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Was Steve Gould wrong? Is evolution predictable?


A recent study of anole lizards in the Caribbean seems to suggest predictability, but …

green anole, Everglades


The predictability of evolution over timescales of millions of years has long been debated by biologists, said Luke Mahler, a postdoctoral fellow at UC Davis and first author on the paper. For example, the late Stephen Jay Gould predicted that if you “rewound the tape” on evolution and started over, you would get an entirely different outcome, arguing that small events — a storm that wiped out a particular pond, a poor season for insects — could have a disproportionate effect.

Mahler found his test subjects in the Anole lizards that live on four neighboring islands — Cuba, Hispaniola (the countries of Haiti and the Dominican Republic), Jamaica and Puerto Rico. Anoles began colonizing these islands, all similar in climate and ecology, about 40 million years ago, and once there, they began to multiply, resulting in a diversity of species on each.

One hundred of 119 anole species were studied.

They found a striking degree of convergence — on each island, evolution had produced a set of very similar-looking lizards occupying similar environmental niches.

Of course, the reality is that these species would probably differ little from each other in any event because their environments are so similar. So it is a pretty easy prediction.

A serious test would require significantly different environments for initially similar species.

What we don’t know from this type of study is how much the lizard can change in any event. Whether any life form can evolve under certain circumstances is a different question from whether a given species can.

See also:

Darwin lobby’s Kevin Padian denounces misrepresentations of evolution in textbooks.

The stink from Haeckel’s embryos

Darwinists use scientifically indefensible language to imply progress in evolution?

