Download Notes from 9/26

A quick review…
•
•
•
•
•
•
Taxon: generally refers to any named group of organisms, such
as species, genus, family, order, etc..
Node: represents the hypothetical ancestor
Branches: lines diverging from a node
Root: oldest divergence of a phylogenetic tree
Terminal branch: most recently evolved taxa
Polytomy: unresolved node, multiple descendents
A quick review…
C
5
C6
1
Species Concepts
•
Morphological Species - A population or group of populations that
differs morphologically from other populations.
•
Evolutionary Species – A single lineage of populations or organisms
that maintains its identity from other such entities and has its own
evolutionary tendencies and historical fate.
•
Phylogenetic Species - an irreducible cluster of organisms, within
which there is a parental pattern of ancestry and descent, and which
is diagnosably distinct from other such clusters
•
Biological Species - Group of natural populations that is
reproductively isolated from other such groups, but in which the
component populations are not reproductively isolated
Species Concepts
•
Morphological Species - A population or group of populations that
differs morphologically from other populations.
•
Evolutionary Species – A single lineage of populations or organisms
that maintains its identity from other such entities and has its own
evolutionary tendencies and historical fate.
•
Phylogenetic Species - an irreducible cluster of organisms, within
which there is a parental pattern of ancestry and descent, and which
is diagnosably distinct from other such clusters
•
Biological Species - Group of natural populations that is
reproductively isolated from other such groups, but in which the
component populations are not reproductively isolated
2
Species Concepts
•
Morphological Species - A population or group of populations that
differs morphologically from other populations.
•
Evolutionary Species – A single lineage of populations or organisms
that maintains its identity from other such entities and has its own
evolutionary tendencies and historical fate.
•
Phylogenetic Species - an irreducible cluster of organisms, within
which there is a parental pattern of ancestry and descent, and which
is diagnosably distinct from other such clusters
•
Biological Species - Group of natural populations that is
reproductively isolated from other such groups, but in which the
component populations are not reproductively isolated
Species Concepts
•
Morphological Species - A population or group of populations that
differs morphologically from other populations.
•
Evolutionary Species – A single lineage of populations or organisms
that maintains its identity from other such entities and has its own
evolutionary tendencies and historical fate.
•
Phylogenetic Species - an irreducible cluster of organisms, within
which there is a parental pattern of ancestry and descent, and which
is diagnosably distinct from other such clusters
•
Biological Species - Group of natural populations that is
reproductively isolated from other such groups, but in which the
component populations are not reproductively isolated
3
Species Concepts
•
Morphological Species - A population or group of populations that
differs morphologically from other populations.
•
Evolutionary Species – A single lineage of populations or organisms
that maintains its identity from other such entities and has its own
evolutionary tendencies and historical fate.
•
Phylogenetic Species - an irreducible cluster of organisms, within
which there is a parental pattern of ancestry and descent, and which
is diagnosably distinct from other such clusters
•
Biological Species - Group of natural populations that is
reproductively isolated from other such groups, but in which the
component populations are not reproductively isolated
Biological Species Concept
• Emphasis is on isolation of
gene flow
• Isolation in fishes
4
Example from last weekend…
Mobile basin
Ecologically similar
Morphologically similar
Similar Range
Similar habitat use
Numerous contact zones
Duvernell, D.D., Meier, S., Schaefer, J.F., and Kreiser, B.R. 2013. Contrasting Phylogeographic Histories Between Broadly Sympatric Topminnows in the
Fundulus notatus species complex. Molecular Phylogenetics and Evolution doi: 10.1016/j.ympev.2013.07.013.
5
Black Creek
Pascagoula River
F. notatus
F. olivaceus
Hybrid
(F1/introgressed)
Are the hybrids viable?
0.8
0.5
a
0.4
a
0.3
a
0.2
b
0.1
0.0
F=12.9, P<0.001
a
Hatching Success (%, +/- 1SE)
Probability of Spawn (% +/- 1SE)
F=39.6, P<0.001
0.6
a
0.4
0.2
b
b
Backcross
F2 Hybrid
0.0
-0.1
Pure
F1 Hybrid
Backcross
Type of Cross
F2 Hybrid
-0.2
Pure
F1 Hybrid
Type of Cross
Sort of.
Are these species?
6
Speciation
• Allopatric:
A
A
A’
• Sympatric:
A
A+A’
•Parapatric:
A
A’
Three Spined Stickleback
• Marine and freshwater
forms distinct
• Marine form planktivore
• Freshwater: Inhabit
post-glacial lakes <15,000 yrs
• Three freshwater
forms
– Benthic form
– Planktivore form
– Intermediate form
7
Hypothesized Evolutionary History
Glaciers recede, lakes formed,
marine form invades
Selection pressure different in
lakes, generalist form uses all
lake habitats… second marine
invasion
Benthic and zooplanktivore
specialists replace intermediate
form and marine form.
Morphological Adaptations in Stickleback
8
Hypothesized Evolutionary History
Experimental Evidence
Marine forms
survival greater
when mixed
with benthic
forms
Marine forms eat more
zooplankton when mixed
with benthic forms = more
competition with
intermediate forms
9
Stickleback Summary
Marine Form
Invades
Freshwater
Freshwater
Intermediate
Freshwater
Intermediate
+
Marine
Invades
Freshwater
Benthic
Planktivore
Biogeography
• Study of the distribution of organisms:
• Isolating mechanisms variable by taxa….
10