BIO108 Evolution and Genetics

• Theodosius Dobzhansky 1973

  "Nothing in biology makes sense except in light of evolution"
• Plato 427-347BC

  -Greek Philosopher

  -Believed in 2 worlds: real and illusionary

  -Typological view of nature-individual variation as the imperfect manifestation of ethos
• Aristotle 384-322BC

  -Greek Philosopher

  -Believed all living organisms could be arranged in a "scale of nature"/Great Chain of Being.

  -Ladder of life-graduation of inanimate materials through plants, lower animals and humans to spiritual beings
• Al-Beruni 973-1048

  -Iranian Scholar

  -Believed man 'migrates' through 'kingdoms' of minerals, plants and animals to reach perfection
• Al-Jahiz 776-868

  -Iraqi Zoologist

  -Believed organisms developed new traits to survive environments

  -Believed that animals evolved with help of God and that God wanted to keep nature in order
• Carolus Linnaeus 1707-1778

  -Established modern system of taxonomy-attempt to discover order in diversity of life "for the greater glory of God"
• "transmutation of species"

  Erasmus Darwin 1731-1802

  Robert Chambers 1802-1871
• Lamarck 1744-1829

  -First articulated theory of evolution

  • Organisms continually arise by spontaneous generation
  • "nervous fluid" acts to move each species up the "great chain of being"
  • Organisms develop adaptations to changing environment through the use and disuse of organs
  • Adaptations are inherited
• "descent with modification"

  Evolution only occurs when there is a change in gene frequency within a population over time.

  • Can lead to diversity of organisms
  • Means we don't have some organisms anymore
  • Provides an explanation for exaggerated phenotypes
  • Explains complex social behavior and cooperation
• Artificial selection

  -Farmers and Breeders

  -Allow certain plants and animals with desirable traits to reproduce
• Mechanisms of change

  • Mutation
  • Migration
  • Genetic drift-random and non selective
  • Natural selection-Darwin 1809-1882--written 1859

  Genetic drift and natural selection cannot operate without genetic variation
• What level does Natural selection act at?

  Genes/individuals
• Selfish herd behaviour

  William Hamilton- Geometry for selfish herd

  happens in species such as sheep

  When facing a predator will group together (flocking) -each individual will try and stay in the middle of the herd so as not to be eaten so they can reproduce and pass on their genes
• Kin selection

  1964 william hamilton

  the evolutionary strategy that favours the reproductive success of an organism's relatives

  Inclusive fitness

  Altruistic behaviours favoured by selection -individuals will give something up to help others- normally own family members so that their genes can still be passed on
• Cooperative breeding

  One couple mates in the population/ family

  The rest of the population will care for the offspring
• kin selection-how much it will cost

  Works out how beneficial it is to sound the alarm to a predator, coting own life but sparing families lives at the same time

  c<b*r

  c= the fitness cost to the individual

  b= sum benefits to recipients affected by the behaviour

  r= relatedness between individuals

  if c= < b*r then it is worth the altruistic behaviour of giving up something/own life
• Haplo-diploid system

  no sex chromosomes in most species of bees and ants. The females develop from fertilized eggs and are diploid. The males develop from unfertilized eggs and are haploid--> 75% related
• Naturalistic fallacy


  the idea that what is found in nature is good
• Infanticide

  seen in species of primates

  killing other fathers offspring so that the female will become fertile again, and have his offspring- increases males own fitness- more genes

  usually one male unit and multiple females. the males compete for the females

  See infanticide after m bands takeover

  can eliminate future competition

  females will fake being fertile whilst pregnant with another males offspring, and will form groups to fight off the males
• Microevolution

  Evolution on a small scale, in a single population (share a gene pool)

  Caused by a change in gene frequency- can be by mutation, migration, genetic drift or natural selection
• Species

  can interbreed- biggest gene pool possible under natural conditions. Definition is not easily applied to species that reproduce asexually- some organisms form hybrids
• Speciation

  lineage-splitting event that produces two or more separate species

  Caused by geographic isolation/ reduction in gene flow (can be over a broad geographical rage or can be caused by barriers like incompatible sex organs)