Changes in the heritable attributes of populations of organisms over time. Major mechanisms include drift, natural selection, mutation, and gene flow (migration).

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How Sex Evolved ? and when?

As I know evolution comes bit by bit mutation by mutation How sex evolved which requires a major change in at least two individuals one to become male and one to become female ? When that happened ...
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867 views

Why do most mammals have long snouts?

It seems like most mammals, e.g. dogs, have long snouts. My pet dog's snout would seem to me like an evolutionary disadvantage, since her canine teeth are way out at the end of her jaw, which acts as ...
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125 views

Same 185th million grandfather?

I was watching a lecture by Richard Dawkins earlier today and he mentioned that “Your 185th million grandfather was a fish.” I started wondering about the following question, Is it true that my 185th ...
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178 views

Probability of Extinction under Genetic Drift

Here is the Wright-Fisher model of genetic drift: $$\frac{(2N)!}{k!(2N-k)!}p^kq^{2N-k} \Leftrightarrow \binom{2N}{k}p^kq^{2N-k}$$ where $\binom{2N}{k}$ is the binomial coefficient. This formula ...
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Is local equilibrium a reasonable assumption for evolutionary processes?

Whenever I look at discussions of fitness landscapes (in particular, Kauffman's NK model) the questions tend to resemble: The population is at a local equilibrium, but another equilibrium of ...
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378 views

How and when did a dedicated immune system evolve?

I have recently been doing a lot of research into the interplay between the innate and adaptive immune systems in humans, and mammalian laboratory models. This has led to my reading some interesting ...
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95 views

If evolution is a gradual and continuous process, how can we say humans came about 200k years ago? What is so special about that point in time?

It just seems arbitrary to me to say "ok, now THIS is officially a human" when you could look at its parents and find no noticeable differences. At no point in the line of my ancestral history is ...
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133 views

A question about the intersection of evolution and thermodynamics

From this 2014 article in Quanta magazine by Natalie Wolchover there is a quote from a physicist with an intriguing idea about evolution: “You start with a random clump of atoms, and if you shine ...
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71 views

Evolution of Chromosome Numbers

Some species have different numbers of chromosomes, as we all know. Throughout evolution, how was a species able to survive with an extra chromosome? How was this organism able to breed successfully ...
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93 views

Disproportion in cranial nerve innervation?

The cranial nerve innervation is highly disproportionate, as far as humans are concerned. I am not sure of the advantage of being innervated by cranial nerve versus being innervated by a normal ...
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141 views

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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66 views

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 ...
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413 views

Why do we assume that the first humans were dark-skinned?

According to the article Dark skin and blue eyes: How Europeans once looked: It is widely accepted that Man's oldest common forefather was dark skinned, and that people became more pale as they ...
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How does Artificial Selection work?

As far as I know for evolution to work mutations are necessary. Mutations are the raw material on which natural selection works. But mutations are always completely random and human beings have no ...
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2k views

Why does so much variation exist within species?

My last phrasing of this question did not go down well, so I will try again. The genotype of species is not always the same. If you ask yourself why not all of these possible expressions except one ...
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483 views

Why did the urinary bladder evolve?

Sure it's convenient to decide when to urinate but not essential for survival or reproduction, as I understand. But just convenience is not a drive for evolution. Does the bladder serve any essential ...
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193 views

Why don't flies avoid the motorway?

Flies have a short lifespan, therefore evolution should technically happen over a shorter period of time (years). Flies die all the time from getting hit by cars on the motorway. Those flies that ...
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446 views

If Evolution Is In Progress, Why Fight Extinction?

Natural selection is a central tenet of evolution. However, most biologists seem determined to prevent the extinction of the species that have been selected against. Why is this? Preservation of ...
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1k views

How did butterflies evolve to have eyes on their wings?

Some butterflies, such as the UK native Peacock butterfly (Google Image Search) have markings on their wings that look just like eyes, complete with a white fleck to imitate a convex, transparency ...
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111 views

What is the point of having evolved two nostrils?

How would having two nostrils be advantageous to your sense of smell or your ability to breath? I already hypothesized that either one of the nostrils could act as a back up for when another gets ...
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133 views

Why are there no tree-like plants that grow in lakes?

Looking at aerial photos of boreal forests, with dense woods clear-cut by quiet lakes, I wondered why exactly are the woods so clear-cut at the edge of water? Why won't trees develop adaptations that ...
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430 views

Evolution: How could all useful traits evolve simultaneously?

I have a basic question about evolution, for which I never found an answer. I understand how evolution works if we focus on one specific organ or trait. With each generation, some organism is more ...
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613 views

Why did abiogenesis only happen once?

If the "primordial soup" theory of abiogenesis is to be believed, self-reproducing organisms spontaneously arose on Earth at least 3.5 billion years ago, surprisingly soon after the Earth cooled down ...
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173 views

Are there other mechanisms for mutation besides imperfect DNA replication?

I was reading http://www.askamathematician.com/2012/05/q-is-quantum-randomness-ever-large-enough-to-be-noticed/ and saw: [...] the evolution of entire species can be changed by a single mistake ...
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136 views

Could cancer be in itself a evolutionary process?

