Interesting question.

natural selection then comes into play.

evolution = mutation + natural selection.

In your example there were always white moths. They just became more common because their color was no longer a detriment to survival.

As they are not adapting to any pressure. These are not selected. For instance (just guessing): the color of your bones just happens to be white, not because of any evolutionary pressure. At least, none that I can think of.

If a change improves chances of survival, it is likely to persist. If not, it may not. For example, in the gray squirrel population here in St. Paul, there are also white and black members of the species which are seen frequently. Neither variation really affects survival all that much, so those variations propagate to some degree. Thus, if you feed squirrels in St. Paul, you are likely to see a black or white variant from time to time. But, since neither increases the chances of survival, the typical gray coloration is far more prevalent.

Bit more complicated than that, but it's going on all the time.

that is why each individual has a unique DNA profile - when you are born, you are born with 100-200 genes that neither of your parents have.

Natural selection is occurring from the very start. Bad gametes (sperm ova) don't make it, a plant or animal of only a few cells doesn't survive or self-destructs, a larger embryo doesn't survive...

Species with a large genetic "toolkit" accumulated over time may be better able to cope with rapid changes in the environment, when selective pressures are strong. Certain individuals may possess genes that are useful in the new environment, maybe genes that were of little consequence in the old environment.

Life has evolved to evolve. There are genetic mechanisms that "recognize" adverse environmental conditions and shuffle things up, tinkering with the rates certain genes are expressed, and the "accuracy" of replication of certain genes in heritable ways.

https://arxiv.org/abs/1402.0468

Simple natural selection and mutation explains a lot, but it's nowhere near the complete picture.

Some have implied mutations = evolution. Some a temporary change in distribution of alleles = evolution.

If evolution is permanent change in the distribution of a feature in the group due to natural selection, esp. the spread of new a feature and loss of an old feature, and that change is driven by pressures, then no. Mutations aren't evolution. They're what evolution requires, they're background, they're always occurring and mostly they vanish after a generation. So they're certainly part of the picture, but evolution is a permanent change in the group, how and why those mutations spread. No single animal evolves, and no community of animals evolves within the time necessary for a single generation; a community of animals evolves over generations.

Other people may have different definitions. This is the one I was taught.

There's a related term, "genetic drift," for random effects. This can include founder effects or the kinds of genetic changes that happen with small populations subject to random population loss. If you're in an isolated area for 1000 years and most of the blond people just happen to live near a river and die during a particularly bad flood, that's going to effect the population. The "pressure" is unrelated to the change in gene distribution.

The change in dark/light moth distribution I've heard termed "microevolution." It wasn't a permanent change and didn't spread any new features. I'd expect as coal became less common and other dark-colored particulates stop having their effect for the distribution to at least partially revert. Unless, of course, the light-colored moths have died out, then it's permanent.

It's worth realizing that probably most mutations happen not because of radiation but because of transcription errors. Even chemical-induced mutations are probably more common than radiation-induced mutations in most places. Most mutations, keep in mind, are fatal to the fetus. Mutations that happen after reproductive tissue is formed and which aren't reflected in reproductive tissue are pointless because they can't be passed along. (How epigenetics affects evolution is an open question, as far as I know.)


Note that the idea of "pressure" brings a certain circularity to the matter, and the word's been redefined numerous times. The requirement that evolution be in response to selection pressure is a damned fine assumption: It leads to more facts, more structure to those facts, and therefore more knowledge. Peacock plumage didn't evolve because of the environment. Natural selection came to include sexual pressure. It can include things like having lactase production in humans survive childhood--some humans are lactose-intolerant, some aren't, and that's an evolutionary trait driven by dietary needs, but that diet was shaped by the domestication of livestock, so humans drove their own evolution. Hairlessness is an evolutionary trait, probably sexual selection, maybe also in response to things like lice. Skin color probably (but not provably) is driven by vitamin D formation due to sun exposure combined with effects of vitamin D on female fertility. Sickle-cell is another trait driven by more usual kinds of evolutionary pressures. There are apparently dozens of genes affecting brain chemistry that show a geographic distribution strongly suggestive of evolutionary pressures, but nobody has a clue what the effects are or what the pressures might be. Having pressures be required for evolution has been a handy assumption. It used to be a reasonable hypothesis, at least 5-8 years ago, that hypertension was more common in the AA community because of the Middle Passage; this was partly a argument from silence, I assume more research has been done on the distribution of the genes predisposing AA populations to hypertension and whether they're common in Africa.

