How can just random mutations explain mimicry? [closed]

Question

I have been reading this article on drug resistance which explained that how random mutations in a bacterial colony can lead to development of drug resistance among some organisms in that colony.

A thought occurred to me that if mutations are just random (by random what I know (or think) here is the number and time of a mutation occurring in an organism in a normal environment may not be fixed but random) events arising from copy errors during DNA replications then how come some animals in nature mimic their surroundings to save themselves from predators or catch prey?

Let's consider for the time being that an animal exhibiting mimicry have evolved through natural selection, after suffering a mutation in their DNA which made them well adapted to their environment, and also saved them from their predators. Now we know a fit organism, in the struggle for existence, produces offsprings which can withstand the adversities of the surroundings and thus increases in numbers. In this way we may assume that due to many such helpful mutations led to the evolution of a new species.

This may sound simple but it actually seems to me as an over simplification of the events that lead to the development of 'that' new species. First of all not all mutations are helpful. Some are lethal as well. Also mutations may often be silent due to the degeneracy of the genetic code and presence of introns in the eukaryote. But let us consider here that the mutation suffered by our test organism was neither silent nor harmful, that too leaves us with infinite number of mutation possibilities to get a favourable organism from an unfit (to the surrounding in which our test organism is struggling) parent generation. Thus I think nature may not test each and every kind of possibility to select the fit one because in that case the test organisms will be far too many in number. Also if we consider that the fit one emerged just by chance out of million other possibilities then its sure that it was either too lucky or there is some other factor except 'just' mutation which can explain mimicry. Thus can only general mutation explain mimicry or we need something more to explain it?

Answer 1

/how come these animals (below) show such striking resemblance with their surroundings/

You are looking at the culmination of millions of generations of these insects. The mutations are random, but only the helpful ones (of all the random ones) produce an advantage for the organism and so persist in the species. If a random mutation caused an insect to look slightly more like its environment, that insect might do better at avoid predators or catching prey. Thus it would be more likely to produce offspring which would also have its mutation. Random mutations that caused an organism to look some other way would not confer any benefit as regards producing more offspring.

In each generation, if there is some random mutation that made the organism more similar to its environment, it could produce better fitness. The end result, over thousands (even millions) of years, is an organism which looks very much like its environment.

Fitness is what drives evolution. Read more at the link if you are interested. The more offspring I have the more I pass along my DNA and the better my fitness is. If I have a mutation that lets me have more offspring, that improves my genetic fitness.

Answer 2

Are mutations random?

I decided to open a new post (and directly attempt at answering it) as this claim is very common and a bit misleading. See Are mutations random?.

Your question does not need to be specific to species looking like their environment

You seem to not understand the basics of evolutionary biology. Your question is specific to why organisms look like their environment but what you should simply understand is the basics of evolution and selection.

You should definitely have a look at an intro course to evolutionary biology such as Understanding Evolution by UC Berkeley for more information.

How can there be such striking similarities between some organisms and their environment?

Natural selection is the (main) answer.

An important reason (but definitely not the only one) for why a population of organisms would evolve to look like their surroundings is camouflage. Camouflaged organisms can typically have a higher fitness in a population that suffers from visual predators.