelii of southern Sri Lanka was determined using length – weight relationship and genetic analyses. Growth performance and pattern was estimated by regression curves and growth coefficient constant of the male and female populations. The growth performance was significantly different between males and females (p< 0.05) within the population, but both sexes indicated negative allometric growth patterns. Genetic analyses were performed using partially amplified mitochondrial 16S rRNA (544 bp) and Cytochrome Oxidases subunit I (COI) (600 bp) gene regions. One and three haplotype were determined from two gene regions respectively. Southern Sri Lanka haplotypes show high divergence levels among other U. duvaucelii sequences for both gene regions which suggest the possibility of presence cryptic species. This suggestion is further confirmed by the formation of separate clade for southern Sri Lankan haplotypes in the phylogenetic trees of both gene regions. This morphologically and genetically distinct population within the genus Uroteuthis should be taken into consideration and prioritized when implimenting fisheries and conservation management programs.