Chapter 22: Descent with Modification: A Darwinian View of Life

Chapter 22: Descent with Modification: A Darwinian View of Life

1. What do you know about evolution?2. What is evolution?

- Gradual change over time3. What is paleontology?-Study of fossils-Allows for relative dating - “older” or “younger” - depends on layer


1. What do you know about evolution?2. What is evolution?3. What is paleontology?4. What was Lamarck’s view?

- Inheritance of acquired characteristics- Evolution within an organism’s lifetime – “use & disuse”- Examples – Blacksmith, giraffe

- Viewed for 150 years as being wrong…but he couldbe partially right! (epigenetics—inheritance of methylation)

5. What was Darwin’s view?- Environment supplies selective pressure—struggle for

existence- REPRODUCTION of the fittest

EnglandEUROPE

NORTHAMERICA

GalápagosIslands

Darwin in 1840,after his return

SOUTHAMERICA

Cape ofGood Hope

Cape Horn

Tierra del Fuego

AFRICA HMS Beagle in port

AUSTRALIA

TasmaniaNewZealand

PACIFICOCEAN

And

esATLANTICOCEAN

Figure 22.5 The voyage of HMS Beagle



- Inheritance of acquired characteristics- Evolution within an organism’s lifetime – use & disuse- Examples – Blacksmith, giraffe


existence- REPRODUCTION of the fittest - Studied Galapagos finches

Figure 22.6 Beak variation in Galápagos finches

(a) Cactus eater. The long,sharp beak of the cactusground finch (Geospizascandens) helps it tearand eat cactus flowersand pulp.

(c) Seed eater. The large groundfinch (Geospiza magnirostris)has a large beak adapted forcracking seeds that fall fromplants to the ground.

(b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects.



- Inheritance of acquired characteristics- Evolution within an organism’s lifetime – use & disuse- Examples – Blacksmith, giraffe


existence- REPRODUCTION of the fittest - not SOTF- Studied Galapagos finches- 1859 – The Origin of Species – 2 main points

- Descent with Modification from common ancestor- Natural selection is the mechanism of evolution

Figure 22.7 Descent with modification

Hyracoidea(Hyraxes)

Sirenia(Manatees

and relatives)

Yea

rs a

goM

illio

ns o

f yea

rs a

go

Dei

noth

eriu

m

Mam

mut

Steg

odon

Mam

mut

hus

Plat

ybel

odon

Bary

ther

ium

Moe

rithe

rium

Elephasmaximus

(Asia)

Loxodontaafricana(Africa)

Loxodontacyclotis(Africa)


1. What do you know about evolution?2. What is evolution?3. What is paleontology?4. What was Lamarck’s view?5. What was Darwin’s view?6. Summarizing Darwin’s view

- Natural selection = differential reproductive success- Natural selection occurs through interactions between

the environment and the variability among individual organisms in a population

Figure 22.9 Variation in a population

Figure 22.11 Camouflage as an example of evolutionary adaptation

(a) A flower mantidin Malaysia

(b) A stick mantidin Africa


1. What do you know about evolution?2. What is evolution?3. What is paleontology?4. What was Lamarck’s view?5. What was Darwin’s view?6. Summarizing Darwin’s view

- Natural selection is differential reproductive success- Natural selection occurs through interactions between

the environment and the variability among individual organisms in a population

- The product of natural selection is the adaptation of a population of organisms to their environment

7. What is artificial selection?- Selective breeding to encourage the occurrence of

desirable traits

Figure 22.10 Artificial selection

Terminalbud

Lateralbuds

Brussels sproutsCabbage

Flowercluster Leaves

Cauliflower

Flowerandstems

Broccoli Wild mustard Kohlrabi

Stem

Kale


1. What do you know about evolution?2. What is evolution?3. What is paleontology?4. What was Lamarck’s view?5. What was Darwin’s view?6. Summarizing Darwin’s view7. What is artificial selection?8. What is the evidence for evolution?

- Homologous structures – similar structures with different functions show signs of evolution from a common ancestor, may be vestigial organs

Figure 22.14 Mammalian forelimbs: Homologous structures

Human Cat Whale Bat




- Comparative embryology - Pharyngeal gill slits- Post-anal tail

Figure 22.15 Anatomical similarities in vertebrate embryos

Pharyngealpouches

Post-analtail

Chick embryo Human embryo





- Molecular biology

Figure 22.16 Comparison of a protein found in diverse vertebrates

Species

Human

Rhesus monkey

Mouse

Chicken

Frog

Lamprey14%

54%

69%

87%

95%

100%

Percent of Amino Acids That AreIdentical to the Amino Acids in aHuman Hemoglobin Polypeptide





- Molecular biology- Biogeography – geographical distribution of species

Fig. 22.17 Different geographic regions, different mammalian “brands”

Sugarglider

AUSTRALIA

NORTHAMERICA

Flyingsquirrel



- Homologous structures- Comparative embryology - Molecular biology- Biogeography – geographical distribution of species- Fossils

Figure 22.18 A transitional fossil linking past and present

Documents

Chapter 22: Descent with Modification: A Darwinian View of Life