Population and Conservation Status of the Flying Fox Pteropus dasymallus in Taiwan.

Pteropus dasymallus is widely distributed on islands throughout the western edge of the Pacific Ocean. The Formosan flying fox, P. d. formosus, is an endemic subspecies in Taiwan found mainly on Lyudao; it was previously thought to have been extirpated. Since 2005, intensive surveys have been conducted to investigate the residency, population size and plant resource utilization of P. dasymallus in Taiwan. Interviews were carried out to investigate its former abundance and the causes of population decline. In Taiwan, P. dasymallus is in a state of ongoing oceanic dispersal and colonization and has considerably expanded its geographic range. In addition to remaining in its historic habitat on Lyudao, P. dasymallus has also established colonies on Gueishan Island and in Hualien on Taiwan's main island in the past few decades. The total population size is estimated to be 240 individuals, and this number is on the rise. Approximately three-quarters of the entire population (73.64%) was found on Gueishan Island. The sex ratio was strongly skewed toward males. A total of 40 plant species were recorded as being used by the flying fox for food, roosts or perches. More agricultural and horticultural plant species were used by the flying fox in urban Hualien. According to the interviews, flying foxes were abundant on Lyudao, but their number dramatically declined from the 1970s to the mid-1980s, mainly due to commercial hunting. Maintaining a sufficient population size and genetic variability is fundamental to the long-term survival of the flying fox. Enforcing conservation laws, restoring habitats, controlling invasive species and improving public awareness are the main steps in the recovery and sustainability of the flying fox population.

ChiroVox: a public library of bat calls.

Recordings of bat echolocation and social calls are used for many research purposes from ecological studies to taxonomy. Effective use of these relies on identification of species from the recordings, but comparative recordings or detailed call descriptions to support identification are often lacking for areas with high biodiversity. The ChiroVox website (https://www.chirovox.org) was created to facilitate the sharing of bat sound recordings together with their metadata, including biodiversity data and recording circumstances. To date, more than 30 researchers have contributed over 3,900 recordings of nearly 200 species, making ChiroVox the largest open-access bat call library currently available. Each recording has a unique identifier that can be cited in publications; hence the acoustic analyses are repeatable. Most of the recordings available through the website are from bats whose species identities are confirmed, so they can be used to determine species in recordings where the bats were not captured or could not be identified. We hope that with the help of the bat researcher community, the website will grow rapidly and will serve as a solid source for bat acoustic research and monitoring.

Genetic Differentiation and Demographic Trajectory of the Insular Formosan and Orii's Flying Foxes.

Insular flying foxes are keystone species in island ecosystems due to their critical roles in plant pollination and seed dispersal. These species are vulnerable to population decline because of their small populations and low reproductive rates. The Formosan flying fox (Pteropus dasymallus formosus) is one of the 5 subspecies of the Ryukyu flying fox. Pteropus dasymallus formosus has suffered from a severe decline and is currently recognized as a critically endangered population in Taiwan. On the contrary, the Orii's flying fox (Pteropus dasymallus inopinatus) is a relatively stable population inhabiting Okinawa Island. Here, we applied a genomic approach called double digest restriction-site associated DNA sequencing to study these 2 subspecies for a total of 7 individuals. We detected significant genetic structure between the 2 populations. Despite their contrasting contemporary population sizes, both populations harbor very low degrees of genetic diversity. We further inferred their demographic history based on the joint folded site frequency spectrum and revealed that both P. d. formosus and P. d. inopinatus had maintained small population sizes for a long period of time after their divergence. Recently, these populations experienced distinct trajectories of demographic changes. While P. d. formosus suffered from a drastic ~10-fold population decline not long ago, P. d. inopinatus underwent a ~4.5-fold population expansion. Our results suggest separate conservation management for the 2 populations-population recovery is urgently needed for P. d. formosus while long-term monitoring for adverse genetic effects should be considered for P. d. inopinatus.

Postnatal growth and age estimation in Scotophilus kuhlii.

Adequate postnatal growth is important for young bats to develop skilled sensory and locomotor abilities, which are highly associated with their survival once independent. This study investigated the postnatal growth and development of Scotophilus kuhlii in captivity. An empirical growth curve was established, and the postnatal growth rate was quantified to derive an age-predictive equation. By further controlling the fostering conditions of twins, the differences in the development patterns between pups that received maternal care or were hand-reared were analyzed to determine whether the latter developed in the same manner as their maternally reared counterparts. Our results indicate that both forearm length and body mass increased rapidly and linearly during the first 4 weeks, after which the growth rate gradually decreased to reach a stable level. The first flight occurred at an average age of 39 days with a mean forearm length and body mass of 92.07% and 70.52% of maternal size, respectively. The developmental pattern of hand-reared pups, although similar to that of their maternally reared twin siblings, displayed a slightly faster growth rate in the 4th and 5th weeks. The heavier body mass of hand-reared pups during the pre-fledging period may cause higher wing loading, potentially influencing the flight performance and survival of the bats once independent.

Speciation processes in putative island endemic sister bat species: false impressions from mitochondrial DNA and microsatellite data.

