The Origin of Species

1
Chapter 24
The Origin of Species
Questions prepared by Jung Choi Georgia Institute
of Technology Michael Dini Texas Tech University
2
Biological Species
Two animals are considered members of different
species if they _____.

1. are members of different populations
2. cannot mate and produce viable, fertile offspring
3. are geographically isolated
4. live in different habitats
5. look different

3
Biological Species
Cynotilapia afra, introduced at West Thumbi
Island in Lake Malawi in the 1960s, has split
into two genetically distinct populations,
located at the north and south ends of the
island. How can scientists determine whether
these populations are now different species,
according to the biological species concept?

1. See whether the two populations are
   morphologically different from each other
   coloring, bone structure, and so on.
2. Determine whether captured individuals from the
   two different populations will mate and produce
   offspring in a laboratory fish tank.
3. Determine whether individuals from one population
   will interbreed with individuals from the other
   population when introduced into each others
   native habitats.

4
Phylogenetic Species
According to the phylogenetic species concept,
what is a species?

• a clone of genetically identical organisms
• a population that is physically able to mate even
  if there are no offspring or the offspring are
  infertile
• a population that interbreeds and produces
  fertile offspring
• a set of organisms with a unique genetic history
• a population with a distinct fossil record

5
Mechanism of Reproductive Isolation
If the two populations of C. afra at West Thumbi
Island have different striping patterns, what
might be a likely mechanism contributing to
speciation?

1. polyploidy
2. female mating preferences
3. differing habitat preferences
4. temporal isolation
5. mechanical isolation

6
Species Concepts
Which species concept is least useful for
classifying prokaryotes?

1. biological species concept
2. phylogenetic species concept
3. ecological species concept
4. morphological species concept

7
Adaptive Radiation
Cichlids in Lake Victoria are thought to have
diversified from a relatively few species to 600
hundred species in about 12,000 years (the last
time the lake dried up). What is the best way to
test this hypothesis?

1. Examine the fossil record in lake sediments.
2. Look for morphological characteristics shared
   among Lake Victoria species that are distinct
   from the species present in other lakes.
3. Look for genetic characteristics shared among
   Lake Victoria species that are distinct from
   species present in other lakes.
4. This is not a testable hypothesis.

8
Mechanisms of Adaptation
In vertebrate radiation, exemplified by African
cichlids, modification of jaws occurs during
adaptation to different food sources. Such rapid
modifications could result from which of the
following?

1. changing the expression of genes that control the
   growth of different jaw bones during development
2. evolving new genes that generate new jaw bones
3. acquiring genes by hybridizing with other species
   that exploit the same food source
4. individuals exercising their jaw muscles in
   different ways, causing the jaws to grow
   accordingly

9
Allopatric Speciation
Which population characteristic would make the
population more likely to undergo allopatric
speciation?

1. having a large number of individuals
2. being highly mobile
3. existing on the edge of the home range
4. having a relatively homogeneous home range
5. having a relatively homogeneous gene pool

10
Speciation and Physical Environment
In what type of environment is a scientist most
likely to find examples of ongoing speciation?

1. areas that have a large range of altitudes, such
   as mountains and deep valleys
2. areas such as large plains that facilitate
   migration of animals
3. extreme physical environments that are marginal
   for supporting life
4. areas that are already species-rich
5. areas that have undergone recent environmental
   disturbance or change

11
Reproductive Isolation Mechanisms
Sea urchins are broadcast spawners They release
their gametes into the water, without courtship.
Which of these reproductive isolation mechanisms
might operate for sea urchin species?

1. behavioral isolation or mechanical isolation
2. gametic isolation or temporal isolation
3. habitat isolation

12
Human Brain Evolution
A comparison of the human and chimpanzee genomes
shows that they are 99 identical, with very few
differences in protein coding genes. What
mechanisms may be responsible for evolution of
the human brain?

1. One or a few novel genes organized new brain
   structures.
2. The timing of the expression of brain development
   genes altered.
3. Brain development genes acquired mutations that
   made them more active in promoting brain growth.
4. Genes that had other functions acquired new
   functions in brain development (exaptation).