... and probably inconsequential on the scale of the universe. (Unless you think life has evolved somewhere with the power to create and delete stars, or move them about in defiance of any physics humans understand. Life in the Q continuum.)

Evolutionary Biology attempts to answer the question "Why are we here?"

It goes against human nature to answer "No reason. It just happened." We used to have religious answers, but thanks to Darwin we now have scientific answers.

The trouble with Evolutionary Biology as it's long been taught is the reflexive rejection of anything deemed "Lamarckism." Even now people refer to "soft" epigenetic inheritance; "soft" as if to take some of the sting out of it.

Years ago when I'd say "Life has evolved to evolve" I'd usually get some friction from people rejecting that premise outright, to people claiming this observation was yet again something "soft," and not quite tangible or important.

Nowadays we're documenting aspects of evolution that are radically non-mendelian, including apparent "mutations" that seem to be directed by other genetic machinery.

Genes that have crossed species "barriers" are another exciting area of research.

Creatures we once considered simple (like rotifers and fungi) turn out to be astonishingly complex; modern gene sequencing technology has confused everything we thought we knew about them, including their presumed family trees and species identification. They mix and match genes in ways that are clearly controlled, but it's not sex as we know it, and it's definitely not mendelian.

I was taught evolution isn't entirely random because of sexual selection. A lot of females pick and choose who to mate with.

Penguins all look pretty much the same. Mom and dad (or dad and dad, or mom and mom) take turns parenting.

Male gorillas, on the other hand, do not look like female gorillas. (People always seem to use peacocks as an example of sexual dimorphism, probably because the gorilla example hits a little too close to home in comparison to human sexual dimorphism.)





https://en.wikipedia.org/wiki/Gorilla

Sexual selection can go both ways, both males and females having largely decorative traits and behaviors that demonstrate an individual's physical fitness to potential mates.

I used "random" in my example in response to Igel's observation of circular reasoning. Evolution has no "direction" except what we observe in hindsight. We describe evolution in terms of direction, from here to there, but it's always branching off in different directions, from less complex to more complex, from more complex to less complex.

which would make them genetically different from the larger original population.

Evolution at its bare minimum.

Species earlier this year and I believe he wrote that he assumed that living things will expand in population to the limit of the available resources. In other words, Darwin's theory of evolution assumes that there is always pressure to adapt, even if there is only one species left.

Charles Darwin is the guy who came up with the theory of evolution. He's on the Google and all that.

It wasn't a new concept at the time. His own grandfather Erasmus was a noted supporter of evolution. Although he mostly expressed his ideas in poetry, of all things, rather than scientific essays.

Charles Darwin was one of the first field scientists to codify the theory of evolution in scientific terms.

Although natural selection is the strongest components, there is still genetic drift and sexual selection. There is almost always some selective pressure.

Animals have two kinds of immune responses, innate and adaptive.

We usually think of the adaptive sort -- you suffer the measles once, your body assembles novel (for you anyways) defensive antibodies that ultimately bring about the destruction of the virus and infected cells, and then "remembers" those antibodies so you never get the measles again.

There are also innate defenses, often accumulated in evolution. A new pathogen presents itself and all the unlucky coelcanths die, leaving only those resistant to the pathogen (for whatever reason) to carry on. It could be antibodies pre-coded in the genes, it could be something else.

Here's a paper:

Fish immune system. A crossroads between innate and adaptive responses

http://www.inmunologia.org/Upload/Articles/6/0/602.pdf

Plants are the champions of evolved immune responses; a good portion of their genome is dedicated to various defenses against pathogens.

Today's ginkgo tree may look a lot like the earliest ginkgo tree fossils, but it certainly has evolved defenses earlier ginkgo trees lacked.

You're right--those who were resistant to whatever harmful pathogens passed on their DNA, those who were not didn't. The microbiology of any living organism will show it has inherited most or all of the genes that allowed its parents to survive long enough to produce the next generation. Tuna that could absorb mercury survived. Those that couldn't eventually dwindled to the point where there were none of them left.

There are lots of birds in areas that have no natural predators (like islands in Indonesia and Malaysia) which have evolved extremely ornamental plumage and elaborate mating rituals just for shits and giggles really.

Arguably the need to mate is a "pressure" but not to adapt in any particular direction other than what the lady birds happen to find attractive.