The number of species in the genus Leopard is going from 5 to 6? The genetic differences between African and Asian leopards are beyond imagination

Leopards are the most adaptable large cats to their environment and are found in a variety of environments including grasslands, mountains, tropical rainforests, wetlands, semi-desert areas, and farmlands. Nowadays, leopards are usually divided into nine subspecies, which are the African leopard, Indian leopard, North China leopard, Far Eastern leopard, Indo-Chinese leopard, Arabian leopard, Persian leopard, Sri Lankan leopard, and Javan leopard. Among them, the African leopard is distributed in Africa and the other eight subspecies are distributed in the Asian region, and they are collectively known as Asian leopards.

The current status of leopards and the importance of genetic research

Over the past century or so, the impact of human activities, such as the destruction of wildlife habitats and overhunting against leopards and leopard prey, has led to a large reduction in leopard habitat and a massive decline in their numbers.

Today, among the nine subspecies of leopards, only the African leopard and the Indian leopard have slightly larger populations of around 10,000 individuals, the Indo-Chinese leopard is estimated to have between 973 and 2,503 individuals, while the other six leopard subspecies have less than 1,000 individuals, and in many areas the leopard is extinct.

In such a situation, detailed genetic studies on leopards to understand their population history, population structure, and population dynamics are very important for conservation efforts. Recently, researchers from several institutions, including the University of Potsdam in Germany, have published a research result in Current Biology (Contemporary Biology) with surprising results.

Genetic analysis using leopard fur specimens from museums

Typically, genetic analysis involves collecting fresh tissue samples from organisms, but this is not a good approach for leopards. Firstly, many leopard subspecies are so rare that finding targets can become difficult, and secondly, such invasive sampling may have adverse effects on the leopard's body. It would be easier to obtain leopard tissue samples in zoos, but many zoo leopards are the offspring of different subspecies crosses.

After considering all things, the scientists turned their sample sampling efforts to some leopard pelts housed in natural history museums.

A total of 26 leopards (14 African and 12 Asian) were genetically sequenced during the study, including 18 fur specimens housed in natural history museums. Based on the genomic data available, the researchers scientifically compared and analyzed the genetic differences of different leopard subspecies.

The genetic differences between African and Asian leopards are beyond imagination

Typically, genetic differences between species are greater than genetic differences between subspecies, yet surprisingly, researchers have found genetic differences between African and Asian leopards that are beyond imagination - greater than those between brown bears and polar bears.

The study found that the genetic diversity of African leopards is very high, on average two times that of Asian leopards; among several leopard subspecies in Asia, the smaller the population size, the lower the genetic diversity, for example, the genetic diversity of Far Eastern leopards is lower than that of Indian leopards and Javan leopards, which is similar to the studies of some previous scientists. In some previous studies, scientists found that the genetic diversity of the African leopard was about four times higher than that of the Far Eastern leopard (Northeastern leopard), two times higher than that of the lion, and five times higher than that of the cheetah.

Why is the genetic diversity of African leopards higher than that of Asian leopards?

By studying the mitochondrial DNA of leopards, researchers speculate that leopards may have originated in northwestern Africa and that a portion of them spread to Asia 500,000 to 600,000 years ago and evolved into the Asian leopards of today. In the hundreds of thousands of years since then, only small-scale hybridization has occurred between African and Asian leopards.

Researchers believe there are two main reasons why the genetic diversity of African leopards is higher than that of Asian leopards today.

(1) The founder effect

The founder effect refers to the fact that a population is initially established by only a few individuals migrating from other places to a new location, and although the population size expands after a period of reproduction, the genetic diversity of the population does not increase. In the beginning, only a few leopards migrated from Africa to Asia, and the genetic diversity of the initial population of Asian leopards was very low.

(2) Influence of geographic isolation

In Africa, geography is less isolating to leopard populations, and leopards can freely travel between habitats and exchange genetic material, thus maintaining and increasing genetic diversity. However, in Asia, geographical factors such as plateaus, mountains, lakes, and oceans isolate leopard populations to a greater extent, and genetic mobility between populations is weaker, making it difficult to maintain or increase genetic diversity, resulting in more similar genes among individuals.

Genetic diversity is of great importance to the survival and continuation of a species. Higher genetic diversity can give animals an advantage in the face of problems such as climate change and habitat destruction. In the past 200 years or so, the habitat area of African leopards has decreased by 48% to 67%, while the habitat area of Asian leopards has decreased by 83% to 87%. While human activities are certainly a factor in the reduction of leopard habitat, researchers believe that the higher genetic diversity of African leopards makes them more resilient than Asian leopards in the face of various natural and man-made disasters.

Will the leopard genus go from five to six species?

As mentioned earlier, the Asian and African leopards diverged 500,000 to 600,000 years ago, while the polar bear and brown bear diverged about 400,000 years ago, the latter two species being well known. Given the results of the genetic analysis, the researchers believe that the Asian and African leopards may be divided into two species.

In recent years, the rapid development of genomics has posed a major challenge to traditional taxonomy, for example, the genus Clouded Leopard has only one species, the clouded leopard. 2006, scientists found after genetic analysis that the clouded leopard living in the Sunda Islands and the clouded leopard living in other parts of Asia are highly genetically distinct, with genetic differences greater than those between lions and tigers, snow leopards, and jaguars. The genetic differences were greater than those between lions and tigers, snow leopards, and jaguars.

Later, scientists separated the Sunda clouded leopard into a separate species, and the genus of a clouded leopard was changed from one species to two - the mainland clouded leopard and the Sunda clouded leopard.

In the current way of classification, there are five species in the cat genus Leopard - tiger, lion, leopard, jaguar, and snow leopard, all of which are large cats. If the Asian leopard and African leopard were divided into 2 different species, the members of the genus Leopard would go from 5 to 6. However, the researchers said that more biological evidence as well as more discussion in the scientific community is needed to get hold of the division of leopards.