The biological species concept defines a species as a group of individuals living in one or more populations that can potentially interbreed to produce healthy, fertile offspring
The biological species concept connects the idea of a species to the process of evolution
Because members of a species can interbreed, the species as a whole has a common gene pool, a collection of gene variants
In order to be considered to be a single species in the biological species concept, a group of organisms must produce healthy, fertile offspring when they interbreed
In some other cases, organisms of different species can mate and produce healthy offspring, but the offspring are infertile, can’t reproduce
Hence it includes the groups which are reproductively isolated so asexual fungi will be least relevant to this group
Decreased surface-to-volume ratio. The dolphin's fusiform body shape and reduced limb size decrease the amount of surface area exposed to the external environment.
Increased insulation. Dolphins deposit most of their body fat into a thick layer of blubber.