Transcript Document

Allopatric speciation
Harris’ groundsquirrel
White-tailed ground squirrel
Allopatric speciation
Albert’s squirrel
Kaibob squirrel
Hawaiian Drosophila
Speciation due to dispersal . . .
Fig. 22.16
. . . can give
rise to huge
numbers of
species.
Adaptive radiation.
Fig. 24.11
Speciation in the lab
Fig. 24.12
Fig 23.1
high
Wind direction
Tolerance
to metals
low
Adults
Off mine
tailings
Adults
On mine
tailings
Sympatric
speciation?
Many species in small isolated,
bowl-shaped lake.
Schliewen, et al. 2001. Genetic and ecological
divergence of a monophyletic cichlid species pair
under fully sympatric conditions in Lake Ejagham,
Cameroon. Molecular Ecology 10:1471.
Sympatric speciation ??
Sympatric Speciation
• Closely related species often sympatric
• Disruptive selection
• Assortative mating
Fig 24.13
Polyploidy
Self
fertilization
New species
with 2n = 12
2n = 6
Error during meiosis
makes gametes with n = 6
Gametes
Zygote - infertile
2n = 14
2n = 28
IV. Macroevolutionary Pattern
A. Tempo of Speciation
1. gradualism
2. punctuated equilibrium
B. Phylogenetic Reconstruction
1. an example
2. the problem of convergent evolution
3. molecular traits
Fig. 24. 17
salamander
frog mouse bird
lizard
E
D
B
C
A
snake
Current species:
salamander
frog mouse bird
lizard
E
D
B
C
A
snake
ancestors:
salamander
frog mouse bird
lizard
E
D
B
C
A
snake
Fig 22.14
humerus
ulna
radius
carpals
phalanges
Some snake species still have non-functional pelvis
bones and little leg bones.
Source: Ray Troll, in Matsen and Troll 1994 Planet Ocean. Ten Speed Press, Berkeley.
The problem of convergent evolution: the Tasmanian wolf
is more closely related to the kangaroo than it is to the North
American red wolf
Red Wolf
Tasmanian Wolf
Homeobox (Hox)
genes have same
order, structure and
similar pattern of
expression in mouse
and fly!