Populations of black-footed cats, a little-known feline in southern Africa, have been declining for half a million years and exhibit very high levels of inbreeding. This could increase their risk of developing a condition called amyloidosis, according to a new genetic study.

“Genomic studies often focus on large, charismatic cats, so smaller species, particularly the very small black-footed cat, are overlooked,” says study author Andrew Kitchener, senior curator of vertebrates at the National Museums of Scotland. “However, all species have interesting stories to tell and the black-footed cat is no exception.”

Weighing about as much as a large pineapple, the black-footed cat (Felis nigripes) is one of the smallest, rarest and arguably most endearing cats in Africa. They are only found in the arid steppes and grassy savannahs of southern Africa, including Namibia, South Africa and Botswana. The IUCN Red List classifies them as vulnerable to extinction.

Like many other endangered species, the black-footed cat is under pressure from habitat loss and degradation, as well as climate change. But there’s also another worry: About 70 percent of black-footed cats in captivity die from amyloidosis, a fatal disease associated with deleterious genetic mutations and considered hereditary. Wild populations are also susceptible, although the mortality rate is almost impossible to determine.

Over the past few decades, researchers have learned much about the conservation needs of the cat, thanks to long-term field studies in South Africa and Namibia. Black-footed cats – beautiful tawny predators with black spots and stripes that almost resemble domestic cats – are extremely successful nocturnal hunters with a voracious appetite, eating a fifth of their body weight in prey each night. Mortality rates are high, with nearly 40 percent of study populations dying each year, mainly from predation and disease, says Alexander Sliwa, project leader of the Black-footed Cat Working Group and curator at the Cologne Zoo. But until now, very little research has been done on their genetics.

To correct this imbalance, Kitchener and his fellow researchers began by generating the black-footed cat genome from a number of reference samples. They then combined this data with previously published genomic data on the species and compared it to the genomes of other small cat species.

The study shows that the black-footed cat came from Felis genus about 3 million years ago, making it one of the oldest small cats. There is evidence of later hybridization with jungle cat ancestors (Felis Chaus), sand cat (Margarita Felis) and the wildcat (Felis silvestris). The researchers also traced the selection of genes that help make the black-footed cat such a successful hunter, including those associated with the ability to track fast-moving objects, acute hearing, and a high metabolic rate that allows it to stay active cool. nights.

But the analysis also shows that the black-footed cat population has been declining over the past half-million years. Researchers have found a worrying degree of inbreeding and, to some extent, even lower levels of genetic diversity than some big cats like lions (panthera lion) and jaguars (P. onca). These high levels of inbreeding are likely due to historical and contemporary habitat fragmentation, the authors write, and may increase the risk of the deadly disease amyloidosis, which is known to have a genetic basis.

Sliwa, who was not involved in the study, says it addresses a real lack of genetic studies on small cats, adding that future studies with larger samples from more geographic areas would be interesting.

Today, black-footed cat populations face myriad threats, including land-use change, habitat fragmentation, climate change, and disease. In long-term Sliwa black-footed cat study sites in South Africa and Namibia, the impacts are alarming.

“I am currently facing a total population collapse in my study areas,” he says.

In 2023 and 2024, Namibia will experience its worst drought in a century, partly fueled by El Niño and climate change. Over the next century, these droughts will likely become more frequent and more severe, according to climate change projections.

Sliwa notes that in his study area, in southern Namibia, there has been virtually no rain over the past two years. The area has always been near the limits of what the black-footed cat can tolerate in terms of aridity. Today, drought is pushing cats out of their preferred short-grass habitats and into river beds, bringing them into closer contact with farmers and their dogs. The twin threats of starvation and being killed by dogs meant that last year all the animals in Sliwa’s study died.

The world of the black-footed cat is also evolving in many other ways. Humans are driving many large carnivores towards extinction, meaning the lion, leopard (Panthera pardus) and the cheetah (Acinonyx jubatus) populations have declined or disappeared across much of the black-footed cat’s range, replaced by medium-sized predators. In the Sliwa study areas, this means more caracals (Caracal caracal) and black-backed jackals (Lupulella mesomelas), both of which kill black-footed cats.

“We’re talking about two very generalized predators versus one highly specialized predator,” says Sliwa. “And those two, the caracal and black-backed jackals, are the primary predators of the black-footed cats, so we’re losing at least 30 percent (of the cats) in terms of predation.”

Sliwa also sees the impact of amyloidosis on the wild population, but says it’s difficult to determine how much of overall mortality is attributable to the disease.

Amyloidosis is a disease in which abnormal proteins are deposited in organs or tissues. In black-footed feral cats, the first sign is excessive thirst. Black-footed cats generally obtain all the fluid they need from the blood of their prey. But as these abnormal proteins affect the kidneys, the sick cat will start going into stagnant water. Once this happens, the cat usually dies within a month, Sliwa explains, either because it dies completely from the disease or because it becomes increasingly disoriented and becomes an easier target. for predators.

“So for us it’s quite difficult to distinguish,” says Sliwa. “Was it pure predation because the animal wasn’t paying attention, or was this animal already sick and was it captured?”

The combination of these threats means that entire populations can disappear, an outcome that Sliwa and his colleagues are working to avoid.

For the black-footed cat and other endangered species, understanding genetic susceptibility to disease is important, Sliwa says, but it alone is not enough to conserve wild populations. This requires field data and funding to support conservation work on the ground, he adds.

Banner image: A male black-footed cat stalking its prey in winter 2019. Black-footed cats feed primarily on small mammals and birds. Their keen eyesight and agility make them extremely successful hunters. Image courtesy of Alexander Sliwa.

Quotes:

Lai, S., Warret Rodrigues, C., O’Donnell, H., Küsters, M., Herrick, J., Lawrenz, A.,… Sliwa, A. (2024). Assessing the effect of predator control on the survival of black-footed cats in central South Africa. African Journal of Ecology, 62.(3), e13316. do I:10.1111/aje.13316

Sliwa, A., Lai, S., Küsters, M., Herrick, J., Lawrenz, A., Lamberski, N.,…Wilson, B. (2022). Causes of mortality in a population of black-footed cats in central South Africa. African Journal of Ecology, 60(4), 1311-1317. do I:10.1111/aje.13033

Yuan, J., Kitchener, AC, Lackey, LB, Sun, T., Jiangzuo, Q., Tuohetahong, Y.,… Li, G. (2024). The black-footed cat genome: revealing a rich natural history and urgent conservation priorities for small cats. Proceedings of the National Academy of Sciences, 121(2), e2310763120. do I:10.1073/pnas.2310763120

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