Changes in the heritable attributes of populations of organisms over time. The mechanisms of evolution are mutation, migration, drift, and selection.

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Does the species of snake that eats Amphidromous inversus have chiral dimorphism?

From what I read at Schilthuizen and Davison (2005), Amphidromous inversus is a species of snail that occurs in 2 forms that are nearly mirror images of each other occurring in nearly equal ...
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Why don't rats have a gallbladder, unlike other rodents?

It has long been known that rats do not have a gallbladder, though other species including humans, monkeys, cows, reptiles, dogs and mice, all have a gallbladder. In this paper from almost 100 years ...
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Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)

Reading this question, Why are there no wheeled animals?, I wondered why no organisms seem to make use of the tensile and other strengths of metal, as we do in metal tools and constructions. I am ...
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37 views

Origin of aerobic respiration [closed]

Since life originated in water, did the first eukaryotic organisms utilize the dissolved oxygen in the water or they respired anaerobically?
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Describing trait evolution across a very small phylogenetic tree [closed]

I am very new to phylogenetic comparative methods but I want to explore the evolutionary patterns of a number of quantitative traits I have across a small sample (5) of closely related species ...
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Why do living fossils like crocodiles remain so constant and not evolve? [duplicate]

Crocodiles have supposedly remained unchanged for millions of years, and several other species are considered as "living fossils". How do such species remain so constant over time given that they will ...
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How much of the genetic differences between humans and chimpanzees are due to genetic drift?

Both natural selection and genetic drift play a part in changing our DNA over time. Are there trustworthy estimates how much of the differences over the whole genome between us and chimpanzees are due ...
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81 views

How to name a case of convergent evolution where the same mutation is involved in both lineages?

Definition of Convergent evolution - from Wikipedia > Convergent Evolution Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent ...
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How do I measure genetic distance?

I'm not sure how to measure genetic distance. There seems to be many different equations out there, and all the ones I found are rather old. In my specific problem I want to see if the twist in ...
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59 views

Development and function of spindle neurons

In his book How to Create a Mind author Ray Kurzweil makes some claims about spindle neurons that he provides no source for. Concretely he states that spindle cells: Are Involved in handling ...
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80 views

Is natural selection still at work in humans in the 21st century? [duplicate]

There has been some disussion on this site about some aspects (e.g. evolution of eye sight, or height, or the effect of medicine, or evolution the past $\sim10000$ years). My question is really more ...
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What is the difference between Founder effect and Bottleneck effect?

Both are examples of genetic drift in which there is a change in the allele frequency when the population size becomes small. What is the difference between the two?
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If evolution is not about increased complexity, why does so much complexity evolve?

In my last question I asked why we don't see increased complexity in artificial life simulations of evolution. It seems I had fallen for a common misconception, that evolution was about improvement by ...
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How did zootoxins evolve?

I've always wondered how toxins in certain organisms have evolved. Particularly, organisms that produce toxins as a deterrent to predators as opposed to organisms that use it to paralyze their prey. ...
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3answers
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Why Is Most Life Symmetrical Externally But Not Internally?

Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance. Take a human for instance, make a line from the top of our head right down the middle. However, ...
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5answers
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Why are not all species hermaphrodites?

If a hermaphrodite animal (like slug, snail, etc) finds a partner they can mate immediately. If another animal with "normal" reproduction (lets say a mouse) finds a partner they can only mate if they ...
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297 views

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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Diffusion approximation to genetic drift

I am reading from the classical textbook Principles of Population Genetics, Hartl and Clark (pdf here). Introduction Let $f(p,x,t)$ denote the distribution of allele frequency $x$ at time $t$ ...
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32 views

Why were the earliest humans hunter gatherers instead of fruit eaters living on trees?

How is it that the earliest humans who evolved from primates (who live on trees and mostly eat fruit) became hunter-gatherers (which seems like a harder, more stressful and more dangerous way to find ...
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333 views

Why do women live longer than men?

According to Wikipedia and many other sources, women live substancially longer than men (over 5 years in the U.S.). Men can reproduce for much longer than women. So longer living men would have the ...
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3answers
330 views

Why are the fertility rates of large predators kept low?

Predators at the top of a food chain, like lions, seem to have a relatively low fertility rate, which fits well to the ecosystem and avoids overpredation. But what is the mechanism that keeps the ...
6
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2answers
13k views

Why is dimethyltryptamine (DMT) being released during death?

I'm not very well informed about all the things related to biology and the current achievements of science in this field so if I'm wrong in anything I say, please let me know. Many times I've come ...
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1answer
215 views

Fecundity per woman in early humans

The average fecundity per woman varies a lot from country to country. I call average fecundity per woman the average number of born children per woman. In Homo sapiens, what was the average fecundity ...
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Why are there so many medicinal plants?

Question Quite a few plant species can be used for medicinal purposes wiki. As an example, Filipendula ulmaria is rich in acetylsalicylic acid (aspirin). An allele that produces a substance which is ...
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28 views

What are the evolutionary benefits for herbs having beneficial health effects on humans? [duplicate]

There are many types of plants which produce chemicals which can be beneficial in treating human illnesses, or at least alleviate painful symptoms. Why would they do that? Is it just random chance, ...
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Evolutionarily, why do male rats and horses lack nipples?

