Body Weight Selection Affects Quantitative Genetic Correlated Responses in Gut Microbiota

The abundance of gut microbiota can be viewed as a quantitative trait, which is affected by the genetics and environment of the host. To quantify the effectsof host genetics, we calculated the heritability of abundance of specific microorganisms and genetic correlations among them in the gut microbiotaof two lines of chickens maintained under the same husbandry and dietary regimes. The lines, which originated from a common founder population, had undergone >50 generations of selection for high (HWS) or low (LWS) 56-day body weight and now differ by more than 10-fold in body weight at selection age. We identified families of Paenibacillaceae, Streptococcaceae, Helicobacteraceae, andBurkholderiaceaethat hadmoderate heritabilities. Although there were no obvious phenotypic correlations among gut microbiota, significant genetic correlations were observed. Moreover, the effects were modified by genetic selection for body weight, which altered the quantitative genetic background of the host.  Heritabilities forBacillaceae, Flavobacteriaceae, Helicobacteraceae, Comamonadaceae,Enterococcaceae, and Streptococcaceaewere moderate and little to zero in the LWS and HWS lines, respectively. The long term selection for body weight also altered the genetic correlations among gut microbiota. These results demonstrate that the quantitative genetics of the host have considerable influence on the gut microbiota.