Chapter 1: Classifying Organisms

(AKA as ‘read this chapter if you have insomnia’!)

Basically, Ch. 1 is:

• 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 needle-leaved conifers in our

area:

• 1. Firs a. Grand fir (Abies

grandis): needle-leaves; 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 3-pronged 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.