Animations
Movies
Words
Appendix
Summary
Art
Art
Chapter
25
Quizzes:
Self
Activities
Chapter
Cum.
Unit 4: Mechanisms of Evolution
Phylogeny and Systematics
Review
is the study of the evolutionary history of species.
is the study of the diversity and
relationships
of organisms, based on shared
characters
inherited from a shared
.
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), when similar environmental pressures and
selection produce similar
(analogous)
in organisms from different evolutionary lineages.
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
hierarchical
categories (taxa):
,
,
,
,
,
, and
. A level above kingdom called
was
added
later.
The scientific name of an organism uses
nomenclature that uniquely identifies an organism in this hierarchy, and is composed of its
and
epithet; examples include
Panthera pardus
and
Homo sapiens
in the
kingdom.
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
must be
, and consists of the
species and all its
descendants.
A
group does not include all the descendants, while a
group may include several organisms that lack a common ancestor. Clades are defined by an evolutionary novelty at the branching point, which constitues a shared
character
for the clade; an
does not possess that character.
The tree of
life
is divided into three great
clades
called
:
(Monera),
, and
.
Animations
Movies
Words
Appendix
Summary
Art
Art
Chapter
26
Quizzes:
Self
Activities
Chapter
Cum.
Unit 5: The Evolutionary History of Diversity
The Tree of Life
Review
The 4.6 billion years of earth's history is divided into three
geologic
, which are further divided into
,
, and
.
There have been several episodes of mass
, when many forms of life
disappeared,
but they were replaced by forms that evolved from the survivors, and the general trend has been an
of diversity over time.
The
(PT)
extinction
was the most
severe,
and claimed over 90% of marine species. The
(KT)
extinction
is famous for the disappearance of
, and was probably caused by the
impact
of a large
.
were Earth’s sole inhabitants from 3.5 to about
billion years ago. The oldest known fossils are
composed of
layers
of
(blue-green algae)
and
, dating back
billion years ago. Cyanobacteria were
photosynthetic
which released
oxygen,
allowing the evolution of
organisms to obtain energy through
cellular
.
The first eukaryotes probably evolved from the
of small prokaryotes living within larger host cells and developing into
organelles
including
and
such as chloroplasts.
Multicellular eukaryotes diversified in the late
eon, when a severe
age
started to thaw. The first multicellular organisms were
,
collections
of autonomously
cells.
Most of the major animal
phyla,
including the
first
, appeared during the early
period in what is known as the
Explosion.
Plants
first colonized land during the
period in the company of
, followed by
. The
relationships between plants and fungi are still common today in
associations.
Humans evolved from terrestrial
vertebrates
called
, during the
epoch. If the
clock
of Earth’s history were scaled to represent an
hour,
humans appeared about one
ago.
The
movement
of the Earth's
due to
continental
has great impact on the habitats in which organisms live, and shaped the diversity of life on Earth.
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