evidence for evolution was darwin wrong? thursday, may 1 st

Evidence for EvolutionWas Darwin Wrong?

Thursday, May 1st

EVOLUTION

• It does not mean random

• It does not mean to improve

• It does not mean morphing during a lifetime

• It does not mean abiogenesis

• It means CHANGE OVER TIME

What is “fitness”?

• What does it mean to be “fit”?

–To be able to survive AND reproduce

The table below gives descriptions of four female mice that live in a beach area which has mostly tan sand with scattered plants.

According to the definition given for fitness, which mouse would

biologists consider the fittest? Explain why this mouse would be the fittest...

Fur color Black Tan Tan and Black

Cream

Age at death

2 months 8 months 4 months 2 months

# pups produced by each female

0 11 3 0

Running speed

8 m/min 6 m/min 7 m/min 5 m/min

What is “fitness”?

• What does it mean to be “fit”?

–To be able to survive AND reproduce offspring that can THEN reproduce

*

Below are descriptions of 4 male lions. According to our newest definition of fitness, which lion would

biologists consider the “fittest”?

Name George Brian Spot Bob

Age at death

13 yrs 16 yrs 12 yrs 10 yrs

# of cubs fathered

19 25 20 20

# of cubs surviving to adulthood

15 14 14 19

Size 10 ft 8.5 ft 9 ft 9 ft

Natural Selection vs Evolution

• Evolution • = The change in the

inherited characteristics of biological populations over successive generations

• Natural selection• = It is a key

MECHANISM of evolution

• is the only known cause of adaptation, but not the only known cause of evolution

*

Who was Charles Darwin?

• English naturalist

• Evolution resulted from natural selection– The struggle for existence

is SIMILAR to artificial selection and selective breeding

• Dog breeds• Beef cattle

*

HMS The Beagle

The 4 Components of NS• 1. Variation = exists among individuals in a population of

species

• 2. Inheritance = Some traits are consistently passed on from parent to offspring.

• 3. Population growth = Most populations have more offspring each year than local resources can support leading to a struggle for resources.

• 4. Survival of the Fittest = Individuals with advantageous variations will be more likely to survive and reproduce

*


• Process of natural selection:

– Populations of organisms can evolve if individuals having certain heritable traits leave more offspring than others

• Variations = adaptations:– Inherited characteristics

that enhance organisms’ survival and/or reproduction

November 24, 1859

*


• Cladistics– Hierarchical classification of species

based on evolutionary ancestry

– Cladograms = Evolutionary “Tree of Life”

– Makes no distinction between extinct and non-extinct species

• Appropriate to include extinct species in the group of organisms being analyzed

*

Cat, lion, seal & human

Who influenced Darwin?• Carolus Linnaeus (1750’s)

– Taxonomy (scientific groupings/names)– Used latin as the universal language

• Ex: Canis lupis – wolf• Ex: Homo sapien - human

• Jean-Bapiste Lamarck (1800)– Organisms change through use and disuse– Inheritance of acquired characteristics– Environments are what cause organisms to

change

Who influenced Darwin?• James Hutton (1785)

– Gradualism (rock formations - SLOW)

– Earth was transformed by imperceptibly slow changes• So natural selection/evolution could be really slow too

• Charles Lyell (1830’s)– Principal of Uniformitarianism

– Geological forces at work in the present day = same as those that operated in the past

– The past can be found in the present

What is the Evidence for Evolution?

• Paleontology– Investigates extinct life-forms as

revealed in the fossil record

• We call this FOSSIL EVIDENCE

• Classifying ancient organisms is difficult– Many do not “fit” well into the modern

form of taxonomy (Classification)


• DNA is made of 4 nucleotides• Adenine, thymine, cystosine and guanine

– Everything living is made of the same material, it’s just rearranged differently

• We call this MOLECULAR EVIDENCE


• You can trace similarities as far back as the beginning

– All fungi, plant and animal cells have nuclei

– All living organisms have RNA and DNA


• Biogeography

– The study of the geographical distribution of living creatures• Which species inhabit which parts of the planet

and why?

– Closely related species tend to be found:• On the same continent (similar species of zebra)• Or within the same group of oceanic islands (diff.

finches on the Galapagos Islands)


• Isolation + Time + Adaptations to local environmental conditions = new species

What is Comparative Anatomy?

