Biology subjects

Schols, R.

Publications and source records attributed to Schols, R..

3 recordsLinked to original sources

bioRxiv2024

Ecosystem Links: Macrophytes, Snail Preferences, and Trematode Transmission in Man-Made Water Bodies

Freshwater snails act as obligate intermediate hosts for trematode parasites that cause trematodiases threatening public and veterinary health, and biodiversity conservation. Therefore, interest has re-emerged in snails as a target for disease control, yet their ecology is poorly understood. We studied the relationship between physical and chemical water parameters, macroinvertebrates, macrophytes, land use, and snail abundance, diversity, and infection rate in man-made reservoirs in eastern Zimbabwe. We observed no significant relationship between water quality parameters or macroinvertebrates and snail communities, but a significant association existed between specific macrophytes and snail species. Schistosome-competent snails (i.e., Biomphalaria pfeifferi and bulinids) were most associated with emergent Cladium mariscus, whereas Physella acuta was associated with submerged oxygen weed, Lagarosiphon major. This offers a possibility to incorporate the management of macrophytes in integrated snail control schemes. Diversity of freshwater snail species significantly varied across land use types with the lowest observed diversity in the commercial tobacco farm section, dominated by invasive exotic P. acuta and Pseudosuccinea columella, as compared to the less impacted conserved area, reflecting the adverse effects of agriculture on biodiversity. Out of the 547 schistosome host snails, 88 were shedding cercariae (16.1%) of various types, including schistosomes and amphistomes. We did not find any significant associations between macroinvertebrate or macrophyte diversity and snails and their infection rate.

ecology↗

bioRxiv2024

First evidence of a causal link between genetic variation and thermal adaptation in a schistosome host snail

Freshwater snails are pivotal in transmitting schistosomiasis, a tropical parasitic disease affecting over 150 million people. The adaptive potential of these snails is a critical factor in determining how climate change and other environmental factors influence disease transmission dynamics, yet it has remained unexplored. Bulinus truncatus is the schistosome intermediate host snail with the widest geographic distribution and therefore plays a pivotal role in determining the maximum range of urogenital schistosomiasis. In this study, we assessed the local adaptation capacity of B. truncatus to temperature through an integrative approach encompassing phenotypic, ecophysiological, and genomic data. Ten snail populations from diverse thermal environments were collected in three countries, with eight populations reared in a common garden. The F2 generation (total N= 2592) was exposed to eight chronic temperature treatments and various life-history traits were recorded for over 14 weeks. Subsequently, ecophysiological analyses were conducted on the ten last surviving snails per population. Genotyping the parental generation collected in the field using a genotyping-by-sequencing (GBS) approach, revealed 12,875 single nucleotide polymorphisms (SNPs), of which 4.91 % were potentially under selection. We observed a significant association between these outlier SNPs, temperature, and precipitation. Thermal adaptations in life-history traits were evident, with lower survival rates at high temperatures of warm- origin snails compensated for by higher reproduction rates. Cold-origin snails, on the other hand, exhibited higher growth rates adapted to a shorter growing season. Ecophysiological adaptations included elevated sugar and haemoglobin contents in cold-adapted snails. In contrast, warm-adapted snails displayed increased protein levels but also more oxidative damage. Furthermore, heightened phenoloxidase levels indicated a more robust immune response in snails from parasite-rich regions. The substantial local adaptation capacity of B. truncatus holds profound implications for its response to climate change, future schistosomiasis risk, and the effectiveness of schistosomiasis control measures. HighlightsO_LILocal adaptation influences species responses to climate change C_LIO_LIThe snail Bulinus truncatus showed a high thermal local adaptation (LA) potential C_LIO_LILA is apparent through variations in life history and ecophysiological traits C_LIO_LIWe identified a significant genetic basis underlying this LA C_LIO_LILA of the hosts could sustain schistosomiasis transmission under global warming C_LI

ecology↗

bioRxiv2023

Host-microbiome transplants of the schistosome snail host Biomphalaria glabrata reflect species-specific associations

Snail-borne diseases affect more than a quarter of a billion people worldwide and pose a high burden in the livestock industry. A fundamental understanding of the drivers of the epidemiology of these diseases is crucial for the development of sustainable control measures. The microbiome is increasingly being recognized as an important player in the tripartite interaction between parasitic flatworms, snail intermediate hosts and the snail microbiome. In order to better understand these interactions, transplant experiments are needed, which rely on the development of a reliable and reproducible protocol to obtain microbiome-disturbed snails. Here we report on the first successful snail microbiome transplants, which indicate that Biomphalaria glabrata can accrue novel bacterial assemblies depending on the available environmental bacteria obtained from donor snails. Moreover, the phylogenetic relatedness to the donor significantly affected the survival probability of the recipients, corroborating the phylosymbiosis pattern in freshwater snails. The transplant technique described here, complemented by field-based studies, could facilitate future research endeavors to investigate the role of specific bacteria or bacterial communities in parasitic flatworm resistance of B. glabrata and might ultimately pave the way for microbiome-mediated control of snail-borne diseases.

microbiology↗