Biosystematics and Biogeographical Implification for Ypthima multistriata Species Group in Taiwan

Abstract

Ypthima multistriata species group is proved to be composed of three species in Taiwan, and they are Y. esakii, Y. multistirata, and Y. akragas. Y. wangi is also considered as the same species in this study. Morphological difference was found between different populations of Y. esakii in various habitats, southern Taiwan, northern Taiwan, northeastern Taiwan, and GuiSan island. In Ypthima multistriata species group, multiple-variable regression shows, except for Y. multistriata in the southern and central Taiwan, the size of the first ocellus responds positively to the increase of temperature. In the second ocellus, the size of it doesn’t show a significant relationship with temperature. However, the difference between these two eyespots increases as temperature goes up. To ensure the difference between the eyespots can be a useable trait in classification of this species group, an F test on the difference between eyespots among every taxon was carried out and showed that the this trait can help in identifying Y. esakii in the southern/central Taiwan. To reassure the taxonomic status of these taxa, COI, COII, and ND5 genes of mitochondria DNA are utilized to examine if any divergence occurs among those undetermined taxa, namely, the Y. esakii populations in southern Taiwan versus those in northern Taiwan, and the population in the northeastern Taiwan versus Y. wangi on GuiSan Islet. Y. formosana, Y. angustipennis, Y. tappana, and Y. norma as the outgroups are designated as the outgroup. 583 bp of COI gene are acquired, and across all taxa 56 sites/ 583 bp (9.6%) are parsimoniously informative. From a heuristic search of unweighted nucleotide data set, one most parsimonious tree was obtained, 65 steps long. As the data set generated high CI value (0.9062), homoplasy is evidently low. All the bootstrap values and Bayesian supportive values are all above 60, mostly above 75, which show that the linking of each node is robust enough. Based on the phylogenetic tree, these taxa were grouped into four main clades. The first clade is composed of different populations of Y. esakii, Y. wangi, and the morphologically similar population in the northeasternTaiwan. The clade consisting of these taxa presents 0% divergence on the 583 bp of the surveyed COI sequence. In sequences of ND5 (500 bp) and COII (409bp), no a single base pair of variation has been found. The other three clades are composed of Y. multistriata, two subspecies of Y. multistirata and Y. akragas. To endorse the result from phylogenetic result, interbreeding is carried out. No reproductive boundary has been found among Y. esakii in southern Taiwan, Y. esakii in northern Taiwan, and NanYa form. It can be concluded they are the same species with different external morphological traits.