Starting small: long‐term consequences in a managed large‐mammal population

Abstract

Small populations are vulnerable to founder effects, stochastic demographic events and inbreeding depression. These factors raise the extinction probability of small populations, and thus effective management plans for endangered species have become essential. The black rhinoceros (Diceros bicornis) survived a historic global population crash and is currently facing renewed threat through poaching, population fragmentation and isolation. South Africa is home to approximately 36% of the world's remaining black rhinos; however, this population is fragmented across parks and reserves, and many of these small populations remain geographically and genetically isolated. The historic population crash, subsequent fragmentation and relentless poaching pressure together threaten the viability of the black rhino population within South Africa. This study employed a practical, non‐invasive sampling protocol and genetic analyses to assess the growth and performance of a small founder population in a fenced reserve. We used these data and recorded life‐history data to compare the population growth and vital rates between the first and second 10‐year periods since founding. We report a decrease in population growth rate and male survival in the second 10‐year period (0.06; 0.89) compared to the first (0.09; 0.97). Genetic diversity (HEXP = 0.405) was low when compared to larger black rhino populations, and average pairwise relatedness was high (0.193). These results suggest that negative genetic consequences and the beginning of density‐dependant growth regulation may be present in this population. This highlights the importance of establishing an evaluation framework for the assessment of small populations of long‐lived mammals in order to inform metapopulation management.

Gut microbiome differences between wild and captive black rhinoceros – implications for rhino health

“…Currently, fewer than 100 black rhinos (southern and eastern sub-species combined) reside in zoological institutions in North America as a reservoir against potential extinction 2 . However, the ex situ population experiences its own threats to survival, including a myriad of unusual disease syndromes not generally described in the wild 3–10 , as well as poor reproduction 11,12 and fragmented populations 3 . Across mammals, recent studies have suggested that microbiome differences between wild and captive populations may influence overall health in general and digestive and immune functions in particular 4 .…”

The faecal microbiome of Exmoor ponies shows step‐wise compositional changes with increasing levels of management by humans

“…Domestication is associated with changes to an animal's natural environment, diet, breeding and behaviour, [1][2][3][4] often with a negative impact on animal health. [5][6][7][8] In particular, captive animals commonly suffer from gastrointestinal (GI) pathology, [9][10][11] indicating that factors such as stress, and diet changes associated with captive management can result in changes to the GI microenvironment which compromise animal health. Horses constitute a prime example of a species which suffers from a high incidence of (often life-threatening) GI disease in captivity [12][13][14] ; prevalence of analogous diseases in wild populations are unknown due to lack of surveillance.…”

“…Domestication is associated with changes to an animal's natural environment, diet, breeding and behaviour, 1–4 often with a negative impact on animal health 5–8 . In particular, captive animals commonly suffer from gastrointestinal (GI) pathology, 9–11 indicating that factors such as stress, and diet changes associated with captive management can result in changes to the GI microenvironment which compromise animal health.…”

The Equine Faecal Microbiota Undergoes Step-wise Compositional Changes in Accordance With Increasing Levels of Domestication

“…Humans have been domesticating animals on this planet for thousands of years, with the rst cases in dogs estimated to be around 16,000 years ago [1]. This process is associated with changes to an animal's natural environment, diet, breeding and behaviour [2,3,4,5], often with a negative impact on animal health [6,7,8,9]. In particular, domesticated and/or captive animals commonly suffer from gastrointestinal (GI) pathology [10,11,12], indicating that domestication can result in changes to the GI microenvironment which compromise animal health.…”