Download Biology 11AP Chapter 24 The Origins of Species p. 488 Essential

Biology 11AP
Chapter 24 The Origins of Species p. 488
Essential knowledge
1.c.1 Speciation and extinction
have occurred throughout the
Earth’s history.
1.c.2 Speciation may occur when
two populations become
reproductively isolated from each
other.
1.c.3 Populations of organisms
continue to evolve.
Chapters/sections
24.3, 24.4, 25.4
24.1
24.2
Illustrative examples covered
• Five major extinctions
• Human impact on ecosystems
and species extinction rates
No illustrative examples listed in
the Curriculum Framework.
• Chemical resistance (mutations
for resistance to
antibiotics, pesticides, herbicides
or chemotherapy drugs
occur in the absence of the
chemical)
• Emergent diseases
• Observed directional phenotypic
change in a population
(Grants’ observations of Darwin’s
finches in the
Galapagos)
• A eukaryotic example that
describes evolution of a
Structure or process such as heart
chambers, limbs, the
brain and the immune system
What is speciation? Also referred to as macroevolution in which new species evolve. It also
explains the differences and similarities between species. __
How does the DNA of this flightless
cormorant from the Galapagos Islands
compare to the DNA of cormorants from the
west coast of South America? Similar
What does this suggest? That the flightless
cormorant may have originated from a south
American ancestor.
What is the difference between
microevolution and macroevolution?
Microevolution involves a change in the
allele frequency within a population while
macroevolution requires a change that leads to a new species.
What is the biological definition of a species?
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What causes members of a species to
resemble each other more than they
resemble other species
See: http://www.pbs.org/wgbh/evolution/library/05/2/l_052_04.html on hummingbird evolution
in the Andes
What is reproductive isolation? ____________The inability to produce viable offspring.
______________________________________________________________________________
______
Reproductive isolation blocks the reproduction of ___hybrid offspring__, which are offspring
that result from interspecific mating.
Here are various prezygotic reproductive barriers: (prevent zygote from forming) page 490
And here are some postzygotic reproductive barriers:
Do these salamanders belong to the same species?
What is allopatric speciation? _ Formation of new species as a result of geographic barriers.
Takes thousands of years.
Here is an example of allopatric speciation in antelope squirrels on opposite rims of the Grand
Canyon:
Allopatric speciation in frog species can be seen to be related to the movement of landmasses:
What do the data in the graph below show is the relationship between reproductive isolation and
distance between populations of dusky salamanders?
______________________________________________________________________________
______________________________________________________________________________
_________
Here is an experiment with fruit fly populations that were experimentally separated and raised
under different conditions . What does the experiment demonstrate?
_______________ allopataric speciation in process
Does a geographic barrier always result in speciation?
What is sympatric speciation? __________________Speciation where there is no geographic
barrier. Eg in Lake Malawi where different species of cichlid fish evolved at different
depths and areas of the lake. See figure 24.12
The development of polyploids in plants is an excellent example of sympatric speciation.
What is an autopolyploid?
_______________________________________________________________
______________________________________________________________________________
_______
What causes the tetraploid organism to be reproductively isolated from the diploid organism?
______________________________________________________________________________
_______
Sympatric
speciation can
also occur through
allopolyploidy, as
shown below:
(more common) Fig 24.11
What are some important crops that are polyploids?
_________________________________________
Here is an example of how sympatric speciation can occur through sexual selection. These are
cichlids from Lake Victoria in Africa: (see p 497 for details of the experiment.
Section 24.3
What is a hybrid zone?
__________________________________________________________________
This diagram illustrates the structure of a hybrid zone between two toad species in Europe:
Here is a diagram to illustrate how hybrids might change over time:
Here is an example where there is
reinforcement of barriers to reproduction
in a hybrid zone between closely related
species of European flycatchers:
Page 512
The breakdown of reproductive barriers
between species can be seen in this
example of cichlid fish species in Lake
Victoria:
How fast does speciation take place? Is it a gradual process, or a very quick process followed by
long periods of little change? This diagram illustrates these two possibilities:
Here is an example in which a single gene change resulted in the development of a new species:
In this example,an allele for flower colour was found to be influencing pollinators preference for
certain species:
Show how bread wheat species evolved from the following three ancestral species:
Question: How do the major morphological transformations of macroevolution occur? Act 24.A
1.
Evolutionary novelties can be modifications of older structures.
See video at: http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.html
2.
Exaptations - gradual modification
of earlier structures for new
functions. Act 24A