Could cancer be in itself a evolutionary process? Maybe in some way could it be a process of variation? Or would this idea be completely without support, if so, why? I don't mean that each case ...
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126 views

Theoretically, is domestication of (virtually) any animal possible?

Looking at ones that manage well alongside us human animals, such as dogs and cats, we see that this is possible for evolved, distant animals to have heritable, preferable traits around people. ...
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231 views

Variations in Genome Sizes

Why is there wide variation in genome size amongst groups of protists, insects, amphibians and plants, but less variation within groups of mammals and reptiles?
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125 views

Is (Brain Mass)/(Total Mass) still considered a valid indicator of intelligence?

I was reading this(1) and it led me back to ask a very basic question (I'm not a neuroscientist). All the way back to undergrad anthropology and neuroscience courses I remember being taught the ...
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210 views

Experimental evidence for the selfish gene vs. the selfish individual

In the Selfish Gene, Dawkins makes the argument that a better view of evolution (i.e. more in accordance with experiment) is obtained if you view the basic unit of evolution to be the gene rather ...
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190 views

What evolutionary pressures pushed Galápagos tortoises to mature so slowly and live so long?

I read that they take up to 40 years (in the wild) to reach the age of reproduction and are thought to live over 100 years, with one in captivity reaching over 170 years. Can someone explain in ...
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191 views

Evolution of umbilical cord and reason of its elongation

To answer a question myself, recently I've read that Years and years ago, a long umbilical cord enabled a woman to grasp her baby after birth and run away from predators" Update: $Question:$ ...
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462 views

Smallest unit on which selection can act

Traditionally, the individual was considered to be the smallest unit on which Natural Selection (NS) acts. Today, we usually consider the gene as being the unit of NS. Of course, we should also ...
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196 views

Ecomorphs as evolutionary definitions

There have been demonstrations of ecomorphs in different taxa, where each morphology type is associated to a single environment. I know that it happens because special morphological characters ...
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651 views

How and why did mouth and nasal cavity evolve separate?

My initial objection is that nose filters air, mouth is for eating but is used for breathing also, plus they both are used to create sounds. What is the cause and reason in this case, why do we need ...
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161 views

What evolutionary mechanism caused felines to develop purring?

And why can some felines roar while others meow?
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220 views

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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89 views

Lost Ability to Regenerate Body Parts during the Transition from Amphibians to Mammals

Why have higher-order animals lost the ability to regenerate body parts during evolution? Wouldn't it be better for survival? What is the evolutionary theory behind it?
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What are some examples of evolving networks in biology?

I'm a master student working on networks analysis in general. A network is something that has nodes and there are links between the nodes. Nodes and links could have attributes. An evolving network is ...
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239 views

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 ...
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159 views

How to get smallest subtree containing a set of nodes from BioPhylo?

I'm testing out various phylogenetic libraries in Python. I want to read in a Newick tree, then, given a list of taxa, generate the smallest tree that contains them all. This task is quite simple and ...
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1answer
137 views

Homologies to insect wings

All winged vertebrates have wings which are homologous to each other and to the forelimbs of the non-winged vertebrates. But what about insect wings? Are all insect wings homologous, and are there any ...
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237 views

What is the benefit for cells having the ATP production regulated in mitochondria compared to being from the nucleus?

Mitochondria have their own DNA and appear to be loosely connected to the nucleus and it role. Why are the functions of mitochondria not in the nucleus? Why doesn't the nucleus control the ...
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26 views

Components of the concept of Developmental Noise?

Developmental noise is a concept that correspond to the amount of possible phenotypic variance of a given genotype in a given environment. Intrinsic noise (aka Cellular noise) is a component of ...
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42 views

Is there any evidence telling us what the oxidation state of early earth's atmosphere was?

I ask this question in relation to the origin of life. I realise it would probably be better suited to a geology stack exchange, but it does not yet exist. The Miller-Urey experiment gives a lab ...
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130 views

What selective factors drove the evolution of lactose in lactation?

As far as I can determine, lactose, and the monosaccharide galactose have few biological uses outside of mammalian lactation. It not only required enzymes for its production, but enzymes in offspring ...
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67 views

Viruses: Adaptation to a new host through repeated host jumps

A friend told me, during a 3 minute discussion, that viruses that are endemic in host $A$ and make repeated jumps to host $B$ but can't be transmitted between individuals of species $B$, may slowly ...
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80 views

Hill-Roberston effects and effective population size

From this article, first page, middle of the second column: Even if harmful alleles do not become fixed, they can still reduce the efficacy of selection on neighbouring loci through a process ...
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205 views

How would constantly growing nails have aided early human?

Nails grow rapidly and constantly, such that without constant artificial trimming they would reach lengths difficult to manage. How did this benefit early humans, say 200kya? Were they used like ...
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65 views

Visualisation of phylogeography

I am working on phylogeography on one model species and I am a beginner. You can imagine one species that came on locality more than 5 mya (million years ago). It was a good environment, so the ...
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130 views

Why was polyploidy not lethal in certain octodontid rodents?

As discussed in Why is polyploidy lethal for some organisms while for others is not?, polyploidy is normally lethal in mammals. However, two species of Octodontidae (South American rodents), are ...