野生ウマにおける個体の空間配置

付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院京都大学新制・課程博士博士(理学)甲第23052号理博第4729号新制||理||1678(附属図書館)京都大学大学院理学研究科生物科学専攻(主査)教授 平田 聡, 教授 幸島 司郎, 教授 伊谷 原一学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDGA

Feral horses’ (Equus ferus caballus) behavior toward dying and dead conspecifics

In the rapidly expanding field of comparative thanatology, reports from a wide range of taxa suggest that some aspects of a concept of death may be shared by many non-human species. In horses, there are only a few anecdotal reports on behaviors toward dead conspecifics, mostly concerning domestic individuals. Here, we describe the case of a 2-month-old, free-ranging male foal that died around 12 h after being found severely injured due to a presumed wolf attack, focusing on other individuals' reactions to the dying foal. We also placed camera traps near horse carcasses to investigate reactions by other horses. Kin and non-kin of both sexes showed unusual interest in the dying foal. However, horses appeared to avoid dead conspecifics. Recording individual reactions to dead and dying conspecifics in naturalistic settings will enhance our knowledge about death-related behaviors in horses, allowing comparisons with other species that have been more thoroughly studied, to understand the evolutionary basis of these behaviors

Social determinants of affiliation and cohesion in a population of feral horses

Investigating affiliative behaviors (e.g. proximity, grooming, cooperative behaviors) is essential to understand group cohesion and stability in animal societies, as they may foster, or be fostered by long-term social bonds and ultimately determine an individual’s lifetime reproductive success. Despite growing interest in affiliative behaviors across a wide range of mammalian taxa, little focus has been given to feral horse populations. In this study, we examined the influence of dyadic social factors (sex, rank difference, familiarity and genetic relatedness) on affiliative behaviors and group cohesion. We collected data on 16 feral horse groups in Northern Portugal who were subjected to both predation pressures and anthropogenic interference. A combination of all occurrence sampling methods and drone technology was used to record the horses’ social behavior and spatial data. Same-sex dyads showed a preference to remain in close proximity, however they did not groom as frequently as different-sex dyads. Similar rank individuals were observed in proximity more often than non-similar rank individuals, but only in newly formed groups. Familiar individuals spent more time in proximity and groomed more often than unfamiliar (new) dyads. However, affiliation between conspecifics was not predicted by genetic relatedness. These results suggest that social bonds and group cohesion are mostly sustained by familiar individuals in both stable and newly formed groups. While maintaining close proximity may function to sustain bonds between same-sex individuals, grooming may reinforce both intra-sexual and inter-sexual bonds. Examining the variation of affiliation patterns on horse populations may shed light on their behavioral plasticity and have crucial implications for the welfare and conservation of horse breeds

Quantitative Estimate of CO2 Emission Reduction from Reuse of Automobile Parts in Japan

In general, reusing automobile parts reduces not only the cost of replacing the failed parts but also the environmental load of manufacturing new parts. However, these effects have not yet been quantified. The present study focuses on determining the emitted CO2 during production and quantitatively evaluating its reduction by the reuse of automobile parts. First, CO2 emissions are calculated during the reused parts production process at the factory site. Thirty-nine automobiles from 27 models prepared in Japan are examined to measure the amount of CO2 emitted in the production of new parts. Furthermore, the CO2 emission reduction effect for different automobile models is estimated through multiple regression analysis. The CO2 emissions are assumed to be the objective variable, whereas the explanatory variables are derived from the data provided in the automobile inspection certificates. The presented quantitative estimate of CO2 emission reduction owing to the exploitation of reused parts is expected to promote policies for further reducing CO2 emissions and arouse public awareness regarding the benefits of recycling automobile parts

Population Characteristics of Feral Horses Impacted by Anthropogenic Factors and Their Management Implications

