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EVOLUTION NOTES.I. The Puzzle of Life’s Diversity

•______-variety of organisms

•______-change over time

•Voyage of the Beagle

–Charles Darwin-sailed______(1831) and collected many scientific observations –particularly of interest at the area around S.America and the Galapagos Islands

–Darwin collected ______remains-some resembled living organisms and some did not---indicating species had disappeared.

–Observed great diversity and saw so many organisms were well suited to their environments and various patterns ----leaving him w/ many questions…

–Although the Galapagos Islands were very near S.America,their climates were different than S.America and each other.The ______and iguanas varied in predictable ways from island to island/also many observations on variations in birds-eg. Size or shape of beak.

•After returning to England , he began to wonder if the animals on different islands were once members of the same species.

II. Ideas that shaped Darwin’s thinking

–Predominate thought was that the earth and inhabitants were only a couple thousand years old.

–______published a detailed hypothesis about the geological forces that have shaped the earth-proposing layers of rocks formed slowly and the physical earth was shaped by a variety of forces..

–______wrote Principles of Geology .---stressed that scientists must explain past events based on processes they can actually observe---eg. By volcanoes that we still observe may we get an idea of how the earth has changed

–______(1809)-realized organisms change over time but he felt that selective use or disuse of organs caused organisms to acquire or lose traits

–1) ______He said all organisms have a tendencies towards perfection ..thus continually acquiring characteristics to improve themselves----Thus he would say birds fly because they long ago tried to and their wings kept developing over the generations to fly.

–2) ______if something is used it is transformed for that purpose while if it not used,it would eventually disappear

–3)______.---If a giraffe stretched its neck to reach its food,it would pass that trait on…

–4)Evaluating Lamarck- incorrect in many ways-

–He did not know an organism’s experiences or behavior have no effect on inheritance

–Population Growth-______-reasoned that if the human population continued to grow unchecked,sooner or later there would be insufficient space & food---war,famine and disease work against this

–Darwin realized this applied less to humans than other animals and plants because ______

Notes –Evolution cont’d

Chapter 15

III. Darwin Presents His Case

A. publication

1858-Alfred Russel Wallace summarized the thoughts on evolutionary change Darwin had been looking @ for 25 years…This gave Darwin the incentive to publish his work

!859—Darwin Published “On the origin of Species…”proposed the mechanism for evolution to be ______

B. Inherited Variation and Artificial Selection

Members of each species vary from one another

Some variation heritable-passed on

______selective genetic variation where nature provides the variation and humans select to breed for this characteristic

  1. Evolution by Natural Selection

1)Struggle for existence

Applying Malthus’ principles,he realized high birth rate and shortage of resources produced ______-struggle for existence---faster,etc. avoid being caught

2)Survival of the Fittest

______=ability of an individual to survive and reproduce

______=any inherited characteristic that increases an organism’s chance of survival

Organisms w/ low levels of fitness are unlikely to survive and reproduce

______=survival of the fittest….may inherited characteristics of a population

3)Descent with Modification

Over long periods ,natural selection produces organisms that have different structures,establish different niches,or occupy different habitats---each species descends ______.

  • Implies all living organisms are related to each other
  • ______all species-living and extinct were derived from common ancestors
  1. Evidence of Evolution

1)Fossil Record-record of the history of life on earth-comparing fossils from different layers

  • Felt the earth was millions of years old
  • Since Darwin,people have discovered many transitional species in fossilized form
  • Gaps remain—providing some uncertainty about how some species evolved

2) Geographic Distribution

With reference to birds he observed,Darwin felt although they varied,they descended with modification from common mainland S.American ancestor

Animals w/certain similarities between areas developed this way due to similar ecological conditions

3)Homologous Body Structures----structures that have different mature forms but develop from the same embryonic tissue

Example:The bones of a bird skeleton more closely resemble homologous bones of certain reptiles than that of bats

  • ______-traces of homologous organs….appear to have no function

4)Embryological Similarities-many embryos look esp. similar during certain stages of development…producing homologous structures

Summary of Darwin’s Theory

Individuals differ and some can be ______.

Organisms produce more offspring that can survive and many do not ______.

Organisms ______for limited resources.

Each unique organism has unique advantages and disadvantages in struggling for existence---Those best suited will reproduce,passing on their traits.

Species alive today descended with modification from ancestral species…uniting us in a single tree of life

Strengths and Weaknesses

Continues to change as new data and technology develop

Argument about extinction

Origin of life

Darwin’s Finches

Evolution cont’d-pieces of Chapter 16 & 17

______=all genes,inc. all the different alleles,that are present in a population

______of an allele= # times that the allele occurs in a gene pool,compared with the # of times other alleles for the same gene occur.(often a %)

In genetic terms ,evolution is any change in the relative frequency of alleles in a population.

Sources of genetic Variation-

  1. mutations
  2. gene shuffling
  • Natural selection can affect the distribution of phenotypes in any of the 3 following ways:
  • Directional selection-Individuals @ one end of curve have higher fitness than those @ middle or other end-Example-birds w/ large,wide beaks can crack large seeds….If the supply of small seeds decreases,they dominate
  • ______-individuals near center of curve have higher fitness—example-babies of average weight survive better than very low or high birth weights.
  • ______-individuals @ upper and lower end of curve have higher fitness than individuals near middle-example mid-sized seeds become less common and large beaked or small beaked birds both benefit.

