CH. 24 STUDY GUIDE: THE ORIGIN OF SPECIES
KEY WORDS
species
postzygotic isolating mechanisms
subspecies
developmental isolation
anagenesis
hybrid inviability
cladogenesis
hybrid sterility
cline
allopatric speciation
subspecies
sympatric speciation
races
polyploidy
speciation
evolutionary bottleneck
microevolution
punctuated equilibrium
macroevolution
gradualism
phylogeny
Geologic time chart
prezygotic isolating mechanisms
index fossils
geographic isolation
radioactive dating
ecological(habitat) isolation
phylogeny
temporal(seasonal) isolation
systematics
behavioral isolation
convergent evolution
mechanical isolation
DNA hybridization
gametic isolation
molecular clock
1
WORD ROOTS
allo - = other; - metron = measure (allometric growth: the variation in the relative rates of growth
of various parts of the body, which helps shape the organism)
ana - = up; - genesis = origin, birth (anagenesis: a pattern of evolutionary change involving the
transformation of the entire population, sometimes to a state different enough from the ancestral
population to justify renaming it as a separate species)
auto - = self; poly - = many (autopolyploid: a type of polyploid species resulting from one species
doubling its chromosome number to become tetraploid)
clado - = branch (cladogenesis: a pattern of evolutionary change that produces biological
diversity by budding one or more new species from a parent species that continues to exist)
hetero - = different (heterochrony: evolutionary changes in the timing or rate of development)
macro - = large (macroevolution: evolutionary change on a grand scale, encompassing the origin
of novel designs, evolutionary trends, adaptive radiation, and mass extinction)
paedo - = child (paedomorphosis: the retention in the adult organism of the juvenile features of its
evolutionary ancestors)
post - = after (postzygotic barrier: any of several species-isolating mechanisms that prevent
hybrids produced by two different species from developing into viable, fertile adults)
sym - = together; - patri = father (sympatric speciation: a mode of speciation occurring as a result
of a radical change in the genome that produces a reproductively isolated subpopulation in the
midst of its parent population)
QUESTIONS
1. Give a biological definition of species.
2. Explain the geographic isolation model of speciation, in doing so take into
account the roles of mutation, natural selection, and the gene pool.
3. How are speciation and microevolution different?
4. Distinguish between extrinsic and intrinsic isolating mechanisms.
2
5. Describe speciation by polyploidy.
6. Explain what is meant by adaptive radiation, and discuss the evidence for
this phenomenon.
7. What factors have contributed to the adaptive radiation of the thousands
of endemic species of the Hawaiian Archipelago?
8. Compare the hypotheses of gradualism and punctuated equilibrium, and
give an example supporting each hypothesis.
9. Explain why the modern concept of the species is difficult to apply to
sexual organisms, fossil organisms, populations at an intermediate stage
of divergence, and allopatric populations.
10. Darwin and Wallace both came up with a theory of evolution at
approximately the same time. Explain how the time was right for these two
men to come up with the same theory at the same time.
11. Describe the Darwin-Wallace theory of natural selection. What is meant by
"survival of the fittest"?
12. Why is it that only inherited changes are important in evolution?
13. Discuss allopatric speciation.
14. Give three definitions of biological evolution.
3
15. Compare and contrast punctuated equilibrium and gradualism. How would
you support your favorite theory?
16. Does evolution produce "perfect" organisms?
17. Give examples of reptilian structures that were exaptations for flight in
birds.
18. Define, discuss and give an example of how each of the following isolating
mechanisms contributes to speciation in organisms.
A. Geographical barriers
B. Ecological (including seasonal) isolation
C. Behavioral isolation
D. Polyploidy
4