The%20Origin%20of%20Species

1
Chapter 24 The Origin of Species (cont.)
2
Caulerpa taxifolia hybrid
Questions to ponder Natural hybridization is
common and hybrids are not uniformly unfit, they
are genotypic classes that are less, equally or
more fit than their parental taxa. Some
scientists think that hybridization could
generate biological diversity.
How? Hybridization is common when populations
invade new environments. Why?
Alexande Meinesz
3
SOME questions from January 18th
1- Do you have practice or old exam for study use
in order to grasp an idea of how your tests will
be formatted? 2-If there are questions such as
the chick discussion on the test, is it safe to
say that you do agree with whichever statement,
but you dont know if there are any factors that
may cancel it? 3- Is a hybrid always a new
species or can they breed back to their parent
species? 4- Are mating habits in species
inherited or are they a consequence of the
environment? 5- How much genetic difference does
there need to be to consider two populations
different species?
4
Modes of Speciation (based on how gene flow among
populations is initially interrupted)
1- How would you characterize each mode of
speciation?
Fig. 24.6
5
Allopatric Speciation
Fig. 24.7
6
Adaptive Radiation
Isolation and occasional dispersal.
Evolution of many diversely adapted species from
a common ancestor.
Fig. 24.11
7
Sympatric Speciation
Fig. 24.14
8
Fig. 24.16
Sympatric Speciation
Orcinus orca
Transient
P. Stap
R. Baird
Resident
menua
unknown
9
Tempo of Speciation
3- How do you characterize each model for the
tempo of speciation?
Fig. 24.17
10
Mechanisms of macroevolution
4- What is the difference between microevolution
and macroevolution? 5- How could complex
structures such as eyes evolve?
11
Mechanisms of macroevolution
6- Allometric growth determines the proportion of
the body due to the different growth rates of
different body parts. How can it act as
mechanism of macroevolution?
Fig. 24.19
12
7- Is evolution goal oriented. Why?
Fig. 24.24