______= random change in allele frequency

see p.400

Founder’s Effect:______

______Principle-allele frequencies in a population will be constant unless one or more factors change it.

5 conditions for it to hold

  1. genetic equilibrium from generation to generation
  2. random mating
  3. large pop.
  4. no emigration or immigration
  5. no mutations or natural selection

______= formation of new species

Due to-

  • Isolation-reproductive isolation due to behavorial,geographic or ______isolation(reproduce @ different times)

______are scientists who study fossils

How fossils form:

  1. sedimentary rock
  2. sometimes an imprint and sometimes a preserved remains
  3. buried in resin-amber
  4. tar pits

Dating-

  1. compare w/other sediments and fossils
  2. radioactive dating using half lives-esp. C-14,since its half life = 5730 years

Geologic Time scale-see p.421

3 eras:Paleozoic,______and Cenozoic

  1. Paleozoic-diversity of marine life
  2. Mesozoic-increasing dominance of Dinosaurs,flowering plants appear
  3. Cenozoic-mammals evolved adaptations to allw them to live in various environments

______-are subdivisions of eras

  • Earth’s early atmosphere probably contained H-cyanide,CO2,CO,N,H2S and H2O
  • Miller & Urey’s experiments suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds.This was not totally accurate –ie. the experiment-but lead to similar experiments-even producing nitrogenous bases .
  • ~ 200-300 million after earth cooled to carry water, cells similar to bacteria developed, beginning w/something similar to a cell membrane
  • Next eukaryotic cells developed by______as a symbiosis formed between prokaryotes….eventually specializing into organelles like______
  • Margulis supported this in the 1960’s w/the following evidence:
  • mitochondria and chloroplasts carry DNA similar to bacterial DNA.
  • mitochondria and chloroplasts have ribosomes similar to that of bacteria
  • mitochondria and chloroplasts reproduce by binary fission a lot like bacteria
  • Patterns of Evolution-
  1. extinction
  2. ______-single species evolve into several different forms in different ways

3.______-unrelated organisms come to resemble one another

4.______-2 species evolve in response to changes in each other over time

  1. ______-long,stable periods,interrupted by brief periods of more rapid change

------In spurts

6. ______--opposite of punctuated equil.---slowly over a long period of time

BIOLOGY NOTES -HUMAN EVOLUTION

I. Primates

  • HUMANS BELONG TO THE GROUP CALLED ______that also include monkeys and apes
  • originally lived in trees
  • strong hands ,fingers and ______thumbs
  • relatively large brains w/ a degree of intelligence
  • complex social behaviors
  • extended parental care
  • only humans can remain ______-walking on 2 legs-for an extended time
  • humans have the largest of primate brains
  • humans have more developed speech

II. Primate Evolution

A. Apes

  • usually larger than monkeys
  • larger brains and no tail
  • surviving apes:______,______,______,and gibbons
  • genetic studies show chimps to be closest ape to humans-----more than 90% genes identical

B. Prosimians and Anthropoids

  • ______(means premonkey)-small monkeylike w/ large forward facing eyes and are ______-active @ night---fossilized ones were rodent-like
  • Modern Prosimians:______,______and ______
  • ______means humanlike -include New World monkeys of S. America w/ prehensile tails-flexible tails(example-spider monkey)
  • anthropoids in Europe,Asia and Africa evolved into 2 groups 1)______and 2)______
  • Old World Monkeys have long prominent noses and non-prehensile tails-example-Baboon

III. Early Hominids

  • ______all anthropoids belonging to human family
  • modern human:______
  • ______are scientists who study the lives and cultures of human through fossils and artifacts
  • probably there was usually more than one hominid @ a time

A. Australopithecus

  • Fossil evidence suggests the split between human and apes happened between 5-8 million years ago
  • Oldest fossil found may be______-meaning southern ape found in southern Africa
  • 1994-4.4 million y old - ______
  • 1924-______-2.7-2.1 mya
  • 1974-______-Lucy-3-4mya
  • They are considered hominids because they are bipedal---note different pelvis
  • Austalapithecus brain still smaller
  • ______and ______-1-2 mya-thicker bones

B. Homo habilis

  • 1964 the Leakies found ______-1st known to use tools-direct ancestor of humans
  • 1960's-another discovery of probably same species
  • larger brain

C. Homo erectus

  • even larger brain
  • migrated out of Africa and into Asia and Europe
  • may have been able to make fire

IV. Homo sapiens

  • maybe 500,000 to 300,000 y ago

A. ______fossils found in Germany in 1856

  • subspecies of Homo sapiens
  • Europe and Asia
  • brains as large as humans
  • faces fairly similar w/ heavier brow
  • burials and decorated tools
  • religion

B. Cro- Magnons

  • 100,000 y a
  • shared earth w/ Neanderthals....may have blended into one group
  • may have drove Neanderthals to extinction
  • 1st fully modern human