despècies

In biology, a *despècies* (a term derived from the Latin *species*, meaning "kind" or "appearance") refers to a group of organisms that share similar characteristics, are capable of interbreeding to produce fertile offspring, and are reproductively isolated from other such groups. The concept of species is fundamental to taxonomy, the science of classifying and naming living organisms. While the definition of a species can vary depending on the context and field of study, it generally serves as a basic unit of classification in the hierarchical system of biological nomenclature.

The biological species concept, proposed by Ernst Mayr in the mid-20th century, defines a species as a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups. This concept emphasizes genetic exchange and reproductive barriers as key factors in species formation. However, alternative definitions exist for organisms that do not reproduce sexually, such as bacteria or some fungi, where morphological or genetic differences are used instead.

Species can be further categorized into subspecies, varieties, or strains based on minor genetic or phenotypic variations. The process of speciation—the formation of new and distinct species—can occur through mechanisms like geographic isolation, genetic drift, natural selection, or polyploidy (in plants). Over time, evolutionary changes can lead to the divergence of species into distinct lineages, contributing to biodiversity.

Identifying and classifying species is essential for understanding ecological relationships, conservation efforts, and evolutionary biology. However, challenges remain in defining species for organisms with complex reproductive systems or those that exhibit hybridizations. Advances in molecular biology and genetics have provided new tools for species delineation, often based on genetic markers rather than traditional morphological traits.