species concept
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Species concept. Different species usually form clusters of phenotypes. Length. Mass. Chronospecies. Evolutionary species. Species concepts. What is a species? What are the criteria for defining a species?. - PowerPoint PPT PresentationTRANSCRIPT
Species concept
Mass
Len
gth
Different species usually form clusters of phenotypes
Chronospecies Evolutionary species
Species concepts
What is a species?
What are the criteria for defining a species?
Species consist of interbreeding populations that evolve independently of other populations
Species concepts
Biological species concept
Phylogenetic species concept
Morphospecies concept
Species concepts
Biological species concept - BSC
species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups
Species concepts
Biological species concept - BSC
species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups
Problems with BSC
-asexual organisms-hybridization
Species concepts
Phylogenetic species concept - PSC
a species is a monophyletic group composed of the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent
Species concepts
Phylogenetic species concept - PSC
a species is a monophyletic group composed of the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent
Problems with PSC
-quantifying synapomorphies
Species concepts
Morphospecies concept - MSC
species are statistically distinguishable from others based upon an analysis of their morphological characteristics
Species concepts
Morphospecies concept - MSC
species are statistically distinguishable from others based upon an analysis of their morphological characteristics
Problems with MSC
-arbitrary-leads to cryptic species
Species concepts
Biological species concept
Phylogenetic species concept
Morphospecies concept
Beware the Procrustes fallacy!
Reliable criteria for identifying species are essential for preserving biodiversity
Indian elephant African elephant
Indian elephant African elephantAfrican forest elephant
The speciation process begins when gene flow is disrupted and populations become genetically isolated
Prezygotic barriers1 potential mates do not meet
temporal isolation, habitat isolation2 behavioral isolation3 mechanical isolation4 gametic incompatibility
Barriers to gene flow
Prezygotic barriers1 potential mates do not meet
temporal isolation, habitat isolation2 behavioral isolation3 mechanical isolation4 gametic incompatibility
Postzygotic barriers1 zygotic mortality2 hybrid inviability3 hybrid sterility4 F2 hybrid breakdown
Barriers to gene flow
Hybridization occurs when offspring are produced by interbreeding between genetically different populations
In intermediate or transitional habitats, hybrid populations may be more fit than either parental population
Hybrid Zones
Hybrid fitness Hybrid zone Outcome
< parents narrow, short lived reinforcement
= parents wide, long lived coalescence
> parents depends stable zone or
speciation