Download Speciation

Science and Creationism
17. Speciation
© Colin Frayn, 2008-2011
www.frayn.net
Speciation vs. Micro Evolution
• Micro evolution = change in allele frequency
– E.g. disease resistance
– E.g. moths in industrial England
• Darker moths hid against sooty buildings, light moths got eaten
• When buildings were cleaned, the trend reversed
• Speciation
– This happens far more slowly
• Usually requires separation of a population
– It has been seen in many species
• Several plants
• Bacteria & viruses
• To list a few specifically:
Culex molestus, Primula kewensis, Oenothera gigas,
Gaelopsis tetrahit, Madia citrigracilis, Mimulus guttatus, Drosophila paulistorum,
Rhagoletis pomonella, Eurosta solidaginis, Nereis acuminata, Chlorella vulgaris, Woodsia
abbeae, etc…
© Colin Frayn, 2008-2011
www.frayn.net
Micro-Evolution
• Did the peppered moth story ever happen?
– Yes, it did…
– …though who cares?
•
Micro-evolution like this is undenied and undeniable
•
To deny this effect, you need to deny at least one of:
1.
2.
3.
4.
•
•
Certain physical traits are genetic
Genetic information is passed on through reproduction
Certain physical traits can affect an individual’s survival chances.
Environmental changes can occur which alter the fitness landscape.
Denial of 1,2 or 3 is impossible
4 is almost certainly true, but it’s irrelevant to biology
© Colin Frayn, 2008-2011
www.frayn.net
Allopatric vs. Sympatric Speciation
Genetic isolation is required for speciation
• Allopatric Speciation
– Geographically separated
• Continental drift
• Mountains, rivers etc.
• Sympatric Speciation
– Sharing a geographical location
– Occupying different niches
• Colouring
• Food preferences
© Colin Frayn, 2008-2011
www.frayn.net
Gaining new genetic information
• Q: Does evolution break some mystical law forbidding
‘increase in information’?
• A: Not at all! (see next slide for theory)
• Q: How can we create ‘information’ from nowhere?
• A: Mutation, insertion, replication.
– All of which are well documented and happen all the time
• Remember – all creatures are made from their genetic
blueprint
–
–
–
–
‘Information’ is just what’s in the DNA
If we can create new DNA, then that’s new ‘information’
The differences between all animals are just DNA differences
We can generate any DNA differences using known muations
© Colin Frayn, 2008-2011
www.frayn.net
Conservation of Information
• Original law
(Medawar, 1984)
– Stated that Kolmogorov information could not increase in a closed
system
• No simple recipe can generate an item more complex than the recipe itself,
for this particular mathematical definition of ‘simple’ and ‘complex’
• Non-scientific version
(Dembski, 1998)
– Dembski completely misunderstands complexity theory
– He confuses Shannon and Kolmogorov complexity
– His resultant theory is worthless
• “Complex Specified Information”
– A term invented by Dembski
– It is never rigorously defined
• Dembski’s law is obviously false
– Genetic ‘information’ is created all the time by evolutionary processes
– (See the previous slide)
© Colin Frayn, 2008-2011
www.frayn.net
Beneficial Mutations
• Most mutations are negative
– So how can progress occur?
• Actually, most mutations are neutral
– See ‘Neutral Evolution’ theory of Kimura
(d. 1994)
• Negative mutations are rejected
– Most are rejected immediately
• Positive mutations survive and are passed on
• Studies of bacteria show how beneficial mutations
accumulate
– See work of Richard Lenski with the bacterium E. coli
– Bacteria evolved the ability to consume citrate
© Colin Frayn, 2008-2011
www.frayn.net
Phylogenetic trees
• These are not based on guesswork!
• They can be generated using sophisticated
clustering algorithms:
– Compare similarity between all individuals
– Optimise a tree to minimise distance between similar
individuals
– You can use any property for ‘similarity’, e.g. any gene
or sequence of genes
– The trees usually agree very well
• Even when they are created from a totally different source
• Which implies that there is a real underlying relationship
© Colin Frayn, 2008-2011
www.frayn.net
Humans
© Colin Frayn, 2008-2011
www.frayn.net