Q.How does allopatric species differ from sympatric species ?

Speciation is the process by which one species evolves into one or more new species — a fundamental process within evolution. A.E. Emerson defined a species as a 'genetically distinctive, reproductively isolated natural population'. If a single lineage evolves into a new species without branching, this is anagenesis/phyletic speciation; if one species diverges into two or more, it is cladogenesis/divergent evolution. Two geographic modes of cladogenesis are recognised: sympatric speciation, where a new species forms within the same geographic area as its ancestor, relying primarily on sexual/reproductive isolation (e.g. phenotypic plasticity initiating divergence within an unseparated population); and allopatric (geographical) speciation, where a physical barrier (land separation, migratio …