lifepsy, my pleasure. It was your material that helped encourage me to explore the subject further. RM+NS certainly looks a lot more like a philosophical necessity than an established mechanism. And it seems to me that the term "evolution" can pretty much just mean "what organisms are observed to do" as long as it also carries with it the materialistic narrative. Jerry,
Diet and environment cause epigenetic patterns to change and this causes phenotype changes as gene expression is affected and affects adaptation. A lot of this seems to be tied together.
And then there's the significant morphological changes that occur rapidly within the space of a single generation: Phenotypic Plasticity and the accompanying paper: Anatomical and Physiological Changes Associated with a Recent Dietary Shift in the Lizard Podarcis sicula. What we are discovering in organisms with regard to morphological change is significant, non-random, non-gradual mechanisms of adaptation and reconfiguration that have little to do with anything Darwinian. Sure, descent with modification happens, but this is an observation, not a mechanism. So the most significant, empirically verifiable modifications to phenotypes are a result of the organism's intrinsic nature -- mechanisms deep within the micro-biological realm that are designed to express form and function in different ways depending largely upon the needs of the organism, interpreted through various types of environmental/external triggers. Darwinism has nothing to contribute here -- other than the self-evident concept that species which are better tuned to their environmental niches are more likely to survive in those niches -- without a non-trivial explanation for how these mechanisms come about. Gradualism loses its appeal when significant, rapid formal changes can occur in the space of a single generation. Chance Ratcliff
Thanks for the comments BA77, Jerry. And Chance for that excellent resource on plasticity you sent me earlier. Yes it is interesting that the darwinian mythos of mutation+selection still surrounds prominent biological changes that are not related to either. "Evolution" is such a convenient descriptor, because it allows researchers to avoid actually discussing biology. One could swap the word "Evolved" with "Pink Giraffe" and lose no content about what is actually happening to an animal. lifepsy
Its presumed convergent evolution took place but not witnessed. Its unlikely there would be such convergence. There would be more likely good differences. if they had found good differences they would parade it as excellent evidence for evolutioni affecting creatures of a common origin. They can't have it both ways. more likely simply development came from innate triggers that these creatures have to adapt to their area. They instantly changed as needed. nO selectionism picking the best suited ones. Prove it evols!! Robert Byers
Developmental/phenotypic plasticity could account for many observed differences in all sorts of animal life, either intra or inter generationally. These plastic changes are brought about by things like diet and various other environmental factors.
Thank you for the references. More to read. I am reading 3-4 things on my ereader. One is Nessa Carey's book on epigenetics. Diet and environment cause epigenetic patterns to change and this causes phenotype changes as gene expression is affected and affects adaptation. A lot of this seems to be tied together. As I said before, Incredible Design. jerry
lifepsy has put together some, IMHO, great videos
I agree. I really like the articles on the fish and lizards too. jerry
Jerry @8, exactly. Developmental/phenotypic plasticity could account for many observed differences in all sorts of animal life, either intra or inter generationally. These plastic changes are brought about by things like diet and various other environmental factors. What Is Phenotypic Plasticity...
Abstract Phenotypic plasticity, the capacity of a single genotype to exhibit variable phenotypes in different environments, is common in insects and is often highly adaptive. Here we review terminology, conceptual issues, and insect plasticity research, including variance partitioning, reaction norms, physiological mechanisms, adaptive value, and evolution. All plasticity is physiological, but can manifest as changes in biochemistry, physiology, morphology, behavior, or life history. Phenotypic plasticity can be passive, anticipatory, instantaneous, delayed, continuous, discrete, permanent, reversible, beneficial, harmful, adaptive or non-adaptive, and generational. Virtually any abiotic or biotic factor can serve to induce plasticity, and resulting changes vary from harmful susceptibilities to highly integrated and adaptive alternative phenotypes. Numerous physiological mechanisms accomplish plasticity, including transcription, translation, enzyme, and hormonal regulation, producing local or systemic responses. The timing, specificity, and speed of plastic responses are critical to their adaptive value. Understanding plasticity requires knowing the environment, physiological mechanisms, and fitness outcomes. Plasticity is thought to be evolutionarily favored under specific conditions, yet many theoretical predictions about benefits, costs, and selection on plasticity remain untested. The ecological consequences of plasticity range from simple environmental susceptibilities to mediating interspecific interactions, and extend to structuring of ecological communities, often through indirect effects. Phenotypic plasticity, through its ecological effects, can facilitate evolutionary change and speciation. Plasticity is important because it is an encompassing model to understand life on earth, it can increase fitness, generate novelity, and facilitate evolution, it structures ecological communities, and it has numerous practical applications. As such, all biologists should understand phenotypic plasticity.
Introduction A young caterpillar feeds on oak flowers and develops into a stunning mimic of an oak catkin (Fig 1b.). A second caterpillar from the same egg batch feeds on leaves and becomes a twig mimic (see Chapter 4, this volume). In response to low-quality, fibrous food, a grasshopper develops larger mandibles and mandibular muscles (Thompson 1992), and another develops a larger gut (Yang and Joern 1994). A different grasshopper alters the number of chemosensilla on its antennae in response to the number of plant chemicals it encounters (Chapman and Lee 1991, Rogers and Simpson 1997). In a nearby aphid colony, females are busy adjusting the future morphology and behavior of their offspring in response to predator threats. When ant bodyguards are absent, females rapidly produce soldier offspring (Shingleton and Foster 2000), and produce winged offspring when predators invade the colony (Weisser et al. 1999). Close by, a gravid fly, unable to locate her normal host plant, deposits her eggs on a novel host. Surprisingly, the larvae survive on the new host, and chemically imprint on it before dispersing as adults. The flies subsequently orient to the novel plant to mate and oviposit, instead of their ancestral plant (Feder et al. 1994, see Chapter 18, this book)...
