EVOLUTION... is descent with modification
              C22 pg 412-422, C23 pg 428-444, C23 pg 445-458, C25 pg 464-473

progressive changes in organisms that persist over time
        helps explain the great diversity, wide geographical
        distribution, adaptations and origins of organisms  24.17

micro-evolution- changes in allele frequency within a species

macro-evolution- new species, new forms replacing old
                         as revealed in the fossil record






Darwinian (classical) Evolution Theory (24 Nov 1859)
    is based upon theory of Natural Selection    Origin of Species
       only small fraction of progeny of a generation survive
            survivors have traits (alleles) promote their survival
            survival depends on all genes acting together

Darwinian Natural Selection is defined as :
       is a change in allele frequency
       from generation to generation, 
       as influenced by environment 
       that promotes progeny survival.
     "Survival of Fittest "

                        The Darwin Awards - improving the human gene
                                                pool by removing oneself from it.







Synthetic (modern) Evolution Theory...
             Darwinian evolution mixed with modern genetic theory

    Population - an interbreeding group of individuals 
    Gene Pool - is sum total of all alleles of all indiv in pop. 
    Variation - is quasi measure of number of alleles
                    none = only 1 allelic form present
                    low = few alleles in population differ
                    high = high heterozygosity, every allele differs
    Adaptation - establishment of organism in particular environment 
                       due to its allelic combinations,
                       that promotes its survival & reproduction
    Fitness - is reproductive success of one genotype over another genotype









        Change in gene pool ....... leads to 
            better fitness ....... which leads to
                adaptation ....... which leads to 
                    reproductive success

       Evolution - better adapted genes leaving more progeny


what we need is a way to measure changes in the gene pool.








  population genetics  Hardy-Weinberg Equilibrium 
              1908 G.H.Hardy, English mathematician & G.Weinberg, German physician
Law of Genetic Equilibrium
         describes the gene pool (i.e., all the alleles present) mathematically
         defines the ideal case of a NON-evolving populations

     for an ideal case...  a number of criteria must be met... 
          - must be an infinitely large populations (large sample sizes)
          - should exhibit random mating
          - absence of forces which can change allele frequencies 
                         no migration (in/out)
                         no mutation
                         no selection
                         each allele is equally viable (no lethals)









HW law states --> 
           original percentage of a genotypes alleles remains constant

   HW can be defined algebraically, by the binomial expansion
           any gene with 2 allelic forms....             A  and  a
                 let frequency of one allele           (A)    =     p
                     & frequency of other allele       (a)    =     q

           then by definition,      p + q   =   1  

           HW equation...        (p + q)  =   p2   +   2 pq   +   q2   =  1
                                                         GG           Gg       gg










In population of canettes Orange is dominant (GG) to Green (gg) 


   of 1000 canettes, we observe that...                  
          40 are Green (gg)     & thus      960 are Orange    (GG or Gg)
            q2  =  freq homozygous recessive (green gg) = 0.04 
40/1000 = [0.04] x 1000 = 40
             q   =  freq of recessive allele sq.root of 0.04        =   0.20  
             p   =  freq dominant allele [G] = 1 - q = 1 - 0.2        =   0.80
         2pq   =  freq of heterozygote [Gg]
                              =  2  (0.2) (0.8)  = [0.32 x 1000]           =    320
           p2 = freq of homozygous dominant 
                              =  (0.8)2 = [0.64 x 1000]                       =     640
(23.3)   cf







agents of evolution... 
            But..... Allele frequencies do change over time via....

