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Chapter 22
The Origin of Species
28
Biology
Undergraduate 2
03/11/2010

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Term
sympatric species
Definition
inhabit the same locale, but remain distinct
co-occur differ phenotypically in their behavior and utilize different parts of the habitat
Term
subspecies
Definition
geographically distant populations of the same species that are distinct from one another
Term
speciation
Definition
the process of how one species becomes another
Term
species
Definition
a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding
Term
allopatric speciation
Definition
the differentiation of geographically isolated populations into distinct species
Term
gene pool
Definition
all of the alleles present in a species
Term
mechanism that prevents the formation of zygotes
Definition
prezygotic isolating mechanism
Term
mechanism called that prevents the proper functioning of zygotes after they form
Definition
postzygotic isolating mechanisms
Term
natural selection directly favors traits that promote
Definition
survival and reproduction
Term
speciation is a two part process...
Definition

first- intially identical populations must diverge

second- reproductive isolation must evolve to maintain these differences

Term
natural selection does not favor traits that lead to reproductive isolation, but....
Definition
traits that favor survival and reproduction in an environment can incidentally result in reproductive isolation.
Term
what are the six types of prezygotic isolation mechanisms
Definition

-geographical

-ecological

-behavioral

-temporal

-mechanical

-prevention of gamete fusion

Term
name a postzygotic isolating mechanism
Definition
hybrid inviability or infertility
Term
process where one ancestral species becomes divided into two desendant species
Definition
cladogenesis
Term
the result of when the continual improvement of prezygotic isolating mechanisms until the two populations were completely reproductively isolated.
Definition
reinforcement
Term
describe how random events and natural seleciton can lead to speciation
Definition

-founder effects in isolated populations

-if adaptation changes occur in a population that lead to reproductive isolation

Term
which is more likely, sympatric or allopatric speciation
Definition
allopatric
Term
an individual that possesses more than two sets of chromosomes
Definition
a polyploid individual
Term
the most common type of polyploidy speciation
Definition
allopolyploidy- which may happen when two species hybridize
Term
instantaneous speciation through polyploidy
Definition
autopolyploidy can instantaneously create a new species because of errors in meiosis, resulting in tetraploidy
Term
sympatric speciation by disruptive selection
Definition

distruptive selection can produce a population with individuals exhibiting two different phenotypes.

-but before the two phenotypes could become two species, they would have to evovle reproducing isolating mechanisms... unlikely due to genetic exchange... rare

Term
adaptive radiation
Definition
Term
discribe a situation where adaptive radiation might occur
Definition
where there are few other species but abundant resources
Term
... allow new environments to be used by a species that we previously inaccessible. ex. development of wings on a bird
Definition
key innovations
Term
is when populations on different islands evolve to become different species. in this process, natural selection in each species favors those individuals that use resources not used by the other species
Definition
character displacement
Term

the accumulation of small changes

-slow evolutionary change (thousands or millions of years)

 

Definition
gradualism
Term

long periods of stasis followed by relatively rapid change

- evidence exists that species experience long periods of stasis punctuated by bursts of evolutionary change occuring over geologically short time periods

Definition
punctuated equilibrium
Term
discribe mass extinctions
Definition

- diversity rebounds, but the recovery is not rapid. and the groups making up that diversity are not the same as those taht existed before the extinction event

-during mass extinction, not all species are equally effected, allowing adaptive radiation to occur among the remaining species

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