Specific vs. General Plasticities Some plastic responses are highly specific in either requisite stimuli or response. For example, some plants possess receptor proteins that detect only their most common natural enemy (Zhao et al. 2005). Such specificity is seen in corn plants that increase defense in response to saliva from young, but not old armyworm caterpillars, perhaps because the plastic defense is only effective against young caterpillars (Takabayahshi et al. 1995). Elm trees produce volatiles attractive to egg parasitoids, in response to oviposition by its primary beetle herbivore, but not to beetle feeding (Meiners and Hilker 2000). Following fires, some grasshoppers will respond to altered light quality by adaptively changing their body color to black (see Uvarov 1966). Other grasshopper species fail to respond to light, but change color specifically in response to temperature, humidity, food, or crowding, or to some combination of these cues (Rowell 1971, Tanaka 2004, Chapters 5, 6).
Does that last part remind you of anything? I can't say for certain that our peppered friends were exhibiting some sort of responsive plasticity, but this "peppered grasshopper" sure is. ;) Also see here: Seeing Past Darwin III: Mary Jane West-Eberhard Seeing Past Darwin IV: Some Experiments Chance Ratcliff
Lifepsy video playlist Topics covered: Orphan Genes Phenotypic Plasticity Non-Random and targeted mutations Epigenetics and soft inheritance micro-RNA and Non-Falsifiable Phylogenetic Trees bornagain77
Jerry, if you have not seen them yet, lifepsy has put together some, IMHO, great videos too: Things Created playlist http://www.youtube.com/watch?v=1Zz6vio_LhY&feature=c4-overview-vl&list=PL22eQqszdBpA7pUorVxj3GHhn7gugSY8x bornagain77
I have a question. In his book, the Greatest Show, Richard Dawkins provides several examples of short term changes in species. He assumes these are due to natural selection and I just assumed they were decent examples of selection. No big thing. Interesting but just minor changes to a species. Could some of these be epigenetic changes? I have to re-read it to see just what the examples were and how different the changes were. One thing Dawkins did not do was provide any example of natural selection working to make major changes in a population over time which basically undermines his basic thesis. Embarrassingly missing from his book. Also could a lot of what Darwin saw, was just epigenetic differences between varieties? The finches are apparently such an example of epigenetic differences. jerry
It’s simple phenotypic plasticity reacting to different lifestyles,
This is the first time I visited your website. Great information. You are right the same phenomenon is apparent in the Galapagos finches. Certain genes get expressed due to environmental stress causing morphological differences. I have always maintained the micro-evolution process which now expands to epigenetic differences is great design. The organism is designed to adapt, not just in differences in the gene pool but in epigenetic ways that cause different gene expression. I just read the article on the lizards and will read the one on fish next. Thanks. jerry
what lifepsy said is correct. This has absolutely nothing to do with "evolution." There is no evidence of random, spontaneous mutation...I don't even know if mutations were involved at all....this is just a case of phenotypic plasticity and this is why the adaptive responses happen so quickly. To wati on just the "right" spontaneously-random genetic mutation would surely require thousands, if not millions of years. Now it could be, as some have suggested, that phenotypic plasticity comes first, and if the environment holds true for many generations that the changes could then be written into the genome, but ultimately the source of variation is not random and and natural selection had nothing to do with the population's adaptive change. I'm amazed at the number of IDists/creationists who blindly accept microevolution as true, but macroevolution is false. The truth is they are both false and that's because the generation of novelty has nothing to do with randomness or dumb luck. vh
Rosemary and Peter Grant, well respected members of the Darwin crowd, say it takes 32 million years to form a new finch species. Maybe these guys haven't had a real shot at evolution yet? We should move some to the South Pacific and come back in another 30 million years to see what happened. I think they need some geographic isolation. jerry
"40 million years of adaptation" ??? Wow. Move the "tree specialists" lizards to a ground-only environment and they will specialize their bodies accordingly within only a few generations, and vise-versa. It has nothing to do with Darwinian evolution of traits. It's simple phenotypic plasticity reacting to different lifestyles, and lizards in particular are known to display such extreme morphological variations in short time periods. This is well-known and discussed extensively in the literature. I documented many references here. http://biota-curve.blogspot.com/2013/03/lizard-plasticity.html lifepsy
Actually, Jerad, we don't even know how much was convergent evolution. They appear to have all started from the same point, were trying to evolve solutions to similar problems, and came up with similar solutions. And how far apart are they genetically anyway? I'd save "convergent evolution" for species that are manifestly far separated in the history of life. News
What I would like to see is a daigram of all the different species of Anole Lizards in a direct line. Then we could look at the difference 40my of evolution has actually made to them. Would it be anything significant? And being so predictable, how much of a difference might there be in another 40my? This I think would be very interesting. How much change has actually taken place in 40my, and, using computer graphics perhaps, how much change might be expected in the future given the same timescale? PeterJ
A serious test would require significantly different environments for initially similar species. What we don’t know from this type of study is how much the lizard can change in any event. Whether any life form can evolve under certain circumstances is a different question from whether a given species can.
Um . . . but this study was studying convergent evolution. Your statement has to do with something else entirely. Jerad

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