BIOL 318 EVOLUTION ALL EXAM 2
LECTURE NOTES
(Virginia Commonwealth University)
, Exam 2: Chapter 4, 5 and 10-15
Chapter 4: Speciation- concepts and
mechanisms
Species and Speciation:
• Species are the fundamental unit of biological diversity
• Speciation refers to the processes that produce species
What are species:
• Species have two components
o Spatial
o Temporal
Evolutionary species concept:
• Problems with a “one size” fits all definition of species
• Defines species as:
o Lineage of ancestral-descendant populations which maintains its
identity from other such lineages and which has its own evolutionary
tendencies and historical fate
Morphological species concept:
• Traits evolve through time, visible traits and their relationships to
another=organisms morphology (phenotype)
• Morphologies can vary across separate evolutionary lineages because of
evolutionary processes
• So, species should be able to be defined by differences in their morphologies
• Quantifying morphological diversity is known as phonetics
Biological species concept:
• Evolutionary history affects the accumulation of differences that allow
different morphological types to produce viable offspring
• We can use the ability of two types (populations, different phenotypes,
lineages) to produce viable offspring as a measure of whether or not they are
from the same or different species
• Requires that enough divergence have occurred such that they cannot mate
successfully
o Gene flow among populations decreases diversity and divergence
among populations
• Can use by studying:
o Patterns of gene flow
o Tests of crossing individuals from different populations lacking
connections via gene flow
Phylogenetic Species Concept:
• Evolutionary history results in an underlying tree like structure describing
this history
• Used to help define species:
o Clades are monophyletic groups and monophyletic groups can be
defined by special characters known as synapomorphies
LECTURE NOTES
(Virginia Commonwealth University)
, Exam 2: Chapter 4, 5 and 10-15
Chapter 4: Speciation- concepts and
mechanisms
Species and Speciation:
• Species are the fundamental unit of biological diversity
• Speciation refers to the processes that produce species
What are species:
• Species have two components
o Spatial
o Temporal
Evolutionary species concept:
• Problems with a “one size” fits all definition of species
• Defines species as:
o Lineage of ancestral-descendant populations which maintains its
identity from other such lineages and which has its own evolutionary
tendencies and historical fate
Morphological species concept:
• Traits evolve through time, visible traits and their relationships to
another=organisms morphology (phenotype)
• Morphologies can vary across separate evolutionary lineages because of
evolutionary processes
• So, species should be able to be defined by differences in their morphologies
• Quantifying morphological diversity is known as phonetics
Biological species concept:
• Evolutionary history affects the accumulation of differences that allow
different morphological types to produce viable offspring
• We can use the ability of two types (populations, different phenotypes,
lineages) to produce viable offspring as a measure of whether or not they are
from the same or different species
• Requires that enough divergence have occurred such that they cannot mate
successfully
o Gene flow among populations decreases diversity and divergence
among populations
• Can use by studying:
o Patterns of gene flow
o Tests of crossing individuals from different populations lacking
connections via gene flow
Phylogenetic Species Concept:
• Evolutionary history results in an underlying tree like structure describing
this history
• Used to help define species:
o Clades are monophyletic groups and monophyletic groups can be
defined by special characters known as synapomorphies
