Evolution__3rd_Edition

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Figure 17.11
Testing vicariance
biogeography by comparing
the area cladograms of four
taxa. (a) The phylogeny and
biogeography of four species.
The species are symbolized
by numbers (1, 2, 3, 4) and
the places where the species
live by letters (A, B, C).
(b) Inferred vicariant history
of the distributions. (c) Taxa
2–3 have distributions that
are congruent with taxon 1,
but taxon 4 is incongruent.
(d) Either there were dispersal
events in the history of taxon
4, or its phylogeny is wrong.
Species 15 may have been
wrongly classified, for example,
because it has evolved rapidly
(the group of species 12–14 in
(c) is then an example of a
paraphyletic group). The
suggested history with
migration is only one of a
number of possibilities that
are compatible with a range
split in the order A + B + C →
A + B/C → A/B/C.
(b)
Common
ancestor
1–4
(c)
Biogeographic
distribution
Species
(d)
C
(a)
CHAPTER 17 / Evolutionary Biogeography 509
Biogeographic
distribution
Species
Common
ancestor
1–3
4
A
1
predicts their area cladograms will be congruent. Congruence is a term that can be
applied to any sort of branching diagram (in phylogeny or biogeography). If two
branching diagrams are congruent, the order of branching in the two do not contradict
each other. The two diagrams do not have to be identical, because one place, or taxon,
might be missing from one of the branching diagrams; but the order of branching in
the entities that are present in both must be the same. In the figure, the area cladograms
2
B
3
Non-vicariant
speciation
of
3, (1, 2)
Common
ancestor 1–2
2, 3 1
+3
B
A
4
4
C C C
Taxon 2 Taxon 3 Taxon 4
A B C A B, C A C B
4 5 6 7 8 9 10 11 12 13 14 15
15 12 13 14 12 15 13 14
Common
ancestor
12–15
Pattern of evolution
Taxon 1
Non-vicariant
speciation
of
B
(12, 13),
14
15
Common
ancestor C
12–14
True phylogeny
B
15
14+ common
ancestor
12–13
C
4
Migration
of 12
A B
12
13, 14
C
15