The species (4): towards a consensual definition

At all times and whatever the concept of species dividers and joiners were opposed first tending to create species, the seconds joining together them.

Thus, Linné had made of all the species of the kind Ophrys only one Ophrys species Ophrys insectifera.

Linné had made of all the various current species of the kind Ophrys, only one Ophrys species Ophrys insectifera.

Contrary, Alexis Jordan (1854 and 1873 in Cuénot, 1936) identified morphological types of various species of plants (Erophila verna, Chelidonium majus for example) and cultivated them by sowing: it noted that the morphological characters were maintained. Each one of these types were for him a species.

The Jordanian species, so called jordanon, once gathered formed the traditional species linéenne (species defined by a morphological type). However, the Jordanian species is often regarded as a row infraspecific because they are morphological types geographically isolated (ecotypes).

ndeed, nowadays, the specific designs are rather broad and of the infraspecific concepts such as the subspecies, the varieties and the forms are retained instead of the narrow species. At the hawthorn, Crataegus laevigata, C. oxyacantha, C. oxyacanthoides, C. palmstruchii, C. curvisepala and C. lindmanii, present in our areas, are classified in a single species Crataegus laevigata gathering various subspecies. In the same way, Pinus will nigra, P. austriaca, P. laricio, P. pallasiana and P. salzmanii belongs to the broad species Pinus will nigra.

Towards a consensual definition

In spite of the debates existing between the 3 principal conceptual schools of the species (morphological, biological, evolutionary), all the authors recognize that the species is a real and paramount elementary notion in the hierarchy of the animal world or plant. Moreover, even if Mayr preaches the biological concept of the species, he considers a vast panoply of tools to delimit the geographically isolated species: morphology, geography, ecology, behavior and molecular biology. This approach resembles the morphological and systematic new discipline integrating systematic molecular called NEM (New Evolutionary Morphology or New Evolutionary Morphology) presented in the article of Jerome Degreef, Elmar Robbrecht & Erik Smets.

Such approaches were already carried out on the species of the Camassia kind (Large & Al, 2001) or of the kind Tetraplasandra (Costello & Motley, 2001). The combined analysis of morphological, molecular and biogeographic data made it possible in these studies to separate the species and to distinguish, for example, the characters plesiomorphologic (morphological “antiquated”) which were by way of derived characters: for example, the ovary super derives from an ovary infers (supposed character “advanced”) at Tetraplasandra. The biogeographic history of the species of Cercis carried out thanks to an analysis DIVA (DIspersal Analysis Vicariousness) and combined with molecular analyzes made it possible to know the history of the speciation of this kind (Fritsch P.W. & Al, 2001).