A group of scientists, operating from a series of Brazilian research institutions, claim to have identified a new neotropical wild cat, in the depths of the Brazilian forests. Quite incredibly, the spotted feline has been hiding in plain sight for many years.
The discovery shows how far scientists have yet to go, in furthering their understanding of the natural world. Speaking to the National Geographic, Eduardo Eizirik, based at the Pontifícia Universidade Católica do Rio Grande do Sul, in Brazil, briefly reflects upon the current gaps in our knowledge:
“So much is still unknown about the natural world, even in groups that are supposed to be well-characterized, such as cats… In fact, there are many basic aspects that we still don’t know about wild cats, from their precise geographic distribution and their diets.”
Researchers initially suspected there to be a single species of Brazilian tigrina. However, novel molecular studies have demonstrated a difference between the populations investigated in northeastern Brazil and those found in southern Brazil.
In the latest study, the researchers established an intricate, evolutionary relationship between tigrinas and two other species of neotropical cat.
Hiding in Plain Sight
From an aesthetic standpoint, the southern tigrina is almost indistinguishable from its northeastern counterpart, with only very subtle clues to show they are two distinct species. The northeastern tigrina has a lighter pelt, smaller spots and a longer tail, with barely perceptible variations in ear shape. To add to the confusion, there appears to be a larger number of physical differences between individuals within each species than between the two species.
It was not until the researchers began studying the genetic differences of tigrinas throughout Brazil that the difference became so apparent. Interpreting the DNA sequences of 115 Leopardus tigrinus, 74 Leopardus geoffroyi and 27 Leopardus colocolo wild cats, the group found there to be startling and unprecedented differences between tigrinas of the northeast and those found in the south and southeast; many of these genetic differences were as large as those discovered between other species of wild cat.
Tatiane Trigo, of the Universidade Federal do Rio Grande do Sul, has assigned the traditional tigrina name (Leopardus tigrinus) to northeastern cats, and a new name (Leopardus guttulus) for the southern tigrinas.
These cats represent cryptic species, consisting of two biological groups that are thought to be almost morphologically indistinguishable, each of which are capable of interbreeding. There are also thought to be several species of frogs, mouse lemurs and killer whales that all belong to a cryptic species complex, to name just a select handful of examples.
A History of Hybridization
One of the most interesting finds was that the wild cats had a history of hybridization. In the past, the researchers believe that mating took place between genetically distinct individuals, hailing from two entirely
separate species. For example, they found hybridization and transmission of genes between the pampas cat (Leopardus colocolo) and the northeastern tigrinas (Leopardus tigrinus).
Named after the lush South American lowlands, pampas cats are predominately localized to forest areas, grassland, shrubland and open plains and are reported to hunt rodents, wild birds and domestic poultry, on a nocturnal basis. The pampas wild cat is relatively small with a body length spanning from 45 to 75 centimeters, and a tail length that measures between 20 and 30 centimeters.
The appearance of the pampas cats’ fur, or pelage, varies considerably between individuals. Some groups display red-brown spots across their sides, along with prominent stripes down their tails and legs. Meanwhile, other groups have an overall dull grey pelt, with spots around their lower abdomen, plain tails (lacking prominent patterns) and red/brown stripes along their legs.
Leopardus tigrinus (a.k.a. Oncilla), however, are small, rosette-spotted wild cats found on the open plains of Central and South America. Leopardus tigrinus is a nocturnal predator that hunts a myriad of different animals, including rodents, birds, lizards and tree frogs.
The Oncilla are small, thin-bodied creatures, with lengths that range between 40 to 60 centimeters (excluding tail) and weigh in at around 1.5 to three kilograms. Their pelts are a soft brown to dark ochre and covered in dark rosettes, dotted across their backs and flanks. It is thought that the hue of their fur provides some form of camouflage with the blotchy sunlight, cast against the lower depths of their tropical forest habitats.
Ultimately, Trigo and her colleagues found that some of the genes of northeastern tigrinas originated from pampas cats. Although the two species are long-thought to have ceased interbreeding, it is theorized that they would have done so in the past. Considering these findings, the authors suggest that the afore-mentioned interbreeding, between ancestors of the pampas cat and those of the northeastern tigras, may have yielded important evolutionary adaptations.
Meanwhile, the newly recognized southern tigrinas (Leopardus guttulus) are now understood to hybridize with Geoffrey’s cats (Leopardus geoffroyi), which are larger, stockier wild cats found on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.
The two species overlap in southern Brazil – a location the authors equate to a “hybrid swarm,” where the majority of southern tigrinas and Geoffrey’s cats are partial hybrids of one another.
Eizirik claims that researchers possess more intimate knowledge of wild cats inhabiting southern regions of the country. On these auspices he highlights the need for further research into the majestic northeastern tigrinas:
“Our study highlights the need for urgent attention focused on the Brazilian northeastern tigrinas, which are virtually unknown with respect to most aspects of their biology.”
Meanwhile, Trigo points out that the differences in the habitats assumed by northeaster and southern wild cat species could provide important clues as to their unique evolution:
“Such distinct habitat associations provide a hint to potentially adaptive differences between these newly recognized species and may have been involved in their initial evolutionary divergence.”
The group believe that understanding the biodiversity, ecology, evolution and genetics of the various wild cat populations could prove key to orchestrating more effective conservation strategies, since all four studied species remain threatened.
The research was recently published in the journal Current Biology, on Nov. 27, entitled Molecular data reveal complex hybridization and a cryptic species of Neotropical wild cat.
By James Fenner