Researcher finds that wood frogs evolved rapidly in response to road salts
phys.org
phys.org
If, for example, tomorrow all governments around the world made it illegal for people taller than 1 meter to have children under penalty of death, then almost all humans would be dwarves after 100 years.
There doesn't need to be new genetic mutations for this to work, natural selection can work off existing mutations which already occurred within the existing population. What can happen is that a trait which was harmful to the host can suddenly become advantageous in terms of survival and reproduction.
And if you think about it, deformities which we consider abnormal and might even consider illnesses are in fact natural occurrences within any sufficiently large population... There is nothing to prevent that so-called deformity or illness from becoming a survival trait in the future. It's just a matter of probability.
There are many reasons - it's in part due to the education growing up in the 90-00's and how science was understood then and how it's taught today. I could go on and on. I just hope it's taught differently in schools today, but honestly I have no clue.
My immediate problem is that so many people are unwilling to change their minds and learn new things. Evolution is almost tied to belief system combined with there's very little every-day-life-"visual cues" that make it obvious. This makes it hard for me to have conversations that point towards evolution.
We hear about evolution or mutation in bacteria and viruses(whose lifespan is so small) all the time. Is there a major difference between frogs resisting salt and drug resistance in bacteria ?
I recall driving and listening to the CBC back in the 90s. Apparently at that time, there had been fruit flies found which could metabolize DDT. It wasn't population wide, but obviously enough had that mutated capability for it to be discovered.
I wonder when that first evolved? Hard to say, but it must have been years before? And wide-spread DDT use started in the 50s.
But of course, fruit flies can reproduced + hatch every week or two?
Hmm, interesting speculation here:
If you don't care or need to know about it, every difference is meaningless. If you are dying from resistant bacteria, differences are exceedingly important.
What leads you to believe this adaptation isn't genetic? Do you have an alternative, non-genetic explanation as to why these certain tadpoles are better able to tolerate otherwise lethal doses of salt?
Evolution happens to populations, not individuals. Selection pressure is exactly what shapes population genetics. During times of stability, genetic diversity is introduced through gene drift, but it is selective pressure that leads to population-level shifts. (Please don't nitpick -- everything is statistical a neutral change can spread through a population even without pressure, but that isn't the main vector).
The article was about frogs, so my comment is in that context. In the case of bacteria, which are asexual and which exist in much greater numbers and have much shorter generation times, the "eureka" model of evolution you seem to be thinking of is more defensible, where one lucky bacterium out of a trillion gets a mutation that gives it some significant new ability (say, like being able to metabolize plastic or something) that allows its descendants to out-compete the rest of the population and take over.
This is hardly "scientific" in the sense we like to think of the term, but it's the best one can do when trying to answer unobservable untestable hypotheses without resorting to the supernatural.
Also, science tests models not history. There’s quite a bit you can predict via evolution that turned out to be verified from new discoveries. Consider you look at the local geology and then make predictions about what fossils will be discovered where and then check the actual rocks, that’s an experiment.
The vanishingly rare trick with speciation by natural selection in sexually reproducing creatures is that you have to have find a compatible partner.
For sexual reproduction simply isolate populations and they drift apart genetically. This is why you can get ring species and populations that can’t get in touch naturally are considered separate species even if when artificially reintroduced they could interbreed. Thus many invasive species technically count if they could naturally get in touch the species would already be in that location.
Anyway that’s based on the current definition used by zoologists though some people find this definition unsatisfying but in both directions. Grizzlies and polar bears can interbreed and therefore count as the same species in that definition even though they are developing different traits not just hair color but body weight is diverging.
In the end biology doesn’t give a fuck about our definitions so things are messy.
I had a bit about horizontal gene transfer being more common on closely related organisms which somewhat maintains the idea of species in a single non sexual world, but it wasn’t worth going into.
The latter is still evolution.
For example, imagine a population with a current mutation-rate of zero, but there's a dominant allele that makes individuals instantly die to new highly-contagious disease. Later on, the (surviving) individuals are all safe from the disease because that allele is gone. Did they evolve? Yes, even if on a chemical level it was purely subtractive.