@Leadfoot,
Quote:
Not at all. I'd say the chances of a change that complex happening in only 100k years at the right moment when the climate demanded it by random chance is close to zero.
"That complex" has left tracks of the foundation population and the evolved population (the without hemoglobin guys). The only thing that separates the two is that the waters around the area of Bouvet Island in which the "No Hemoglobin sticklebacks" live, is evidence of the several "STEP" process by which the stickelbacks lost their hemoglobin and gained an antifreeze in their blood.
1. STEP ONE --One of the 2 genes that code for the "globin" pqrt of the larger hemoglobin molecule, had first gone extinct-- where it resides as a pseudogene in order on the sticklebacks chromosomes. Its become a "fossil gene"
2. STEP 2--The second globin gene had eroded completely (Johaan Ruud did the sequencing nd the comparative work as part of his dissertation ).
3. STEP3--Over several million years the southern Oceans began cooling to about 100 K YBp when it reached a below freezing temp (for slt free water) #0 or so million years go Antarctica seprted from South America and began moving toward the pole. Many fish species did go extinct as a bevy of cores showed their fossils.
4.STEP 4 The family Notothenoidea ,which contains about 200 species, all adapted in the same stepwise fashion. (examples of convergence based on a focused adaptation.(This isnt critical to the Icefish but to all life that still remains in the Antarctic seas today
5. STEP 5-- To the icefishThe hematocritic percentage had precipitously dropped (that amount of hemoglobin in blood). This value is about 45% in humans, about 15% in normal sticklebacks, and IS ZERO in the Icefish descendants of the normal sticklebacks. Frigid water is xceptionally oxygen dense so the icefish stickelbacks (by fossil evidence for times before 100K YBp) had grown unusually large gills nd gill rakers and skeletal tubules that aided in maintaining the fishes fish shape as the fishes bones shrank in thickness
This is a story told from a rich amount of fossil and genetic evidence> It sings of extreme adaptation to an extreme environment. (ALL BEING DONE WHILE THE LITTLE GUYS WENT ABOUT THE DAILY LIVES OF THEMSELVES AND THEIR DESCENDENTS)
There are several more stepwise adaptations (such as the loss of the gene that codes for myoglobin). ALL THESE can be seen beautifully exposed in a clear sequence that is there for us to wonder at. So far, the Creationists and IDers hve been quiet about it. (Im sure that , now that Ive tikled the pad with more (but not all) the information about this fish and about "evolution thats clearly visible", you will, no doubt try to find some counter (evidence free, your stuff has always been evidence-free) opinions more than likely by Dr Behe of the Discovery Institute.
This one, by being clearly visible is probably a one way adaptation that would go extinct if the oceans warmed and the adaptations would be lethal
