Species are defined as a group of organisms that can successfully breed and produce fertile offspring.
The various types of species concepts are as follows:
Biological species concepts: A biological species is a group of organisms that can reproduce with each other in nature and then produce fertile offspring.
Evolutionary species concept: The lineage of an organism's ancestral population is the concept of an evolutionary species that retains its identity from other such lineages and which has its own evolutionary traits and historical destiny.
Typological species concept: The concept of species as a group whose members have certain characteristics that distinguish them from other species.
Nominalistic species concept: The concept of the named species is the concept of Okem and his followers, the belief that nature produces only individuals.