Bio1151b
Chapter
24
The Origin of Species
Evolutionary change of a species over time is
called
, while in
a parent species may branch off to yield multiple
species.
A
species is a group of organisms whose members can
interbreed
in nature and produce
offspring.
Reproductive
can prevent interbreeding and result in reproductive
.
Prezygotic
barriers
prevent the formation of
, and include
,
,
,
, and
isolation.
Postzygotic
barriers
prevent the
from developing into a fertile adult, and include reduced hybrid
, reduced hybrid
, and hybrid
.
Speciation
can occur by
(“Other Country”) speciation, or by
speciation.
In
speciation, geographic separation can reduce
flow and result in
reproductive
where the isolated
subpopulations
can evolve separately.
In
speciation, geographically overlapping populations can evolve into separate
species
due to habitat
.
Adaptive
can produce many species, adapted to different
, from a common ancestor which was introduced to a new environment, such as the
Hawaiian
archipelago.
The decline and
of some species often provides
opportunities
for other species to occupy the
and
that open up.
Summary.
Bio1151b
Chapter
25
Phylogeny and Systematics
is the evolutionary history of species.
is the
relationships
of organisms, based on shared
characters
inherited from a common
.
Some of the tools biologists use include the
record,
as well as
and
comparisons
to infer
evolutionary
relationships.
Most of the
record is found in
layers
of
rock called
.
similarity can be misleading due to
evolution (
analogy
).
homologies that make use of computer programs to analyze
segments
can reveal many relationships not attainable by other methods.
Carolus
Linnaeus
introduced a system, called
, for classifying species in seven
hierarchical
categories
(taxa).
The scientific name of an organism uses
nomenclature composed of its
and
epithet, such as
Panthera pardus
and
Homo sapiens
.
Phylogenetic relationships are shown as branching trees where each
branch
point represents the
of two
when they shared a common
.
Shared ancestry and shared
characters are drawn on a
to show evolutionary relationships; this practice is
called
.
A clade must be
, and consists of the
species and all its
descendants.
A
depicts the
chronology
of divergences by having the
of a branch reflect the number of changes that have taken place in a particular
sequence in that lineage.
The tree of
life
is divided into three great
clades
called
:
(Monera),
, and
.