Friday, February 03, 2006
Wanted: Evolution of a Polyphenism by Genetic Accommodation (Science)
[Suzuki & Nijhout, Science, Feb '06]
Abstract:
Polyphenisms are adaptations in which a genome is associated with discrete alternative phenotypes in different environments. Little is known about the mechanism by which polyphenisms originate. We show that a mutation in the juvenile hormone-regulatory pathway in Manduca sexta enables heat stress to reveal a hidden reaction norm of larval coloration. Selection for increased color change in response to heat stress resulted in the evolution of a larval color polyphenism and a corresponding change in hormonal titers through genetic accommodation. Evidently, mechanisms that regulate developmental hormones can mask genetic variation and act as evolutionary capacitors, facilitating the origin of novel adaptive phenotypes.
http://www.sciencemag.org/cgi/content/abstract/311/5761/650
John
Model of an Internal Evolutionary Mechanism
http://members.aol.com/jorolat/index.html
UPDATE: Reprints can be requested from Yuichiro Suzuki's email address here
Abstract:
Polyphenisms are adaptations in which a genome is associated with discrete alternative phenotypes in different environments. Little is known about the mechanism by which polyphenisms originate. We show that a mutation in the juvenile hormone-regulatory pathway in Manduca sexta enables heat stress to reveal a hidden reaction norm of larval coloration. Selection for increased color change in response to heat stress resulted in the evolution of a larval color polyphenism and a corresponding change in hormonal titers through genetic accommodation. Evidently, mechanisms that regulate developmental hormones can mask genetic variation and act as evolutionary capacitors, facilitating the origin of novel adaptive phenotypes.
http://www.sciencemag.org/cgi/content/abstract/311/5761/650
John
Model of an Internal Evolutionary Mechanism
http://members.aol.com/jorolat/index.html
UPDATE: Reprints can be requested from Yuichiro Suzuki's email address here
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Thursday, February 02, 2006
Wanted: 'Obscure' 1889 Paper on Trilobite Eyes & The Fibonacci Series
Can anyone help me find the 'obscure' paper by JM Clarke that Niles Eldredge refers to on page 64 of "Time Frames"? A scan of the page is available here:
http://members.aol.com/jorolat/trilobite.html
In fact I would be grateful for any information regarding the appearance of the fibonacci series in the lens arrangement of trilobite eyes!
If you know the citation (or better still, have a copy) then please email me or post here.
NB This isn't the paper I'm looking for:
CLARKE, J. M. 1889. The structure and development of the visual area in the trilobite Phacops rana Green. Journal of Morphology, 2:253270.)
Finally, I emailed Niles Eldredge and he said "I've lost touch with it [the paper]--journal such as American Naturalist..". I don't have a subsciption to Jstor. Someone did a search of American Naturalist on my behalf but couldn't find anything ('sigh').
John Latter
Model of an Internal Evolutionary Mechanism
http://members.aol.com/jorolat/index.html
http://members.aol.com/jorolat/trilobite.html
In fact I would be grateful for any information regarding the appearance of the fibonacci series in the lens arrangement of trilobite eyes!
If you know the citation (or better still, have a copy) then please email me or post here.
NB This isn't the paper I'm looking for:
CLARKE, J. M. 1889. The structure and development of the visual area in the trilobite Phacops rana Green. Journal of Morphology, 2:253270.)
Finally, I emailed Niles Eldredge and he said "I've lost touch with it [the paper]--journal such as American Naturalist..". I don't have a subsciption to Jstor. Someone did a search of American Naturalist on my behalf but couldn't find anything ('sigh').
John Latter
Model of an Internal Evolutionary Mechanism
http://members.aol.com/jorolat/index.html
technorati tags: trilobite, trilobite+eyes, time+frames, niles+eldredge, fibonacci, fibonacci+series, american+naturalist, jm+clarke, john+latter
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