#speciation

• Allochronic — Occurring or developing at different times or during distinct geological eras; relating to organisms, species, or biological processes that are temporally isolated, thereby preventing hybridization or ecological overlap. In evolutionary genetics, the concept describes a structural mechanism of speciation whereby populations become reproductively isolated because their mating or activity periods do not coincide in time.
• Allopatric — Relating to related species, populations, or organisms: occupying completely different geographic ranges, isolated or separated by natural physical barriers (mountains, rivers, deserts) that prevent gene flow and direct interbreeding. In evolutionary biology, allopatric isolation represents the primary structural mechanism triggering speciation, leading to the accumulation of independent genetic mutations in the separated populations.
• Allopolyploidy — The state, property, or structural phenomenon consisting of the presence of more than two chromosome sets originating from distinct species following interspecific hybridization. Allopolyploidy represents a major evolutionary engine in the plant kingdom, allowing the instantaneous emergence of new, fertile species reproductively isolated from their parents, combining the genetic advantages of both ancestral lines.
• Amixia — The absence of sexual reproduction or the genetic and structural inability to crossbreed between individuals belonging to different species or populations, leading to their reproductive isolation. In a broader sense, it describes the lack of normal mixing or gametic fusion within a biological cycle, with direct implications for genetic purity or speciation.
• Anagenesis — A macroevolutionary mechanism or process characterized by the linear and progressive evolution of a single phyletic lineage, wherein an entire species undergoes structural and genetic transformations accumulated over time, gradually transforming into a new species without branching. This evolutionary phenomenon, opposite to cladogenesis, involves the complete replacement of the old gene pool through continuous adaptation to the environment, leading to the emergence of superior morphological and physiological traits.
• Autophylogeny — A theoretical concept or rare scientific neologism used to describe the historical evolution and phylogenetic development of an isolated genetic lineage or species, based exclusively on its own gene pool and without influences from external gene flow or hybridization. In macroevolutionary analyses, the term emphasizes strictly endogenous genetic drift and speciation within a completely closed habitat.