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This is in between an extended comment and an answer. What do you mean by "Natural"? The question makes no sense as the term "natural" isn't properly defined. (I am voting to close as unclear). For example, if you go to an area where there is "naturally" a high radioactivity, this will increase your mutation rate. Is this a natural way to change your ...


3

This is just going to be a quick answer, as it's too long for a comment (I'll leave it to others to fill in the gaps if they wish). The image you present in your question is based on a false premise. Humans did not evolve from apes. Humans and apes evolved from a common ancestor, which was neither human nor ape. So, the arrow on the left of the image, saying ...


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Every species on the planet is "transitional" - this is because there is no ultimate or final species. Species branch out from one another, sometimes species go extinct, leaving gaps between the extant branches. But it also comes down to how you look at it; if you were comparing blue whales and humans, then chimpanzees (and many other species) would be "...


1

There is no modern book of evolutionary biology that is not about the modern synthesis. So what you are looking for is just an introductory book to evolutionary biology. I think the 2 most common introductory textbook to evolutionary biology are: "Evolution: Making Sense of Life" by Carl Zimmer "Evolution" by Futuyma Note by the way that one can find ...


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According to "The selfish gene," animals evolved not to produce more kids than they can get enough food to rear because those that produce more kids rear fewer. The rate that nature produces food for any species is not constant. When the rate that nature produces food is increasing, the evolutionary stable strategy is for some females to produce 3 kids at ...


0

According to http://www.atlasobscura.com/articles/whatever-you-do-do-not-eat-touch-or-even-inhale-the-air-around-the-manchineel-tree, it evolved to be poisonous to discourage animals from digging into it. Here's one possible way that could have happened. It was once only a tiny speck more poisonous than other trees by random fluctuations in toxicity. By ...


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It appears it is all vertebrates. "All vertebrates started out with a glial blood-brain barrier 4–500 million years ago" All extant vertebrates have a blood-brain barrier (BBB), a specialized layer of cells that controls molecular traffic between blood and brain, and contributes to the regulation (homeostasis) of the brain microenvironment. ... The ...


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Until this study, medical dogma had been that when a bacterium develops resistance to a drug, it becomes weaker as a human pathogen. According to that very rosy scenario, drug-resistant strains should eventually extinguish themselves in the environment, because they can't compete with the original, drug-susceptible organism.


3

A co-worker of mine told me, that there are some mutations in the genome during the life of a human body. So, the body changes genes to fit better into the surrounding environment. Yes mutations accumulate during the lifetime but they are random. They are not targeted in a way that the organism adapts to the environment. Evolution happens through multiple ...


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In my opinion there might be two reasons why the camel hump (rather than bump) might be one of the adequate adaptations of camels to living in the cold (additional to their flat feet giving hold on both snow and sand and tooth structure, Rybczynski et al., 2012). Both match the humps being fat storages in modern camels. The first is also provided by ...


2

It is not always easy to say this with full force in natural sciences, but: NO, this theory is NOT true, probably not even by any means. Extraordinary claim require extraordinary evidence. But wow, there is NO evidence AT ALL for this claim. Before tackling the main point, I give a side note that would actually be sufficient to not be concerned with the ...


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both Suidae and Primates like every creature on earth have a common ancestor in history , but they are simply too different to breed together . Therefore the theory makes no sense , unless it uses pig and chimp in a metaphoric sense .


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Briefly, the "theory" makes no genetic sense. Pig and human genomes have both been sequenced, and their sequences are completely incompatible with this model. The "theory" is completely idiotic in many other ways -- debunking it almost becomes difficult because there are so many ways it fails to make sense -- but the genetics alone make it impossible.


6

What is evolution? The first step is to remind ourself of the definition of the term "evolution". Evolution is most often defined as "any change in allele frequency in a population". Forces that drive evolution Categorizing the processes that affect allele frequencies might be subject to issues of semantics. Without going into the details, we generally ...


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I know that marine habitats have a higher phylogenetic diversity (see also Faith 2006) than terrestial habitats, even though they host far fewer species, which is a result of their deeper evolutionary history. Unfortunately, I cannot find a good reference to this claim right now (see http://biodiversity.europa.eu/topics/ecosystems-and-habitats/marine for ...


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My hypothesis when the curls are left ungroomed they will form knots. These knots form a barrier that works similar to woven wool. Unlike strait hair the mat of knots (dreadlocks) collect dirt and form denser material that insulates against direct light and mosquitoes better than strait material. The wave length does play a part as well. The smaller the ...


3

Turtles are not amphibians because they have (largely) non-permeable skin whereas amphibians can absorb oxygen through their skin. There are also differences in their reproductive cycle: turtles are amniotes, so they produce eggs that must be laid on land, whereas amphibians - like fish - are not and must lay their eggs in water. Since the categorisation ...


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In addition to @Gerardo's answer: Reptiles The term Reptiles as used in popular language does not represent a monophyletic group. When using the term Reptiles, one is typically thinking of turtles, snakes and lizards but excluding birds and mammals (and a few other things not worth mentioning). There are two clades (monophyletic groups) whose name sounds ...


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Amphibians are not defined for having a moist skin, neither are reptiles defined for having scales on their body. In biology, organisms (elements) are grouped according to their evolutive history in monophyletic groups, also known as clades. Basicaly, a monophyletic group is A group consisting of an ancestral and all its descendants. "Tetrapoda" is a ...


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There certainly is a general trend of later reproductive age and longer lifespan. This is simply because the organisms need to live at least until their reproductive age to be able to reproduce. However, other than that I think there is no definitive correlation that animals normally live approximately eight times as long as their reproductive age (as your ...


