@phdthesis{Ostner2002,
  author    = {Ostner, Julia},
  title     = {Sex-specific reproductive strategies in redfronted lemurs (Eulemur fulvus rufus, Primates, Lemuridae)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-5011},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2002},
  abstract  = {The number of males in animal groups is an essential determinant of male and female reproductive strategies. Females may benefit from living with several males, whereas males generally strive to monopolize a group of females. Due to male intrasexual competition, the sex ratio of groups of anthropoid primates is generally female-biased. Gregarious Malagasy lemurs deviate from theoretical expectations derived from sexual selection theory and from patterns found among anthropoids because they live in relatively small groups with an even or male-biased adult sex ratio and lack sexual dimorphism. The aim of this thesis was to investigate sex-specific reproductive strategies relating to the unusual group composition of redfronted lemurs (Eulemur fulvus rufus) by combining behavioral, demographic and endocrinological data. In the first of a set of four studies I investigated the applicability of non-invasive endocrine measurements for monitoring ovarian function in wild redfronted lemur females in order to evaluate the degree of estrus synchrony. Further, I tested the prediction that males living in multi-male groups rely on indirect mechanisms of intrasexual competition, such as physiological suppression of testicular function. Several possible benefits gained from living with many males have been proposed and the hypothesis that additional males improve social thermoregulation was tested in the third study. Finally, I examined the proximate determinants of the unusual sex ratio within groups, the variation in the adult sex ratio as well as possible social benefits of the high number of males for both sexes. The study was conducted in Kirindy Forest, Madagascar, between April 1999 and July 2000. I recorded >3000 hours of focal animal data on social and sexual behavior of all adult members of five groups. Additionally, >2200 fecal samples of males and females were collected for subsequent hormone analysis using enzymeimmunoassay (EIA). Further, I analyzed demographic data from seven Eulemur fulvus rufus groups collected between 1996 and 2002. The analyses of fecal estrogen and progestogen excretion in wild and captive females revealed that monitoring ovarian function is principally possible in redfronted lemurs, as demonstrated by the analysis of samples from captive females. Characterization of ovarian cycles in wild females, however, was not possible, because of a high day-to-day variability in excreted hormones. Nevertheless, the study provided reliable information on gestation and cycle length as well as endocrine changes associated with gestation. Additionally, I established a method for prenatal sex determination using maternal fecal samples collected during late gestation. The excretion pattern of androgens in samples of males revealed no differences between dominant and subordinate males, indicating that dominant males did not suppress the endocrine function of subordinate rivals. High frequencies of matings in combination with large testes size suggest that male reproductive competition relies at least partly on sperm competition. Females did not benefit from the high number of males in their groups in terms of improved thermoregulation because surplus males did not participate frequently in huddling groups with females. Analysis of the demographic data revealed that birth and mortality rates were not sex-biased and that males migrated considerably more frequently than females, providing no proximate explanation for the unusual sex ratio. Females in this study may proximately regulate group composition by synchronizing their fertile periods, which were inferred indirectly from the temporal distribution of births within groups. Both males and females benefit from the high number of co-resident males because reduced male group size seemed to be the main predictor of take-over rate, and thus, infanticide risk. The results of these studies suggest that certain life history traits (fast maturation, short inter-birth intervals) may ultimately determine the high number of males and the lack of single-male groups seen in redfronted lemurs. An accelerated male life history may facilitate joint group transfers and take-overs of male coalitions without a transitional time outside bisexual groups. Because males and females both benefit from a high number of males the conflict of interests between the sexes is considerably defused.},
  subject      = {Rotstirnmaki},
  language  = {en}
}
@phdthesis{Schuelke2002,
  author    = {Sch{\"u}lke, Oliver},
  title     = {Living apart together},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-5029},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2002},
