An Atlas of hair from southern African mammal species with reference to its taxonomic and ecological significance

Abstract

ENGLISH: This thesis is a study of the microstructure of hair of southern African mammals, in particular of the Carnivora. It serves to fill a gap in knowledge of hair studies from this region, and points to the use of these studies in various fields. A major portion of the work is a hair atlas of southern African Carnivora, in which micrographs and coloured plates of hairs are presented with locality data and a descriptive text for each species. Although the findings of the atlas do not lend themselves to the formation of dichotomous key, it serves as a reference system and has proved useful in the identification of hairs from selected study areas where species distribution is defined. This is intended to form part of a comprehensive atlas which will include examples of all southern African mammal species. Techniques for studying hair structure are discussed and the micrographs of both thin and thick cross-sections are included to demonstrate the results of different methods used. The taxonomic importance of hair identification is well known and examples of this are discussed , mainly in regard to the smaller mammals, such as the Muridae. The extent to which hair morphology can be used as a taxonomic criterion varies with various groups however, but more often than not, by using a combination of parameters it is possible to differentiate many species. The identification of unknown hair samples has been discussed, with special reference to the highly practical field of epidemiology. Examples of both laboratory investigations, as well as field surveillance, in which hair identification is used have been cited as an important aspect of hair studies. The extent to which hair is related to ecology forms a broad field of study, and for this reason those situations where ecologically selective pressures are more clearly defined have been chosen for particular mention. Thus the aquatic habitat and the desert environment are discussed with reference to the hair types such as guard hairs, underfur, and the microstructure of hair as well as its mechanical and surface properties. Thermoregulation is referred to and arising out of this aspect a hypothesis is presented in which the part played by the medulla in the absorption of longwave infrared radiation is discussed.AFRIKAANS : Hierdie proefskrif handel oor 'n studie van die mikrostruktuur van die hare van soogdiere van suidelike Afrika en in besonder die van karnivore. Dit vul 'n leemte aan in ons kennis ocr haarstudies in hierdie gebied en dui op die gebruike van hierdie studies op verskillende terreine. 'n Groot deel van die werkstuk word beslaan deur 'n haaratlas van die karnivore van suidelike Afrika waarin mikrofotos en kleurplate van hare tesame met lokaliteitsdata en beskrywende teks vir elke spesie aangebied word. Alhoewel die bevindinge aangebied in die atlas hulle nie leen tot die opstelling van 'n tweedelige identifikasiesleutel nie, dien die atlas wel as 'n nuttige hulpmiddel vir die identifikasie van hare in sekere areas waar spesieverspreiding bekend is. Hierdie resultate sal uiteindelik deel uitmaak van 'n omvattende atlas oor die hare van soogdierspesies in suidelike Afrika . Tegnieke vir die studie van haarstruktuur word bespreek en mikrofotos van beide dun en dik dwarsnitte word ingesluit om die resultate wat met die verskillende metodes verkry is, te demonstreer. Die taksonomiese belang van haaridentifikasie is welbekend en voorbeelde hiervan word bespreek, veral wat die kleiner soogdier betref soos die Muridae. Die mate waartoe haarmorfologie as taksonomiese maatstaf gebruik kan word, varieer egter in die verskillende groepe maar gewoonlik, deur die gebruik van verskillende parameters, is dit moontlik om tussen baie spesies te onderskei. Identifikasie van haarmonsters van onbekende oorsprong word bespreek met spesiale verwysing na die hoogs praktiese veld van epidemiologie. Voorbeelde van laboratoriumondersoeke sowel as veldopnames waar haaridentifikasie gebruik is, word aangehaal as ‘n belangrike faset van haarstudies. Die verband tussen hare en ekologie behels ‘n breë studieveld en om die rede is toestande waar ekologiese selektiewe druk meer duidelik gedefineer is spesiaal vermeld. Die akwatiese habitat en woestynomgewing word dus bespreek met verwysing na haartipes soos beskermhare, onderpels en die mikrostruktuur van hare sowel as die meganiese en oppervlakte-eienskappe van hare. Daar word na termoregulering verwys en voortspruitend daaruit word 'n hipotese voorgestel waarin die bydrae van die medulla in die absorpsie van lang infra-rooi-radiasie bespreek word. Copyright