Geographic divergence pattern and morphological variability of the Japanese greater horseshoe bat

概要

Background
The Japanese greater horseshoe bat, Rhinolophus nippon Temminck, 1835, is widely occurring
from the Japanese Archipelago through the Korean Peninsula, to northeastern and southwestern China,
Sikkim, Nepal, and northern India. Previous phylogenetic studies revealed that R. nippon is a sister
species of R. ferrumequinum (Schreber, 1774) occurring from England through northeastern Africa,
western to eastern Europe, Crete, northeastern Iraq, Iran, Turkmenistan, Afghanistan, southern
Kazakhstan, to Kashmir. However, no qualitative and quantitative discriminant character between two
species has revealed. The current phylogenetic study of R. nippon revealed that Northeast Asian
lineage including populations from the Japanese Archipelago, the Korean Peninsula, northeastern
China, and those peripheral islands is the most recently diverged lineage, and the Japanese Archipelago
population has been considered the monophyletic clade on the basis of phylogenetic tree constructed
by cytochrome b and D-loop mitochondrial DNA (mtDNA). However, all Japanese specimens were
collected from eastern Japan and only sequenced cytochrome b region, and the specimens from
western Japan and Kyushu and other mtDNA region such as D-loop were lacked, so that the
monophyly of the Japanese Archipelago population has not been clear. Moreover, R. nippon in the
Japanese Archipelago has been reported the variation of echolocation call frequency of maximum
energy (PF) increasing from northern to southern Japan and peripheral island populations. In order to
answer this echolocational variation, previous study hypothesized the negative correlation between PF
and the body size, however, the other morphological study indicated that nasal capsule height and
pinna size is more suitable for the indicator of PF than forearm length, thus the PF variation is
considered to be promoted by the vocalization-related morphological variations.
In this dissertation, the author investigates three steps to solve taxonomic and phylogenetic
problems and to reveal the morphological variation of the unique cranium of R. nippon. First, finding
the morphological difference between R. nippon and R. ferrumequinum. Second, revealing the
monophyly of the Japanese Archipelago population of R. nippon. Third, revealing the echolocationrelated morphological variation and its variability, especially the variation on nasal swellings which
contains smooth and ridge structures and have been poorly understood.
Materials and Methods
In Chapter 2, the author conducts three morphological methods on their skulls: linear measurement of
nine cranial character; geometric morphometrics; evaluating diagnostic characters for the two species
by comparing skull photographs. ...