Zambia’s Lions Roam Areas Previously Believed to Be Uninhabitable

A select group of migrating big cats ensures high levels of genetic diversity throughout the country’s lion population

Researchers extracted DNA from more than 400 lions (Yathin S. Krishnappa via Wikimedia Commons under CC BY-SA 2.0)

By Meilan Solly

SMITHSONIAN.COM
SEPTEMBER 27, 2019 2:47PM

Approximately 1,200 lions call Zambia—a U-shaped country in southeast Africa known for its abundant wildlife—home. These big cats, constituting one of the continent’s largest lion populations, live in two distinct groups separated by seemingly insurmountable barriers.

But new research suggests a small number of lions do, in fact, move across areas previously believed to be uninhabitable by the species. As researchers led by Caitlin J. Curry, a biologist at Texas A&M University, report in the journal PLoS ONE, these select felines then mate with members of other prides, ensuring high levels of genetic diversity throughout Zambia’s wider lion population.

According to a Conversation article written by Curry, the landlocked country’s lion subpopulations are divided between the Greater Kafue Ecosystem in the west and the Luangwa Valley Ecosystem in the east. Scientists have long believed that geographical and anthropogenic barriers, including different habitats and the presence of a large city lacking wildlife protection, prevent the groups from interacting, but as the new survey found, Zambia’s lions are not as isolated as one might think.

To assess the animals’ genetic diversity, the team extracted DNA from 409 lions, as represented by hair, skin, bone and tissue samples collected between 2004 and 2012.


“The nuclear DNA is inherited by both parents, so you get an idea of diversity in the entire population, whereas the mitochrondial DNA is only inherited through the mother,” Curry says in a press release. “By examining both, you’re getting two different views of inheritance through the populations.”


Writing for Science Trends, Curry explains that previous DNA studies pointed toward the existence of two genetically distinct lion subpopulations in Zambia. The latest analysis confirmed these findings while also identifying similarities between the groups—namely, shared nuclear DNA attributed to male-mediated gene flow, or the movement of genes from one geographic location to another via male animals’ migration.

When mating, male lions cover long distances in search of new prides; females, meanwhile, remain close to their original pride and mate with new males arriving in the area. As a result, Zambia’s lions exhibit gene flow in mitochondrial, rather than nuclear, genes.

Based on the latest findings, the researchers suggest gene flow occurs largely through the southern regions of the eastern subpopulation, with lions traveling between the Lower Zambezi National Park and eastern corridor to the Kafue National Park in western Zambia. “We can’t tell which way they’re moving, but by looking at where lions are more closely related, we can see where genes are being moved,” Curry notes for the Conversation.

According to Curry, higher levels of genetic diversity offer lions a better chance of adapting to their changing environment. She continues, “Both the eastern and western subpopulations have high levels of genetic diversity, but they are still staying genetically distinct enough to remain two sub-populations.”



Moving forward, the team hopes to use this data to support lion conservation and wildlife management across Zambia. Per the Conversation, knowing where lions roam will help scientists ensure the big cats’ safe passage from one part of the country to another, perhaps by creating protected land corridors between various habitats. Doing so could also reduce human-wildlife conflict; as Curry concludes in the statement, “That’s probably why they’re having that conflict in the first place, because they’re not taking into consideration that lions actually are moving across it.”


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https://theconversation.com/sn...able-for-them-123504


Link has map and graph.



Sneaky lions in Zambia are moving across areas thought uninhabitable for them

September 25, 2019 8.12am EDT

Author
Caitlin J. Curry
Phd Student in absentia of Veterinary Pathobiology, Texas A&M University

Disclosure statement
This project received funding from Zambia Wildlife Authority, Professional Hunters Association of Zambia, Safari Hunters and Outfitters Association of Zambia, the Boore Family Foundation, Dallas Safari Club, Safari Club International Foundation and the Texas A&M Foundation.

Partners
Texas A&M University

Texas A&M University provides funding as a founding partner of The Conversation US.


Zambia, a country in southeast Africa, has approximately 1,200 lions, one of the largest lion populations on the continent. More than 40% of the U-shaped country is protected land, with over 120,000 square miles of national parks, sanctuaries and game management areas for lions to roam.



