Ch 15 Vocabulary
Name:____________
1. Biological Species Concept- definition of a species as a population or group of
populations whose members can breed with one another in nature and produce fertile
offspring
2. Macroevolution- major biological changes evident in the fossil record
3. Speciation-formation of new species
4. Reproductive Isolation- condition in which a reproductive barrier keeps two species
from interbreeding
5. Geographic Isolation- separation of populations as a result of geographic change or
migration to geographically isolated places
6. Adaptive Radiation- evolution from a common ancestor of many species adapted to
diverse environments
7. Punctuated Equilibrium- evolutionary model suggesting species often diverge in spurts
of relatively rapid change, followed by long periods of little change
8. Embryology- study of multicellular organisms as they develop from fertilized eggs to
fully formed organisms
9. Geologic Time Scale- Earth's history organized into four eras: Precambrian, Paleozoic,
Mesozoic, and Cenozoic
10. Radiometric Dating- determination of absolute ages of rocks and fossils through
calculations based on a radioactive isotope's fixed rate of decay
11. Half-Life- time it takes for 50 percent of a radioactive isotope sample to decay
12. Continental Drift- motion of continents about Earth's surface on plates of crust floating
on the hot mantle
13. Mass Extinction- episode of great species loss
14. Taxonomy- identification, naming, and classification of species
15. Binomial- two-part Latin name of a species
16. Phylogenetic Tree- branching diagram, suggesting evolutionary relationships, that
classifies species into groups within groups
17. Convergent Evolution- process in which unrelated species from similar environments
have adaptations that seem very similar
18. Analogous Structures- similarities among unrelated species that result from
convergent evolution
19. Cladogram- phylogenetic tree constructed from a series of two-way branch points,
suggesting ancestral relationships among species
20. Derived Character- homologous characteristic that unites organisms as a group
ANSWERS - Chapter 15: Origins of Biological Diversity
Concept Check 15.1
1. Why are donkeys and horses considered different species?
- Donkeys are infertile offspring of a horse and mule.
2. What is macroevolution?
-Major evolution changes evident in fossils record; origin of new species,
extinction of species, evolution of major new adaptations.
3. Give an example of a reproductive barrier that may separate two similar
species.
- Timing of, courting behavior, habitat, incompatible structures, zygotes fail to
develop, infertile offspring
4. Describe conditions that could make a new island a likely place for adaptive
radiation.
- Have different habitats with varying environmental conditions; Organisms
may adapt to varied conditions in different ways resulting in species diversity.
5. How does punctuated equilibrium relate to Darwin's theory of natural
selection?
- Natural selection and genetic drift cause most change as a new species. Major
change is less common once a species is established.
Concept Check 15.2
1. How can evolution explain the range of complexity of eyes in modern
organisms?
- Complex eyes could have evolved from modifying existing, simpler structures.
Simpler eyes still exist in some modern species.
2. Give an example of evolutionary remodeling of an existing structure to a new
function.
- Exoskeleton protect land arthropods from drying out, modified wings enable
penguins to swim
3. Identify one possible event during an organism's embryonic development
that can result in a change in body form.
- Mutations in the homeotic gene; change in rate or timing during development
Concept Check 15.3
1. Which parts of organisms are most commonly found as fossils?
-Hard parts such as shells, bones, and teeth
2. What main characteristic distinguishes the fossil record of the Paleozoic Era
from that of the Precambrian Era?
-Great diversity of multicellular animal fossils with hard parts
3. How are the relative ages of fossils in sedimentary rock determined?
-Relative age is based on the position of rock layers. Longer ago the fossil was
formed, the deeper the layer of fossils.
4. How does a mass extinction change conditions for species that survive?
-Makes new opportunities for the survivors, making adaptive radiation
possible.
Concept Check 15.4
1. Give two reasons why common names of organisms can lead to confusion.
-May describe more than one species, differ in areas of country or in languages
2. Why are analogous structures not useful for classifying species in an evolutionary
context?
- Analogous structures do not reflect evolutionary relationships
3. What does a branch point in a cladogram represent?
- Branch point is an ancestor common to all organisms that extend from that branch
point.
4. How does the three-domain model of classification differ from the five-kingdom
model?
- Three domain separates two groups of prokaryotes and one eukaryotes. In five
kingdom model- bacteria and archaea are in one group called Monera.