LIFE SCIENCE

Ex-situ conservation of wildlife faces major challenges


Wild animals are precious treasures in nature, they reproduce freely in the natural environment, live freely and live in harmony with humans. However, with the continuous disturbance and destruction of natural ecology by humans, more and more wild animals are facing a crisis of survival. In this case, ex situ conservation is another major way to protect endangered wild animals in addition to in situ conservation, and zoos, as important places for ex situ conservation, belong to a typical captive environment. But can captive wild animals really protect their survival?

Recently, the discipline group of animal evolutionary adaptation and endangered species protection of the Northwest Institute of Plateau Biology, Chinese Academy of Sciences, took the Tibetan wild donkey in the wild and zoo as the research object, and analyzed the composition and function of the intestinal flora of the Tibetan wild donkey through metagenomic technology, and found that compared with the Tibetan wild donkey in the wild, the diversity of the intestinal flora of the Tibetan wild donkey in the zoo was reduced, and the types and abundance of potential pathogenic bacteria and resistance genes increased significantly. Affecting the composition and function of gut microorganisms, captive wild animals have a high risk of pathogenesis. The results were published in Integrative Zoology.

Wild Tibetan wild ass. Photo courtesy of Northwest Institute of Plateau Biology.

Impact of ex situ conservation on wildlife

Zoos in various cities are the main sites for ex situ conservation implementation, which can provide a relatively safe environment for wildlife. In the wild, wild animals face multiple threats such as natural predators, disease, food scarcity, etc., and in zoo environments, these threats can be effectively controlled and managed so that wild animals can survive and thrive safely. In addition, captive wild animals can also provide convenience for scientific research, which is convenient for observing and studying the behavioral habits and ecological habits of wild animals. If future rewilding is not considered, this approach can improve and increase the survival rate of wild animals.

However, long-term living in such an environment, wild animals will lose some of their original characteristics, resulting in the degradation of running ability, weakening of plant-fed food digestion, loss of intestinal flora diversity, enhanced drug resistance, etc., if ex situ conservation can not provide the necessary resources and conditions for the wild environment, it will destroy the original intestinal microecological balance of wild animals, affect the immune system of wild animals, cause a series of chronic diseases, thereby affecting the health of wild animals, and weaken the survival and adaptability of wild animals. If released back into the wild, its survival rate will be greatly reduced.

Captive wild Tibetan wild ass. Photo courtesy of Northwest Institute of Plateau Biology.

There were significant differences in gut microorganisms between wild and captive Tibetan wild asses

Tibetan wild ass is currently the only large-scale odd-ungulated wild animal living on the Qinghai-Tibet Plateau, a high-prototype herbivore, is a first-class protected animal in China, and is also an endemic species distributed in the Qinghai-Tibet Plateau, belongs to a typical monogastric animal, its intestine contains a large variety of functional microorganisms, these microorganisms play an important role in the fermentation and decomposition of plant fibers that are not easy to digest in plant-fed food.

“We used Tibetan wild donkeys in the wild and zoo as research subjects to perform metagenomic sequencing on their fecal samples to clarify the composition of the gut microbiota of Tibetan wild donkeys in different environments.” Gao Hongmei, a member of the discipline group of animal evolutionary adaptation and endangered species protection of the Northwest Institute of Plateau Biology, told China Science News that compared with captive individuals, the abundance of bacteroides in the dominant intestinal phylum of wild Tibetan wild ass increased significantly, and at the same time, based on the CAZY database, the types and abundance of most carbohydrate active enzymes were significantly enhanced at the level 1 and level 2 levels, and these changes were conducive to the digestion and use of plant-eating foods such as grasses, sedges and goldenrods in wild Tibetan wild asses. There are seasonal changes in the composition and nutrient composition of wild food, the intestinal flora of wild Tibetan wild donkey will also change, cellulose and other components in winter food increase, the ratio of the abundance ratio (F/B) of firmicutes to Bacteroides in the intestinal flora of Tibetan wild donkey is significantly reduced, various metabolic functions are enhanced, the symbiotic network of core flora (genus level) is more complex, and the plasticity of intestinal flora composition and abundance plays an important role in the adaptation of wild Tibetan wild donkey to the environment.

In addition to oat grass, zoos also provide concentrates, which contain a high proportion of crude protein, carbohydrates and energy. In order to make better use of these nutrients, the firmicutes in the intestinal flora of captive Tibetan wild donkeys increased significantly compared with the wild, and the F/B value of the intestinal flora of captive Tibetan wild donkeys did not differ significantly between seasons due to the long-term provision of the same food. The relatively stable environment and fixed food made the intestinal microorganisms of Tibetan wild donkeys no longer significantly adjusted according to environmental changes, and the diversity of intestinal flora in captive Tibetan wild donkeys decreased.

“The results of potential pathogenic bacteria analysis and resistance genes showed that the types and abundance of potential pathogenic bacteria and resistance genes in captive Tibetan wild donkeys were higher than those in wild groups, and this change increased the risk of disease in captive Tibetan wild asses.” Gao Hongmei told reporters that under the action of a variety of antibiotics and drugs, the intestinal flora of captive Tibetan wild donkeys will increase drug resistance, which will affect the composition and abundance of drug-resistant microbiomes in the body, and also make the treatment of diseases more and more difficult.

The research team is on a field trip. Photo courtesy of Northwest Institute of Plateau Biology.

How to better protect wildlife ex situ

Wildlife conservation is a sustainable process, and protecting wildlife is not just about protecting species, but also about all the resources it covers. In the process of ex situ conservation, we should also pay more attention to and protect some of the original characteristics of wild animals. “In order to better protect wildlife, it is recommended that zoos increase food diversity, reduce the feeding of concentrates, and increase the proportion of natural food intake to improve the diversity and stability of the intestinal flora.” Gao Hongmei said that in the protection of wild animals, the use of antibiotics and other drugs should also be reduced, the abundance of potential pathogenic bacteria in wild feces should be regularly monitored, animal feces should be cleaned up in time to reduce the cross-transmission of pathogenic bacteria, and the stability of the intestinal flora of captive wild animals should be gradually improved and enhanced.

In summary, as an important place for ex situ conservation, zoos can provide a relatively safe environment, provide abundant food, and facilitate scientific research, but there will also be some factors that are unfavorable to wildlife. Ex-situ conservation of wild animals still faces some challenges, and it is urgent to improve the captive environment. In order to better protect wild animals, appropriate protection methods should be selected to ensure the survival and reproduction of wild animals and achieve the purpose of long-term protection of wild animals. (Source: Ye Manshan, China Science News)

Related paper information:https://doi.org/10.1111/1749-4877.12726



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