What is a "species"?
Biological Species Concept
• First recorded by John Ray (1628-1705)
• "Species are groups of reproducing organisms"
• If A and B can produce offspring, then they are considered the same species
• Problems with BSC:
◦ Not testable in allopatric organisms (don't live in the same place)
◦ Not testable in allochronic organisms (live in different times)
◦ Not testable in fossil record
◦ How does this apply to organisms that reproduce asexually?
• Mayr: "species are groups of actually or potentially interbreeding natural populations, which are
reproductively isolated from other such groups"
◦ actually or potentially: wiggle room for allopatric conspecifics (don't live in the same place)
◦ natural: eliminates zoo hybrids
◦ reproductively isolated: does not specify genetically isolated; means that these things do not
Other Species Concepts
• Recognition SC: a species is an inclusive population of individual biparental organisms which share a
common fertilization system
◦ things that recognize each other as potential mates belong in the same species
• Ecological SC: a species is a lineage (or closely related set of lineages) which occupies an adaptive
zone minimally different from that of any other lineage in its range and which evolves separately from all lineages
outside its range
• Phylogenetic SC: a species is a diagnosable cluster of individuals within which there is a parental
patter of ancestry and descent, beyond which there is not, and which exhibits a pattern of phylogenetic ancestry
and descent among units of like kind
◦ share some set of traits that others do not in your evolutionary history
• Phenetic SC: we may regard a species as a) the smallest (m