   Mutation... 1/10,000, random, non-directional
   Gene Flow... migration of breeders... in/out
   Genetic Drift... random loss of alleles  - due to failed matings  
            in very small populations, it's a statistical anomaly  
                                can lead to fixation or deletion of alleles
   Bottleneck Effect... natural disasters leave  survivors    

                    which are not representative of whole population     
   Non-Random Mating... in-breeding lessens heterozygosity...
           Founder's Principle...
little dispersal - new allele predominates - small human tribes
   Selection... better fit individuals are better reproducers
           Artificial - animal husbandry selects best -  mustards-      
           Natural - acts on individuals of populations










  factors that may affect selection... 
     ABIOTIC - non-living factors
                           temp, humidity, presence heavy metals, Chernobyl
        BIOTIC - living factors
                           predators, parasites, population density, growth rates

Types of Selection      (23.11
       STABILIZING - limits extremes of population
                    one optimum phenotype - ex: human birth weight
       DIRECTIONAL- one best phenotype, not the mean
                              gradual replacement one by another
       DIVERSIFYING (disruptive)- increases the fitness of extremes
                    no optimum phenotype (2 or more) - patchy environments
                              ex: sexual dimorphism 











How do you win the game of evolution:

           the mother of all bumper stickers......

the one who leaves behind the best fit genes, wins...










How species form 
                MICROEVOLUTION   ---->    MACROEVOLUTION

Definition of a SPECIES   
(latin - meaning KIND)    table 24.1 p 450
   morphospecies - most common definition - 
different species look different from each other
   geographical species - occur in particular places (habitat)
   reproductive species - group of actual/potential interbreeding 
           natural populations, which are reproductively isolated
           from other such groups (can't form hybrids)....
i.e., all individuals which can interbreed & produce progeny
                                     ex: all dogs,    all pigeons

BEST definition... a group of organisms, which does not interbreed with
      others groups and is thus reproductively isolated from other such groups...









Speciation via reproductive isolation

SPECIATION occurs when a gene pool splits & becomes reproductively isolated... 
      i.e., selection favors one allele over another

Some Evolutionary barriers to forming hybrids which can 
                 lead to REPRODUCTIVE ISOLATION (speciation)    

1. Pre-Zygotic - prevent mating &/or fertilization        24.5
          Geographical isolation ....English oak & California oak (deer mice- 24.6)
          Ecological (habitat) isolation..........Tiglons & Ligers
          Temporal isolation..........different breeding seasons
          Behavorial isolation.........distinct mating rituals 
          Mechanical isolation........structural differences 
2. Post-Zygotic - no development of fertile adults 
         horse + donkey = mule (sterile chromosome mismatches)  see 24.4













Some Evidences microevolution might lead to macroevolution

   - all are adaptations via Natural Selection 
           changes in allele frequency, which altered makeup of a
           population..... making some of it better adapted to its environment

1 - Poecilla reticulata (pg 15-17) - guppies in Trinidad pools (web)

     predation by...  killifish favored survival of LARGER indivduals at maturity
                           pike-cichlids favored survival of SMALLER fish at maturity










2- Industrial Melanism & Peppered moth ...     H.B.D. Kettlewell
       Biston betularia of England 
       in original butterfly population most had light colored wings


       late 1800's- dark winged form increases in freq in populations
                          esp. in industrialized areas... to almost 100%

             light form was preyed upon when on soot blackened trees
             dark form not preyed upon... thus an increase in dark's frequency
                     changed populations allele frequencies via predation









   ex: #3....     Darwin's Finches 
       there are 13 species of Galopagos Island finches

         main difference among brids is structure of their beaks -
                  an adaptation to their specifc diets     (25.7)
                  seed eaters, cactus eaters, insect eaters, fruit eaters

         medium ground finch's beak - 22.7 p422 (408)
                 eats mostly small (easier to crush) seeds
                     wet years = lots small seed = beak has smaller avg depth of beak
                     dry years = few small seed.... mostly larger seed 
                                                 = greater avg depth (top to bottom) of beaks 
                                                    birds w stronger beaks can eat large seed 
               advantage for "deep beak alleles" during drought years 
                                  can reproduce greater number of offspring to survive








 Some types or patterns of speciation...

