Q.Define species. Explain with an example.

[!TLDR] A species is a group of populations whose members can interbreed and produce fertile offspring, and are reproductively isolated from other such groups. …

[!ANSWER] A species is the fundamental taxonomic unit, defined by the ability of its members to interbreed and produce fertile offspring, and by reproductive isolation from other species.

The most widely used definition (the biological species concept) states that a species consists of one or more populations whose individuals can actually or potentially interbreed with one another in nature and produce viable, fertile offspring. Crucially, members of a species are reproductively isolated from members of other species — even if two different species can occasionally interbreed under artificial conditions, this either does not happen in nature, or the resulting offspring are typically infertile or fail to survive (for example, a mule, the offspring of a horse and a donkey, is generally infertile, which is why horses and donkeys remain classified as separate species). …

• Defining species only by physical similarity, without mentioning the interbreeding/fertile-offspring criterion. …