Evolution von Miniaturisierung in arktisch-alpinen Lebensräumen in Petasites Mill., Endocellion Turcz. ex Herder, Homogyne Cass. und Tussilago L. (Asteraceae) sowie Soldanella L. (Primulaceae)

Hintergrund: Miniaturisierung ist ein häufig beobachtetes Phänomen bei Pflanzen in arktisch-alpinen Lebensräumen und wird als Anpassung an niedrige Jahresmitteltemperaturen und eine kurze Vegetationsperiode interpretiert. Ziele: In der vorliegenden Arbeit wird im Petasites-Clade (Petasites Mill., Endocellion Turcz. ex Herder, Homogyne Cass., Tussilago L.; Asteraceae) und in Soldanella (Primulaceae) die Evolution der Miniaturisierung arktisch-alpiner Arten untersucht. Zudem wird innerhalb von Homogyne untersucht, ob unterschiedliche edaphische Präferenz von H. alpina (variabel) und H. discolor (kalkliebend) genetisch fixiert ist. rnMethoden: Molekulare Phylogenien des Petasites-Clades und von Soldanella wurden mit nukleären und plastidären Markern erstellt, und mit den in den Alpen vorkommenden Soldanella-Arten wurde zudem eine Fingerprint-Studie (AFLPs) gemacht. Zur Datierung der Diversifizierungsereignisse im Petasites-Clade diente eine molekulare Uhr, und die Evolution von Miniaturisierung wurde rekonstruiert. Mit H. alpina und H. discolor wurde ein vergleichendes Kulturexperiment durchgeführt.rnErgebnisse: Miniaturisierung entstand mehrere Male unabhängig voneinander in den arktisch-alpinen Vertretern des Petasites-Clade, aber nicht alle arktisch-alpinen Arten sind klein. Das Alter der arktisch-alpinen Arten deutet darauf hin, dass diese Taxa ihren Ursprung in der arkto-tertiären Flora haben. In Soldanella sind reduzierte Blütenmorphologie sowie Kleinwüchsigkeit der beiden alpinen Arten zweimal parallel entstanden. Homogyne alpina und H. discolor zeigen keine edaphischen Unterschiede hinsichtlich des Keimverhaltens, aber in Kultur zeigt sich, dass die Präferenz von H. discolor für Kalk wahrscheinlich genetisch fixiert ist.rnSchlussfolgerungen: Miniaturisierung von Pflanzen in größerer Höhe und höherer geographischer Breite kann in der Regel beobachtet werden. Allerdings kann die Evolution arktisch-alpiner Arten auch durch Faktoren wie Nährstoffverfügbarkeit, Konkurrenz und Störung beeinflusst werden, die dem Effekt der Temperatur entgegenwirken, so dass nicht alle Pflanzen in arktisch-alpinen Habitaten klein sind. Blütenmorphologische Reduktion in Soldanella kann als Anpassung an einen höheren Grad an Selbstbestäubung interpretiert werden, um eine geringere Bestäuberaktivität im alpinen Lebensraum zu kompensieren.

The prehistoric inhabitants of the Wadi Howar : an anthropological study of human skeletal remains from the Sudanese part of the Eastern Sahara

All currently available human skeletal remains from the Wadi Howar (Eastern Sahara, Sudan) were employed in an anthropological study. The study’s first aim was to describe this unique 5th to 2nd millennium BCE material, which comprised representatives of all three prehistoric occupation phases of the region. Detecting diachronic differences in robusticity, occupational stress levels and health within the spatially, temporally and culturally heterogeneous sample was its second objective. The study’s third goal was to reveal metric and non-metric affinities between the different parts of the series and between the Wadi Howar material and other relevant prehistoric as well as modern African populations. rnThe reconstruction and comprehensive osteological analysis of 23 as yet unpublished individuals, the bulk of the Wadi Howar series, constituted the first stage of the study. The analyses focused on each individual’s in situ position, state of preservation, sex, age at death, living height, living weight, physique, biological ancestry, epigenetic traits, robusticity, occupational stress markers, health and metric as well as morphological characteristics. Building on the results of these efforts and the re-examination of the rest of the material, the Wadi Howar series as a whole, altogether 32 individuals, could be described. rnA wide variety of robusticity, occupational stress and health variables was evaluated. The pre-Leiterband (hunter-gatherer-fisher/hunter-gatherer-fisher-herder) and the Leiterband (herder-gatherer) data of over a third of these variables differed statistically significantly or in tendency from each other. The Leiterband sub-sample was characterised by higher enamel hypoplasia frequencies, lower mean ages at death and less pronounced expressions of occupational stress traits. This pattern was interpreted as evidence that the adoption and intensification of animal husbandry did probably not constitute reactions to worsening conditions. Apart from that, the relevant observations, noteworthy tendencies and significant differences were explained as results of a broader spectrum of pre-Leiterband subsistence activities and the negative side effects of the increasingly specialised herder-gatherer economy of the Leiterband phase. rnUsing only the data which could actually be collected from it, multiple, separate, individualised discriminant function analyses were carried out for each Wadi Howar skeleton to determine which prehistoric and which modern comparative sample it was most similar to. The results of all individual analyses were then summarised and examined as a whole. Thus it became possible to draw conclusions about the affinities the Wadi Howar material shared with prehistoric as well as modern populations and to answer questions concerning the diachronic links between the Wadi Howar’s prehistoric populations. When the Wadi Howar remains were positioned in the context of the selected prehistoric (Jebel Sahaba/Tushka, A-Group, Malian Sahara) and modern comparative samples (Southern Sudan, Chad, Mandinka, Somalis, Haya) in this fashion three main findings emerged. Firstly, the series as a whole displayed very strong affinities with the prehistoric sample from the Malian Sahara (Hassi el Abiod, Kobadi, Erg Ine Sakane, etc.) and the modern material from Southern Sudan and, to a lesser extent, Chad. Secondly, the pre-Leiterband and the Leiterband sub-sample were closer to the prehistoric Malian as well as the modern Southern Sudanese material than they were to each other. Thirdly, the group of pre-Leiterband individuals approached the Late Pleistocene sample from Jebel Sahaba/Tushka under certain circumstances. A theory offering explanations for these findings was developed. According to this theory, the entire prehistoric population of the Wadi Howar belonged to a Saharo-Nilotic population complex. The Jebel Sahaba/Tushka population constituted an old Nilotic and the early population of the Malian Sahara a younger Saharan part of this complex. The pre-Leiterband groups probably colonised the Wadi Howar from the east, either during or soon after the original Saharo-Nilotic expansion. Unlike the pre-Leiterband groups, the Leiterband people originated somewhere west of the Wadi Howar. They entered the region in the context of a later, secondary Saharo-Nilotic expansion. In the process, the incoming Leiterband groups absorbed many members of the Wadi Howar’s older pre-Leiterband population. The increasing aridification of the Wadi Howar region ultimately forced its prehistoric inhabitants to abandon the wadi. Most of them migrated south and west. They, or groups closely related to them, probably were the ancestors of the majority of the Nilo-Saharan-speaking pastoralists of modern-day Southern Sudan and Eastern Chad.