Small Ne of the Isolated and Unmanaged Horse Population on Sable Island.

The research focuses on assessing the risk of genetic threats, specifically inbreeding and loss of genetic diversity, to the isolated and unmanaged horse population on Sable Island. The researchers find that, despite a lower than advised effective population size, no current negative effects from these threats have been identified, leading to a recommendation against immediate management intervention.

Objective of the Research

• The research was undertaken to evaluate the threats to the unmanaged horse population on Sable Island caused by inbreeding and loss of genetic diversity.
• Such genetic threats are common concerns for conservation of small, isolated populations like that on Sable Island.
• The researchers sought to assess the immediate risk of these genetic threats by estimating the effective population size (Ne) of the horses.

Research Findings

• The research findings, from five different methods, consistently estimated the effective population size to be around 48 individuals.
• While smaller than the recommended “50/500 rule”, where a population size of less than 50 is seen as susceptible to inbreeding depression, the researchers did not find evidence of negative effects that can be directly linked to inbreeding depression in the Sable Island horse population.
• Furthermore, simulations and historical data indicate that this horse population is just beginning to approach an equilibrium between mutation, drift, and genetic diversity.

Recommendations

• Despite their findings about the low effective population size, the researchers recommend against immediate management actions like translocations, because such interventions have led to undesirable outcomes in other situations.
• Instead, they suggest continuous monitoring of genetic diversity and fitness, which will allow the detection of any significant changes or trends that might take place in the future.

Significance of the Data

• These findings represent an important source of information because they come from one of the very few unmanaged horse populations in the world.
• In addition to offering insights into conservation efforts for the horses on Sable Island, the data also contributes to broader understanding of how natural processes affect parameters like reproduction, mortality, and population growth.