Cases of geographically restricted co-occurring sister taxa are rare and may point to potential divergence with gene flow. The two bat species Murina gracilis and Murina recondita are both endemic to Taiwan and are putative sister species. To test for nonallopatric divergence and gene flow in these taxa, we generated sequences using Sanger and next-generation sequencing, and combined these with microsatellite data for coalescent-based analyses. MtDNA phylogenies supported the reciprocally monophyletic sister relationship between M. gracilis and M. recondita; however, clustering of microsatellite genotypes revealed several cases of species admixture suggesting possible introgression. Sequencing of microsatellite flanking regions revealed that admixture signatures stemmed from microsatellite allele homoplasy rather than recent introgressive hybridization, and also uncovered an unexpected sister relationship between M. recondita and the continental species Murina eleryi, to the exclusion of M. gracilis. To dissect the basis of these conflicts between ncDNA and mtDNA, we analysed sequences from 10 anonymous ncDNA loci with *beast and isolation-with-migration and found two distinct clades of M. eleryi, one of which was sister to M. recondita. We conclude that Taiwan was colonized by the ancestor of M. gracilis first, followed by the ancestor of M. recondita after a period of allopatric divergence. After colonization, the mitochondrial genome of M. recondita was replaced by that of the resident M. gracilis. This study illustrates how apparent signatures of sympatric divergence can arise from complex histories of allopatric divergence, colonization and hybridization, thus highlighting the need for rigorous analyses to distinguish between such scenarios.

Comparative rangewide phylogeography of four endemic Taiwanese bat species.

Phylogeographic reconstructions of codistributed taxa can help reveal the interplay between abiotic factors, such as altitude and climate, and species-specific attributes, in shaping patterns of population genetic structure. Recent studies also demonstrate the value of both rangewide sampling and species distribution modelling (SDM) in comparative phylogeography. Here, we combine these approaches to study the population histories of four phylogenetically related forest-dependent bat species. All are endemic to the mountainous island of Taiwan but show differences in their tolerance to altitude, with Murina gracilis considered to be a high-altitude specialist, M. recondita and Kerivoula sp. low-altitude specialists, and M. puta an altitudinal generalist. We tested the prediction that contrasting habitat preferences would impact on patterns of past and contemporary gene flow and found broad concordance between the results of population genetic analyses and species distribution models based on the Model for Interdisciplinary Research on Climate. Both lowland species showed evidence of genetic divergence between the east and west of the island, consistent with SDMs that indicated the Central Mountain Range (CMR) has presented a long-term and continuous barrier to gene flow since before the Last Glacial Maximum. In contrast, Murina gracilis and M. puta showed lower degrees of historical isolation and genetic differentiation associated with the CMR, reflecting greater gene flow, possibly coupled with past population growth in M. puta. Together our results highlight the usefulness of combining distribution models with phylogeographic analyses to understand the drivers of genetic structure.

Determinants of echolocation call frequency variation in the Formosan lesser horseshoe bat (Rhinolophus monoceros).

The origin and maintenance of intraspecific variation in vocal signals is important for population divergence and speciation. Where vocalizations are transmitted by vertical cultural inheritance, similarity will reflect co-ancestry, and thus vocal divergence should reflect genetic structure. Horseshoe bats are characterized by echolocation calls dominated by a constant frequency component that is partly determined by maternal imprinting. Although previous studies showed that constant frequency calls are also influenced by some non-genetic factors, it is not known how frequency relates to genetic structure. To test this, we related constant frequency variation to genetic and non-genetic variables in the Formosan lesser horseshoe bat (Rhinolophus monoceros). Recordings of bats from across Taiwan revealed that females called at higher frequencies than males; however, we found no effect of environmental or morphological factors on call frequency. By comparison, variation showed clear population structure, with frequencies lower in the centre and east, and higher in the north and south. Within these regions, frequency divergence was directional and correlated with geographical distance, suggesting that call frequencies are subject to cultural drift. However, microsatellite clustering analysis showed that broad differences in constant frequency among populations corresponded to discontinuities in allele frequencies resulting from vicariant events. Our results provide evidence that the processes shaping genetic subdivision have concomitant consequences for divergence in echolocation call frequency.

Population genetic structure and demographic history of the endemic Formosan lesser horseshoe bat (Rhinolophus monoceros).

Intraspecific phylogenies can provide useful insights into how populations have been shaped by historical and contemporary processes. Taiwan formed around 5 million years ago from tectonic uplift, and has been connected to mainland Asia several times since its emergence. A central mountain range runs north to south, bisecting the island, and potentially impedes gene flow along an east-west axis. The Formosan lesser horseshoe bat (Rhinolophus monoceros) is endemic to Taiwan, where it is found mainly at low altitude. To determine the population structure and the demographic and colonization history of this species, we examined variation in the mitochondrial DNA control region in 203 bats sampled at 26 sites. We found very high haplotype and nucleotide diversity, which decreased from the centre to the south and north. Population differentiation followed a pattern of isolation by distance, though most regional genetic variance was attributable to differences between the relatively isolated southern population and those from other regions. A haplotype network was consistent with these findings and also suggested a southward colonization, followed by subsequent secondary contact between the south and other regions. Mismatch distributions were used to infer a past population expansion predating the last glacial maximum, and a neighbour-joining tree showed that R. monoceros formed a monophyletic grouping with respect to its sister taxa. Taken together, our results suggest that this taxon arose from a single period of colonization, and that demographic growth followed in the late Pleistocene. Current genetic structure reflects limited gene flow, probably coupled with stepwise colonization in the past. We consider explanations for the persistence of the species through multiple glacial maxima.