Questions tagged [natural-selection]
A mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success.
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Do beneficial viruses exist? If so, what examples are there?
Typically, people call viruses some kind of organic compounds that cannot reproduce autonomously and which lower the fitness of their hosts. Even the word "virus" means "venom" in Latin.
But from the ...
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Why do some bad traits evolve, and good ones don't?
If a trait would be advantageous to an organism then why hasn't it evolved yet?
Conversely, if a trait is not advantageous or mildly disadvantageous, why does it exist?
In other words why does ...
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Is there evidence that some non-human species perform sexual selection based primarily on intelligence? How do they do this?
I'm a biology amateur, but it seems like sexual selection is almost always performed based on physical characteristics, the outcome of physical contests, or some sort elaborate courtship. But do any ...
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Why are there species instead of a continuum of various animals?
As I understand it, various animal traits have to evolve gradually, but what happens to the species that are "neither here nor there"?
To put it differently, if a species evolved from another, it did ...
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How could a species be engineered to go extinct?
Non-biology background here.
I read this very interesting article: https://www.wired.com/story/crispr-eradicate-invasive-species/
However I am having a hard time wrapping my head around something:
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Why do only two sexes exist for animals?
Why, from the natural selection point of view, do only two sexes exist for animals?
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Is there a biological mechanism for evolution encoded into our DNA?
Throughout high school, I remember learning about Darwin's theory of evolution as if it were near-fact. But something always seemed wrong about the ideas presented.
Survival of the fittest
Random ...
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Did Darwin ever reach the conclusion that selection will remove variation?
According to simple models of selection the genetic variance in a population should be reduced by selection. (Fisher's fundamental theorem states that the rate at which a population can evolve is ...
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Why did humans become bipedal?
Somewhere in evolutionary history homo started walking upright and became bipedal. You hear these hypotheses that, by walking upright, they could see better across the grassy savannas to escape ...
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Why has grey hair evolved?
A vast majority of humans get at least some grey hair as they age. As far as I know this applies to both genders and all races. Presumably this means that at least some grey haired humans have ...
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Structure of fitness landscapes in the NK model
The NK model of rugged fitness landscapes consists of $N$ sites where fitness contribution of each site depends on its state $\{0,1\}$ and is epistatically affected by $K$ other sites. When defining ...
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What does fitness really mean?
Fitness is certainly the most important concept in the theory of evolution. My question does not have to do with practical measures of fitness but with the theoretical definition of it.
I am a bit ...
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The evolutionary process in bird wings, especially with regard to winglets
In this answer on aviation.SE a comparison is made between the shapes of airplanes wings and the shapes of birds wings. It concludes with the following remark:
After all, no bird has winglets. Not ...
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What is the definition of "Natural Selection"?
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
Natural selection, a process that results in the adaptation of an organism to its ...
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Why are the Galápagos islands so special?
Why did Darwin formulate his theory of evolution just after his visit to the Galápagos islands? Why were they so special from an evolutionary point of view?
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How does Natural Selection shape Genetic Variation?
Background
Importance of the additive genetic variance
As stated here, the fundamental theorem of Natural Selection (NS) by Fisher says:
The rate of increase in the mean fitness of any organism ...
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The replicator equation vs the Lotka-Volterra equation
Background
The replicator equation with $n$ strategies is given by the differential equation:
\begin{equation}
\dot x_{i} = x_{i} \left( \sum_{j=1}^{n} a_{ij}x_{j} - \phi \right)
\qquad i = 1, \...
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What percentage of the fitness variance is explained by the 'n'- most important loci?
Introduction
Standard models in population genetics look up at the evolution of few loci which impact fitness. The variance in fitness is determined by the genetic variance and the environmental ...
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Are there any scientifically based predictions or theories of future human evolution?
Reading this question of the stack exchange got me thinking. I believe human evolution is an ongoing process and will not stop. Are there any predictions/theories about the phenotypes and genotypes of ...
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Genetic Diversity and Adaptation
I am somewhat new to evolutionary biology, having studied it on my free time as a computer science student. There is one particular thing that has always bothered me for which I have not seen a good ...
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Why might long telomeres be selected for in laboratory mice?
In a recent episode of The Portal, Eric Weinstein sits down with his brother Bret Weinstein to discuss Bret's Reserve-Capacity Hypothesis. It's an incredible story of scientific discovery and academic ...
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Expected time for a neutral allele to reach a frequency of $p_1$ when starting at frequency $p_0$
Kimura and Ohta (1968) showed that the expected time for a neutral allele to reach fixation (given that it will reach fixation) is
$$\bar t(p_0)=-4N\left(\frac{1-p_0}{p_0}\right)\ln(1-p_0),$$
where ...
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How does Darwinian Evolution work?
Let me explain... A friend and I read some articles, part of a Biology book, and watched a video on evolution. We then tried to explain what Evolution is to each other.
My friend said that Natural ...
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Intuitive explanation for Kin- and Group- selection
It is known from theoretician in the field of kin selection that kin selection (inclusive fitness theory) and group selection are actually two sides of the same coin. In other words, these two ...
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Fisher's Geometric Model for Dummies
Fisher's geometric model is still today one of the most important and fundamental model in evolutionary biology but it seems to me that most student in evolutionary biology don't really understand it (...
