Disentangling direct from indirect effects of habitat disturbance on multiple components of biodiversity
Creators: name: Schwensow, Nina Isabell
name: Heni, Alexander Christoph
name: Schmid, Julian
name: Montero, B. Karina
name: Brändel, Stefan Dominik
name: Halczok, Tanja Katharina
name: Mayer, Gerd
name: Fackelmann, Gloria
name: Wilhelm, Kerstin
name: Schmid, Dominik Werner
name: Sommer, Simone
Publisher: name: Universität Ulm
Year: 2022
Subjects: subject: biotic interactions
subject: host genetic diversity
subject: human disturbance
subject: intestinal parasite diversity
subject: microbiome heterogeneity
subject: DDC 570 / Life sciences
subject: DDC 590 / Animals (Zoology)
subject: Species diversity
subject: Biotic communities
subject: Artenreichtum
subject: Biodiversität

description: Human habitat disturbance affects both species diversity and intraspecific genetic diversity, leading to correlations between these two components of biodiversity (termed species–genetic diversity correlation, SGDC). However, whether SGDC predictions extend to host-associated communities, such as the intestinal parasite and gut microbial diversity, remains largely unexplored. Additionally, the role of dominant generalist species is often neglected despite their importance in shaping the environment experienced by other members of the ecological community, and their role as source, reservoir and vector of zoonotic diseases. New analytical approaches (e.g. structural equation modelling, SEM) can be used to assess SGDC relationships and distinguish among direct and indirect effects of habitat characteristics and disturbance on the various components of biodiversity. With six concrete and biologically sound models in mind, we collected habitat characteristics of 22 study sites from four distinct landscapes located in central Panama. Each landscape differed in the degree of human disturbance and fragmentation measured by several quantitative variables, such as canopy cover, canopy height and understorey density. In terms of biodiversity, we estimated on the one hand, (a) small mammal species diversity, and, on the other hand, (b) genome-wide diversity, (c) intestinal parasite diversity and (d) gut microbial heterogeneity of the most dominant generalist species (Tome's spiny rat, Proechimys semispinosus). We used SEMs to assess the links between habitat characteristics and biological diversity measures. The best supported SEM suggested that habitat characteristics directly and positively affect the richness of small mammals, the genetic diversity of P. semispinosus and its gut microbial heterogeneity. Habitat characteristics did not, however, directly impact intestinal parasite diversity. We also detected indirect, positive effects of habitat characteristics on both host-associated assemblages via small mammal richness. For microbes, this is likely linked to cross species transmission, particularly in shared and/or anthropogenically altered habitats, whereas host diversity mitigates parasite infections. The SEM revealed an additional indirect but negative effect on intestinal parasite diversity via host genetic diversity. Our study showcases that habitat alterations not only affect species diversity and host genetic diversity in parallel, but also species diversity of host-associated assemblages. The impacts from human disturbance are therefore expected to ripple through entire ecosystems with far reaching effects felt even by generalist species.