14

Official definition Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly? I don't think there is such a concept as an "official definition" of any concept in science. There are common definitions though. The definitions you cite Let's go through your three definitions ...


9

Good question. And good analysis. I have little to add! I'll simply provide my own list of thoughts to complement your ideas, which are not mutually exclusive. The fact that it wasn't discarded during the course of the species' evolution suggests it must have offered some benefit. This statement is speculative. The key word here is suggests. i can ...


8

I've adapted your definitions to another process that I think will be less controversial to you. Eating is the intake of food by taking into the mouth, chewing, and swallowing. Eating, the process that results in digestion by taking in food and chewing and then swallowing. Eating, then, can be defined as the intake and digestion of food items, ...


6

The idea according to Darwin is that the slightest harmful effect a hereditary trait(s) would bring to a population then with time it would result in extinction of the population with that trait(s). Citation? I certainly don't think any modern biologist would claim that a single deleterious allele will doom a population. Therefore natural selection ...


5

Natural selection is an important part of evolution, but not the only part Evolution is described as changes in heritable characteristics over time: you can look at changes in allele frequencies and call that evolution. Genetic drift, for example, describes genetic changes that are caused by random sampling rather than selection. A natural disaster (if we ...


4

S Pr lists a number of reasons that might allow non-adaptive traits to spread. One other that's probably important in some populations is "allelic surfing". If you imagine a smallish population that suddenly expands (say, starlings in the Americas, or humans in the past few thousand years), the original genes are going to expand no matter what - even ...


4

Short answer Survival does not get your genes into the gene pool, reproduction does. thus reproduction based selective pressures can be stronger than survival based ones. there are plenty of organisms that die during or right after mating because of this. Consider an example In species A finding a mate is fairly rare, it may only happen a few times in an ...


4

It's possible, but very unlikely. Usually it takes a substantial number of genetic differences to qualify two organisms as different species. One might think that reversing the direction of selection pressure could reverse a genetic change, but genetic change begins with random mutations which are not determined by selection pressure. It's very unlikely ...


3

The Selfish Gene theory "can be defined as the idea that the gene is the ultimate beneficiary of selection". Argren, in Selfish genetic elements and the gene’s-eye view of evolution lays out the history of the theory and the arguments for and against it. The theory is almost certainly correct; and it's almost certainly incomplete. The theory is testable. ...


3

Generally speaking, there are sequences that are under purifying selection (where new mutations are often deleterious) and there are sequences that are neutral. Sequences under constant positive selection do not really exist. So, when you ask If a sequence is under selection will it acquire more changes over time because of faster fixation than if changes ...


3

Is a change in allele frequency resulting from a catastrophe evolution by natural selection? The catastrophe itself is an example of a change in environment that brings with it a change in selective pressure. The events you describe (a volcano eruption, or a comet strike) would select for existing variation in the population. Heritable traits that are more ...


3

I just want to report the finding of one paper here. I don't know much about the rest of the literature and can't comment on it. Otto et al. (2015) investigate this question in sexually reproducing organisms. As I understand it, they assume that the amount of time spent in on phase of the life cycle is proportional to the amount of selection happening in ...


2

What is complexity? "Complexity" in this case is derived from the SEG algorithm, which is based on Shannon's information entropy. This is not necessarily repeated regions, but regions in which a limited pool of characters are used (for example transmembrane regions, in which you are far more likely to see a hydrophobic residue than a polar one). These ...


2

Recipe for selection There is selection on a specific phenotypic trait if and only if There is variance for this trait in the population This variance is, in part at least, explained by genetic variance The trait covaries with fitness The first two points can be reduced to a single point by stating "The trait has some non-zero heritability in the ...


2

As Remi points out there is not an official definition of anything as complex as natural selection in science. Science is a collective consensus, not a hierarchical structure, official things are rare and usually not directly connected to the science. The neo-Darwinian synthesis might count but that is far too large to be considered a definition, it is more ...


