Phylogenetic classification

 

Le panda roux : Plus proche du panda géant ou du raton-laveur ?

 

The Chinese call it the “cat-bear”, the English the “firefox”, or the “Himalayan raccoon”. The scientists who discovered it in 1825 named it «Ailurus», a Latin term derived from the Greek «Ailuros», which means a cat.

Pas étonnant que le panda roux soit resté si énigmatique pendant toutes ces années ! Qui est son plus proche parent ? Le chat, le renard, le raton laveur ? Ou peut-être le panda géant ?

Red fox
Racoon
Giant panda

To help us answer this question, we interviewed Stéphane Peigné, the deputy director of the Centre for Research on Palaeobiodiversity and Palaeoenvironments. Mr. Peigné holds a PhD in Systematics and Evolution of Paleogene Feliform in Eurasia. He has been a researcher at the National Scientific Research Centre (CNRS) since 2003, and has worked at the National Museum of Natural History (MNHN) since 2007.

 

Morphological approach

The small panda was first described by Frédéric Cuvier in 1825. Consequently, its systematic position has not ceased to pose questions among the scientific community. Depending on the morphological criteria studied, the red panda looks more like a mustelid (otter), a procyonid (raccoon) or a viverrid (civet), depending on the general morphology of the body, the color, the length of the snout, the dentition, or the legs.

Otter
Civet

En 1843, Gray est le premier à utiliser le terme « ailuridé », qu’il entend comme une sous-famille. Dans la classification de Gray, les Carnivora sont divisés en deux groupes, l’un comprenant les félidés (félins), les hyaenidés (hyènes), les viverridés, les canidés (loups) et les mustélidés, l’autre les ailuridés, les procyonidés et les ursidés (ours). Mais le terme « ailuridés » ne sera pas réutilisé avant la fin du XXe siècle.

Until the mid-1960s, the majority of studies placed the genus Ailurus among the procyonids, or described them as cousins. The morphological criteria used are: dentition, skull, general anatomy, skull base, genetics and ecological evidence.

Red panda skull  
Racoon skull

Mais la majorité de ces caractères n’est pas pertinente, car ils peuvent résulter par exemple d’une variation intraspécifique, ou encore être trop généraux. Par exemple, prenons le nombre de molaires présentes sur chaque mandibule : les ours en comptent trois, alors que les pandas roux n’en possèdent que deux…

Crâne d’ours

Il faut également savoir que les premières études ne comparaient que quelques taxons entre eux. En 1964, Davis, qui étudie alors le panda géant, réalise une comparaison plus exhaustive avec, cette fois-ci, un certain nombre d’autres espèces de Carnivora. Il en résultera de son étude que le panda géant fait partie de la famille des ursidés, avec une spécialisation alimentaire herbivore ; Davis fait un autre constat : le panda roux est différent du panda géant et n’est pas un ursidé. A partir de la fin des années 1980, les scientifiques incluent plus de Carnivora dans leurs études, permettant ainsi de préciser la classification systématique.

 

Historic approach

We now know that the family of ailuridae comprises nine genera, and twenty-six species, almost all fossils. The only species still alive is Ailurus fulgens, the red panda. But it has not been easy to determine the systematic position of all these species because scientists sometimes have little material to carry out their research (skeletons often incomplete). Thus the origin of the family is still to be determined, but the oldest ailurid found would be dated to 28 million years, at the end of the oligocene era. This is Amphictis. All Amphictis skeletons have been discovered in Europe, which determines the cradle of the family in this region. Then ancestors of the red panda would have migrated to Asia and North America. The genus Ailurus appears in China in the middle of the Pleistocene period.

Taking all of these fossils into account has established a close relationship between these species, with 31 significant morphological characters (related to the skull, mandible, dentition, and a modified wrist bone, also known as “fake thumb”)., thus classifying them in a very special family, that of the ailuridae. But not all ailuridae are alike! The species of the genus Simocyon, for example, appeared 9 million years ago, at the end of the Miocene era, were the size of a puma, and carnivorous, unlike the red panda, which feeds on bamboo.

Simocyon batalleri

 

Molecular approach

The first biochemical studies were carried out in the late 1960s, and the first molecular studies were carried out in the mid-1980s. During this period, the position of the red panda has evolved considerably among the arctoids (taxon grouping ursids, procyonids, mustelids, mepihtidae, pinnipeds and ailuridae). This is due to different major parameters such as the number of taxa used for analyses, or the number and diversity of genes.

These early biochemical and molecular studies showed a link between the red panda and the giant panda. It is true that the vernacular name “panda”, derived from a Nepalese word meaning “bamboo eater”, and the geographic distribution of these animals tended to confirm this link.

Geographic distribution of red panda          
Geographic distribution of giant panda

In addition, at that time, the systematic position of the giant panda was also controversial. It was not until 1964 that he was assimilated to a bear. Moreover, until the late 1980s, studies compared the red panda only to the giant panda, a few bears, a few procyonids and a few other arctoids. From 1989, the scientists took into account many other Carnivora, making it possible to better define the classification. In 2000, thanks to their molecular analysis, Flynn and his colleagues establish that the taxon of Musteloïdea includes four families: mustelidae (otters, martens), procyonidae (raccoons), mephitidae (skunks) and ailuridae! For this study, they took into account all caniforms, that is, arctoids and canidae.

Phylogenetic tree of caniforms

 

Ainsi, depuis sa découverte en 1825, le panda roux n’a cessé d’évoluer dans la classification systématique. Il faudra attendre le début du XXIe siècle pour que paléontologues et biologistes moléculaires s’accordent et lui octroient sa place si particulière. C’est l’unique descendant encore vivant d’une famille à part entière : les ailuridés. Sa relation avec le panda géant se limite à son appellation. Il n’est pas rare d’ailleurs que des espèces animales portent le même nom, comme par exemple, le rhinocéros : gros mammifère herbivore et également insecte coléoptère. Nous pouvons donc conclure en répondant à notre question initiale : Le petit panda est plus proche du raton-laveur !

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