Chapter 14
 Biological Species Concept
 Morphological Species Concept
 Ecological Species Concept
 Phylogenic Species Concept
 Primary Definition
 Considered the same species if they produce fertile
offspring
 Not useful for asexually reproducing organisms
 Not useful when examening fossils
Grolar – hybrid from Grizzly &
Polar Bears
Photo:via Inhabitots.com
 1.8 million species have been
identified using this method
 Useful for assexual and extinct
species
 Problem : subjective & open to
dispute (often heated!)
 Species identified by niche
 Two different species may look similar, but have
different feeding patterns or live in different
environments
 Defines a species as the smallest group of individuals
sharing a common ancestor
 Can be based on genetic differences or morphological
differences
 Can often cause disputes
 Allopatric Speciation
 Reproductive barriers are formed as populations
diverge
 Sympatric Speciation
 Polyploid Speciation
 Adaptive Radiation
 Geographic isolation leads to speciation
 Hybrid offspring are
less fit than parents
 This reinforces
reproductive barriers
 Speciation process
reverses and two
hybridizing species
fuse into one
Hybrid
Zone
Original
Population
Allopatric Speciation
Reproductive Isolation
results from
Isolating mechanisms
which include
Behavioral isolation
Geographic isolation
Temporal isolation
produced by
produced by
produced by
Behavioral differences
Physical separation
Different mating times
which result in
Independently
evolving populations
which result in
Formation of
new species