Publications by authors named "Jorg U Ganzhorn"

Article Synopsis
  • * The article proposes a comprehensive approach to accurately define species boundaries, using integrated evidence and focusing on geographic isolation, specifically applied to the mouse lemurs, a debated group of primates.
  • * The study reveals that previous estimates of species diversity were inflated, mainly mistaking geographic variation for new species, and suggests that a clearer understanding of species limits can inform better conservation strategies.
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We present the first open-access, island-wide isotopic database (IsoMad) for modern biologically relevant materials collected on Madagascar within the past 150 years from both terrestrial and nearshore marine environments. Isotopic research on the island has increasingly helped with biological studies of endemic organisms, including evaluating foraging niches and investigating factors that affect the spatial distribution and abundance of species. The IsoMad database should facilitate future work by making it easy for researchers to access existing data (even for those who are relatively unfamiliar with the literature) and identify both research gaps and opportunities for using various isotope systems to answer research questions.

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Objectives: The investigation of morphological variation in animals is widely used in taxonomy, ecology, and evolution. Using large datasets for meta-analyses has dramatically increased, raising concerns about dataset compatibilities and biases introduced by contributions of multiple researchers.

Materials And Methods: We compiled morphological data on 13 variables for 3073 individual mouse lemurs (Cheirogaleidae, Microcebus spp.

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Adenoviruses (AdVs) are important human and animal pathogens and are frequently used as vectors for gene therapy and vaccine delivery. Surprisingly, there are only scant data regarding primate AdV origin and evolution, especially in the most basal primate hosts. We detect and sequence AdVs from faeces of two Madagascan lemur species.

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Background: Fleshy fruits evolved to be attractive to seed dispersers through various signals such as color and scent. Signals can evolve through different trajectories and have various degrees of reliability. The strongest substrate on which reliable signals can evolve is when there is an inherent link between signal and reward, rendering cheating costly or impossible.

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Among mammals, the order Primates is exceptional in having a high taxonomic richness in which the taxa are arboreal, semiterrestrial, or terrestrial. Although habitual terrestriality is pervasive among the apes and African and Asian monkeys (catarrhines), it is largely absent among monkeys of the Americas (platyrrhines), as well as galagos, lemurs, and lorises (strepsirrhines), which are mostly arboreal. Numerous ecological drivers and species-specific factors are suggested to set the conditions for an evolutionary shift from arboreality to terrestriality, and current environmental conditions may provide analogous scenarios to those transitional periods.

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Article Synopsis
  • Microsatellites have been widely used to study genetic diversity but their high mutation rates can create uncertainty in deeper evolutionary analyses, particularly in hybridization studies.
  • This study employed RADseq data to investigate interspecific hybridization in a contact zone between two mouse lemur species in Madagascar, re-evaluating earlier findings suggesting hybridization based on microsatellite data.
  • Findings showed no evidence of hybrid ancestry, indicating that previous claims of hybrid individuals were likely false positives, leading to the conclusion that the two species are fully reproductively isolated and changing our understanding of how reproducible isolation occurs in primates.
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Parasitic infections disturb gut microbial communities beyond their natural range of variation, possibly leading to dysbiosis. Yet it remains underappreciated that most infections are accompanied by one or more co-infections and their collective impact is largely unexplored. Here we developed a framework illustrating changes to the host gut microbiome following single infections, and build on it by describing the neutral, synergistic or antagonistic impacts on microbial α- and ß-diversity expected from co-infections.

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Increasing anthropogenic disturbances in Madagascar are exerting constrains on endemic Malagasy lemurs and their habitats, with possible effects on their health and survival. An important component of health is the gut microbiome, which might be disrupted by various stressors associated with environmental change. We have studied the gut microbiome of gray-brown mouse lemurs (), one of the smallest Malagasy primates and an important model of the convergent evolution of diseases.

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Until recently, the study of major histocompability complex (MHC) mediated immunity has focused on the direct link between MHC diversity and susceptibility to parasite infection. However, MHC genes can also influence host health indirectly through the sculpting of the bacterial community that in turn shape immune responses. We investigated the links between MHC class I and II gene diversity gut microbiome diversity and micro- (adenovirus, AdV) and macro- (helminth) parasite infection probabilities in a wild population of non-human primates, mouse lemurs of Madagascar.

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Diel activity patterns of animal species reflect constraints imposed by morphological, physiological, and behavioral trade-offs, but these trade-offs are rarely quantified for multispecies assemblages. Based on a systematic year-long camera-trap study in the species-rich mammal assemblage of Lake Manyara National Park (Tanzania), we estimated activity levels (hours active per day) and circadian rhythms of 17 herbivore and 11 faunivore species to determine the effects of body mass and trophic level on activity levels and cathemerality (the degree to which species are active throughout the day and night). Using generalized least squares and phylogenetic generalized least squares analyses, we found no support for the hypothesis that trophic level is positively associated with activity levels.

