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19

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 ...


10

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 ...


8

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 ...


7

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 ...


7

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 ...


6

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.


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 ...


5

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 "...


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 ...


4

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 ...


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 ...


3

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 ...


3

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 ...


3

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.


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 ...


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, ...


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 ...


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 ...


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 ...


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 ...


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 ...


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 ...


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 ...


1

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 ...


1

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/...


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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