Analysis of gut microbiomes in distantly related vertebrates from urban and rural areas has revealed the so-termed ‘humanization of the microbiota’ of wildlife living in cities.
Human populations continued to increase rapidly around the world and one consequence of this is urbanization. In turn, the expansion of town and city dwelling is altering Earth’s environments.
The environmental changes are impacting on resident wildlife, including events occurring at the microbial level, as evidenced by research into the microbiome of the gut.
This is demonstrated in research into coyotes (Canis latrans), crested anole lizards (Anolis cristatellus), and white-crowned sparrows (Zonotrichia leucophrys). Each of these three species has been shown to acquire gut microbiota constituents found in humans. All told, the scientists analysed nearly 500 microbiota profiles from the three target animals and from volunteer human subjects.
In particular, the acquisition of microorganisms includes gut bacterial lineages associated with urbanization in humans. This is drawn out from comparisons of urban and rural wildlife and human populations, where the overrepresentation of human-related organisms is apparent in urban wildlife relative to rural wildlife.
According to lead researcher Professor Brian Dillard: “With the influence of humans on ecosystems becoming more pronounced globally, there is a need to better understand the effects of urbanization on global wildlife microbiota.”
He adds: “Others have shown that urbanization can alter the composition of gut microbiota in diverse species of wildlife, leading to differences between wildlife living in urban and rural settings, but we did not know whether urbanization has similar effects on the microbiota across host species.”
The bacterial lineage most overrepresented is a Bacteroides sequence variant, as demonstrated by genetic testing. This family of bacteria are also the most significantly overrepresented in urban human populations, making up a majority of the bacterial species in the human intestinal microbiota (the “gut microbiome”).
The Cornell University-led researchers conclude evidence of the twined effects of urbanization on human and wildlife gut microbiota and a spill over of bacteria from humans into wildlife in cities.
As to the significance of the study, interspecies transmission of microbes can lead to deleterious effects for the recipient host, although the specific effects the microbes are having on urban wildlife is unknown.
Given that changing the microbiome can affect health and behaviour; hence, it becomes a new priority to investigate what the consequences are for this human transmission upon wildlife hosts.
The novel research appears in the journal eLife, titled “Humanization of wildlife gut microbiota in urban environments.”
