Mendel's Century (1900 ~ 2000)
    Classical genetics evolves into molecular genetics           
           
Behavior of crosses versus gene function
            Genetic data
directly available from Protein & DNA


Meeting of Genetic & of Evolutionary Thought: Mendel's Century

1900: Gregor Mendel re-discovered: solves Darwin's biggest worry
          Darwin (1859) relied on “hard genetics": offspring resemble parents
          F Jenkin (1867) shows “blending inheritance” logically incompatible with Selection
              Politically correct “Purple People Eaters
          Mendel
(1867) demonstrated “particulate inheritance

              Purple People Eaters as Green & Yellow Peas

        GH Hardy (1908) Hardy-Weinberg Theorem sets null hypothesis

        RA Fisher (1930) Genetical Theory of Natural Selection establishes General Selection Model
                 
Mendelian genetics consistent with incremental Natural Selection
[S&R 1.3]
        S Wright (1931) Evolution in Mendelian Populations
                
Adaptive landscape as metaphor
[S&R 1.4]
                 Random genetic drift important

The Modern Synthesis (1940s ~ 1960s)
        Th Dobzhansky (1937) Genetics and the Origin of Species
                "Evolution is the change in genetic composition of populations"
                Chromosome polymorphism in Drosophila adaptive
        E Mayr (1942)  Biological species concept; Allopatric speciation             
        GG Simpson (1944)  Rates & patterns in fossil record; Evolutionary species concept
        GL Stebbins (1950)  Plant evolution similar to animal evolution

        E Mayr (1963) Animal Species & Evolution capstone of Synthesis       
            =>  Natural Selection acting on single genes explains trans-specific evolution
                  Evolution proceeds slowly & gradually

             
        
Variation measured as H:
                      H low: Classical vs Balanced schools differ on how low

                  Microevolution explains Macroevolution
                       
Species differences Genus differences etc by accumulated change
        Stumbling block: inter-species genetic variation not measurable

Molecular Genetics (slowly) revives Evolution

        DNA structure of gene (1953) (yawn)
        Genetic Code (1965) (Oh?):
DNA > RNA > Protein
        Protein Electrophoresis (1966) in Drosophila, Homo
             ***Rapid proliferation of protein variation studies: allozyme
                 Lots of variation: is it important ?
                 Neutralist versus Selectionist schools
[S&R 1.9 corrected]
        Molecular Clock
concept from immuno-genetic analysis (1967)
                Ex.: Chimp & Human separate 3 ~ 5 MYA
(!?!), 99% similar (!!??!!) (1975)

DNA data ascendant
(>1980)


         RFLP maps of mitochondrial DNA (mtDNA) (1979)
             ***
Rapid proliferation of within & among species mtDNA studies
[S&R 1.10]
                    Ex.: “Out of Africa” hypothesis from RFLP maps of human mtDNA (1987)

         Dideoxy DNA sequencing
(1977, routine from 1990)
             
*** "Sanger” sequencing remained method of choice for 40 years

        DNA Fingerprinting described; forensic applications (1985)

              *** Rapid proliferation of microsatellite nucDNA population studies

         Polymerase Chain Reaction in vitro amplification of DNA (1983) [S&R 1.11]
             
*** Rapid proliferation of within & among species DNA studies

         Automated DNA sequencing (1986) uses Sanger method [S&R 1.12]
                   Dideoxy terminators tagged with fluorescent markers: A C G T
                  
E. coli genome sequenced: 4.6 Mbp (1997)
                  
Human Genome Project: 3,200 Mbp (2003): Big Science Biology
        ***
Technical developments lead to Next-Gen sequencing


21st Century: Too Much Information (?)
       GenBank
: 654 Gb
(August 2020, Release 239) [running count]

                Data base for identification, retrieval, annotation, interpretation, manipulation, etc
                CRISPR-cas technology (2013)

              Ex.: “Environmental Sequencing” of 1,500 L seawater: 1.2M genes in 1 Gbp (2004)

         One Thousand Genomes Project (1KGP) announced (2008)

         Next-Generation Sequencing  routine from 2012 [S&R 1.13 & 14]

             Ex. Illumina Sequencing specs:
                      Throughput >> 106 nucleotides / second,
                      ~ 1 human genome at 1x coverage / hour
                      ~ 1 human genome at ~30x coverage / day

  Complete human genome in 16 hour

*** "Here it comes: assimilate it."
       Waaay
too much data: Bioinformatics

   

Text material © 2021 by Steven M. Carr