Social environment and weather during early life influence gastro-intestinal parasite loads in a group-living mammal

Abstract

Conditions experienced during early life have been frequently shown to exert long-term consequences on an animal's fitness. In mammals and birds, the time around and shortly after weaning is one of the crucial periods early in life. However, little is known about how social and abiotic environmental conditions experienced around this time affect fitness-related traits such as endoparasite loads. We studied consequences of social interactions and rainy weather conditions around and after weaning on gastro-intestinal nematode loads in juvenile European rabbits Oryctolagus cuniculus. Infestations with the gastric nematode Graphidium strigosum and with the intestinal nematode Passalurus ambiguus were higher in animals experiencing more rain during early life. This might have been due to the higher persistence of nematodes' infective stages outside the host body together with the animals' lower energy allocation for immune defence under more humid and thus energetically challenging conditions. In contrast, infestations with P. ambiguus were lower in animals with more positive social interactions with mother and litter siblings. We propose that social support provided by familiar group members buffered negative stress effects on immune function, lowering endoparasite infestations. This is supported by the negative correlation between positive social behaviour and serum corticosterone concentrations, indicating lower stress in juveniles which integrated more successfully into the social network of their group. In conclusion, the findings offer a pathway showing how differences in the abiotic environment and social life conditions experienced early in life could translate into long-term fitness consequences via the effects on endoparasite loads.

Early social isolation impairs development, mate choice and grouping behaviour of predatory mites

“…In mammals, social isolation commonly enhances defensiveness in subordinate individuals yet increases aggression in dominant ones (Blanchard et al, 2001). European rabbits reared in isolation suffer from reduced immune functions compared to those reared in groups (Rödel & Starkloff, 2014). Social isolation impairs white matter development and leads to abnormal connectomes in the brain cortex of adolescent rodents (Buwalda, Geerdink, Vidal, & Koolhaas, 2011; Liu et al, 2016).…”

Gastrointestinal parasite infestation in the alpine mountain hare (Lepus timidus varronis): Are abiotic environmental factors such as elevation, temperature and precipitation affecting prevalence of parasite species?

“…Nevertheless, it might be possible that some effects of abiotic environmental factors on parasite infections were missed as we examined only the temperature and precipitation within the 10 days before faecal samples were collected and not during earlier seasons. As an example, rainy weather conditions during the first weeks after emergence above ground has an effect on intestinal nematode loads in European rabbits ( Oryctolagus cuniculus ) during later life (Rödel and Starkloff, 2014). Our findings revealed also a negative relationship between the ambient temperature and the infection of Alpine mountain hares by any parasites traceable in faeces.…”

Estimating Sustainable Harvest Rates for European Hare (Lepus Europaeus) Populations

“…In contrast, higher amounts of precipitation have been shown to be associated with decreased juvenile survival in various vertebrate species (e.g., [83][84][85][86][87][88][89]). The disease infection risk may be higher under more humid conditions [90][91][92], and energetic costs may increase when animals are exposed to rainy and cold weather [87,93,94]. Negative effects of high precipitation on Age Class 1 survival due to the increased probability of diseases such as coccidiosis and pseudotuberculosis are often described for European hares [11,24,36].…”