Abstract
As one of the most important tool for biodiversity restoration and endangered species conservation, reintroduction has been implemented worldwide. In reintroduction projects, prerelease conditioning could effectively increase postrelease fitness and survival by improving animals’ adaptation to transformation from artificial to natural environments. However, how early-life diet training affects individuals’ adaptation, fitness, and survival after release remains largely unknown. We hypothesized that early-life diet training would adjust the host’s gut microbial community, the gut microbial community would influence the host’s diet preference, and the host’s diet preference would impact its adaptation to diet provision transformation and then determine postrelease fitness and survival. To verify this hypothesis, we investigated the growth characteristics and gut microbes of Yangtze sturgeon (Acipenser dabryanus) trained with natural and formula diets at both the prerelease and postrelease stages. The results showed that (1) the gut microbial communities of the individuals trained with a natural diet (i.e., natural diet group) and formula diet (i.e., formula diet group) evolved to the optimal status for their corresponding diet provisions, (2) the individuals in the natural diet group paid a lower cost (i.e., changed their gut microbial communities less) during diet transformation and release into the natural environment than did the individuals in the formula diet group, and (3) the gut microbes in the natural diet group better supported postrelease fitness and survival than did the gut microbes in the formula diet group. The results indicated that better prerelease diet training with more appropriate training diets and times could improve the reintroduction of Yangtze sturgeon by adjusting the prerelease gut microbial community. Because a relationship between diet (preference) and gut microbes is common in animals from insects (such as Drosophila melanogaster) to mammals (such as Homo sapiens), our hypothesis verified by the case study on Yangtze sturgeon applies to other animals. We therefore encourage future studies to identify optimal training diets and times for each species to best adjust its prerelease gut microbial community and then improve its postrelease fitness and survival in reintroduction projects.
Highlights
With increasing human activities, biodiversity has decreased globally (Butchart et al, 2010; Pimm et al, 2014), which has impacted Earth’s ecosystems and human well-being (Cardinale et al, 2012; Hooper et al, 2012; Oliver et al, 2015)
Declines in abundance and occurrence have rendered remaining wild populations too fragile to act as continuous sources (Todd and Lintermans, 2015; Brichieri-Colombi et al, 2019), so captive-bred populations are the only choice for reintroduction projects
Understanding the mechanism of diet training effects is crucial for successful reintroduction projects
Summary
Biodiversity has decreased globally (Butchart et al, 2010; Pimm et al, 2014), which has impacted Earth’s ecosystems and human well-being (Cardinale et al, 2012; Hooper et al, 2012; Oliver et al, 2015). Captive-bred populations often have a relatively low postrelease success in terms of survival, behavior, or breeding performance (Letty et al, 2007; Todd and Lintermans, 2015; Brichieri-Colombi et al, 2019). Short-term postrelease (varying from a few weeks to 1 year in different long-lived species) survival is the crucial first step for the success of reintroduction projects (Svåsand et al, 2000; Armstrong and Seddon, 2008; Tavecchia et al, 2009; Bertolero et al, 2018; Cayuela et al, 2019). Starvation is still a significant source of mortality in captive carnivores post release, and foraging deficiencies are underrepresented in the literature (Berger Tal et al, 2019)
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