Transcript Chapter 1: Classifying Organisms

Chapter 1: Classifying Organisms
(AKA as ‘read this chapter if you have
insomnia’!)
Basically, Ch. 1 is:
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History of naming organisms
Important people who named organisms
Different ways to think about naming
Somewhat uninteresting……
Major points in Ch. 1:
• How we name organisms has a long history.
• People to know:
• Linnaeus: invented the modern naming
system
• Tournefort: invented the concept of the genus
level of classification (genus = group of related
species).
Grouping organisms:
• Modern way: cladistics.
• Cladistics tries to be extremely objective
(neutral) when comparing traits of organisms.
• Uses measurable/quantifiable traits only;
examples include:
– DNA
– Morphological & Anatomical traits
Cladistics
• Groups related organisms into ‘clades’
Traits
• Traits are based on whether they are common
(=plesiomorphic) or rare (apomorphic).
• Common traits are considered ancestral or
primitive
• Rare traits are considered more newly
evolved, and thus aren’t as common
Common Traits:
• Common traits are shared, and thus, are supposed to
represent the ancestral condition, for example, most primates
have 24 pairs of chromosomes, but humans have 23 pairs
• Thus, 24 pairs of chromosomes is common for primates
Rare traits:
• In humans, the #2 chromosome is a fused
chromosome consisting of the #2 and #3
chromosome in other primates.
• Thus, a fused #2 chromosome is rare in
primates, and only the human line has it.
Humans did not evolve from chimpanzees. Humans and chimpanzees are
evolutionary cousins and share a recent common ancestor that was neither
chimpanzee nor human.
Humans are not "higher" or "more evolved" than other living lineages. Since our
lineages split, humans and chimpanzees have each evolved traits unique to their
own lineages.
Non-flowering plants: Liverworts
• DNA shows oldest land plant group, maybe
475my old!
Non-flowering plants: Mosses
• Very old group,
maybe 400my old
Non-flowering plants: Horsetails
• Also old, 350my?
• Used to be quite tall,
firsts forests on land
Horsetail forests
Non-flowering
plants: Ferns
• About 320my
old
Non-flowering
plants: Conifers
• Produces seeds
protected in
cones
• Also called
gymnosperms
(‘naked’ ‘seeds’)
because seeds
not protected
by fruits
Conifers
• About 600 species of conifers
• About 1/3 are pine species (nearly 250)
Conifers
• Conifer=‘to bear cones’
• Phylum Pinophyta (old
name: Coniferophyta)
• Evolved a bit later than ferns
• Major conifers: pine, spruce,
fir, cypress, junipers, etc.
• Either needle-leaved or
scale-leaved
• Adapted for cold & dry env.
Needle leaves
Conifers
• Contain the largest (most massive) organisms on
Earth: redwoods
• the tallest organisms: redwoods
• and the oldest: bristlecone pines
Common needleleaved conifers in our
area:
• 1. Firs
a. Grand fir (Abies
grandis): needleleaves; wider leaves
than Douglas fir and
are notched at tips. 2
whitish bands on leaf
bottom. Cones point
up. Can reach nearly
300 feet!
Common needle-leaved
conifers in our area:
• 1. Firs (cont.)
b. Douglas fir (not a
true fir) Pseudotsuga
menziessi; needle
leaves; main timber
tree west of the
Cascades. Cones
hang down, have 3pronged bracts on
cones. Can get
nearly 300 feet tall.
Common needle-leaved conifers in
our area:
• 2. Spruces:
a. Sitka Spruce
(Picea
sitchensis):
rare in our
area.
Common needle-leaved conifers in
our area:
• 3. Pines--Usually
only 2 species here:
a. Lodgepole pine
(Pinus contorta)—
not too common
here.
b. Western white
pine (Pinus
ponderosa)—5
needled. Long
needles.
Common needle-leaved conifers in
our area:
• 4. Hemlocks:
a. Western Hemlock
(Tsuga heterophylla)
thin needle-leaves,
rounded at tips. Short
and longer leaves occur
together. Topmost
branch droops. Cones
hang down.
Common scale-leaved conifers in
our area:
• Cedars (not real
cedars):
a. Western Red Cedar
(Thuja plicata)—can
grow up to 230 feet
tall! Branches tend to
droop. Two sets of
alternating scales.
Cones point upward if
seeds are present,
downward once
seeds are gone.