  abstract  = {Cohesiveness between members of a social unit is a defining characteristic of animal social organization. Dispersed social organizations, where members of a social unit spend the main part of their activity period apart, have only recently been distinguished from cohesive social organizations and are still poorly understood with respect to their ecological basis and reproductive consequences. The general goal of this dissertation was to study the three components of the social system of fork-marked lemurs (Phaner furcifer), a small nocturnal primate from Madagascar living in dispersed pairs. First, I characterise their social organization, focusing on behavioural mechanisms of cohesion between pair partners. Second, through application of van Schaik's ecological model, I investigate predictions about the ecological basis of female intra-sexual avoidance, male-female social relationships and the determinants of differential female reproductive success. Finally, I analyse behavioural and genetic aspects of the mating system to test a recent hypothesis that proposes high extra-pair paternity in dispersed primate pairs resulting from constraints on male mate guarding. The study was conducted in Kirindy Forest in Madagascar between September 1998 and April 2001 during three field seasons for a total of 20 months. During more than 1400 hours of focal animal protocols, I sampled year-round data on space use, feeding ecology, time budgets, and social behaviour of all adults and three subadults of 8 families, complemented by simultaneous focal follows of both pair partners, year-round information on sleeping site use, measures on food abundance in each territory, morphological measurements, and DNA-microsatellite data for seven newly discovered polymorphic loci. Across eight social units and three breeding seasons, pairs were the prevailing grouping pattern (18 of 21 family years). Most pairs were stable for more than three mating seasons and used well defined stable territories. Although both pair partners used the same territory in a fairly similar fashion, average distance between pair partners was 100m, which was far considering that many territories measure only 200m in diameter. Pair partners spent only about 20\% of activity time in less than 25m distance of each other and shared a sleeping site on average only every third day. Females were found to be dominant over their partner as well as over neighbouring males in all behavioural contexts. Most important food resources were exudates of a small number of tree species. Major food resources were distributed in small, defendable patches characterized by fast depletion and rapid renewal. In accordance with the ecological model, this led to strong within-group contest and scramble competition and weak between-group contest competition over food, as indicated by a positive dominance effect and a negative group size effect on female physical condition. Female reproductive success was determined mainly by family size. Paternity likelihood and exclusion analyses revealed that four out of seven offspring were most likely sired by an extra-pair male. Behaviour during the mating season implied that females as well as males take an active part in obtaining extra-pair copulations and that males try to guard their mates. Dispersed social organization in itself, i.e. low cohesion between pair partners, cannot explain high extra-pair paternity. I propose instead that several other factors common to most primates living in dispersed pairs constrain mate guarding and lead to high EPP. The ecological settings determine the mode of food competition and have shaped the social system of fork-marked lemurs in several ways. Intense within-group competition for food may have ultimately led to female intra-sexual avoidance and range exclusivity which represents an evolutionary precursor of pair-living. Although it remains elusive why females ultimately associated with single males, patterns of within-group contest competition for food explain why pair partners avoid each other during nocturnal activity. The limited number of food resources that is used in repetitive fashion and incomplete knowledge about the pair partners position explain why pair partners meet relatively often and why most encounters involve agonistic conflict. Rigid feeding itineraries characteristic of exudate feeders are likely to pose high costs to offspring dispersing to unfamiliar areas. Feeding ecology can, therefore, explain why parents tolerate delayed natal dispersal despite a negative effect on actual female reproductive success. In conclusion, the present study successfully applied existing socio-ecological theory to a new area of research, refined a recent evolutionary model and contributed important comparative data to our understanding of dispersed pairs in particular and primate and animal societies in general.},
  subject      = {Gabelstreifiger Katzenmaki},
  language  = {en}
}
@phdthesis{Kunz2008,
  author    = {Kunz, Britta K.},
