evidence of evolution -...

© Cengage Learning 2015

Biology Concepts and Applications | 9e

Starr | Evers | Starr


Chapter 16

Evidence of Evolution


Emergence of Evolutionary Thought

19th century naturalists discovered global

patterns that could not be explained in framework

of traditional beliefs

How did these 3 flightless birds with very similar

features end up on different continents?



Why do these plants have outward features that are very

similar but reproductive parts that are very different?



coccyx

(tailbones)

Vestigial structures – body parts with no

apparent function, e.g. tailbones in humans

(coccyx)


Darwin: “Descent with Modification”

Darwin used ideas from Lyell (geology) and Malthus

(economics)


Fossil glyptodon and armadillo

Though widely

separated in time, they

share many traits:

armadillos only live

where glyptodons

once lived. Both have

a shell and helmet of

keratin-covered bony

plates.


Natural Selection: Differential reproductive

success of individuals with different phenotypes

NOTE: Natural

selection functions

at the

POPULATION

level


Evidence for Evolution: Fossils

Hard

parts

Amber or

ice

Trace

fossils


How do we measure the age of fossils?

Radiometric dating – determines age by measuring

content of radioisotope and daughter elements


How do we measure the age of fossils?


Using fossils to piece together evolutionary

history

A

B

C

D

ankle bones

Rodhocetus antelope


How has earth changed over geologic

time?

fault hot spot trench trench ridge 1 2 3 4

Plate Tectonics Theory


600 mya

430 mya

340 mya

240 mya

200 mya

150 mya

65 mya

present

Gondwana

Pangea

Earth’s geologic

history (along with

fossils) helps explain

the past and present

distribution of species


Evidence for Evolution: Homologous

Structures

Body structures that are similar due to

common ancestry

Figure 16-14 p267

Morphological

convergence can

result in analogous

structures (can cause confusion when

relying on comparative

morphology!)


Evidence for Evolution: Comparative

Embryology

• Closely related organisms often have

similar patterns of embryonic development

Human, Mouse, Bat, Chicken, and Alligator Embryos


Evidence for Evolution: Similarities in

DNA and Proteins

The more recently

two lineages

diverged, the less

time there has been

for unique mutations

to accumulate (so

genes and associated

proteins will be more

similar)


What killed the dinosaurs?

K-Pg boundary

sequence -- an

unusual, worldwide

sedimentary rock

formation that

formed 66 million

years ago

Shocked quartz

Only forms under

sudden extreme

pressure, e.g. atomic

bomb explosion or

meteorite impact


What killed the dinosaurs?


K-Pg Boundary Sequence: Data Analysis

1. What was the iridium content of the K-Pg boundary

sequence?

2. How much higher was the iridium content of the

boundary layer than the sample taken 0.7 meter

above the sequence?

evidence of evolution -...

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