Evolution

Evolution

1. Process

2. Oranizing principle

3. Change

4. Process of evolution

   • Biological evolution
     • Change in characteristics of a biological population that occurs over generations
       • Considered evolutionary those that are passed from parents to offsprings via genes
         • Natural selection process by which populations adapt to their changing environment
       • Changes in environment are not evolutionary
         • EX: Women dress not evolution
         • Ex of head lice is evolution
           • Change in genes
   • Macroevolution
     • Changes that result in the origen of new species

5. Biological population

   • group of individuals of the same species isolated from others by geography
     • Changes that occur here are microevolution

6. Theory of evolution

   • Theory
     • Tentative explanation with little sistematic support
       • exampe: theory of why my team is loosing
   • Scientific theory
     • Statements that provide the current best explanation of how the universe works
     • supported by numerous lines of evidnce and repeated experimental tests
     • Theory of evolution
       • Principle for understanding how species originated and why they have their characteristics
   • All species present on earth are descendants of a single common ancestor and all species represent the product of millions of years of accumulated microevolutionary changes
     • Theory of the common descent
       • Opposite to Darwinism

7. Examining the evidence for common descent

   • Linnaean Clasification
     • Carl Von Linne
       • Swedish physician and botanist
         • Gave all species a binomial name in latin
         • Hierarchy: Kingdom Phylum Class Order Family Genus Species
           • Later modifications: adition of domain level and "sub" and "super"
           • All organisms within a category share basic characteristics
             • Placed humans, monkeys and apes in the same order.
               • Primates
               • Today scientistis place humans and apes in the same family: Hominidae
                 • Share: elongated skulls, short canine teeth, reduced hairiness
   • Anatomical homology
     • Hipotesis: If modern species represent the descendants of ancestors that also gave rise to other species we can observe other similarities between human and apes in anatomy, behavior and gens
     • Homology
       • Similarities between human and chimpanzee
         • Distinct opposable thumb
     • Homology of mammals forelimb
       • convergent evolution
         • Development of similar structures in unrelated organisms with similar lifestyles
       • Vestigial trails
         • Humans and great apes have a tail bone like other primates but they dont have a tail
         • Remainder of biological heritage
           • example: ostrich
   • Developmental Homologies
     • Genes that control development are similar among animals
     • Example of similarity among chordate embryos
       • Embryos are similar in fisrst sage (snake, Chicken, Cat, human)
   • Molecular Homology
     • Scientists now understand that deifferences between individuals arise from diferences in their genes.
     • The best way to measure similarities of two species genes is to evaluate similarities in DNA secuencies.
     • Genes that code for histone are found in algae, fungi, fruit flies and humans
     • Relationship between clasification and gene sequence similarity
       • DNA sequence of humans and gorilas are identical on 98.9% of their length
     • DNA evidences has question grupings like reptiles and birds. Some of them could be related.
     • Humans and chimpanzees share a more recent common ancestor than either species share with monkeys.
     • Molecular clock is the rate of change in certain DNA sequencies due to the acumulation of mutations that affect the DNA sequence but not the protein sequence
   • Biogoegraphy
     • Distribution of species on earth.
     • Darwin found that the tortoise species in Galapagos are different from the tortoise found in other similar tropical islands
     • Observations suggest that species in a geographic location are generally descendent from ancestors in nearby geographic locations
       • Supports the theory of branching descent from common ancestors
   • The fosil record
     • Evidence of human ancestors come from fosils
     • Fosils provide direct evidence of change in organisms over time
       • For example transition between ancient and modern horses
     • A fosil is a rock model of an organic structure
     • Hominin fosils can be distinguished from other primates fossils for example for the way they move
     • Neanderthal Man 1856 Germany
       • Homo erectus 1891 Indondesia
         • Taung Child South Africa, first african hominin fosil 1924 (Australopithecus)
           • Much older than neardenthal and Homo erectus
           • Lucy 1974 Ethiopia. Australopithecus afarensis
             • Walks upright
   • The record of our ancestors
     • Radiometric dating
       • Has led to estimate the age of earth (4.6 billion years) based on the age of oldest rocks.
       • Relies on radioactive decay
         • Rate of decay is meassured by the element half life.
       • With this technique they determined that the most ancient hominin fosil is Ardepithecus ranidus. 5.2 to 5.8 million years old
     • The common ancestor of humans and chimpanzees is called "Missing link" because it has not been identified.