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I can't find a very fine writings/documents to support this or satisfy your question. I think, it's related somehow. Let's take a sample: (It's not super accurate but you can make a search) ------------------------------------------------------------ | Creature Lifespan Reproductive Age | -------------------------------------------...


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Certainly it is not necessarily the case that having two of the same allele is a bad thing - if there is a "bad" allele then there is a "good" allele. It can be that the heterozygote is equal, better than, or worse than either homozygote. When the heterozygote is fitter than both homozygotes it is called heterosis and, when this is the case, outbreeding/...


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The phrasing in quite unclear and I would not be able to comment on it. In short: yes, hybridization can cause offspring to have either particularly low or particularly high fitness. Hybrid depression refers to cases where hybrids have low fitness while heterosis or hybrid vigour refers to cases where hybrids have a higher fitness than any of the two parent ...


2

You are correct in thinking that traits that improve (impede) ones reproductive rate should be spread through (removed from) the population by selection. However, the process of evolution rests upon more than just selection. There are four mechanisms by which evolution operates; mutation, migration, drift, and selection. Mutation brings new variation in to ...


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Question: QuestionWhat is another physical example similar to the laryngeal nerve that refutes the idea of intelligent design and what does it indicate about our past? Dawkins: The path of the human vas deferens is a similar example. from Reddit AMA with Richard Dawkins So (at least) according to Dawkins the path which the vas deferens takes is ...


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Oops I wrote a lot! This is almost a very brief introduction to some concepts of population genetics. A little bit of terminology first Locus A locus (plur. loci) is a position on a chromosome. Allele At a specific locus, different individuals may have different variants. One individual might be ATTCTA while another might be ATTCAA for example. These ...


0

Unfortunately, your question isn't clear. "Why" could mean different things. What course of events led to it? What benefits does it provide? We could just say, it's not disadvantageous this way, so why not. So perhaps you could clarify. Evolutionarily, through the stages as our ancestors evolved from small mammal to human, the changes that occurred were ...


2

I would like to expand a little on Remi.b's answer and point out that there are two key forms of sexual conflict. Sexual conflict arises when the sexes have different routes by which they maximise fitness. In the case of the ducks (and many other species) the males increase fitness by mating as much as possible, whereas females may optimise fitness by ...


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I am no expert on comparative anatomy, but I will give this a shot. Please edit if you know more about this subject! The configuration of opposing elbow and knee joints is a feature we humans share with large group of mammals. For example, below is an image of a shrew skeleton. Opposing joints are course a major feature of mammalian anatomy, and there ...


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Sexual Conflict is the word you are looking for! Sexual Conflict occurs whenever the optimal mating strategy for the female and the male differ. For example, in Drosophila, it is beneficial for a male to mate as much as possible, while it is beneficial for a female to mate only a few times.


5

Let's start with your definition. "Selection for traits that would be beneficial to a population of units at the expense of an individual unit possessing the trait" This is not a good definition of group selection. In reality, selection can act on groups regardless of the direction of selection at the individual level. This definition sounds to me (your ...


2

Natural Selection Natural selection is the differential in survival and/or reproductive success among different individuals. As such, natural selection also refers to the process by which genotypes associated with greater fitness increase in frequency in the population through time. More information on wikipedia > Natural Selection Adaptation An ...


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It's an amazing question, really. And you might be right about your assumption. In the womb, our legs and arms bent in the same direction. But as the foetus continued to develop, the legs and arms rotated to bend in opposite direction (to each other). As of now, there is no rational explanation as to why this happens. So I guess all we can do is be grateful ...


2

There is another way to look at this question, which I suspect is even quicker (it is certainly more intuitive for me). Mathematically, it is identical to Mark's answer. If the parent chooses to not sacrifice herself to save the child, they have a net fitness of 1.5 (1 parent + 0.5 child) if they escape, and 0 fitness if they do not. Therefore, their ...


3

It doesn't have to be that complicated. The evolutionary value of the offspring to the mother is half that of herself (0.5). Then the relative value of both mother and offspring is 1 + 0.5 = 1.5. So the value of preserving both lives is about 3 times the value of preserving the offspring alone, given the simplistic assumptions from the question. Therefore, ...


1

Plant defense against herbivory Plenty of plant species evolved defense mechanisms. There is a large variety of defense mechanism. Have a look at the wikipedia article Plant defense against herbivory for more information. Such defense mechanism often comes at a cost and therefore the mechanism can be maintained only if herbivory is sufficiently common and ...


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What is beauty? Averageness: It was observed that producing an image of a face with average features from a population yields the image of an attractive face, i.e. beauty might mean averageness. But why did we evolve to find averageness beautiful/attractive? The koinophilia hypothesis states that average features are preferred because extreme features ...


2

Comments You seem to use the term evolutionary advantageous vs disadvantageous for the species rather than for individuals. It is a very common misconception from the general public. You might want to follow an introductory course to evolutionary biology such as Understanding Evolution (UC Berkeley) for example. younger crocodiles with more slightly ...


0

I am afraid this question is too broad and I am voting to close. Evolution of inter-specific mutualism is a large subject. Here is not a complete answer but just a few comments on your two conditions 1.If mutualism gives one specie a competitive edge over its competitors then it could arise. This is mainly wrong. Mutualism is likely to increase if ...


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Evolutionary biology is a highly quantitative science and offers a fair amount of predictive power. However, in the same time, there are plenty of things that we are completely unable to predict. What are we good at predicting? There are plenty of things and it is impossible to list them all. Here are a few examples of things we can predict. Number of ...


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This is from Darwin's Notebook B: Transmutation of species from 1837–1838. From what I understand, the tree is a hypothetical depiction of descent used to discuss differences and relatedness between forms/species. This is the text that accompanies and follows the sketch (notebook pages 36-44): I think (sketch) Case must be that one generation ...



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