Evol a Genet Flashcards
Tree of life is used for? What do all living things share? What is evolution?
- We can draw a Tree of Life to show how every species is related
- All living things share a common ancestor
- Evolution is the process by which one species gives rise to another and the Tree of Life grows
Is evolution a theory or fact?
- both
- The theory of Evolution deals with how Evolution happens. Our understanding of this process is always changing.
- Evolution is also a fact as there is a huge amount of indisputable evidence for its occurrence.
What was thought from Classical times until long after the Renaissance?
-species were considered to be special creations, fixed for all time
How was evolution discovered?
- Around 1800, scientists began to wonder whether species could change or transmute (verwandeln)
- Lamarck thought that if an animal acquired a characteristic during its lifetime, it could pass it onto its offspring (Nachwuchs)
- ex: giraffes
What did William Smith find?
- At about the same time, geologists like William Smith were mapping the rocks and fossils of Britain
- He and others showed that different species existed in the past compared with today
What was Darwin’s voyage (Reise)?
- From 1831-1836, a young naturalist called Charles Darwin toured the world in HMS Beagle.
- He was dazzled by the amazing diversity of life and started to wonder how it might have originated
The theory of survival of the fittest?
-In his Origin of Species, published in 1859, Darwin proposed how one species
might give rise to another
-Where food was limited, competition meant that only the fittest would survive
->this would lead to the natural selection of the best adapted individuals and eventually the evolution of a new species
The story btw. Huxley vs. Wilberforce
-Darwin’s idea of Evolution by Natural Selection was met with huge controversy
-A famous debate in 1860 pitted Bishop Wilberforce against Darwin’s bulldog,
Thomas Henry Huxley.
->Evolutionists got the better of the debate, but few were convinced by Darwin’s idea of Natural Selection
Genetics with Gregor Mendel (story)
- From 1856-63, a monk called Gregor Mendel cultivated 29,000 pea plants to investigate how evolution worked i.e., how characteristics were passed down the generations
- > He figured out the basic principles of genetics. He showed that offspring received characteristics from both parents, but only the dominant characteristic trait was expressed
- Mendel’s work only came to light in 1900, long after his death
When and how did scientist start to make sense of how evolution worked?
- In the early 20th century
- Building on Mendel’s genetics, studies showed how characteristics in a population could be selected by environmental pressures
- This Modern Synthesis, as Julian Huxley called it, brought Darwin’s Natural Selection back to the centre of evolutionary theory
What did the opposition (christians) do?
-Despite the achieval of scientific consensus on
evolution, some Christian groups continued to oppose the concept
->in 1925, the teaching of evolution was outlawed (verboten) in Tennessee, USA, resulting in the infamous Scopes Monkey Trial
Define phenotype and genotype? Phenotype is influenced by?
-The genetic make-up of an organism is known as
its genotype
- An organism’s genotype and the environment in which it lives determines its total characteristic traits i.e. its phenotype
When was the double-helix structure discovered? What did it show?
- The double-helix structure of DNA was discovered in 1953 (by Watson and Crick)
- This showed how genetic information is transferred from one cell to another almost without error
When can mutation or copying errors occur? Mutations are caused by?
- However, occasional mutations or copying errors can and do occur when DNA is replicated
- may be caused by radiation, viruses, or carcinogens
- Mutations are rare and often have damaging effects
- > Consequently organisms have special enzymes whose job it is to repair faulty DNA
Name the different types of mutations?
-deletion, duplication, inversion, insertion
What are variants of a particular gene called?
-some mutations will persist and increase genetic variation within a population;
are called:
-alleles
-For example, the one of the genes for hair color comprises brown/blonde alleles
Describe the process of natural selection
-Mutant alleles spread through a population by sexual reproduction
-If an allele exerts a harmful effect, it will reduce the ability of the individual to reproduce and the allele will probably be removed from the population
in contrast, mutants with favorable effects are preferentially passed on
Describe natural selection with peppered moth
-The Peppered Moth is an
example of Natural Selection
in action discovered by Haldane
-During the Industrial Revolution the trees on which the moth rested became soot-covered (rußbedeckt)
->This selected against the allele for pale colour in the population (which were
poorly camouflaged from predators (Raubtieren))
and selected for the dark colour allele
Dogs as an example for microevolution
-The dog is another example of how selection can change the frequency of alleles in a population
-Dogs have been artificially selected for certain characteristics for many
years, and different breeds (Rassen) have different alleles
-All breeds of dog belong to the same species, Canis lupus (the wolf) so this is an example of Microevolution as no new species has resulted
What is Macroevolution and why does it occur?
- However, if two populations of a species become isolated from one another for tens of thousands of years, genetic difference may become marked
- If the two populations can no-longer interbreed, new species are born
- > called Macroevolution.
- Darwin’s Galapagos finches are an example of this process in action
Which two theses does Charles Darwin include in the Evolution Theory?
- 1.Evolution occurred by branching (opposing Lamarckism)
- 2.Natural selection is the main mechanism of evolution
Describe difference between natural selection and Lamarckism (for giraffe)
- naSel: taller neck, reaches more food than short neck, reproduces more than short neck, long necks more common in population
- Lam: cannot teach taller ranches, neck lengthens, offspring born with longer neck
Describe the principles of Darwin’s Evolution Theory
- Modification of inherited traits in a species generates variation
- Favorable variations survive during the “struggle for existence” ->Natural Selection
- Natural selection of favorable traits leads to adaptation of species to various environmental changes
- Accumulation (Ansammlung) of favorable traits leads to speciation
- However, Darwin did not explain how variation arised
Give definition of microevolution and macroevolution
- Microevolution= the change of allelic frequencies within a short period of time (i.e coloring of beetles)
- Macroevolution= evolution at the level of species or higher over a long period of time, i.e. generation of any new species; appearance of feathers on birds during their evolution from dinosaurs
- They are not two separate phenomena, they are more like two different viewpoints of evolution process
