Evolution

Evolution

1. Principles of evolution

   • 1. organisms beget like organisms
     • Lamark
       • Transformation
         • spontaneous change, towards complexity, changing environment, inheritance of acquired characteristics
   • 2. the number of individuals that survive and reproduce is smaller than the number of individuals in the original population
     • Thomas Malthus
       • sociology and economics
         • Population increase - food shortage - starvation
   • 3. in any given population, there are variations among individual organisms, and some are inheritable
   • 4. Inherited favourable variation become more common from each generation to the next, through natural selection
   • 5. Natural selection leads to the slow accumulation of adaptive changes that differentiate groups, speciation

2. History

   • Setting the stage for Darwin
     • Physical science
       • Galileo, Newton
     • Fossil record
       • Cuvier
     • catastropism
       • Cuvier
     • gradualism
       • James Hutton
       • Charles Lyell influenced by Hutton
         • Geology age of the earth
           • Earth must be ancient
           • Slow and subtle process overtime can result in dramatic change
   • Essentialism : two co-existing world : ideal + illusionary
     • Plato
   • teleology: Belief in a divine order or purpose of life
     • Aristotle
   • taxonomy
     • Linnaeus
       • Linnaerian classification
         • Hierarchical, not evolutionary

3. Macroevolution: above the level of species

   • Darwin's evidence
     • The abundance and diversity of species
     • Biogeography : particular kinds of organisms are found in particular areas
       • first suggested common decent
       • Mechanism underlying the pattern: continental drift ( darwin wasnt aware of this)
     • Fossil record: organisms had a long history, changed through time, some even became extinct.
       • evidence of continuity and descent with modification
         • now supported by molecular archive
     • Homologous structures of diverse organisms: historical relationship or common history
     • Adaptation: evidence of selective forces, imperfection of adaptations- historical constraints on evolutionary change
       • organisms are influenced by changing environments (through adaptations)
       • evidence of unrelated organisms that occupy similar niches adapting in similar ways
         • convergence

4. Microevolution: below the level of species

   • examples of artificial selection as evidence of the importance of natural variation

5. Natural selection

   • Major categories
     • Stablising
     • Disruptive
     • Directional
   • Sexual selection
     • intersexual selection
     • intrasexual selection
   • population level forces affecting variation
     • Recessive refuge
     • Genetic drift : change in allele frequency of the gene pool: chance event
       • Bottleneck effect
         • population number reduction due to catastrophic events
       • Founders effect
         • new colony established by a small group from the original population
       • to restore variation: Gene flow
     • Gene flow
     • Inbreeding depression: mating between closely related individuals and subsequent loss of variation, decreasing heterozygosity, reduced reproductive success and increased susceptibility to disease
   • mimicry and coevolution: involving in response to another
     • Mullerian mimicry: two harmful species mimic eachothers warning signals (coevolutionary cooperation)
     • Batesian mimicry: harmless species mimic harmful species warning signals (coevolutionary cheating)
   • Cline - gradual change in a character or feature across the distributional range of a species or population, usually correlated with an environmental or geographic transition.

6. The origin of species

   • Speciation
     • Allopatric
     • Sympatric
       • polyploidy
       • disruptive selection
     • principle modes
       • Dispersal: chance movement to new habitats
       • Vicariance: geographical disruption of distributions
   • Reproductive isolating mechanisms
     • Prezygotic
     • Postzygotic
       • hybrid inviability
       • hybrid infertility
   • Patterns of speciation in the macroevolutionary record
     • Phyletic change/ Anagenesis: gradual change within a single lineage overtime
     • Cladogenesis: evolutionary change produced by the branching of populations to form new species.
     • Adaptive radiation
     • Extinctinon
     • Punctuated equilibrium
       • long, stable periods interrupted by briefs periods of rapid change
   • species concept
     • Biological species concept: a group of natural populations whose members can interbreed with one another but cannot interbreed with members of other populations
     • Phylogenetic species concept: based on common evolutionary history
     • Ecological species concept
     • Morphological species concept

7. Phylogenetics - the evolutionary classification of organisms

   • characters
     • ancestral
     • derived
     • homologous
       • Structures of similar origins but used for different functions.
     • Analogous
       • Structures of similar function but of different origins.
   • Grade : organisms with similar characteristics, a single ancestor hasnt been identified.
   • clade (cladogenis,phyletic change): section of the biologic tree that shows all descendants from a common ancestor. including only monophyletic branching events
   • phylogenetic systems
     • polyphyletic: x and y derived from different intermediate ancestors
     • monophyletic: all descendants with their intermediate common ancestor
     • paraphyletic: includes some but not all of the descendants of intermediate ancestral specie.

8. The descent of man

   • The primates
     • Prosimians: lories, bush babies, lemur and tarsiers
     • Anthropoids: new world(baboon), old world(spider mokey) monkeys, ape
     • Hominoids: humans (hominins) and other great apes
   • dispersal models
     • Out of Africa model
     • Multiregional model

9. Hardy Weinburg Equilibrium

   • p2 + 2pq + q2 = 1
   • p + q = 1
   • Assumptions: no mutation, no geneflow, no genetic drift, random mating, no selection
   • describes an ideal condition against which the effects of these influences can be analyzed.