Science and Creationism 17. Speciation © Colin Frayn, 2008-2011

Science and Creationism

17. Speciation

© Colin Frayn, 2008-2011www.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…


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. Certain physical traits are genetic2. Genetic information is passed on through reproduction3. Certain physical traits can affect an individual’s survival chances.4. 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

Allopatric vs. Sympatric SpeciationGenetic 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



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


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)


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


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


Humans

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Science and Creationism 17. Speciation © Colin Frayn, 2008-2011