[BIOL 1001] - Midterm Exam Guide - Ultimate 32 pages long Study Guide!

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BIOL 1001
MIDTERM EXAM
STUDY GUIDE
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1
Chapter 17: The Origin of Species
I. Define species.
A. Group of populations that evolves independently
B. Each species follows a separate evolutionary path
C. The basic unit of taxonomic classification, consisting of a population or group of
populations or group of populations that evolves separately from other populations
D. A group of populations whose members interbreed freely with one another under natural
conditions but do not interbreed with members of other populations
II. What is the biological species concept?
A. Biological species ~ what defines a species
B. Naturally interbreeding populations that are reproductively isolated from other such
populations
C. Based off observation that reproductive isolation ensures evolutionary independence
D. Biological species concept has two main limitations:
1. Because the definition is based on patterns of sexual reproduction, it does not
help us to determine species boundaries among asexually reproducing organisms
2. Its not always practical or even possible to directly observe whether members of
two different groups interbreed
E. Reproductive isolation
1. Inability to successfully breed outside the group
2. The failure of organisms of one population to breed successfully with members of
another
3. May be due to premating or post mating isolating mechanisms
F. Isolating mechanisms
III. What does appearance say about a species?
A. Appearance can be misleading
1. Differences in appearance do not always mean that two populations belong to
different species
2. And some organisms w very similar appearance belong in difference species
o Example F17-2 first paragraph on 301 for better understanding
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2
IV. Describe isolating mechanisms
A. A geographical, ecological, temporal, or behavioral difference that prevents members of
two species from interbreeding and maintain reproductive isolation
B. Premating isolating mechanisms
1. Any structure, physiological function, or behavior that prevents organisms of two
different species from exchanging gametes
C. Geographic isolation
1. Prevents interbreeding between populations that do not come into contact
because they live in different, physically separated places
2. NOT considered a mechanism that maintains reproductive isolation between
species
D. Ecological isolation
1. Reproductive isolation that arises when species do not interbreed because they
occupy different habitats
a) Example
o Two populations that use different resources may spend time in different habitats
with in the same general area and thus exhibits ecological isolation
E. Temporal isolation
1. Reproductive isolation that arises when species do not interbreed because they
breed at different times
2. Cannot mate if they have different breeding seasons
a) Example
o Bishop and Monterey Pines
(1) They coexist in nature. In the laboratory they produce fertile
hybrids. In the wild however, they do not interbreed, because they release
pollen at different times of the year. For this reason the two species do not
interbreed under natural conditions
o Spring cricket and fall cricket
(2) Can be found in many North American places but names suggest
they breed during different seasons
F. Behavioral isolation
1. Signals and behaviors that differ from species to species
2. Reproductive isolation that arises when species do not interbreed because they
have different courtship and mating rituals
a) Example
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