[BIO 101] - Midterm Exam Guide - Everything you need to know! (111 pages long)

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BIO 101
MIDTERM EXAM
STUDY GUIDE
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Chapter 18: Evolution and the Origin of Species
18.1 Understanding Evolution
I. Introduction
a. Evolution is an ongoing process.
b. The theory of evolution is the unifying theory of biology.
c. Plato believed that species were static and unchanging, yet many ancient Greeks
expressed evolutionary ideas.
d. Naturalist Georges-Louis Leclerc Comte de Buffon observed that different several
geographic regions have different plants/animals, even when the environments were
similar.
e. James Hutton proposed that geological change occurred gradually as a result of small
changes from processes operating like they are today over long periods of time.
i. This contrasted the widely held belief that geology was a consequence of
catastrophic events occurring relatively recently in the past.
f. Charles Lyell gave more time for gradual change in species and thought that the changes
in species were gradual.
g. Jean-Baptiste Lamarck proposed an inheritance of acquired characteristics by which
modifications in an individual are caused by the environment (theory of use and disuse),
and these characteristics could be inherited by offspring.
II. Charles Darwin and Natural Selection
a. Charles Darwin and Alfred Russel Wallace independently discovered the actual
mechanism of evolution.
b. While on the Galapagos Islands, Darwin observed similar species on different islands
with distinct differences. He proceeded to investigate finch beak size/shape, realizing
that there as a orrelatio etee tpe of eak ad the aial’s food
source/acquisition.
c. Natural Selection: individuals with favorable traits will survive environmental change as
a result of these traits and will be more likely to reproduce, passing these traits to
offspring
i. also ko as surial of the fittest
ii. Dari’s eplaatio for ho/h eolutio takes place
iii. Natural selection is an outcome of 3 principles (according to Darwin):
1. Most characteristics are passed from parent to offspring (inherited).
2. More offspring are produced than are able to survive, so resources for
survival and reproduction are limited.
a. The capacity for reproduction in all organisms outstrips the
availability of resources.
b. Thomas Malthus discussed this principle in relation to humans.
3. Offspring vary with respect to the characteristics they inherit.
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a. Due to organisms with the best traits surviving/reproducing, these
traits will be better represented in the next generation. This will
lead to a change in populations over generations, which Darwin
tered deset ith odifiatio.
d. Natural selection leads to greater adaptation of the population to its local environment.
It is the only mechanism for adaptive evolution.
e. Darwin published his findings in his book, On the Origin of Species.
III. Processes and Patterns of Evolution
a. Natural selection can only occur if there is genetic variation among individuals in a
population.
b. There are two sources of genetic diversity:
i. Mutation: a change in DNA which creates new alleles or new genetic variation
1. Three possible outcomes for the phenotype:
a. Reduces fitness (lower likelihood of survival/reproduction)
b. Increases fitness (benefits organism)
c. No effect on fitness
ii. Sexual Reproduction: when two parents reproduce, a unique combination of
alleles assembles to produce the unique genotypes of each offspring
c. Adaptation: a heritable trait that helps the survival and reproduction of an organism in
its present environment
i. Organisms are becoming adapted to their environment when a change in genetic
variation occurs over time that increases or maintains the fitness of the
population to its environment.
d. Divergent Evolution: when two species evolve in diverse directions from a common
ancestor
i. Ex) reproductive organs of flowering plants
e. Convergent Evolution: similar traits evolve independently in species that do not share a
recent common ancestor
i. Ex) wings in bats and insects
f. Natural selection acts on individual organisms, which can shape an entire species.
IV. Evidence of Evolution
a. Fossils
i. The fossil record shows a progression of evolution by recording animals that
existed in the past.
b. Anatomy and Embryology
i. Homologous Structures: similar structures in species with a common ancestor
that begin to change as a result of evolution
1. Ex) human, dog, bird, and whale forelimb
ii. Analogous Structures: similar structures in species without a common ancestor
that result from similar selective pressures
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