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Model for fluctuating selection
Is there any mathematical model to predict the behaviour and long-term consequence of counter-acting selection at different time scale?
For example, let's consider the bi-allelic gene A, with alleles ...
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Is Mutation Theory still "valid" for complex organisms?
I'm afraid like most people I suffer from having learned "A History of Evolution" in school, rather than cutting to the chase and learning the actual "up to date" version of the subject. (Imagine if ...
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Has it been enough time for evolution through simple natural selection?
Let first state that I understand natural selection. I am not asking if evolution happened. I see evolution as a fact, but I do not assume the current theory of natural selection as fact.
I wonder if ...
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The evolution of dogs through domestication and artificial selection
I am currently reading Richard Dawkins's book 'The Greatest Show On Earth: The proof for evolution' and in the second chapter he talks very much about the evolution of dogs.
He says centuries ago ...
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Is hunting animals, crafting and attacking/defending from enemies intellectually equivalent to learning quantum physics? [closed]
Our brains were shaped after natural selection. Which means that, as long as we were being affected by it, our brains were changing, evolving.
Once we stepped out of nature and stopped being targets ...
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What is meant by `individuals do not evolve, populations do`?
My university professor stated that "individuals do not evolve, populations do". But aren't populations made up of individuals? That's like saying when a compound changes in stability, none of the ...
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Why is it beneficial for trees to grow that tall?
Why is it beneficial for trees to grow that tall?
This sounds like a kid's question Mom, Dad... why are trees so tall?
Costs and Benefits
There are some obvious ...
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Is there an evolutionary basis for why women mature faster than men?
Females develop both physically and mentally earlier than males do. For example; females start puberty at an earlier age than males, and females brains mature more quickly than male brains.
Girls ...
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What exactly does adaptive mean?
This is a quote from Dey et al 2014:
Hatching asynchrony is thought to be adaptive because...
What exactly does adaptive mean here? Does it mean hatching asynchrony has fitness benefits? Or does ...
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Are there real world examples of one way isolation between two populations?
I know that for two populations A and B, there are situations in which there is a two way exchange of individuals between the populations, and there are situations in which there is no exchange of ...
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Empirical evidence for Group Selection?
A controversial concept in Biology "Group Selection", has caused confusion and conflict amongst scientists since the since the mid 1990s. The more general realm of study is termed the "unit of ...
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Why does the slope of parent-offspring regression equals the heritability in the narrow sense?
Background
---- Notations and assumptions ----
let $W_{ij}$ be the fitness associated to the genotype $AiAj$. $x$ is the frequency of the allele $A1$ in the population. The frequency of the allele $...
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What is the relationship between sexual and natural selection?
In Evolutionary ecology: Novelty makes the heart grow fonder, they say:
Thus, it seems that the diverse coloration in this species is promoted by both natural and sexual selection.
I had always ...
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Empirical evidence for species selection
Do we have any empirical evidence in favor of species (or lineage) selection? Do we know some cases that can only be explained (or seem to be only explained) by lineage selection? What are today the ...
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How to determine whether changes of an allele's frequency are due to genetic drift or selection?
Given that both natural/artifical selection and genetic drift are evolutionary mechanisms that influence how allele frequencies shift in a population:
Are there ways to determine whether a frequency ...
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Hamilton's inclusive fitness approach
The underlying intuition of Hamilton's model of inclusive fitness is that we should study social behaviors from the point of view of actors -- rather than the recipients. To build his model, Hamilton ...
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Effects of selection on effective population size
Background
The effective population size ($N_e$) is a central concept of evolutionary biology and is influenced by several parameters. For example: sex ratio bias affects $N_e$ $\left(N_e = \frac{...
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Reformulation of Hamilton's rule
Who (and in which article) was the first to reformulate Hamilton's rule using the letters $B$ and $C$?. See below comments on this reformulation.
Hamilton, in his 1964's article gave a mathematical ...
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What is most ancestral: isogamy or anisogamy?
Sexual reproduction can be feasible with anisogamy (gametes of different sizes i.e. genders) or isogamy (gametes of same size i.e. mating types) or with undifferentiated gametes (i.e. true random ...
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What does "Mutational Variance" mean?
Background
The concept of mutational variance can be found in many articles including this one for example. The mutational variance of a trait number $i$ can be found in the M-matrix in position $m_{...
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Alternatives to fittest-win and Moran processes as simple mathematical models of selection
When modeling selective sweeps as a micro-building block in models of macroevolution (not to be confused with misuses of this in creationist arguments), I use the fittest-win model of selection as a ...
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What is the difference between the evolution of fins in whales and fish?
For a homework assignment I received the following question:
Which statement best explains the evolution of fins in whales and fish?
a. The common ancestor of whales and fish possessed genes for ...
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Can I force evolution in a group of cells by removing all the smaller cells?
I actually have algae growing in water in a container. I was thinking if it was possible to filter the water so that all the small cells will be filtered out and only the bigger ones will remain to ...
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Correlation between genome size and mutation rate?
Martin Nowak in his book "Evolutionary Dynamics" talks about a given correlation between genome size and mutation rate.
What correlation does exactly exist between these two concepts?
Is it a linear ...
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Survival curve in early humans
The survival curve/function describes the probability of a given individual to survive to age $x$. In humans, today's survival function is very much influenced by medicine. This leads me to wonder ...