Ecological and evolutionary drivers of haemoplasma infection and bacterial genotype sharing in a Neotropical bat community

Speer

Korstian

et al. 2020

Preprint

Self Cite

381. Contaminants such as mercury are pervasive and can have immunosuppressive effects on 39 wildlife. Impaired immunity could be important for forecasting pathogen spillover risks, 40 as many land-use changes that generate mercury contamination can also bring wildlife 41 reservoir hosts into close contact with humans and domestic animals. However, the 42 interactions between contaminants, immunity, and infection are difficult to study in 43 natural systems, and empirical tests of possible directional relationships remain rare. 44 2. We capitalized on extreme mercury variation in a diverse Neotropical bat community in 45 Belize to test association between contaminants, immunity, and infection. By comparing 46 a previous dataset of bats sampled in 2014 with new data from 2017, we first confirmed 47 bat species with more aquatic prey in their diet had higher fur mercury. We then tested 48 covariation between mercury and cellular immunity and determined if such relationships 49 mediated associations between mercury and common bacterial pathogens (hemoplasmas 50 and Bartonella). Lastly, as bat ecology can dictate exposure to mercury and pathogens, 51 we also assessed species-specific patterns in these mercury-infection relationships. 52 3. Across the bat community, individuals with higher mercury had fewer neutrophils but not 53 lymphocytes, suggesting stronger associations with innate immunity. However, the odds 54 of infection for both pathogens were generally lowest in bats with high mercury, and 55 relationships between mercury and immunity did not mediate infection patterns. When 56 considering species-specific relationships between mercury and infection, mercury was 57 associated with especially low odds for Pteronotus mesoamericanus and Dermanura 58 phaeotis for hemoplasmas. Yet for Bartonella, mercury was associated with particularly 59 low odds in the genus Pteronotus but especially high odds within the Stenodermatinae.60 4. Synthesis and application: Lower infection risk in bats with high mercury despite weaker 61 innate defense suggests contaminant-driven loss of pathogen habitat (i.e., anemia) or 62 vector mortality as possible causal mechanisms. Strong positive associations between 63 mercury and Bartonella in the Stenodermatinae, however, alongside negative 64 associations between mercury and neutrophils in this clade, suggest these bats could be 65 especially vulnerable to immunosuppression. Greater attention to these potential causal 66 pathways could help disentangle the complex relationships between environmental 67 contaminants, immunity, and infection in natural systems and forecast disease risks. 68 69Wildlife are commonly exposed to a range of contaminants that are ubiquitous in the 70 environment, including heavy metals, organic compounds, and pesticides (Smith et al., 2007).

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

“…Here we built upon our prior studies of Hg and of infectious disease in Neotropical bats (e.g., Becker, Chumchal, et al, 2018;Becker, Speer, et al, 2020) to address three study aims.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Disentangling interactions among mercury, immunity, and infection in a Neotropical bat community

Speer

Korstian

et al. 2020

Preprint

Self Cite

“…However, despite the enduring focus on virus ecology, more zoonoses are caused by bacteria than any other pathogen group (Han, Kramer, & Drake, 2016). To develop a more comprehensive understanding of zoonotic risk in bacteria, greater attention should be paid to whether the general patterns in zoonotic potential, pathogen richness and pathogen sharing observed for viruses persist for bacterial pathogens (Becker et al., 2020). In particular, theory suggests that high levels of phenotypic plasticity, low evolutionary rates and recombination ability typical of bacteria should reduce their propensity to specialize, which may generate distinct pathogen sharing patterns from viruses (Bonneaud, Weinert, & Kuijper, 2019).…”

Section: Figurementioning

confidence: 99%

Expanding host specificity and pathogen sharing beyond viruses

Albery

2020

Molecular Ecology

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Most emerging pathogens of humans can infect multiple host species (Woolhouse & Gowtage‐Sequeria, 2005). This simple fact has motivated multiple large‐scale, comparative analyses of the drivers of pathogen sharing and zoonotic pathogen richness among hosts as well as the factors determining the zoonotic potential of pathogens themselves. However, most of this work focuses on viruses, limiting a broader understanding of how host range varies within and between pathogen groups. In this issue of Molecular Ecology, Shaw et al. (2020) compile a comprehensive data set of host–pathogen associations across viruses and bacteria and test whether previous patterns observed in the former occur in the latter. They find most viruses and bacteria are specialists, and viruses are more likely to be generalists; however, generalist bacteria encompass multiple host orders, whereas viral sharing occurs more within host orders. Lastly, the authors demonstrate that many factors previously identified as predictors of zoonotic richness for viruses occur for bacteria and that host phylogenetic similarity is a primary determinant of cross‐species transmission. However, pathogen sharing with humans was more common and more weakly related to phylogenetic distance to Homo sapiens for bacteria compared to viruses, suggesting the former could pose greater spillover risks across host orders. This work represents a key advance in our understanding of host specificity and pathogen sharing beyond viruses.

Tropical bat ectoparasitism in continuous versus fragmented forests: A gap analysis and preliminary meta‐analysis

Heckley

2023

Ecology and Evolution

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Tropical regions are experiencing rapid rates of forest fragmentation, which can have several effects on wildlife, including altered parasite dynamics. Bats are a useful host group to consider the effects of fragmentation, because they are abundant in the tropics, serve important ecological roles, and harbor many parasites. Nevertheless, research on the effects of fragmentation on bat ectoparasites is still limited. To help guide ongoing and future research efforts, this study had two objectives: (1) conduct a gap analysis to characterize the state of currently available research on fragmentation effects on bat ectoparasites and (2) conduct a preliminary meta‐analysis to identify current trends. We systematically highlighted several research gaps: Studies comparing the effects of fragmented versus continuous forests on ectoparasites are limited and have primarily been conducted in the Neotropics, with a focus on bats in the superfamily Noctilionidea (especially frugivorous phyllostomids). Our preliminary meta‐analysis suggested that ectoparasite prevalence (but not the mean or variance in intensity) was higher in fragments than in continuous forests. Moreover, prevalence increased with increasing roost duration, and mean intensity was higher for bats with higher wing aspect ratios. Intensity variance was affected by an interaction between forest type and wing aspect ratio, such that variance increased for bats with high‐wing aspect ratios in continuous forests but decreased in fragments. These results suggest that fragmentation can shape aspects of bat ectoparasitism and could have implications for the ecology, health, and conservation of bats in fragmented landscapes. However, existing research gaps could bias our current understanding of habitat change and bat health, and future research should thus investigate these effects in the Paleotropics and with other bat families.