Warmup
Complete the sentences:
1) Separate species…
2) Speciation happens when…
3) It is different than genetic drift in that…
DECEMBER 15TH 2010
Learning Goals
Be able to use and create a dichotomous key to identify organisms.
Relevant Standard:
•Students know how to construct a simple branching diagram to classify living
groups of organisms by shared derived characteristics, and expand the diagram
to include fossil organisms.
Be able to describe recent evolution resulting in modern humans.
Dichotomous Key
Dichotomous Keys are used to classify organisms based on only a few
observations.
They use simple “either or” questions, and based on the answer to the
question redirect you either to another question or the scientific name of
the species.
Good dichotomous keys are both easy to use and reflect how species are
related according to evolutionary branching tree diagrams (phylogeny).
Guided Practice
The genus is “Nornos”. Find the full
scientific name for each organism using
the dichotomous key.
A)
1. Has pointed ears - go to 3
Has rounded ears - go to 2
2. Has no tail - Kentuckyus
Has tail - Dakotus
3. Ears point upward - go to 5
D)
Ears point downward - go to 4
4. Engages in waving behavior - Dallus
Has hairy tufts on ears - Californius
5. Engages in waving behavior - WalaWala
Does not wave - go to 6
6. Has hair on head - Beverlus
Has no hair on head (maybe on ears) - go to 7
7. Has a tail - Yorkio
Has no tail, aggressive – Rajus
B)
C)
E)
F)
G)
Guided Practice Solutions
A)
B)
C)
D)
E)
F)
G)
Nornos WalaWala
Nornos Californus
Nornos Rajus
Nornos Kentuckyus
Nornos Dallas
Nornos Beverlus
Nornos Yorkio
http://www.biologycorner.com/worksheets/dichoto.html
Independent Practice
Create a dichotomous key for some common hominids.
Human Chimpanzee Gorilla
Orangutan
Gibbon
Independent Practice
Trade dichotomous keys with a partner and see if they are useful for identifying
these two hominids:
Main Fossil Sequence
Brain Size
Language Use
Tool Use
Upright
Bipedal
Species
Time
Ardipithecus Ramidus
5.64.5M
X
Australopithecus Afarensis
3.93.0M
X
X
380-430 cm3
Australopithecus Africanus
3.02.3M
X
X
400-500 cm3
Homo Habilis
2.51.6M
X
X
X
Homo Erectus
1.70.2M
X
X
+
X
850-1200 cm3
Homo Sapiens
0.2M
X
X
+
X
1200-1450 cm3
300-350 cm3
590-650 cm3
Noteworthy:
•“Lucy” and “Ardi”
•Walking upright developed early on.
•Brain size and tool use developed
simultaneously.
•Increased brain development meant
more child-care, which meant more
opportunity to educate/culture
offspring.
•True language use developed last.
•The common ancestor w/
chimpanzees is estimated to be
5M8M old.
•The common ancestor w/ a
chimpanzee is not the same as a
modern chimpanzee.
Monogenesis Theory vs.
Multiregional Theory
Recall the difference between genetic drift and speciation.
The Multiregional Theory states that modern humans evolved in parallel in
multiple parts of the world. They presumably interbred which reduced
genetic diversity to its present level. The “Java Man” and the “Neanderthal
Man” contributed genes to the modern Homo Sapiens.
The Monogenesis Theory states that multiple migrations originated in
Africa, where each wave outcompeted previous waves and gradually
replaced populations such as the “Java Man” and “Neanderthal”. While
some interbreeding is possible, it was not a significant factor.
More evidence favors the Monogenesis Theory.