2

You're asking if cells arose with 100% replication accuracy and if lower accuracy was selected for under a feedback loop. Maybe there was a sweet spot for DNA replication accuracy in terms of efficiency, but it's highly unlikely that our ancestor cells had 100% fidelity in DNA replication because if we look at yeast for example, there are many genes ...


2

There is previous research for that field of macroevolution.... Horse shoe crabs change slowly and tropical fish change fast. You are right, it's not just random variation, it's fine tuned by DNA transcription processes which are too developed to be random, so the complexity of the processes leads scientists to think "WTF" regarding epigenetics, ...


2

If reproductive isolation was to be caused by a single mutation, then the first individual to carry this mutation would likely have a very low fitness. At the extreme, in a purely sexually reproducing species without hermaprohiditism, this individual carrying the first mutation causing reproductive isolation would have no-one to reproduce with and would have ...


2

I've mostly skimmed the formalism you introduced, but getting to the 2nd half of your post, the answer is yes, you understood correctly the distinction between natural selection (aka adaptive evolution) and drift (aka neutral evolution), as well as the fact that it's not a given that natural selection would be the predominant effect in arbitrary ...


2

Yes. The rate of de novo mutations has been found to be higher in paternally derived DNA from several papers. A recent paper from a quick search [1] found that ~80% of 15,746 de novo mutations in 225 families were paternally derived. Based on the total mutations yes, but they are also even more likely to bring deleterious mutations. So per base probably not....


2

This has a lot to do with how development works, there is no gene that makes the nerve this long. Instead, there are genes that tell the nerve where to grow and what path to take using other tissues as landmarks. At each step of the neck getting longer letting the nerve follow this path is more beneficial than the complex evolution of pathways necessary to ...


1

Drake's rule Let $L$ be the size of the genome. Let $\mu$ be the average per nucleotide mutation rate, then the genome-wide mutation rate $U$ is $U=L \mu$. There is a general relationship between the genome size of an organism and the nucleotide mutation rate that makes that the genome-wide mutation rate is often approximatively 1. There is of course ...


1

There are multiple definitions of complexity, ranging from algorithmic complexity to computational complexity. In biology, I'd say that algorithmic complexity (Kolmogorov complexity) is most relevant. Unfortunately, we don't yet know enough about genetic circuits and all the other things that go on at the subcellular level even to make plausible estimates ...


1

I'm not sure how to address this question so that we may arrive at a suitable answer, but I'm sure that the recurrent laryngeal nerve is an example of bad design. Evolution works from traits already possessed by the parents. Mammals evolved from fishes in our evolutionary past and fishes do not have a neck. As a result the recurrent laryngeal nerve of ...


1

While it doesn't go nearly to the extent of speciation, the classic example is the British peppered moth: https://en.wikipedia.org/wiki/Peppered_moth_evolution Originally it was mostly white with black spots, which made a good camoflage on tree trunks &c. During the industrial revolution, the "dark satanic mills" put out a lot of soot, turning the tree ...


1

In short, no evolution is not a result of variation. Evolution is a process in which each population in a system compete for a limited number of resources and each population has a fitness score (how well suited for the environment they are, this score is a man made concept to help illustrate the point), the populations with a higher fitness score tend to ...


1

If I actually understand your premises, which is a big if, you're asking if the genetic material in the sperm has been subjected to more mutation than its counterpart in the egg... by the time of mating. In case of humans, where's there's a lot of research and the answer is almost certainly yes. Recent [GWAS] studies have shown that 76% of new mutations ...


1

natural selection was an idea proposed by darwin a scientist. he said that nature select the fittest. he concluded following points after his research In a population, some individuals will have inherited traits that help them survive and reproduce (given the conditions of the environment, such as the predators and food sources present). The individuals ...


1

Modern grass crops (cereals) haven't run out in the wild is because that was the whole purpose of their development. What differs them from their wild counterparts are the domestication traits, like, seed shattering, uniform maturity, day length sensitivity etc. Modern grass based crops are significantly superior to wild grasses, they grow faster, are ...


Only top voted, non community-wiki answers of a minimum length are eligible