Thank you. That was very interesting and helpful. Gives you the warm and fuzzies that they really can measure mutation rates.
What I'm also wondering is whether there is a pathway from some primitive organism to a more complicated modern one (understanding of course that evolution doesn't know ahead of time specifically what it is building) and whether this pathway can be achieved in the times allotted via the mutation rates.
Happy to help.
Your question is a very broad one. There is a good (but incomplete) understanding of the major mutation steps that caused the evolution of complex multi-cellular life from primitive unicellular bacteria-like organisms. But that is a very long drawn out process on which entire books have been written. The best one I can recommend is "Life Ascending" which is an excellent book that is under $10 in Kindle,
https://www.amazon.com/Life-Ascendi...p/B0041G68LO/ref=mt_kindle?_encoding=UTF8&me=https://www.amazon.com/Life-Ascendi...p/B0041G68LO/ref=mt_kindle?_encoding=UTF8&me=
Your second question is whether the mutation rate is enough to account for the evolutionary changes from simple cells to complex life of today. The answer is yes. Mutation rates are
vastly in excess to that required to make it happen. In most cases natural selection's task is to
eliminate most of these mutations to keep the genome stable at a fitness maxima. This is called
purifying selection. However, when environments change, suddenly the genome shifts away from the fitness peak. Then, and
only then, does natural selection drives evolutionary change by
selecting and
fixing mutations that change the genome towards a new fitness peak. Thus evolution occurs in
relatively rapid bursts during
times of environmental stress, followed by
periods of stasis when the species is close to optimum adaptation in its environment.
Rapid Evolution Changes Species in Real Time | DiscoverMagazine.com
Most recently, evolutionary biologist Yoel Stuart found that green anole lizards on islands in Florida’s Indian River Lagoon needed just 20 generations to adapt to an invasion of brown anoles. Driven to higher perches by the invaders, the green anoles became better at clinging to branches
by developing larger toepads with more scales —
in just 15 years. It’s more evidence of “evolutionary change on observable time scales,” says Stuart, now at the University of Texas at Austin.
Adding to those examples, evidence of evolution occurring faster than previously appreciated has continued to accumulate over the past few decades. It is now clear that, while observed rates of change may well be rapid relative to the evolutionary timescales that Darwin theorized about, they’re not at all exceptional. “Within evolutionary biology there really has been an unheralded paradigm shift between 1980 and now,” says Reznick. “Most evolutionary biologists consider it routine to think of evolution as a contemporary process.”
The concept, appropriately termed contemporary evolution, is now well accepted, agrees
Stephen Ellner, an ecologist and evolutionary biologist at Cornell University. “At this point, there’s a general understanding that this is happening, and it’s happening all over.” The research has now shifted from documenting this phenomenon to studying its consequences.
https://www.the-scientist.com/?arti...tion-s-Quick-Pace-Affects-Ecosystem-Dynamics/
After the
Nature and
Science studies came out, Hendry and Kinnison got together to develop
a framework for quantifying rates of evolutionary change. They promoted the use of the
haldane (a change of one standard deviation in a phenotypic trait per generation; named after evolutionary thinker J.B.S. Haldane) over
the darwin (the proportional change in a phenotype per million years; named after you-know-who), and encouraged researchers to provide confidence intervals and measures of statistical significance. If done correctly, “
evolutionary rates provide a convenient way to compare the tempo of evolution across studies, traits, taxa, and time scales,” Hendry and Kinnison wrote in 1999.
8
In total, the researchers gathered data on 30 different animal species, for a total of 2,151 evolutionary rates calculated in haldanes, and another 2,649 in darwins.
Many scientists had been able to document dramatic change over short time frames was precisely because they were limiting the duration of observation;
in the short term is when evolution’s at its fastest.
“If populations are really tracking dynamic environments—year-to-year variation in climate, other species that they depend upon or compete with, or the like—then you would expect their traits to be bumping around pretty rapidly.
But over the long term, a lot of these processes average out, [which] flattens those rates down.”
However, if the environmental change is directional and consistent (like an ice age, a global warming, large scale volcanism or mountain building etc.) then the fast speed of evolution at the local time scales accumulate to create very large directional evolutionary changes in species over a few million years or less. This is what we see in the major evolutionary events like whale evolution, bird evolution or human evolution from ancient apes even.
