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Convergent Evolution - Penguins/Murres (1 Viewer)

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Matt_RTH

Well-known member
I find it very fascinating that Murres and Penguins seem to have so much in common. I always thought of Murres as Northern Penguins. I realize, as any book will confirm they are quite different, but am fascinated by their similarities.

Consider that they are from opposite poles. So they have adapted to the cold, which entails great swimming, ability to generate and regulate body heat, etc.

However, if this evolution took millions of years, consider that the earth started with one large land mass (as any globe will confirm, almost like a jigsaw puzzle). Further, I believe current geological thought indicates that the north and south poles used to be what are now East and West.

So over the millions of years it would take for the appropriate evolution to take place, and given the geological change, was there even time for a convergent evolution to take place for penguins and murres? Or, are the similarities purely coincidental?

Matt
 
The most recent supercontinent, pangaea, began to break up around 180 million years ago and the last big breaks occurred around 60 million years ago. All modern birds, with all their diversity, have evolved in this time - Archaeopteryx is only 150 million years old. So in evolutionary terms this is plenty of time for all the divergence and subsequent convergence to occur.

Graham
 
I believe one of the messages in Darwin's work (if not in his writing) is that evolution or at least selection can go extremely fast. If there is a strong enough selective force, so that all except the best adapted die, the average phenotype can change dramatically. We know that from for example the history of domestic animals. During 50 years diring the 1900s, the average time from a chicken was born to it reached slaughter weight was halved, just to mention one example (half of the change roughly is supposed to be improved food, the rest changes in genetic make-up). There is a similar example for milk production in dairy cattle.

Niels
 
incidently, 'penguin' was the original name for Great Auk, a northern 'murre', and the name was subsequently given to southern hemisphere penguins by later explorers who thought they were more or less the same thing.
 
The story has it that the name comes from Welsh: Pen gwyn, meaning 'white head' with reference to the white on the face of the Great Auk.

Apparently the Welsh migrants, arriving in Patagonia South America (there is a large contingent still there) thought the penguins looked like (Great) auks thus called them Pen gwyn (= penguin).

Also the scientific name of Great Auk, given later, is Pinguinus

Good story eh?

(but believed true!)

PS behind the individual names of penguins; Adelie, Gentoo and particularly Macaroni, there are more good stories to tell......
 
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njlarsen said:
I believe one of the messages in Darwin's work (if not in his writing) is that evolution or at least selection can go extremely fast. If there is a strong enough selective force, so that all except the best adapted die, the average phenotype can change dramatically.
Click to expand...

Darwin thought that evolution proceeded by very slow, steady steps. The realisation that it can operate very fast indeed - marked changes, given suitable selection pressure, in tens of years rather than millions of years - is quite recent.

(With, of course, a matching ability to have little or no change over long periods.)
 
njlarsen said:
I believe one of the messages in Darwin's work (if not in his writing) is that evolution or at least selection can go extremely fast. If there is a strong enough selective force, so that all except the best adapted die, the average phenotype can change dramatically. We know that from for example the history of domestic animals. During 50 years diring the 1900s, the average time from a chicken was born to it reached slaughter weight was halved, just to mention one example (half of the change roughly is supposed to be improved food, the rest changes in genetic make-up). There is a similar example for milk production in dairy cattle.

Niels
Click to expand...


Important not to confuse two often confused issues :

(1) Phenotypic variation / changes in the frequency of particular genes that can result in quite rapid changes in behaviour, apearance, etc etc, but only to a certain extent (i.e. constrained by genes there in the first place). This can occur rapidly (years to decades) and are what has resulted in e.g. domestic animals, blackcaps over-wintering in Britain etc. etc.

(2) Genetic mutation - this is the process that governs major evolutionary processes, resulting in e.g. completely different species, but happens slowly (millions of years).
 
without wishing to speak for Ilya i'd imagine that yes he is a supporter of natural selection, he's just pointing out that:-

although natural selection can cause rapid (relatively) superficial changes in species due to changes in the frequency of genes that are already there,

more profound changes due to natural selection require the emergence of new genes by mutation and thus take time, as the rate of mutation is pretty slow and isn't generally affected by selective pressure
 
James Lowther said:
without wishing to speak for Ilya i'd imagine that yes he is a supporter of natural selection, he's just pointing out that:-

although natural selection can cause rapid (relatively) superficial changes in species due to changes in the frequency of genes that are already there,

more profound changes due to natural selection require the emergence of new genes by mutation and thus take time, as the rate of mutation is pretty slow and isn't generally affected by selective pressure
Click to expand...

Yes. Pretty much what I meant. Thanks. Natural selection affects both the prevailence of existing genes and whether or not mutated genes survive to become prevailent so does have a role in both.
 
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