       the initial block to GENE FLOW is GEOGRAPHIC
             mts, glaicers, land bridges, land locked lakes, followed by micro-evolution
       a subpopulation becomes reproductively isolated in the
            midst of the parental population.  ex: autopolyploidy - doubling of chrm #'s
             is the emergence of "new" species from single common
             ancestor that spreads out to new environments
                          best example: Darwin's Finches of Galopogos Islands.
ANAGENESIS (phyletic evolution is static
             is the transformation of a single unbranched line of
             organisms toward a "new" species.                     (24.1)
CLADOGENESIS (branching evolution - diversifying)
             budding off of a "new" species from a parent that
         continues; favors biological diversity & increases total # of species. 












  the rates of evolution ??? 
                    is it SLOW & CONSTANT ? 
                                   or does it occur in rapid SPURTS?

   GRADUALISM (24.13)           
               suggests a very slow constant rate...    26.3
                   periods of stasis, which lack significant evolution change 
                        ex: Lung fishes...  have not changes in 150 mil yr

              suggests rapid significant changes in a short period 
                   followed by a stable and constant rate of change 
                            [any advantageous role for intron & exons?]






The Cambrian Explosion...               tbl 5.1 pg 467
    a period of geological time [from roughly 543 mya to 490 mya
         marking the emergence of (sea) ANIMAL life
                  see great diversity of fossilized animals absent in late Precambrian
an adaptive radiation due to (?) unique circumstances (?)        
                  most extraordinary biological event on our planet

    by 505 mya...  
majority of all animal phyla (between 28-40) had appeared
                                all basic animal body plans had been established

Possible causes of rapid evolution of animal life in Cambrian Explosion...
   1.  O2 levels reached some critical value - favored oxidative metabolism
                     favored biochemical evolution allowing making of hard skeletons
   2.  large amounts of nutrients became available
                     phosphorites, nitrates, & Fe  (via deep sea upswellings)
   3.  temperatures become moderate
   4.  continental drift (which lasted 10-15 my) was occurring at this time

Is there animal life elsewhere in the Universe or is it a "Rare Earth"? 



















 Cystic Fibrosis  (cc)

is a recessive GENETIC DISEASE of childhood that is characterized by
    respiratory & digestive problems and is usually fatal. 
The average life span of 
    its victims is only about 24 years

       Effects include heavy production of thick mucus in respiratory tracts, which increases
        susceptibility to respiratory infections;  90 percent of all patients die of chronic lung disease.
Secretions that block pancreatic ducts cause important digestive enzymes to fail to reach the
       small intestine.  Treatment is directed toward relief of symptoms, and no cure is yet known.

Cystic fibrosis apparently is caused by the inability of chloride ions to cross the specialized epithelial cells of salivary, mucus, and sweat glands and the pancreas.  The ductal systems become clogged with thick secretions.  Cystic fibrosis is a recessive condition from a mutation to a single gene, which produces a disfunctional chloride channel protein.   






Gene lies on Chromosome 7
CFTR gene : cystic fibrosis transmembrane conductance regulator
          mutation:   ΔF508 ; deletion of 3 nucelotides at positions 507-508 in the CFTR protein

T       ISOLEUCINE 506
C                                   --->    ISOLEUCINE  507      
T      PHENYLALANINE 508    --> NO 508
G      GLYCINE 509   
T      VALINE 510










The disease is a commonly inherited disease among Caucasians; 

1/2,500 whites have the disease      cc      (0.0004 %)   

How many carriers Cc are there is U.S. population?















frequency of cc  is 0.0004%   thus freq of  "c" is sq.root  =  0.02%
if       freq  of c  =  0.02 then freq of C1 - 0.02  =  0.98%
            then   freq of  2(
Cc) =  2 (.98) (.02) = 0.039%

4% of American whites are asymptomatic carriers
                 4 out of 100 whites are carriers (C
                 1 out of 25 in
U.S. Caucasian population