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Forest restoration is a prime goal within the 2021-2030 UN "Decade of Ecosystem Resoration". As part of these activities, natural regeneration has to be promoted for biological as well as for economic reasons. For this, the processes of seed dispersal, seed predation and germination have to be understood in the original as well as in degraded vegetation formations.

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Traditional socio-ecological models consider that folivorous primates experience limited feeding competition due to the low quality, high abundance, and even distribution of leaves. Evidence from several folivorous species that experience similar constraints to frugivores does not support this hypothesis. The sympatric lemur genera Avahi (Indriidae) and Lepilemur (Lepilemuridae) are good models to understand how food availability constrains folivores since they are both nocturnal, folivorous, and have a comparable body mass.

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Thorough knowledge of the ecology of a species or population is an essential prerequisite for understanding the impact of ecology on the evolution of their respective social systems. Because of their diversity of social organizations, baboons ( spp.) are a useful model for comparative studies.

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Little is known about the presence of vector-borne bacteria in southwest Madagascar. Anthropogenic alteration of natural habitats represents an important driver for the emergence of new diseases. Especially the involvement of livestock and the involuntary maintaining of invasive synanthropic animals (particularly rats) facilitate disease transmission from wildlife to humans and associated animals and vice versa.

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Plant species with fleshy fruits offer animals rewards such as sugar, protein, and fat, to feed on their fruits and disperse their seeds. They have also evolved visual and olfactory signals indicating their presence and ripeness.In some systems, fruit color serves as a reliable visual signal of nutrient content.

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Adenovirus (AdV) infections are one of the main causes of diarrhea in young children. Enteric AdVs probably disrupt gut microbial defences, which can result in diarrhea. To understand the role of the gut microbiome in AdV-induced pathologies, we investigated the gut microbiome of a naturally AdV-infected non-human primate species, the Malagasy mouse lemur (Microcebus griseorufus), which represents an important model in understanding the evolution of diseases.

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Human encroachment of natural habitats bears the threat of disease transmission between native and introduced species that had not come into contact before, thus promoting the spread of new diseases in both directions. This is a matter of concern especially in areas where human-wildlife contact has not been intense in the recent past. In southwest Madagascar, we collected ectoparasites from various mammalian hosts and chicken, and examined their host preferences and their prevalence in relation to season and habitat degradation.

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Long-term genetic monitoring of populations is essential for efforts aimed at preserving genetic diversity of endangered species. Here, we employ a framework of long-term genetic monitoring to evaluate the effects of fragmentation and the effectiveness of the establishment of corridors in restoring population connectivity and genetic diversity of mouse lemurs . To this end, we supplement estimates of neutral genetic diversity with the assessment of adaptive genetic variability of the major histocompatibility complex (MHC).

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Objectives: Geophagy has several hypothesized functions, among them (1) detoxification of plant secondary compounds, for example, tannins, (2) buffering stomach pH to alleviate acidosis caused by high sugar intake, and (3) supplementing the diet with mineral nutrients. We tested these hypotheses in Nepal gray langurs (Semnopithecus schistaceus), a foregut fermenter for which fruits and leaves dominate the diet at different times of the year.

Materials And Methods: We collected data on feeding time per food item for 21 unprovisioned adult langurs at Ramnagar, Nepal, for 1 year using instantaneous sampling (773 observation hours).

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The uneven representation of frugivorous mammals and birds across tropical regions - high in the New World, low in Madagascar and intermediate in Africa and Asia - represents a long-standing enigma in ecology. Several hypotheses have been proposed to explain these differences but the ultimate drivers remain unclear. Here, we tested the hypothesis that fruits in Madagascar contain insufficient nitrogen to meet primate metabolic requirements, thus constraining the evolution of frugivory.

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Phylogeographic analysis can be described as the study of the geological and climatological processes that have produced contemporary geographic distributions of populations and species. Here, we attempt to understand how the dynamic process of landscape change on Madagascar has shaped the distribution of a targeted clade of mouse lemurs (genus Microcebus) and, conversely, how phylogenetic and population genetic patterns in these small primates can reciprocally advance our understanding of Madagascar's prehuman environment. The degree to which human activity has impacted the natural plant communities of Madagascar is of critical and enduring interest.

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Objectives: The proximate and ultimate determinants that may have prompted some primates to shift from an arboreal to terrestrial feeding niche, whether due to environmental change, seasonality, and/or predation pressure, are poorly understood. Within a fragmented littoral forest in southeast Madagascar, an arboreal strepsirrhine population spends a large proportion of time on the ground, thus we aimed to identify which factors influence terrestrial feeding.

Methods: From January to December 2013, we conducted 103 full-day focal follows on three social groups of southern bamboo lemurs H.

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Dietary characteristics and environmental variables are important selective factors directing ecological diversification in rodents. On Madagascar, the introductions and spread of the commensal black rat (Rattus rattus) can be seen as example cases to study dietary niche occupation and dietary adaptation in an insular environment. We investigate how tooth wear as a measure of dietary adaptation of black rats differs between four distinct habitats (village, manioc fields, spiny forest, and rainforest) with different dietary resources.

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