Section
2: Organizing our Living World
I.
Evolution
and ancestry
II.
How
evolutionary trees are used to predict the biology of organisms
III.
The
Linnaean Hierarchy
IV.
Major
Groups of Organisms
I.
Evolution
and ancestry
v
What is
evolution, anyway?
o
Your
definition:
o
The most
accepted biological definition:
v
By studying
microevolution, we can test concepts of evolution that we cannot witness in our
lifetimes.
o
Microevolution
focuses on single populations.
o
Examples:
guppy experiment, house sparrow size, mosquito response to global warming
trends, insect resistance to pesticides
v
Much like
genealogists organize related groups of people into family trees, systematists organize groups of different organisms into
evolutionary trees (phylogenies).
o
Groups are
related through their most recent common ancestor
§
Shared
derived features help determine most recent CA
o
Convergent
features do not indicate relatedness
o
DNA
comparisons help determine evolutionary relationships
II.
How
evolutionary trees are used to predict the biology of organisms
v
Close
relatives are expected to share many of the same features passed down by their
most recent common ancestor.
·
Ex: Closest
relatives of birds (after dinosaurs) are crocodiles and alligators
·
The dentist
and patterns of HIV transmission to patients
III.
The
Linnaean Hierarchy
v
It is
estimated that there are 3-30 million different species of organisms on the
earth. As scientists make new
discoveries, they attempt to classify these organisms into groups based on
shared characteristics.
v
Three major
systems for classifying all of life:
1.
Evolutionary
Tree of Life
2.
Kingdoms of
the Linnaean Hierarchy
o
Developed
in 1700s by Carolus Linnaeus
o
An
organism’s scientific name is a two-word Latin name that includes the
organism’s genus and specific epithet. The scientific name is always italicized
or underlined with the Genus name capitalized and the specific epithet
underscored (Ex: Homo sapiens or Homo
sapiens)
o
The
following hierarchy is the Linnaean Hierarchy, in order from most inclusive to
least inclusive.
§ Kingdom
§ Phylum
§ Class
§ Order
§ Family
§ Genus
§ Species
3.
Domain
System
o
Most
biologists have also adapted a higher level of organization called the Domain
§
Bacteria: prokaryotic unicellular organisms that reproduce
asexually
§
Archaea: differ from Bacteria in the composition of the ribosomal RNA and the
structure of the plasma membrane and cell wall; inhabit extremely harsh
environments (extremophiles)
·
Methanogens
·
Halophiles
·
Thermoacidophiles
§
Eukarya: unicellular or multicellular organisms with cells that have a
membrane-bound nucleus
v
Organisms
can also be identified as prokaryotes or eukaryotes
o
Prokaryotes
(Domains: BACTERIA, ARCHAEA)
§
Simple, but
successful
§
Reproduce
asexually
§
Diverse
methods of obtaining nutrition
§
Thrive in a
variety of environments
§ Play important roles in biosphere and human society
§ Are classified by certain distinguishing features
§
Remember,
Bacteria and Archaea exhibit key differences from each other (see above).
Kingdoms
of Eukarya include:
v
Protists
o
Oldest
kingdom of Eukarya
o
Primarily
single-celled eukaryotes (though some multicellular forms exist)
o
Diverse in
size, shape, and lifestyle
o
Some
plant-like, some fungus-like, some animal-like
o
Reproduce
sexually
o
Well-known
for disease-causing abilities
v
Plants
o
Great
pioneers and highly diverse
o
Plants are the
basis of land ecosystems
o
Plants have
special structures that can include:
§
Chloroplasts
for photosynthesis
§
Leaves to
house chloroplasts
§
Root system
to absorb water and nutrients
§
Cuticle to
protect from water loss
§
Rigid cell
walls to provide structure
§
Vascular
systems
§
Seeds
§
Flowers
o
Major plant
groups are:
§
Bryophytes
§
Seedless
vascular
§
Gymnosperms
§
Angiosperms
v
Fungi
o
Include
yeasts, molds, mushrooms, etc.
o
Most poorly
understood of the major groups of organisms
o
Some are
costly, but some are beneficial
o
Three
distinct groups:
§
Zygomycetes
§
Ascomycetes
§
Basidiomycetes
o
Many fungi
are decomposers, some are parasites, and others are mutualists.
o
Complex
mating systems
v
Animals
o
Most
familiar major group (what we are!)
o
Always
multicellular
o
Complex
features including the potential to have:
§
True issues
§
Organs and
organ systems
§
Complete
body cavities
o
There are a
few basic body plans within Animalia
§
Arthropods=exoskeleton
made of chitin, segmented body plan
§
Vertebrates=internal
backbone, segmented body plan (though less obvious than in arthropods)
o
Animals
exhibit a wide variety of behaviors
o
Animals
play key roles in ecosystems