Developmentally male rats don't have nipples because (reddit) Testosterone release in the fetal male rat happens before the stage of mammogenesis where the teat is formed whereas other species ...
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Cell evolution: immortality vs reproduction

Many sci fi movies produce interesting ideas and technologies that we seem to be able to realize in real life at some point. "Lucy" was not one of those movies. But Morgan Freeman's speech in the ...
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Do babies resemble their father?

An often heard theory is that newborns and babies resemble the father more than the mother, a theory apparently ignited by a Nature paper by Christenfeld and Hill (1995). Figure 1 shows one of the ...
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103 views

How does discontinuous distribution provide evidence for evolution?

One of the evidences for evolution is bio-geographical evidence. In it,'discontinuous distribution' is mostly cited as an evidence. For example, Alligators are found only in south-eastern US & ...
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Are there examples of selection on males influencing female phenotypes?

I've been studying selection on female body color in a sexually dimorphic species and am intrigued by the possibility that selection on males, whether it be through sexual or natural selection, may ...
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65 views

Why does the Vas Deferens detour over the pubic bone?

I was surprised to learn that the vas deferens detours over the pubic bone instead of taking the obviously more direct path. https://human.biodigital.com/widget?be=u1P&uaid=1ly5V Because I would ...
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2answers
168 views

What does 'direction' mean in the statement “mutations are non-directional”?

I was reading the Mutation theory of De Vries; there I encountered this following statement: Mutations are discontinuous, random & non-directional.This is in contrast to Darwinism where ...
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603 views

Why are eggs “egg” shaped?

Is there a reason as to why chickens lay "egg" shaped eggs, as opposed to spherically shaped eggs (or a random shape)? <--- Main Question For extra points (actually just to add more words in ...
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897 views

What is the evolutionary explanation for bat's echolocation [closed]

The bat's ability for echolocation is amazing (so are other the abilities of other animals). I was wondering how all of it came to be.
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Why are there different species of bacteria?

The usual (high school or intro to bio) explanation for diversification of species comes from multicellular, usually sexually reproducing organisms, and seems to be closely tied to the biological ...
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49 views

How did dolpins acquire the dorsal fin?

I had been thinking bout atavism when I saw a picture of a dolphin. I had seen it before, but suddenly the dorsal fin startled me. How did this dorsal fin evolve, especially, is it some atavism from ...
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97 views

What's the mechanism or structure responsible for new species genetic code generation? [closed]

I always had this question in mind. I think, If humans find answer to it then we can trigger the next evolution of human specie. What is the mechanism or structure responsible for evolution ? I don't ...
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Why plants and animals are so different even though they come from the same ancestors?

All the documentaries I have watched, books I have read so far on the starting of life on earth only talk about animals. The very first life form on earth was bacteria. Then evolution took us this ...
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102 views

Are human beings evolved to eat meat? [duplicate]

I know humans can cook, and prepare almost anything, but are humans specifically adapted to eat meat. One of my doubts humans are not particularly well adapted to eat meat because they lack canine ...
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91 views

Escaping resource limitations during tumor evolution

In their discussion of the importance of r- and K-selection on tumors, Aktipis et al. (2013; figure 3) provide the following illustration of a hypothetical cancer growth curve: In it, you can see ...
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How to incorporate intraspecific variation in discrete characters in comparative analyzes?

I'd like to run a multivariate analysis (Pavoine et al. 2011) that aims to disentagle the effect of environmental gradients on traits, considering its autocorrelation with phylogeny and space. It uses ...
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110 views

Why did multicellular organisms evolve when a single cell can survive on its own? [duplicate]

Since unicellular organisms can survive, why would there be evolution of multicellular organisms?
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84 views

Crossing over and exon shuffling?

Campbell Biology 10e, in discussing the functions of introns, writes: The presence of introns in a gene may facilitate the evolution of new and potentially beneficial proteins as a result of a ...
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Why did eukaryotic cells develop? [closed]

If eukaryotic cells can survive in extreme conditions, then why are their still prokaryotic organisms?
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55 views

Do animals demonstrate target practice (i.e., playful accuracy behavior)?

Do animals demonstrate any sort of accuracy-motivated play? (please provide examples!) Consider most human sports and related hobbies. Most share the common goal of hitting a target or being ...
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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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1answer
71 views

Evolution of dominance of alleles

Can someone tell me where can I find detailed text about mechanisms of evolution of dominance? Or, if it is possible, I would be grateful if someone will tell me about them here.
5
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1answer
144 views

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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Does the bending of a tree's trunk in the wind stimulate and strengthen root growth?

Recently Southern California experienced extreme wind velocities and afterwards the news reported over 300 trees had fallen in San Diego County. I had either heard or read somewhere that the action of ...
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What came first? The DNA or the DNA polymerases?

I know this sounds a lot like chicken and egg question and while the latter has an answer, I am intrigued about the former. A modified form of the question would be, in the course of abiogenesis, ...