[_ Old Earth _] The pupils and optical systems of gecko eyes.

[Crying Rock]

A review of:

Roth, L. S. V., Lundström, L., Kelber, A., Kröger, R. H. H., & Unsbo, P. (2009). The pupils and optical systems of gecko eyes. Journal of Vision, 9(3):27, 1–11, http://journalofvision.org/9/3/27/, doi:10.1167/9.3.27.

Abstract

The nocturnal helmet gecko, Tarentola chazaliae, discriminates colors in dim moonlight when humans are color blind. The sensitivity of the helmet gecko eye has been calculated to be 350 times higher than human cone vision at the color vision threshold. The optics and the large cones of the gecko are important reasons why they can use color vision at low light intensities. Using photorefractometry and an adapted laboratory Hartmann–Shack wavefront sensor of high resolution, we also show that the optical system of the helmet gecko has distinct concentric zones of different refractive powers, a so-called multifocal optical system. The intraspecific variation is large but in most of the individuals studied the zones differed by 15 diopters. This is of the same magnitude as needed to focus light of the wavelength range to which gecko photoreceptors are most sensitive. We compare the optical system of the helmet gecko to that of the diurnal day gecko, Phelsuma madagascariensis grandis. The optical system of the day gecko shows no signs of distinct concentric zones and is thereby monofocal.

http://journalofvision.org/9/3/27/Roth- ... 9-3-27.pdf

“…diurnal lizards, their eyes have lost the typical vertebrate duplex retina with both
rods and cones and are instead left only with different types of single and double cones (Ro¨ll, 2000; Underwood, 1970; Walls, 1942). However, at some point in evolution a
group of lizards, the geckos, turned to a nocturnal lifestyle. In response to the demands of nocturnal vision without rods, the cones of nocturnal geckos have become much larger and more light-sensitive than those of their diurnal relatives (Ro¨ ll, 2000)…â€Â

http://journalofvision.org/9/3/27/Roth- ... 9-3-27.pdf

“…many creatures are successful night hunters without color vision. This indicates that the nighttime environment alone is an insufficient cause for developing these particular gecko eyes, which apparently did not “need†to exist for survival. Indeed, other nocturnal geckos have monofocal eyes like humans, and they have survived quite well without major changes…â€Â

Thomas, B. Fossilized Gecko Fits Creation Model. ICR News. Posted on icr.org September 8, 2008, accessed May 8, 2009.


“…Eyes adapted for vision at night, such as the eyes of nocturnal geckos, with a large pupil and a short posterior nodal distance (here also called focal length, f ), are especially affected by longitudinal chromatic aberration. As a result, light of short wavelengths is refracted more strongly and thus focused closer to the lens than light of long wavelengths. If this is not corrected for in an eye adapted for nocturnal vision, the retinal image is severely blurred. Multifocal optical systems with distinct concentric zones of different refractive powers have been suggested to correct for some of the defocus on the retina caused by chromatic aberration (Kro¨ger, Campbell, Fernald, & Wagner, 1999). Kro¨ger et al. have shown that the eyes of the nocturnal gecko, Homopholis wahlbergi,
have multifocal optical system. We were interested to know whether the differences between zones of different refractive power match the range of wavelengths the
nocturnal geckos are sensitive to. In addition, the light-adapted pupils in nocturnal geckos
are different variations of vertical slit pupils. Apart from the effectiveness in shutting out light during the day, the mode of constriction of slit pupils has been suggested to be of advantage in multifocal eyes, since it allows for all refractive zones of the optical system to be functional at all states of pupil constriction (Kro¨ger et al., 1999; Malmstro¨m & Kro¨ger, 2006). We investigated the pupil dynamics and the multifocal optical system of helmet geckos to see whether the light-adapted pupil allows for all concentric zones of the optical system to refract
incoming light…â€Â

http://journalofvision.org/9/3/27/Roth- ... 9-3-27.pdf


“…However, there is no evidence that the mere presence of an environmental demand can cause the coordinated physiological changes required to bridge the differences between monofocal eyes and this gecko’s multifocal, supersensitive eyes. Nor is there any evidence that mutations can do anything but corrupt existing genetic information, the opposite process to what is needed to invent the required whole sets of genetic material that specify the various interdependent parts that comprise these eyes…â€Â

http://www.icr.org/article/4641/


“Gecko Visionâ€Â: Key to the Multifocal Contact Lens of the Future?

