Population Genetic Structure of Nephila maculata in Taiwan. (NSC 89-2311-B-029-008)

Abstract

Currently, most phylogeographic studies of terrestrial animals in Taiwan focus on vertebrates. Results from most studies show that many terrestrial vertebrates can be divided into eastern and western groups according to their population genetic structures. It is suggested that the common phylogeographic pattern exhibited by so many taxa results from the following factors: 1) isolation resulting from the upheaval of the Central Mountain Range, which led to differentiation of eastern and western populations, and 2) the connection between Taiwan and mainland China during glacial periods of the Pleistocene, which enhanced migrations of terrestrial organisms. In this study, the widely-distributed giant wood spider Nephila maculata Fabricius 1793 is used to investigated if population differentiation pattern of Taiwanese terrestrial arthropods resembles that of terrestrial vertebrates. Mitochondrial cytochrome oxidase I (COI) was used as genetic marker and its partial sequences were determined in 158 specimens collected from 24 localities (Ryukyu islands, Taiwan and China). I successfully amplified 617 bases of COI gene sequence from DNA extracted from leg muscle and identified 11 haplotypes from all specimens examined. Phylogenetic trees constructed by neighbor-joining (NJ) and maximum parsimony (MP) methods using Nephila clavata Koch 1877 as outgroup indicate that N. maculata populations can be separated into two major clades, group A and group B, with high bootstrap values (89% in NJ tree and 93% in MP tree). Group A consists of most specimens in twenty-two localities. Group B consists of specimens from southwestern China and northwestern Taiwan. Another minor clade is group C, which consists of 3 specimens from northeastern Taiwan. The wide distribution of EA haplotype in western and eastern Taiwan indicates that the population differentiation pattern of N. maculata is different from those of terrestrial vertebrates. Central Mountain Range did not seem to be a major geographic barrier to N. maculata. The coexistence of specimens with EA haplotype in Taiwan and China suggests that some of the present populations in Taiwan might have split from an ancestral population in mainland. In addition, judging from phylogenetic trees and the distribution patterns of haplotypes, invasion of N. maculata from China into Taiwan might have occurred several times.

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Updated: Jan-24-2014 11:34:24 (Taiwan, GMT+08:00).