Chapter 19 13-03-03 1:59 PM
Biological species concept: the definition of species based on the ability of
populations to interbreed and produce fertile offspring.
Problems: some species reproduce asexually.. so are these not species…?
What about androdioecous organisms (all males) and gynogenetic organisms
What about hybridization? Is the hybrid a new species? Are the two species
Phylogenetic Species concept: defines a species as a group of organisms
bound by a unique ancestry.
Ecological species concept: defines a species as group of organisms that
share a distinct ecological niche (occupy the same location with the same
Morphological species concept: is the idea that all individuals of a species
share measureable traits that distinguish them from individuals of other
There are total of 12 concepts
Ring species: some plants and animals have ring shaped geographic
distribution that surround uninhabitable terrain. Adjacent species of these
ring species can exchange genetic material directly, but gene flow between
distant populations occurs only through intermediary populations.
Clinal (cline) variation: a pattern of smooth variation along the
Usually results from gene flow between populations… you can “see” the
evolution along a line…. Can be very different at the ends.
Allopatry (allopatric speciation): the evolution of reproductive isolating
mechanisms between two populations that are geographically separated.
Parapatry (parapatric speciation): speciation between populations with
adjacent geographical distributions. Sympatry (sympatric speciation): speciation that occurs without the
geographic isolation of populations
Sympatric: occupying the same spaces at the same time
Species cluster: a