Download Chapter 22 Study Guide

Chapter 22 Study Guide
Vocabulary:
Word Roots:
bio- = life
geo- = the Earth
homo- = like, resembling
paleo- = ancient
taxo- = arrange
vestigi- = trace
Key Terms:
Artificial selection: The selective breeding of domesticated plants and animals to encourage the
occurrence of desirable traits.
Catastrophism: The hypothesis by Georges Cuvier that each boundary between strata corresponded
in time to a catastrophe, such as a flood or drought, that had destroyed many of the species living
there at that time.
Convergent evolution: A kind of evolution wherein organisms evolve structures that have similar
(analogous) structures or functions in spite of their evolutionary ancestors being very dissimilar or
unrelated.
Descent with modification: Darwin’s initial phrase for the general process of evolution.
Evolution: All the changes that have transformed life on Earth from its earliest beginnings to the
diversity that characterizes it today.
Evolutionary adaptation: An accumulation of inherited characteristics that enhance organisms’
ability to survive and reproduce in specific environments.
Fossil: A preserved remnant or impression of an organism that lived in the past.
Gradualism: A view of Earth’s history that attributes profound change to the cumulative product of
slow but continuous processes.
Homologous structures: Structures in different species that are similar because of common ancestry.
Homology: Similarity in characteristics resulting from a shared ancestry.
Natural selection: Differential success in the reproduction of different phenotypes resulting from the
interaction of organisms with their environment.
Paleontology: The scientific study of fossils.
Taxonomy: A set of characteristics used to assess the similarities and differences between various
species, leading to a classification scheme; the branch of biology concerned with naming and
classifying the diverse forms of life.
Uniformitarianism: Charles Lyell’s idea that geologic processes have not changed throughout Earth’s
history.
Vestigial organ: A structure of marginal, if any, importance to an organism. Vestigial organs are
historical remnants of structures that had important functions in ancestors.
Chapter 22 Important Points:
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3 major observations of life are:
1. Life forms share many common traits (unity)
2. Life forms have many differences as well (diversity)
3. Life forms are matched to their environments
The Theory of Evolution strives to provide a biological mechanism to explain these 3
observations
Charles Darwin was a British naturalist who presented what we now call evolutionary
theory (he referred to it as “Descent with Modification”) in his groundbreaking book “The
Origin of Species”
The main idea behind Darwin’s theory is that organisms can vary in their inherited traits and
not all variations are as likely as others to foster survival and therefore reproductive success
Those organisms that possess traits better adapted to the current environment will survive
over those that do not have those traits and will therefore pass the inherited traits on to
their offspring
This preferential survival of some traits over others is called natural selection
o Artificial selection occurs when humans selectively breed certain desirable traits
with sometimes little regard to natural survival possibilities
Many other scientists and their theories influenced Darwin as he developed his theories of
natural selection and evolution; some supporting his ideas, some disagreeing (support or
lack of supported is noted even if not contemporaries)
o Aristotle: Believed in a scala naturae or a fixed ladder of life on which organisms
would not change their position (against evolution)
o Linnaeus: Developed field of taxonomy or classification of all living organisms
(against evolution because he believed in a divine placement of organisms in his
classification system)
o Cuvier: Paleontologist who believed in catastrophism in which sudden and
dramatic changes in geology are responsible for the disappearance of previous
species thus allowing for new species to move into areas (against evolution since
didn’t take into account the slow, gradual changes which could allow for new
speciation)
o Hutton and Lyell: Geologists who suggested geological changes occur due to
constant, slow processes and the same ones operating today have been for all of
Earth’s time (uniformitarianism) (support evolution with same slow change idea
and also made Darwin realize the Earth was older than previously believed which
allowed for the time for the biological changes evolution required)
o Lamarck: Biologist who erroneously suggested the mechanism for species changing
over time was through the inheritance of acquired characteristics or use and disuse
(against evolution in the sense the mechanisms he suggested were different from
Darwin but supported idea that populations of organisms could change in their
traits)
o Wallace: Biologist who independently developed his own theory of evolution which
matched Darwin’s (support evolution)
Mathus: Economist who studied the effects of overpopulation in humans and the
inherent limitation of populations because of limited resources (supports evolution
since it provides an explanation that only some organisms will survive if there is not
enough resources for all organism, following logically that those that do survive are
best adapted)
Key points about evolution and natural selection
o Only inherited traits are those that natural selection can work on
o These traits must be found in variations in the population
o Natural selection for some traits over others will change if the environmental
pressures change
Homology arises when organisms have similar anatomical (homologous) structures that
may have different current uses yet evolved from a common ancestor
o Comparative embryology can show homologous structures in embryos that are not
evident in adult organisms
o Vestigial structures are currently in organisms but do not have a noticeable function
but might have had one in an ancestor of the species
Convergent evolution of analogous structures occur when distinct lines of organisms
independently evolve similar structures based on natural selection in similar environments
or pressure; does not require common ancestors
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