evolution mtc section bio 101 Darwin natural selection
Darwin, evolution, origin of life
Important Dates in Geological Time
4.5 billion years ago
Origin of Life
4.0 - 3.0 billion years ago
Oldest prokaryotic organisms
3.5 billion years ago
Earliest eukaryotic organisms
1.5 billion years ago
0.5 billion years ago
1862 - Louis Pasteur (France)
disproves the belief in "spontaneous generation"
life has to come from life
1920 - Alexander Oparin (Russia) & the early atmosphere
Oparin believed the early atmosphere consisted of
water vapor (H2O)
methane (CH4) and
but no molecular oxygen (free O2 by itself). This represented an atmosphere that contained not only the four essential elements in biochemistry but was also a "reducing atmosphere" that would favor the formation of more complex molecules necessary to form the first cells.
1953 - Stanley Miller (United States)
proved: Inorganic molecules can react to produce small organic molecules.
performed experiments to test whether the atmospheric conditions that Oparin suggested would allow the formation of the molecules necessary to form cells. Miller discovered that Oparin's reducing atmosphere was conducive to the formation of carbohydrates, proteins, nucleic acids, and lipids.
Major Events Necessary to the Origin of Life on Earth
1. Atmosphere must contain sources of carbon, hydrogen, oxygen, and nitrogen.
2. Large molecules (carbohydrates, lipids, proteins, and nucleic acids) must form from the smaller compounds in the atmosphere and primitive seas.
3. Cell membranes must form from the large molecules.
4. Genetic machinery must be installed within a cell to control replication and other cell functions.
5. Eukaryotic cells must evolve from prokaryotic cells.
Proposed Early "Cells"
1. coacervates - first cells had lipid-based membranes as proposed by Oparin.
2. microspheres - first cells had protein-based membranes as proposed by Sidney Fox.
Origin of the Cell's Genetic Machinery
The first cell is most likely RNA genes that are capable of replicating themselves & directing protein synthesis
Reverse transcription could have led to DNA genes
RNA was responsible for both DNA and protein formation
Eventually protein synthesis would have been carried out according to the central dogma, with information flowing from DNA to RNA to protein
From Prokaryotic to Eukaryotic Cells
Prokaryotic cells preceded eukaryotic cells. The present structure of the eukaryotic cell was formed by enfolding the cell membrane
The mitochondria and the chloroplasts present in cells evolved from a bacteria-like organism (mitochondrion) and an alga-like organism (chloroplast) that invaded early cells and developed a favorable (mutualistic) association.
eras oldest to youngest
4.6 billion - 590 million years ago
No multicellular creatures; marine creature dominant; origin of prokaryotes and eukaryotes
590 - 248 million years ago
Dominant animals include amphibians and fish; first vascular plants
248 - 65 million years ago
Dominant animals include the dinosaurs; dominant plants include conifers
65 million - present
Current era; dominant animals include mammals, dominant plants include flowering plants; modern man
the changes that have transformed life on earth from its earliest beginnings to the diversity that exists today. Evolutionary biology provides a cohesiveness to nature and allows us to "make sense" of the world that surrounds us.
the theory proposed by Charles Darwin to explain the process of evolution
the mechanism that brings about adaptation to the environment as evolution occurs
Believed species to be fixed and permanent; living things could be arranged on a scale of complexity Scala naturae (scale of nature)
Carolus Linnaeus (1707-1778)
Swedish physician and botanist
the "father of modern taxonomy"; created a taxonomic system based on morphological (form and structure) comparisons. (kingdom, phylum, class, order, family, genus, and species)
created binomial nomenclature and standardized the language of taxonomy through the use of Latin.
Believed in the immutability of species, "God creates, Linnaeus arranges".
Georges Cuvier (1769-1832)
French anatomist who developed the science of paleontology
developed theory of catastrophism: a belief that the boundaries between various fossil assemblages could be explained by catastrophic events occurring in earth's past
staunch opponent of evolution
Charles Lyell (1797-1875)
English geologist who wrote Principles of Geology,
theory of uniformitarianism: which implied that geological processes are so uniform that their rates must balance out through time; implied an old age for the earth.
never fully accepted idea of evolution
Jean Baptiste Lamarck (1744-1829)
theory of use and disuse, theory of inheritance of acquired characteristics (both discredited)
(1) that evolution was the best way to explain what can be observed in the fossil record
(2) the great age of the earth
(3) the important role the environment plays in the evolution of organisms.
Charles Darwin's grandfather who speculated about evolution as a process in Zoonomia (1794). His writings may have had some influence on his grandson's theories.
Alfred Russell Wallace (1823-1913)
Independently developed a theory of evolution by a process nearly identical to what Darwin referred to as "natural selection".
English anatomist and physiologist; nicknamed "Darwin's Bulldog" due to his staunch defense of Darwin's view of evolution by natural selection.
Charles Darwin (1809-1882)
Developed the theory of evolution by natural selection (gradualism); in 1859 published The Origin of Species.
Austrian monk considered the "father of Genetics" due to his research in 1865, but his research was unknown to Wallace and Darwin.
5) What group of islands observed during his voyage greatly influenced Darwin’s thinking about evolution? where are they?
off the coast of south america
(6) Name 2 groups of animals that were observed on these islands that would later be referenced in Darwin’s work on evolution?
(12) Which scientist developed an idea very similar to that of Darwin, which encouraged Darwin to go ahead and publish?
Alfred Russell Wallace
(13) List 5 major points to Darwin’s theory of natural selection?
(1) Population tend to exhibit exponential growth; there is a tremendous potential in nature for overproduction of offspring.
(2) Resources needed for survival are limited in nature, which leads to a struggle for survival.
(3) Individuals within populations vary. Some of these variations are more or less
advantageous in the struggle for existence.
(4) The individuals with the best combination of characteristics will survive ("survival of the fittest").
(5) The survivors will have an opportunity to reproduce and pass the characteristics that gave them the survival edge on to their offspring.
(14) What is meant by “fitness” in a Darwinian context? Would fitness necessarily mean the physically strongest organism?
fitness: is the relative reproductive success of an individual (Barney Fife who has 5 kids is more fit than The Rock who has 0)
Change that helps a species become more suited to its environment
English Pepper Moths - example of natural selection; darker moths were selected for survival as the industrial revolution wore on and pollution became more pronounced
evidence that evolution has occurred
molecular biology (biochemistry)
remains or evidence of some organism that lived long ago
are a common ancestor for two different groups of organisms
the distribution patterns of organisms
classification which implies descent
homologous organs and structures
parts of organisms that exhibit similar basic structures and embryonic origins
parts of organisms that are similar in function only
remnant of a structure that was functional in some ancestor but is no longer functional in the organism in question
All vertebrate embryos have:
A postanal tail
Paired pharyngeal (gill) pouches
Molecular biology (biochemistry)
All living organisms:
1. Use the same basic biochemical molecules
2. Utilize same DNA triplet code
3. Utilize same 20 amino acids in their proteins
DNA base-sequence differences: (cytochrome c)
When very similar, suggest recent common descent
When more different, suggest more ancient common descent