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Chapter 10

BIO 101 Chapter Notes - Chapter 10: Macroevolution, Archaea, Eukaryote

Bioscience & Biotechnology
Course Code
BIO 101
Meshagae Hunte- Brown

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Chapter 10
What is a species? (10.4)
Species- natural populaons of organisms that can interbreed and are reproducvely isolated from other
such groups
Biological Species Concept- a denion of species described as populaons of organisms that interbreed,
or could possibly interbreed, with each other under natural condions and that cannot interbreed with
organisms outside their own group
Prezygoc Barrier- a barrier to reproducon caused by the physical inability of individuals to mate with
each other, or the inability of the male’s reproducve cell to ferlize the female’s reproducve cell
Postzygoc Barrier- a barrier to reproducon caused by the inferlity of hybrid individuals or the inability
of hybrid individuals to survive long a!er ferlizaon
Hybrid- o#springs of individuals of two di#erent species
Two key features of the biological species concept:
oactually interbreeding or could possibly interbreed
This emphasis means that just because two individuals are physically separated, they
aren’t necessarily of di#erent species.
o“natural” populaons
this disncon is important because occasionally, in capvity, individuals may interbreed
that would not interbreed in the wild, such as zebras and horses
There are two types of barriers that prevent individuals of di#erent species from reproducing (remember
an egg that has been ferlized by a sperm cell is a zygote)
oPrezygoc barriers make it impossible for individuals to mate with each other or, if they can mate,
make it impossible for the male’s reproducve cell to ferlize the female’s reproducve cell.
These barriers include situaons in which the members of the two species have di#erent
courtship rituals or have physical di#erences that prevent mang or ferlizaon
oPostzygoc barriers occur a!er ferlizaon and generally prevent the producon of ferle
o#spring from individuals of two di#erent species. These barriers are responsible for the
producon of hybrid individuals that either do not survive long a!er ferlizaon or, if they do, are
inferle or have reduced ferlity. Mules, for example, are the hybrid o#spring of horses and
donkeys, and although they can survive, they cannot produce their own o#spring.
How do we name species? (10.5)
Genus- In the system developed by Carolus Linnaeus, a classicaon of organism’s consisng of closely
related species
Specic Epithet- In the system developed by Carolus Linnaeus, a noun or adjecve added to the genus
name to disnguish a species
Every species is given a scienc name that consists of two parts, a genus and a specic epithet
Hierarchical System
oInclusive categories at the top leading to more and more exclusive categories below
How do new species arise? (10.7)
Speciaon- the process by which one species splits into two disnct species. The rst phase of speciaon
is reproducve isolaon; the second is genec divergence, in which two populaons evolve over me as
separate enes with physical and behavioral di#erences
Allopatric Speciaon-Speciaon that occurs as a result of a geographic barrier between groups of
individuals that leads to reproducve isolaon and then genec divergence
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