Species & Speciation UPDATED ACTUAL QUESTIONS
AND CORRECT Answers
Taxonomy the science of naming and classifying groups of biological organisms
Species name: two-parts 1. Genus to which species belongs
2. Specific name that identifies the species within the genus
Species names are always in italics, with the genus capitalized and the name
uncapitalized
Ex. Homo sapiens
What is a species? A "kind" or an "appearance"
--> very vague
--> simply assessing whether groups are distinct from one another based on
appearance alone is misleading
→ generally speaking, species are groups of organisms that are similar in
appearance, physiology, biochemistry, and/or DNA sequence
Species Plot: Showing Variation Within and Between
Species
Biological Species Concept (BSC) For individuals to be members of the same species, they must be
reproductively compatible and produce offspring that are also fertile.
Although a horse and a donkey can mate to produce a mule, the mule is
infertile. Therefore, horses and mules are different species.
, Complications of the BSC: Hybridization Some closely related species are able to interbreed and reproduce.
The hybrid offspring do not look like either parental species and are not a
species distinct from the parental species, which suggests:
1) Natural selection may act against hybrids, and
2) reproductive isolation has not completely evolved between the two species.
Morphospecies Concept • The morphospecies concept states that members of the same species usually
look alike.
• This doesn't always work for identifying species. Here are three species of
butterfly that superficially look like one another.
• When you look at the chromosomes of each species, it can be seen that they
are very different from one another.
Ecological Species Concept The ecological species concept (ESC) is based on the idea that there is a one-
to-one correspondence between a species and its niche.
Phylogenetic Species Concept (PSC) • According to the phylogenetic species concept, all members of a species
have descended from a common ancestor and share a common fate.
• This species concept is useful for asexually reproducing species.
How we define a species depends on the definition we Species definitions:
are using -Biological species concept
-Morphospecies concept
-Ecological species concept
-Phylogenetic species concept
How do we reconcile all these different definitions? Which one do we use?
Which one(s) are correct?
***This issue is aptly named "the species problem" - it's difficult to settle on one
concrete definition
Molecular species concept -Using genetic differences to delineate species
Ex. DNA barcoding
DNA Barcoding a method of species identification where DNA sequences from specific gene(s)
are compared
DNA BArcoding Rationale Rationale:
-Certain genes are very well-conserved (Present across species and largely
unchanged over evolutionary time) over evolutionary history
-These genes have little intraspecific variation (within species) and greater
interspecific variation (between species)
DNA Barcoding Commonly Used Genes Genes commonly used: mitochondrial genes (ex. CO1), ribosomal genes such
as 16S and 18S
AND CORRECT Answers
Taxonomy the science of naming and classifying groups of biological organisms
Species name: two-parts 1. Genus to which species belongs
2. Specific name that identifies the species within the genus
Species names are always in italics, with the genus capitalized and the name
uncapitalized
Ex. Homo sapiens
What is a species? A "kind" or an "appearance"
--> very vague
--> simply assessing whether groups are distinct from one another based on
appearance alone is misleading
→ generally speaking, species are groups of organisms that are similar in
appearance, physiology, biochemistry, and/or DNA sequence
Species Plot: Showing Variation Within and Between
Species
Biological Species Concept (BSC) For individuals to be members of the same species, they must be
reproductively compatible and produce offspring that are also fertile.
Although a horse and a donkey can mate to produce a mule, the mule is
infertile. Therefore, horses and mules are different species.
, Complications of the BSC: Hybridization Some closely related species are able to interbreed and reproduce.
The hybrid offspring do not look like either parental species and are not a
species distinct from the parental species, which suggests:
1) Natural selection may act against hybrids, and
2) reproductive isolation has not completely evolved between the two species.
Morphospecies Concept • The morphospecies concept states that members of the same species usually
look alike.
• This doesn't always work for identifying species. Here are three species of
butterfly that superficially look like one another.
• When you look at the chromosomes of each species, it can be seen that they
are very different from one another.
Ecological Species Concept The ecological species concept (ESC) is based on the idea that there is a one-
to-one correspondence between a species and its niche.
Phylogenetic Species Concept (PSC) • According to the phylogenetic species concept, all members of a species
have descended from a common ancestor and share a common fate.
• This species concept is useful for asexually reproducing species.
How we define a species depends on the definition we Species definitions:
are using -Biological species concept
-Morphospecies concept
-Ecological species concept
-Phylogenetic species concept
How do we reconcile all these different definitions? Which one do we use?
Which one(s) are correct?
***This issue is aptly named "the species problem" - it's difficult to settle on one
concrete definition
Molecular species concept -Using genetic differences to delineate species
Ex. DNA barcoding
DNA Barcoding a method of species identification where DNA sequences from specific gene(s)
are compared
DNA BArcoding Rationale Rationale:
-Certain genes are very well-conserved (Present across species and largely
unchanged over evolutionary time) over evolutionary history
-These genes have little intraspecific variation (within species) and greater
interspecific variation (between species)
DNA Barcoding Commonly Used Genes Genes commonly used: mitochondrial genes (ex. CO1), ribosomal genes such
as 16S and 18S
