Lennart W Pyritz

Publications of Lennart W Pyritz

• Reaching a Consensus: Terminology and Concepts Used in Coordination and Decision-Making Research.

  Authors: Lennart W Pyritz, Andrew J King, Cédric Sueur, Claudia Fichtel

  International journal of primatology. 12/2011; 32(6):1268-1278.

  Research on coordination and decision-making in humans and nonhuman primates has increased considerably throughout the last decade. However, terminology has been used inconsistently, hampering theResearch on coordination and decision-making in humans and nonhuman primates has increased considerably throughout the last decade. However, terminology has been used inconsistently, hampering the broader integration of results from different studies. In this short article, we provide a glossary containing the central terms of coordination and decision-making research. The glossary is based on previous definitions that have been critically revised and annotated by the participants of the symposium "Where next? Coordination and decision-making in primate groups" at the XXIIIth Congress of the International Primatological Society (IPS) in Kyoto, Japan. We discuss a number of conceptual and methodological issues and highlight consequences for their implementation. In summary, we recommend that future studies on coordination and decision-making in animal groups do not use the terms "combined decision" and "democratic/despotic decision-making." This will avoid ambiguity as well as anthropocentric connotations. Further, we demonstrate the importance of 1) taxon-specific definitions of coordination parameters (initiation, leadership, followership, termination), 2) differentiation between coordination research on individual-level process and group-level outcome, 3) analyses of collective action processes including initiation and termination, and 4) operationalization of successful group movements in the field to collect meaningful and comparable data across different species.

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• Coordination of Group Movements in Wild Red-fronted Lemurs (Eulemur rufifrons): Processes and Influence of Ecological and Reproductive Seasonality.

  Authors: Lennart W Pyritz, Peter M Kappeler, Claudia Fichtel

  International journal of primatology. 12/2011; 32(6):1325-1347.

  Group-living species have to coordinate collective actions to maintain cohesion. In primates, spatial movements represent a meaningful model to study group coordination processes across differentGroup-living species have to coordinate collective actions to maintain cohesion. In primates, spatial movements represent a meaningful model to study group coordination processes across different socio-ecological contexts. We studied 4 groups of red-fronted lemurs (Eulemur rufifrons) in Kirindy Forest, Madagascar, between 2008 and 2010 across different ecological and reproductive seasons. We collected data on ranging patterns using GPS collars and observational data on different predefined parameters of group movements, including initiation, leadership, followership, overtaking events, termination, and travel distances. Cohesion of these relatively small, egalitarian lemur groups was high year-round, but daily path length and home range size varied considerably between ecological seasons, presumably due to long-distance migrations of some groups at the beginning of the rainy season. Individuals of different age and sex classes successfully initiated group movements. However, stable female leadership prevailed year-round, irrespective of ecological and reproductive season, which might be due to higher or more specific energetic requirements of reproduction. In contrast to lemur species with a more despotic social structure, female red-fronted lemurs did not recruit more followers than males. Adult leaders recruited more followers than subadult ones. Further, recruitment success was higher during the peak of the dry season, when predation risk appeared to be higher. Distances of single group movements did not depend on the initiator's sex and age or on ecological seasons. Our results provide new insights into seasonal variability of coordination processes and the role of social dominance in lemur group movements, thereby contributing to a comparative perspective from a primate radiation that evolved group living independently of anthropoids.

• Effects of Habitat Structure and Fragmentation on Diversity and Abundance of Primates in Tropical Deciduous Forests in Bolivia.

  Authors: Lennart W Pyritz, Anna B S Büntge, Sebastian K Herzog, Michael Kessler

  International journal of primatology. 10/2010; 31(5):796-812.

  Habitat structure and anthropogenic disturbance are known to affect primate diversity and abundance. However, researchers have focused on lowland rain forests, whereas endangered deciduous forestsHabitat structure and anthropogenic disturbance are known to affect primate diversity and abundance. However, researchers have focused on lowland rain forests, whereas endangered deciduous forests have been neglected. We aimed to investigate the relationships between primate diversity and abundance and habitat parameters in 10 deciduous forest fragments southeast of Santa Cruz, Bolivia. We obtained primate data via line-transect surveys and visual and acoustic observations. In addition, we assessed the vegetation structure (canopy height, understory density), size, isolation time, and surrounding forest area of the fragments. We interpreted our results in the context of the historical distribution data for primates in the area before fragmentation and interviews with local people. We detected 5 of the 8 historically observed primate species: Alouatta caraya, Aotus azarae boliviensis, Callithrix melanura, Callicebus donacophilus, and Cebus libidinosus juruanus. Total species number and detection rates decreased with understory density. Detection rates also negatively correlated with forest areas in the surroundings of a fragment, which may be due to variables not assessed, i.e., fragment shape, distance to nearest town. Observations for Alouatta and Aotus were too few to conduct further statistics. Cebus and Callicebus were present in 90% and 70% of the sites, respectively, and their density did not correlate with any of the habitat variables assessed, signaling high ecological plasticity and adaptability to anthropogenic impact in these species. Detections of Callithrix were higher in areas with low forest strata. Our study provides baseline data for future fragmentation studies in Neotropical dry deciduous forests and sets a base for specific conservation measures.

• Visual attention to plain and ornamented human bodies: an eye-tracking study.

  Authors: Silke Wohlrab, Bernhard Fink, Lennart W Pyritz, Moritz Rahlfs, Peter M Kappeler

  Perceptual and motor skills. 07/2007; 104(3 Pt 2):1337-49.

  Signaling mate quality through visual adornments is a common phenomenon in animals and humans. However, humans are probably the only species who applies artificial ornaments. Such deliberateSignaling mate quality through visual adornments is a common phenomenon in animals and humans. However, humans are probably the only species who applies artificial ornaments. Such deliberate alterations of the skin, e.g., tattoos and scarring patterns, have been discussed by researchers as potential handicap signals, but there is still very little information about a potential biological signaling value of body modification. In this study eye-tracking was employed to investigate the signaling value of tattoos and other body modification. Measurement of gaze duration of 50 individuals while watching plain, scarred, accessorized, and tattooed bodies of artificial human images indicated that participants looked significantly longer at tattooed than at scarred, accessorized, and plain bodies. Generally, male participants paid more attention to tattooed stimuli of both sexes. More detailed analyses showed that particularly female tattooed stimuli were looked at longer. These findings are discussed within an evolutionary framework by suggesting that tattoos might have some signaling value which influences the perception of both male and female conspecifics and may hence also affect mating decisions.