The Feline Family

The Feline Family

Categorising is a human speciality; items, colours, music, cats. Nothing escapes. All objects –animate or otherwise –are ruthlessly shunted into infinite figurative pigeonholes based on their similarities and differences. This grouping of like items becomes a beast unto itself within biology. For the uninitiated, I would like to take a moment to welcome you to the wonderful world of taxonomy and systematics, the naming and classification of living things.

In 1735, the world of biological science was forever changed by Swedish naturalist Carl Linnaeus upon the publishing of his magnum opus, Systema Naturae. Within this extensive tome, he painstakingly included entries for over ten thousand species of plants and animals and with them a binomial (two name) classification system which is still in use to this day. Whilst he was not the first to create this kind of system (that honour belongs to the Bauhin brothers, both botanists –try saying that when you have had a few drinks!) he was the first to publish using it. Of course, many of Linnaeus’ original groupings of plants and animals are now known to be incorrect. Back in Linnaeus’ day, there was not the fancy technology available for assessing DNA and subsequent genetic relations, so he had to base all his assumptions on the outward looks (or morphology) of the plant or animal. This is problematic when you think about how similar birds and bats are on the outside but are completely different groups genetically.

Nowadays, genetic analysis through marvellously sophisticated techniques is allowing us to get ever closer to discovering and refining which species are truly related to each other. Even so, scientists still squabble about what belongs where. The only constant is the use of the Linnaean naming system, or more simply, taxonomy.

The word taxonomy is derived from the Greek roots ‘taxis’ and ‘nomia’ (the former meaning arrangement and the latter, method). Taxonomic classification is divided into a series of ranks, some of which were created by Linnaeus. The highest of these is known as Domain. Ever since its (fairly recent) creation, the number of Domains has been hotly debated. Generally, the proposal of three Domains is most widely accepted. These are Bacteria, Archaea (microorganisms that are almost identical to Bacteria) and Eukarya (plants, animals, fungi and more). Within each Domain lies our next rank, Kingdom. Kingdom was originally the highest rank proposed by Linnaeus. He devised three Kingdoms: Plants, Animals and Minerals. No prizes for guessing which are still used today. As with Domain, there are several disagreements as to just how many Kingdoms there are, the most recent research has suggested seven but in the interests of our furry feline friends, we shall focus on one: Animalia.

Kingdom Animalia is split into a number of Phyla (singular Phylum). These Phyla sought to group animals initially by their morphology, but now by genetics. This has resulted in various animal groups being involved in taxonomic musical chairs as they have been propelled from one Phylum to the next. Luckily, our Phylum of interest, called Chordata (i.e. animals within this group have a ‘cord’ of spinal nerves as well as other defining features) has remained relatively stable. Within the realms of Chordata are some hopefully more familiar faces. The Sub-phylum Vertebrata contains seven living Classes (we are getting there, I promise). Three of these classes pertain to fish, the others are Amphibia, Reptilia, Aves (Birds) and Mammalia.

From Class, we progress into our next taxonomic rank, Order. At last count, there were 29 different Orders of mammals. However, the one we are interested in comprises a surprisingly diverse array of beasts. The Order Carnivora contains, among other groups, the seals, weasels, bears, dogs, hyaenas and, most importantly, cats. As an interesting aside, it is a common misconception that hyaenas are dogs, or at least closely related to them. In fact, they have their own group within Carnivora (a rank known as Family) and are more closely related to cats! However, now it is time for the Family we have all been waiting for, Felidae –the cats.

Studies have shown that felids as we know them evolved in the Miocene period, around ten million years ago, diverging from closely related groups such as the linsangs (small arboreal cat-like mammals). This makes them quite a recent addition to Class Mammalia. It has been discovered that there were eight separate evolutionary lineages which radiated from a common ancestor in Asia. The first of these lineages to evolve gave rise to the majority of the so-called ‘big cats’. Many of the smaller species then evolved rapidly in part due to many ancestral individuals migrating between continents and becoming adapted to new environments. The lineage which our lovely pet cats’ ancestors were part of was one of the most recent to have developed, possibly as late as 6.2 million years ago.

Today, there are 14 different extant (living) Genera (the singular Genus may be a familiar term) within Family Felidae. These are:

Acinonyx –The fast and furious, the cheetah (1 species).

Caracal –Funnily enough contains the adorable caracal and another not so aptly named species (2 species).

Catopuma –Interestingly does not contain the puma, but small Asian cats instead (2 species).

Felis –This is the Genus your cat belongs to. It also includes close relatives such as our native wildcat! (7 species).

Herpailurus –The shy Jaguarundi of the Americas (1 species).

Leopardus –The South American contingent (7 species).

Leptailurus –The African serval and its marvellous ears (1 species).

Prionailurus –A variety of small southeast Asian cats (4 species).

Puma –This one contains the puma (or mountain lion, or cougar, or one of its many names) (1 species).

Genera group related Species, of which there are, according to a 2016 study, 38 in total, though depending on who you ask, it fluctuates due to difference of opinion on genetic evidence. Genus and Species form the two parts of the animal’s Latin name in the aforementioned Linnaean binomial system. Let’s take the domestic cat, for example. Its Genus is Felis and its Species, catus.

You will notice that the Genus is always capitalised, and the Species, always lower case. The binomial name is also required to be italicised. Often, the chosen name will relate to the animal (a fun example is the brown bear, Ursos arctos, which directly translates to ‘bear bear’) or be named after a famous biologist. Ridiculous rules and naming conventions aside, scientists were still not happy. Due to the fickle mistress that is evolution, species are always changing and as such, this leads to minor differences between groups within a species, often due to location of populations. This is a small step towards becoming a brand-new species, bringing us to our final taxonomic rank, Subspecies. Domestic cats are not usually classified to Subspecies level, but our cat can take a trip into the trinomial for the sake of example, becoming Felis catus domesticus.

This taxonomic overview is just that, an overview. No matter where living things are categorised, someone will always disagree. Scientists are constantly completing new genetic analyses and reviewing the taxonomy of all kinds of species. If you were not already convinced that scientists are never able to agree on matters of taxonomy, they have introduced a number of subcategories such as Tribe, Suborder and many others which just make classification even more convoluted than it already was. To confuse things even further, sometimes species may have more than one correct classification! This extends to many felids, which may be known under different Genus names. Nevertheless, taxonomy and systematics is a fascinating field which shapes how we understand the natural world and pleases our innate need to categorise. Our brief tour of taxonomy will serve as an introduction to a wider series about Family Felidae covering each species in turn from the majestic tiger to the tiny black-footed cat and everything in between including our beloved pets. I hope you will join me for this exciting journey where we will investigate the biology, evolution, behaviour and the issues our feline friends face with ever-increasing human encroachment.

Composed by,

Thea Mainprize, Undergraduate of Zoology