Scientists Have Proposes For Saving The Slow-Reproducing Giants

Editorials News | May-21-2019

Scientists Have Proposes For Saving The Slow-Reproducing Giants

"The critical thresholds in so-called vital rates, such as mortality and fertility rates between men and women of different ages may indicate a collapse of the population that is approaching well before the numbers fall below a point of no return", says the lead author, Dr. Shermin. De Silva, president and founder of the Asian elephant conservation charity Trunks & Leaves. "We propose that conservation effort for Asian elephants and other slow-breeding megafauna be aimed at maintaining their 'safe demographic space': that is, the combination of key life rates that support a non-negative growth rate."

A vision of mammoth

Published in Frontiers in Ecology and Evolution, the study suggests that a combination of key life rates that govern population growth is a better indicator of the viability of a species than short-term trends in population size and distribution.

"History confirms it", argues de Silva. "Genomic studies of the last mammoths isolated on Wrangel Island, between Russia and Alaska, have shown that, although they could persist for thousands of years beyond the extinction of continental populations with only about 300 individuals, they had accumulated numerous mutations This may have contributed eventually to its extinction.”

In other words, megafauna’ populations can become biologically unviable long before they disappear, if they are pushed beyond their "safe demographic space."

Females and calves key to save the Asian elephant.

The group applied the concept of 'safe demographic space' to the case of the Asian elephant.

"Asian elephants are classified as 'Endangered' on the IUCN Red List because it is believed that populations have decreased by at least 50% in less than a century," de Silva explains. "There are less than 50,000 wild Asian elephants that live today."

Studies show that wild Asian elephants breed extremely slowly, most producing only one calf in six years or more. Using mathematical models, de Silva and his colleagues discovered that the almost optimal reproduction and high survival of calves are necessary to maintain a non-negative population growth compared to a moderate increase in mortality among the age classes of adult women.

The approach shows a clear conservation priority for Asian elephants, a species in which the vast majority do not have fangs.

"The measures to improve the survival of the calves, and in particular of the females, are key to save the Asian elephant", emphasizes De Silva.

"But while the world's attention has been focused on the ivory trade, for critically endangered Asian elephant populations, the biggest threat is the loss of habitat, followed by illegal trade in live animals and parts.

 

By: Preeti Narula

Content: https://www.sciencedaily.com/releases/2019/05/190517081640.htm


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