The science of anatomical shape and design

• An organism’s body structure – Called its “basic plan”

• We call this ANATOMICAL EVIDENCE

• Can you guess what is similar between all of the organisms on the next slide?


• All of these organisms have an INTERNAL skeleton

http://www.hitchams.suffolk.sch.uk/skeletons/boa_constrictor.htm


• Homologous structures

– Similar structures that related species have inherited from a common ancestor

– Ex: Paired bones of the lower leg (tibia and fibula) can be traced back to the 1st “bird”, Archaeopteryx


• Analogous vs Homologous

• Wings– Maple seed– Albatross – Analogous

• Both allow the organism to travel on the wind– Both did not develop from the

same structure


• Vestigial structures– Structures that have lost most of their

original function in a species through evolution

– Appear to serve no useful function

• Examples:– Snakes: tiny pelvic bones & limb bones– Flightless beetles: have wings sealed that

never open


• Vestigial organs are often exactly the same as organs that are useful in other species– Our tailbone is homologous to the

functional tail of other primates

– Organisms having vestigial structures probably share a common ancestry with organisms that have use for the organ.


• Embryology

– Examines the revealing stages of development that embryos pass through before birth or hatching

– Many organisms look extremely similar when developing in the womb


• Embryonic structures can be adapted to different ultimate uses, for example, pharyngeal arches ("gill slits")– fish gill cartilage, the

reptilian jaw, and the mammalian middle ear

• Developmental ancestry: structures arise from the same tissue in embryonal development

What are the different types of evolution?

• Divergent– Adaptive radiation

• 2 or more related species become more and more dissimilar

• Adapting to different environments–Kit fox plains & deserts (sandy

colored fur & large ears)–Red fox mixed farmlands & forests

(red fur)


• Convergent– Unrelated species become more and more

similar in appearance– Adapting to the same kind of environment– Creates analogous structures

• Example – wings of–Pteranodon–Bats–Birds


• Co-evolution the evolution of 2 species totally dependent on each other

– An explosion of insect diversity seemed to correlate with the abundance of flowering plants.

• Angiosperms (flowering plants) depend on pollinating insects in order to survive and the insects depend on flowers for food.


• Gradualism– Change is SLOW, CONSTANT &

CONSISTENT– Selection & variation occur more gradually– Over a short period of time, it’s hard to notice– Very gradually, over a long period of time, the

population changes


• Punctuated equilibrium– CHANGE COMES IN SPURTS– Predicts that a lot of evolutionary change

takes place in short periods of time – Speciation is likely to occur at the edge of a

population• Where a small group can become separated

geographically from the main body population

So what is evolution anyway?

• It’s not necessarily a DECISION – the organisms that are best at surviving will produce babies (offspring)

• The organisms that cannot survive… well, they can’t really have offspring if they’re dead, right?

• We call that NATURAL SELECTION or Survival of the Fittest – Only the fit survive and reproduce – mutations that

affect an organism prior to reproduction tend to get “eliminated”

Evidence for Evolution

THE TOP EIGHT8. Wings on flightless birds

– Ostriches– Emus– Kiwi

7. Hind leg bones in whales– Baleen and humpback whales


6. Erector pili and body hair– When you get scared, your hair stands on end– When mammals get scared, it makes them

look BIGGER

5. The human tailbone– Was once used for balance, communication

(think dogs) or a prehensile limb


4. Wisdom teeth in humans– Gorillas have these teeth to help chew and

grind food– We brush our teeth, so we don’t lose our teeth

as often

3. Whiptail lizards– There are ALL female!– These lizards literally clone themselves


2. Male breast tissue and nipples

– This tissue is not functional, although a small percentage of males have been able to lactate

– ALL mammals, male and female, have mammary glands

– Males can also contract breast cancer


1. The Human Appendix

– In herbivores, the appendix helps by breaking down plant material for digestion

– Unfortunately, this organ no longer helps us with digestion what so ever

– In 2006, over 300,000 appendectomies were performed in the United State and over 400 people have died from appendicitis.

evidence for evolution was darwin wrong? thursday, may 1 st

Documents

charles darwin

populations of organisms

cause organisms

group of organisms

evolutionwas darwin

known cause of evolution

newest definition of

known cause of adaptation