Genetic identification of bat species for pathogen surveillance across France

With more than 1400 chiropteran species identified to date, bats comprise one-fifth of all mammalian species worldwide. Many studies have associated viral zoonoses with 45 different species of bats in the EU, which cluster within 5 families of bats. For example, the Serotine bats are infected by European Bat 1 Lyssavirus throughout Europe while Myotis bats are shown infected by coronavirus, herpesvirus and paramyxovirus. Correct host species identification is important to increase our knowledge of the ecology and evolutionary pattern of bat viruses in the EU. Bat species identification is commonly determined using morphological keys. Morphological determination of bat species from bat carcasses can be limited in some cases, due to the state of decomposition or nearly indistinguishable morphological features in juvenile bats and can lead to misidentifications. The overall objective of our study was to identify insectivorous bat species using molecular biology tools with the amplification of the partial cytochrome b gene of mitochondrial DNA. Two types of samples were tested in this study, bat wing punches and bat faeces. A total of 163 bat wing punches representing 22 species, and 31 faecal pellets representing 7 species were included in the study. From the 163 bat wing punches tested, a total of 159 were genetically identified from amplification of the partial cyt b gene. All 31 faecal pellets were genetically identified based on the cyt b gene. A comparison between morphological and genetic determination showed 21 misidentifications from the 163 wing punches, representing ~12.5% of misidentifications of morphological determination compared with the genetic method, across 11 species. In addition, genetic determination allowed the identification of 24 out of 25 morphologically non-determined bat samples. Our findings demonstrate the importance of a genetic approach as an efficient and reliable method to identify bat species precisely.

Sexual dimorphism in bat wing morphology – variation among foraging styles

Sexual dimorphism can lead to differences in foraging style among conspecifics due to morphological differences. Within bats, maneuverability and speed of flight are influenced by wing shape and size, which may differ between sexes. Female bats gain about 30% of their body mass during pregnancy, affecting their agility and flight efficiency. To fill the same foraging niche as males, pregnant female bats would require wing size and/or shape modifications to maintain maneuverability. We investigated sexual dimorphism in bat wing morphology and how it varies among foraging guilds. Wing photos of male and female adult bats (19 species) in Canada, Belize, and Dominica were analyzed using 2D geometric morphometrics, wing loading, and aspect ratios. Nonpregnant female bats had higher wing loading than males, suggesting they are less maneuverable than males. Additionally, mass increases during pregnancy may not permit female bats to forage as male conspecifics do. Wing shape differed minimally among foraging guilds with only frugivores differing significantly, from all other guilds. Further studies should investigate how female bats forage during their reproductive cycle and determine how frugivore wings differ and whether there are individual differences in wing shape that are not consistent among bat species.

A proximal–distal difference in bat wing muscle thermal sensitivity parallels a difference in operating temperatures along the wing

Flight is a demanding form of locomotion, requiring fast activation and relaxation in wing muscles to produce the necessary wingbeat frequencies. Bats maintain high body temperatures during flight, but their wing muscles cool under typical environmental conditions. Because distal wing muscles are colder during flight than proximal muscles, we hypothesized that they would be less temperature sensitive to compensate for temperature effects, resulting in proximal–distal differences in temperature sensitivity that match differences in muscle operating temperature. We measured contractile rates across temperatures in the proximal pectoralis muscle and an interosseous in the handwing of Carollia perspicillata , a small neotropical fruit bat, and compared their thermal dependence with that of a forearm muscle measured in a previous study. We found that the contractile properties of the pectoralis were significantly more temperature sensitive than those of the distal muscles. This suggests that cooling of the distal wing muscles imposes a selective pressure on muscle contractile function which has led to shifts in temperature sensitivity. This study is the first to demonstrate differences in temperature sensitivity along the length of a single limb in an endotherm and suggests that temperature variation may be underappreciated as a determinant of locomotor performance in endotherms generally.

On a wing and a prayer: limitations and gaps in global bat wing morphology trait data

Species’ life history traits have a wide variety of applications in ecological and conservation research, particularly when assessing threats. The development and growth of global species trait databases are critical for improving trait-based analyses; however, it is vital to understand the gaps and biases of available data. Bats are an extremely diverse and widely distributed mammalian order, with many species facing local declines and extinction. We conducted a literature review for bat wing morphology, specifically wing loading and aspect ratio, to identify issues with data reporting and ambiguity. We collected data on field methodology, trait terminology, and data reporting and quality. We found several issues regarding semantic ambiguity in trait definitions and data reporting. Globally we found that bat wing morphology trait coverage was low. Only six bat families had over 40% trait coverage, and of those none consisted of more than 11 total species. We found similar biases in trait coverage across IUCN Redlist categories with threatened species having lower coverage. Geographically, North America, Europe, and the Indomalayan regions showed higher overall trait coverage, while both the Afrotropical and Neotropical ecoregions showed poor trait coverage. The underlying biases and gaps with bat wing morphology data have implications for researchers conducting global trait-based assessments. Implementing imputation techniques may address missing data, but only for smaller regional subsets with substantial trait coverage. However, due to the low overall trait coverage, increasing species representation in the database should be prioritized. We suggest adopting an Ecological Trait Standard vocabulary to reduce semantic ambiguity in bat wing morphology traits to improve data compilation and clarity. Additionally, we advocate that researchers adopt an Open Science approach to facilitate the growth of a bat wing morphology trait database.

Aerodynamic Performance of a Flapping Wing Inspired by Bats

Bio-inspiration is a design method where natural observation was used to solve a mechanical problem. In this study, a bio-inspiration meth-od was used to design a flapping wing for a Micro Air Vehicle (MAV) that is inspired by bat wings. The objective of this study is to study the aerodynamic performance of a flapping wing based on bat wings at different angles of attack. This is done using Computational Fluid Dynamics (CFD) simulation where the aerodynamic performance a wing derived from a natural bat wing shape was studied. The wing was generated by tracing the wing shape of a bat wing and the shape was generalized to produce the wing shape. In the simulation, a 2-way Fluid Structure Interaction (FSI) method was used where a Finite Element Analysis (FEA) solver was coupled with a CFD solver to simulate the wing during flapping flight. The flight condition was set at 1 m/s flight speed at a flapping frequency of 2.5Hz. From the results, it was shown that the wing has a zero-lift angle at 0o and a stall angle at 16o. It is also shown that the wing has a minimum drag angle at 3o and a maximum aerodynamic efficiency at angle of attack 12o.