http://www.arvo.org/EWEB/dynamicpage.as ... 8f7e26d468

 

[Barbarian]

Nor is there any evidence that mutations can do anything but corrupt existing genetic information
, the opposite process to what is needed to invent the required whole sets of genetic material that specify the various interdependent parts that comprise these eyes…â€Â

Demonstrably false. Barry Hall, observing a culture of E. coli, observed the evolution of a new, irreducibly complex enzyme system, produced by random mutations to a different enzyme, followed by natural selection. Gradually, the enzyme became better and better evolved to it's new substrate, and eventually evolved a regulator, making the whole system irreducibly complex.

BTW, the first such "multifocal" system evolved in mid to late trilobites. It's a pretty sophisticated thing, but it can evolve gradually. Would you like to see how?

 

[Crying Rock]

...Nor is there any evidence that mutations can do anything but corrupt existing genetic information, the opposite process to what is needed to invent the required whole sets of genetic material that specify the various interdependent parts that comprise these eyes…â€Â

Demonstrably false. Barry Hall, observing a culture of E. coli, observed the evolution of a new, irreducibly complex enzyme system, produced by random mutations to a different enzyme, followed by natural selection. Gradually, the enzyme became better and better evolved to it's new substrate, and eventually evolved a regulator, making the whole system irreducibly complex.

Will you quote the Materials and Methods' portion of Barry Hall's peer reviewed report where he claims he observed the evolution of a new, irreducibly complex enzyme system? If you don't have the actual report, will you cite a reference so I can download it?

Thanks,

CR

 

[Barbarian]

Will you quote the Materials and Methods' portion of Barry Hall's peer reviewed report where he claims he observed the evolution of a new, irreducibly complex enzyme system? If you don't have the actual report, will you cite a reference so I can download it?

Of course, "irreducibly complex" is not a scientific term, so he merely calls it "regulated." Do you understand why regulated enzyme systems are irreducibly complex?

Genetics. 1982 Jul-Aug;101(3-4):335-44.
Evolution of a regulated operon in the laboratory.
Hall BG.
The evolution of new metabolic functions is being studied in the laboratory using the EBG system of E. coli as a model system. It is demonstrated that the evolution of lactose utilization by lacZ deletion strains requires a series of structural and regulatory gene mutations. Two structural gene mutations act to increase the activity of ebg enzyme toward lactose, and to permit ebg enzyme to convert lactose into allolactose, and inducer of the lac operon. A regulatory mutation increases the sensitivity of the ebg repressor of lactose, and permits sufficient ebg enzyme activity for growth. The resulting fully evolved ebg operon regulates its own expression, and also regulates the synthesis of the lactose permease.

 

[Crying Rock]

B wrote:

Demonstrably false. Barry Hall, observing a culture of E. coli, observed the evolution of a new, irreducibly complex enzyme system, produced by random mutations to a different enzyme, followed by natural selection

CR wrote:

Will you quote the Materials and Methods' portion of Barry Hall's peer reviewed report where he claims he observed the evolution of a new, irreducibly complex enzyme system? If you don't have the actual report, will you cite a reference so I can download it?

B wrote:

Of course, "irreducibly complex" is not a scientific term, so he merely calls it "regulated."

So you can't produce a peer reviewed citation where Hall claims he observed the evolution of a new, irreducibly complex enzyme system?

B wrote:

Barry Hall, observing a culture of E. coli, observed the evolution of a new, irreducibly complex enzyme system, produced by random mutations to a different enzyme, followed by natural selection.

 

[Barbarian]

So you can't produce a peer reviewed citation where Hall claims he observed the evolution of a new, irreducibly complex enzyme system?

I can show you where he documents that it's irreducibly complex. Perhaps the problem is you don't know what "irreducible complexity" means.

The definition:
"composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning"


What are the minimum number of parts needed for a regulated enzyme system?