2- Evolutionary theory Flashcards
how have definitions of evolution changed over time?
pre Darwin - unfolding scroll
origin of species (1859) - “descent with modification”
modern - change in frequency of alleles over time
do individuals evolve?
no, its the frequency of alleles
was Darwin the first to propose an evolutionary theory
no, greek roman and islamic scholars all proposed kinds of evolutionary theory.
e.g. Al Janis (776-868 CE) - ‘animals that survive to breed can pass on their successful characteristics to their offspring’
other examples of evolution thinking before Darwin
Jean-Baptiste Lamar
Robert Chambers
Darwins contributions
On the origin of species (1859)
- theory of evolution by natural selection (also Wallace)
- credible mechanism for evolutionary change
- explanation for adaptation
- lots of evidence to support
The Descent of Man (1871)
- applied evolutionary theory to humans
- introduction to theory of sexual selection
what is natural selection?
- not the same as evolution - is an evolutionary process but not the only one
- causes adaptation and appearance of design
- not all evolutionary change is adaptive, can be neutral
- unlike evolution, can be observed within our lifetimes e.g. 40 year street of Darwins finches - Rosemary and Peter Grant
how does natural selection work
variation - competition - inheritance
variation
in traits that affect survival e.g. asian ladybird beetle
competition
struggle for existence (not always physical competition)
“favourable variations would tend to be preserved, and unfavourable ones to be destroyed” - Darwin, 1887
inheritance
traits must be heritable
e.g. roloway guenon (cercopithecus roloway)
Darwins natural selection quotes
variation - if it vary however in any manner profitable to itself
competition - there is a frequently occurring struggle for existence
inheritance - any selected variety will tend to propagate its new and modified form
(all from origin and species - same paragraph)
artificial selection
demonstrates how selection can cause evolutionary change, same process sped up by humans, used as evidence by Darwin in the origin of species
Red Queen hypothesis
- adaptation is an ‘arms race’ even if abiotic environments stable
-species continually respond to one another - Introduced by Van Valen (1973)
“Now, here, you see, it takes all the running you can do, to keep in the same place” - Lewis Carroll Alice through the looking glass
sexual selection
- peacocks tail makes me sick! Darwin (1860)
- proposed in the descent of man
- traits can evolve due to increased chance of reproduction
- males often more showy traits e.g. Male mandrill
evolution of diversity
- environmental variation and adaptation
- adaptive radiations e.g. EXAMPLE
- neutral processes
- speciation (reproductive isolation - allopatric or reproduction isolation - sympatric)
- hybridisation - question species boundaries. look at barrel et al 2009
evolution of complexity
- paleys watch? designer?
- origin of species, Darwin (1859) “organs of extreme perfection and complication” by natural selection does seem absurd
-“numerous gradations from a simple and imperfect eye to one complex and perfect”
misconceptions about evolution
- individuals evolve over time
- Darwin discovered evolution
- Natural selection is evolution
- All evolution is adaptive
reality of evolution
- frequency of alleles in populations evolves over time
- Darwin co-discovered the theory of evolution by natural selection
- natural selection is one of many evolutionary processes
- evolutionary change can be a neutral process
Aristotle
History of Animals - placed animals into a hierarchy, animals > plants due to senses and modes of reproduction e.g. those who gave birth to live young above those who laid eggs.
Concept of higher and lower beings inspired medieval “Great Chain of Being” by Didacus Valadas
Early Islamic scientists
Al- Jahiz and Ibn al-Haytham.
Ibn al-Haytham - contributed a lot to understanding of vision and optics.
His method of investigation to verify theory influenced the scientific method.
Western European evolutionary thought
Francis Bacon - scientific method
John ray - concept of a species
Linnaeus - binomial nomenclature.
FINISH THIS CARD
Darwins definition of evolution
decent with modification - look like parents but with some modification.
(didn’t explain why…