Feral horses form relatively stable harems over time that are characterized by long-lasting bonds among their members, a characteristic that makes them an exceptional case of a social system among terrestrial ungulates. Their social system has been described as uniform despite the wide differences in their environment and demography. Horse populations subjected to human interference often show higher levels of population instability that can ultimately compromise their reproductive success. In this article, we describe demographic and dynamic changes of a Portuguese population of Garranos in Serra d’Arga (SA), which is impacted by human and predation pressures, over six breeding seasons. Furthermore, we tested several hypotheses related to the impact of anthropogenic disturbance on the structure and dynamics of this population. Our results revealed that the SA population had relatively little human interference at the start of the project in 2016. This was supported by the natural composition of the herd (total number of individuals, 206), which consisted of several single- and multi-male harems (n = 17 and 7, respectively) and bachelor males (n = 9). However, from 2017 to 2021, SA’s Garrano population suffered a drastic decline. Approximately two-thirds of the individuals and all bachelor males disappeared, and 76% of adult female transfers occurred after the death or disappearance of the harem male. Predatory pressures and poor management of the population, which allowed illegal human interference, contributed to this population crisis. A low population growth rate, reduced birth and foal survival rates, in addition to a delayed primiparous age were observed in this population and exacerbated after its drastic decline; suggesting the viability and survival of this Garrano population were compromised. Investigating the population demographic changes and their causes and consequences can provide guidelines for managing populations and help fight the extinction of horse breeds

Bacterial Degradation of Aromatic Compounds

Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms

Lateral position preference in grazing feral horses

Behavioural lateralisation is an effective way for animals to manage daily tasks by specialising behaviour to either side of the body. Many types of lateralisation are linked to the function of each brain hemisphere. Lateralisation of monitoring behaviour in mother–infant relationships occurs in a wide range of mammals, where infants frequently use their left eye to monitor their mother. However, few studies have focused on this type of spatial relationships among adults in daily life, such as during foraging. The present study focused on monitoring adult feral horse behaviour using quantitative analysis of spatial relationships, using drone technology. We found that horses form a localised spatial relationship with their nearest neighbour. Specifically, the nearest neighbour was located to the left rear of a target individual significantly more frequently than to the right rear. Furthermore, the nearest neighbour was less frequently located behind a target individual. We propose that this relationship is caused by a left‐eye preference, because information via the left eye predominantly proceeds to the right hemisphere, which is dominant for social processing

Spatial positioning of individuals in a group of feral horses: a case study using drone technology

Spatial positioning of individuals in animal groups has been studied from numerous perspectives. However, although many studies have focused on spatial position in flocks of birds and schools of fish, relatively few studies have been conducted in mammals with high accuracy. Because some mammal species form societies, we wondered how social relationships among mammals within a group influence each individual’s spatial position. To address this issue, we used drones to obtain accurate positioning of individuals in a feral horse group on the Serra D’ Arga mountain in Portugal. The results of our study revealed the following characteristics: (1) the male in between social and spatial relationships indicated that they are independent from each other. The present study is the first to reveal the characteristics of spatial positioning in a mammalian group using drone technology. The harem group was located in the periphery; (2) as in other species, individuals had areas of repulsion and attraction, and (3) nearest neighbors were located more toward the sides than to the back or front. We also measured the social relationships between individuals in terms of grooming frequency. Social network analyses of the correlation between social and spatial relationships indicated that they are independent from each other. The present study is the first to reveal the characteristics of spatial positioning in a mammalian group using drone technology

Functional reassignment of Cellvibrio vulgaris EpiA to cellobiose 2-epimerase and an evaluation of the biochemical functions of the 4-O-beta-d-mannosyl-d-glucose phosphorylase-like protein, UnkA

The aerobic soil bacterium Cellvibrio vulgaris has a beta-mannan-degradation gene cluster, including unkA, epiA, man5A, and aga27A. Among these genes, epiA has been assigned to encode an epimerase for converting d-mannose to d-glucose, even though the amino acid sequence of EpiA is similar to that of cellobiose 2-epimerases (CEs). UnkA, whose function currently remains unknown, shows a high sequence identity to 4-O-beta-d-mannosyl-d-glucose phosphorylase. In this study, we have investigated CE activity of EpiA and the general characteristics of UnkA using recombinant proteins from Escherichia coli. Recombinant EpiA catalyzed the epimerization of the 2-OH group of sugar residue at the reducing end of cellobiose, lactose, and beta-(1 -> 4)-mannobiose in a similar manner to other CEs. Furthermore, the reaction efficiency of EpiA for beta-(1 -> 4)-mannobiose was 5.5x10(4)-fold higher than it was for d-mannose. Recombinant UnkA phosphorolyzed beta-d-mannosyl-(1 -> 4)-d-glucose and specifically utilized d-glucose as an acceptor in the reverse reaction, which indicated that UnkA is a typical 4-O-beta-d-mannosyl-d-glucose phosphorylase