Parasite–microbiota interactions potentially affect intestinal communities in wild mammals

1. Detecting interaction between species is notoriously difficult, and disentangling species associations in host-related gut communities is especially challenging. Nevertheless, due to contemporary methods, including metabarcoding and 16S sequencing, collecting observational data on community composition has become easier and much more common. 2. We studied the previously collected datasets of intestinal bacterial microbiota and parasite compositions within longitudinally followed mouse lemurs by analysing the potential interactions with diversity metrics and novel joint species distribution modelling. 3. Both methods showed statistical association between certain parasite species and bacterial microbiota composition. Unicellular Eimeria sp. had an effect on diversity of gut microbiota. The cestode Hymenolepis diminuta had negative associations with several bacterial orders, whereas closely related species Hymenolepis nana had positive associations with several bacterial orders. 4. Our results reveal potential interactions between some, but not all, intestinal parasites and gut bacterial microbiota. Host variables contributed over half of the total variation explained with the model, and sex was the most important single host variable; especially with microbiota, there were sex-related differences in the community composition. 5. This study shows how joint species distribution modelling can incorporate both within-host dynamics of several taxa and host characteristics to model potential interactions in intestinal community. These results provide new hypothesis for interactions between and among parasites and bacterial microbiota to be tested further with experimental studies.Peer reviewe

Genetic determinism in the Finnish upper secondary school biology textbooks

Genetics is a fast-developing field and it has been argued that genetics education is lagging behind. Genetics education has for example been suspected of indoctrinating strong genetic determinism. As the updating of the national upper secondary school curricula is about to start, we decided to study how the current curriculum manifests in Finnish biology textbooks. We studied the main four textbooks for historical gene models and definitions of genes using content analysis. Hybrid models were pervasive in textbooks. The textbooks expressed sometimes even strong genetic determinism, which might be linked to the dominance of older historical models in the textbooks. We also found instances of determinism which we call ‘weak determinism’: genes were depicted as more important factor than environment in relation to the expressed properties. Subsequently, there were no modern gene models found. We suggest gene models should be presented explicitly to reduce misconceptions about genes. We argue that genetics education needs to take more into account than environmental effects and there needs to be more emphasis on the temporal and developmental aspect of genotype-phenotype link. Specifically in Finland this could be done by a more explicit formulation of the national curriculum.Peer reviewe

Population- and individual-level dynamics of the intestinal microbiota of a small primate

Longitudinal sampling for intestinal microbiota in wild animals is difficult, leading to a lack of information on bacterial dynamics occurring in nature. We studied how the composition of microbiota communities changed temporally in free-ranging small primates, rufous mouse lemurs (Microcebus rufus). We marked and recaptured mouse lemurs during their mating season in Ranomafana National Park in southeastern mountainous rainforests of Madagascar for 2 years and determined the fecal microbiota compositions of these mouse lemurs with MiSeq sequencing. We collected 160 fecal samples from 71 animals and had two or more samples from 39 individuals. We found small, but statistically significant, effects of site and age on microbiota richness and diversity and effects of sex, year, and site on microbiota composition, while the within-year temporal trends were less clear. Within-host microbiota showed pervasive variation in intestinal bacterial community composition, especially during the second study year. We hypothesize that the biological properties of mouse lemurs, including their small body size and fast metabolism, may contribute to the temporal intraindividual-level variation, something that should be testable with more-extensive sampling regimes.Peer reviewe

Exploring non-invasive sampling of parasites by metabarcoding gastrointestinal nematodes in Madagascar frog species

Peer reviewe

Metabarcoding gastrointestinal nematodes in sympatric endemic and non-endemic species in Ranomafana National Park, Madagascar

Sympatric species are known to host the same parasites species. Nevertheless, surveys examining parasite assemblages in sympatric species are rare. To understand how parasite assemblages in sympatric host species differ in a given locality, we used a noninvasive identification method based on high-throughput sequencing. We collected fecal samples from sympatric species in Ranomafana National Park, Madagascar, from September to December in 2010, 2011, and 2012 and identified their parasites by metabarcoding, sequencing a region of the small ribosomal subunit (18S) gene. Our survey included 11 host species, including endemic primates, rodents, frogs, gastropods, and nonendemic rats and dogs. We collected 872 samples, of which 571 contained nematodes and 249 were successfully sequenced. We identified nine putative species of parasites, although their correspondence to actual parasite species is not clear as the resolution of the marker gene differs between nematode clades. For the host species that we successfully sampled with 10 or more positive occurrences of nematodes, i.e., mouse lemurs (Microcebus rufus), black rats (Rattus rattus), and frogs (Anura), the parasite assemblage compositions differed significantly among host species, sampling sites, and sampling years. Our metabarcoding method shows promise in interrogating parasite assemblages in sympatric host species and our results emphasize the importance of choosing marker regions for parasite identification accuracy.Peer reviewe

Comparison of parasitic infections and body condition in rufous mouse lemurs (Microcebus rufus) at Ranomafana National Park, southeast Madagascar

Body condition may be an important indicator for many infectious diseases and parasites, and may ultimately affect an individual’s fitness. Although some research has correlated body condition and parasite loads in other nonhuman primates, little information has been investigated in prosimian primates. In this study we compare parasitic infections and body condition in a member of the Cheirogaleidae family (Microcebus rufus: rufous mouse lemur) at Ranomafana National Park, southeast Madagascar. This species is characterized by seasonal fattening in preparation for the dry season followed by torpor, and it is important to understand the fluctuation between parasites and infections according to seasonal body condition. We trapped 72 individuals of the species inside Ranomafana National Park (RNP) after the dry season. These individuals were brought to the Centre Valbio Laboratory (CVB) and were subcutaneously micro-chipped with subdermal transponders for permanent identification. We recorded morphometric data, body condition, species richness and prevalence of ectoparasites and gastrointestinal parasites. We found that individuals that had both high number of parasite species as well as high prevalence of ectoparasites and gastrointestinal parasites had better body condition. There is some indication that being in good condition is important in controlling infections.Peer reviewe