Zambian lions are split into two subpopulations, with one in the Greater Kafue Ecosystem in the west and the other in the Luangwa Valley Ecosystem in the east. Between these two geographically different regions lies Lusaka, Zambia’s largest city, which is surrounded by farmland.

People had assumed that the two groups of lions did not – even could not – mix. After all, they’re separated by a geographical barrier: the two regions feature different habitats, with the east an offshoot of the Great Rift Valley system and the west part of the southern savannas. The lions are also separated by what’s called an anthropogenic barrier: a big city that lacks wildlife protection, making it seemingly unsuitable for lions.

So my colleagues and I were surprised when we found that a small number of lions are in fact moving across the area in between presumed to be uninhabitable by lions. These sneaky lions – and their mating habits – are causing the high levels of genetic diversity we found in the entire Zambian lion population.

Identifying which genes are where

Working with the Zambian Wildlife Authority, biologist Paula White collected hundreds of biological samples from lions across Zambia between 2004 and 2012. Eventually a box of this hair, skin, bone and tissue, meticulously packaged and labeled with collection notes and sampling locations, arrived at my lab at Texas A&M University.



Our goal was to investigate genetic diversity and the movement of various genes across Zambia by extracting and analyzing DNA from the lion samples.

From 409 lions found inside and outside of protected lands, I looked at two kinds of genes, mitochondrial and nuclear. You inherit mitochondrial DNA only from your mom, while you inherit nuclear DNA from both of your parents. Because of these differences, mitochondrial and nuclear genes can tell different genetic stories that, when combined, paint a more complete picture of how a population behaves.



My mitochondrial analysis verified that, genetically, there are two isolated subpopulations of lions in Zambia, one in the east and one in the west. However, by also looking at the nuclear genes, we found evidence that small numbers of lions are moving across the “unsuitable” habitat. Including nuclear genes provided a more complex picture that tells us not only which lions were moving but also where.

Genes on the move as lions roam

The amount of variation from alternate forms of genes found within a population is known as genetic diversity. Genetic diversity is important for a wildlife population because more genetic options give animals a greater chance for adaptation in a changing environment. Genetic diversity can also tell biologists about ways a population can fluctuate.

To a geneticist, migration, also referred to as gene flow, is the movement of genes from one geographical place to another. Mitochondrial DNA, inherited from the mother, can only tell researchers where genes from mom have been.

In the lion mating system, males travel long distances to find new prides, while females remain in or close to the pride they were born in. So, for the lion, it’s primarily males that are responsible for the movement of genes between prides. This male-mediated gene flow explains the lack of gene flow seen in mitochondrial genes compared to that of nuclear genes – female lions aren’t making the journey, but they do mate with new males who come from far away.

Male-mediated gene flow has helped keep the lions of Zambia genetically healthy, increasing genetic diversity by introducing new genes to new areas as male lions move between subpopulations. The eastern and western subpopulations each have high levels of genetic diversity; since only a few lions move between the groups each generation, the subpopulations stay genetically distinct.



My colleagues and I were also able to determine where the lions are moving based on which individuals are more genetically similar to each other. Lions in the North and South Luangwa National Parks, part of the eastern subpopulation, appear completely separated from the western subpopulation. Gene flow is occurring through the southern regions of the eastern subpopulation.

Lions are most likely traveling a route between the Lower Zambezi National Park and eastern corridor to the Kafue National Park in the west, possibly along the Kafue River. We can’t tell which way they’re moving, but by looking at where lions are more closely related, we can see where genes are being moved.



Lion data can help manage wildlife overall

Human-lion conflict is a big issue in Zambia, particularly outside of protected land. If lions were moving across human dominated areas, you’d think they’d be seen and reported. But these lions are sneaking through virtually undetected – until we look at their genes.

As a large, charismatic carnivore, lion research and conservation influences many other species that share their habitat.

Wildlife managers can use these findings to help with lion conservation and other wildlife management in and around Zambia. Now that we generally know where lions are moving, managers can focus on these areas to find the actual route the big cats are taking and work to maintain or even increase how many lions can move across these areas. One of the ways of doing this is by creating more protected land, like corridors, to better connect suitable habitat.