  title     = {Frugivory and Seed Dispersal: Ecological Interactions between Baboons, Plants, and Dung Beetles in the Savanna-Forest Mosaic of West Africa},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37519},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {Das Guinea-Savanne-Wald-Mosaik Westafrikas weist einen hohen Reichtum an Pflanzenarten auf, deren Samen durch Frugivore ausgebreitet werden. Afrikanische Savannen beherbergen zudem die artenreichste Dungk{\"a}ferfauna weltweit. Dennoch wurden Interaktionen zwischen Fruchtpflanzen, Primaten und Dungk{\"a}fern in Savannen{\"o}kosysteme bisher kaum erforscht. Meine Untersuchungen am Anubispavian (Papio anubis Lesson 1827, Cercopithecinae) im Como{\´e} Nationalpark (CNP), im NO der Elfenbeink{\"u}ste, zeigten, dass sich westafrikanische Pavianpopulationen in verschiedener Hinsicht von Populationen in Ostafrika unterscheiden. Paviane werden zumeist vornehmlich als Pr{\"a}datoren der Samen ihrer Nahrungspflanzen angesehen. Im Savannen-Wald-Mosaik Westafrikas ern{\"a}hren sie sich jedoch {\"u}berwiegend frugivor und sind bedeutende Samenausbreiter einer Vielzahl von Geh{\"o}lzpflanzenarten mit unterschiedlichen Fruchttypen und Samengr{\"o}ßen. Sie breiten intakte Samen von mind. 22\% der regionalen Geh{\"o}lzpflanzenarten aus. Ihr "Ausbreitungspotential" bzgl. Samenzahl und Samengr{\"o}ße ist mit dem der großen Menschenaffen vergleichbar. Der Anteil der Baumarten im Nahrungsspektrum der Paviane ist signifikant h{\"o}her als es aufgrund des Anteils im regionalen Artenpool der Geh{\"o}lzpflanzen zu erwarten w{\"a}re. Fruchtarten, die von Pavianen gefressen wurden, waren signifikant gr{\"o}ßer als nicht konsumierte Arten. Von verschiedenen morphologischen Fruchtmerkmalen eignen sich Fruchttyp und Farbe am besten, um vorherzusagen, ob die Fr{\"u}chte einer Art Nahrungsbestandteil der Paviane im CNP sind. Fruchttyp und Samengr{\"o}ße wiederum sind am besten geeignet, um auf die Art der Nutzung (Samenausbreitung bzw. -pr{\"a}dation) zu schließen. Die Samengr{\"o}ße einer Pflanze ist ein wichtiges Fitnessmerkmal, das verschiedene Abschnitte von der Fruchtentwicklung bis zur Etablierung des Keimlings beeinflussen kann. Sie weist bei vielen Pflanzenarten erhebliche intraspezifische Schwankungen auf. Primaten k{\"o}nnten aus unterschiedlichen Gr{\"u}nden Fr{\"u}chte mit bestimmter Samengr{\"o}ße ausw{\"a}hlen, zum Beispiel um unverdaulichen Ballast zu reduzieren oder um den Fruchtfleischgewinn pro Frucht zu optimieren. Bei acht von zehn untersuchten Pflanzenarten, die sich in Fruchttyp, Samenzahl und Samengr{\"o}ße unterscheiden, erwiesen sich die Paviane als selektiv in Bezug auf die Samengr{\"o}ße. F{\"u}r die intraspezifische Fruchtauswahl der Paviane scheint unter anderem das je nach Frucht- und Samenform unterschiedlich variierende Verh{\"a}ltnis von Fruchtfleisch zu Samen eine Rolle zu spielen. Als Habitatgeneralisten (mit einer Pr{\"a}ferenz f{\"u}r Waldhabitate), die relativ große Gebiete durchstreifen, scheinen Paviane besonders wichtig f{\"u}r den genetischen Austausch der Pflanzen zwischen entfernten Waldinseln. Da die meisten Geh{\"o}lzpflanzenarten im Savannen-Wald-Mosaik des CNP mittelgroße bis große Fr{\"u}chte und Samen haben, kommt den Pavianen eine herausragende Rolle bei der Samenausbreitung und nat{\"u}rlichen Regeneration dieses {\"O}kosystems zu. Die Bedeutung der Paviane f{\"u}r die Samenausbreitung von Pflanzenarten mit kleinen Fr{\"u}chten sollte jedoch nicht untersch{\"a}tzt werden. Meine Untersuchungen an typischen "vogelausgebreiteten" Baumarten, von denen V{\"o}gel fast ausschließlich unreife Fr{\"u}chte fraßen, weisen darauf hin, dass eine qualitative und quantitative Beurteilung verschiedener Frugivorengruppen allein aufgrund der Fruchtsyndrome nicht immer zuverl{\"a}ssig ist. Anubispaviane breiten in der Regel mehrere Pflanzensamen in einzelnen F{\"a}zes aus was {\"u}blicherweise als ung{\"u}nstig f{\"u}r die Pflanze angesehen wird. Die Samen aller Pflanzenarten, die in Pavianf{\"a}zes im CNP w{\"a}hrend Zeiten saisonal hoher Dungk{\"a}feraktivit{\"a}t zu finden waren, k{\"o}nnen jedoch potentiell von Dungk{\"a}fern ausgebreitet werden. Die Dungk{\"a}fer-Aktivit{\"a}t im Untersuchungsgebiet an Pavianf{\"a}zes war hoch, es wurden 99 Arten aus 26 Gattungen nachgewiesen. Sowohl die Wahrscheinlichkeit sekund{\"a}rer Samenausbreitung durch Dungk{\"a}fer als auch das sekund{\"a}re r{\"a}umliche Ausbreitungsmuster h{\"a}ngen von der Struktur und Zusammensetzung der Dungk{\"a}fergemeinschaft am Ort der prim{\"a}ren Ausbreitung ab. Die Dungk{\"a}fergemeinschaft wiederum scheint stark von der Vegetation beeinflusst zu sein. Im Savannen-Wald-Mosaik Westafrikas erwartete ich daher deutliche Unterschiede in der sekund{\"a}ren Ausbreitung zwischen Samen, die von Pavianen in die Savanne bzw. in den Wald ausgebreitet werden. Experimente ergaben, dass Samen, die von Pavianen in die Savanne ausgebreitet werden, eine h{\"o}here Wahrscheinlichkeit haben (a) {\"u}berhaupt sekund{\"a}r durch Dungk{\"a}fer ausgebreitet zu werden, (b) horizontal von Telekopriden vom Ort der prim{\"a}ren Ausbreitung wegbewegt zu werden, (c) relativ schnell aus den F{\"a}zes entfernt zu werden und (d) {\"u}ber relativ gr{\"o}ßere Distanzen ausgebreitet zu werden als Samen im Wald. Generell sollten Savannenpflanzen und Habitatgeneralisten unter den Pflanzenarten, deren Samen von Pavianen in die Savanne ausgebreitet werden, am ehesten von sekund{\"a}rer Ausbreitung durch Dungk{\"a}fer profitieren.},
  subject      = {Anubispavian},
  language  = {en}
}