Tag Info

New answers tagged

3

The behavior can be explained evolutionarily just like any other trait. It came about either through adaptation, neutral evolution, or as a by-product of another adaptation. An intermediate step, like the one you suggested, is not required. But if it did occur, there's no reason to believe that such a trait would cause extinction. Bloody eyes, whether they ...


1

Without any molecular evidence you could infer convergent evolution if the species being compared shared a common ancestor that lacked the trait in question. With genomic and developmental data you would measure the degree of similarity shared between the relative factors in each species. Little or no similarity indicates convergent evolution. Horizontal ...


3

Regeneration of limbs in amphibians is an adaptation where new limbs are generated by dedifferentiated cells. This process is tightly linked to the embryonic program which, in most animal cells, is a difficult program to access once terminal differentiation has occurred (but it's possible, e.g. induced pluripotent stem cells). Of note, amphibians have a ...


2

There isn't always an intermediate step like "oozing blood eyes", I suspect that this particular trait is pretty easily explained by having an area of weakness in a blood vessel that made the lizard bleed under high stress situations. maybe in early version the lizard had to get some trauma or could intentionally hit its head on a rock or something... I ...


2

I'm speculating here, but it's likely that the taste of the blood has something to do with this. The blood of the horned lizard tastes foul to feline and canine predators. Therefore, a small amount of blood leaking out of the eye might put predators off immediately after the first attack, if that attack was aimed at the head. Obviously, this is an advantage ...


-1

If an inbetweener offers a slight advantage to survival, and if the full-fledged trait even more so, then once the full-fledged population becomes sufficiently large, they will have the advantage and the inbetweeners will die out.


12

Mathematician/computer programmer's answer here: There is a continuum of different animals — in fact it's pretty fair to say that every animal occupies a different place on this continuum. They're just not uniformly distributed over the continuum; they're clustered around forms that are most likely to survive and reproduce, and the lowest-energy paths ...


4

More specifically, the lack of observable gradual change between species. Most significant phenotype differences occur over several thousand generations, which means several thousand years on up. While we certainly can create experiments where a controlled form of evolution occurs within a very small time-frame, I'm going to assume that you're not ...


8

Nothing happens to them. Organisms exist. They breed with other organisms who are genetically compatible. We humans might try to categorize them according to certain traits, but our labels are just labels, biology isn't governed by them. Over time, we might see that a population used to have one trait, and its descendants no longer have it, they look ...


14

I am not sure I'll answer your question so let me know if I miss your point or if I help! What factors determine weather some species "stick"? Natural selection is nothing but differential fitness (fitness is a measure of both reproductive success and survival) among individuals within a population. Individuals having greater fitness will leave more ...


6

Typically when both new and old species still exist it is because evolution pushed the new one into a different habitat or role. As a hypothetical example reef fish vs deep water fish and their relative size. Lets say deep water fish evolved into reef fish, but we still have deep water fish. So there were deep water fish that were a little smaller than ...


4

Could not fit in a comment... This sounds like a very basic question in evolutionary biology that often ask for a very long answer. But I think that you may get the answer you're looking for just if we ask you back how many inbetweeners would you expect to exist between the hammerhead shark and whatever is the closest currently living species of the ...


5

In my view, we simply don't have good enough data to answer this question. The fossil evidence is too sparse prior to the Cambrian and the evidence that we do have suggests that the phyla were already too separated. Meanwhile, the depth of time and the different lifecycles and circumstances of the species involved mean that any "genetic clocks" we might use ...


4

As far as I know there is no phylum which appeared after the Cambrian. Every discussion beyond that is close to speculation, as the divergence estimates of different studies vary significantly. You might want to look into one of the resources mentioned below: http://www.timetree.org/index.php http://www.onezoom.org/


1

Indeed natural selection decrease variability and therefore decrease information and mutation recreate this information. You can think of a bunch of pens of different colors. If you select for the red pens you will decrease the variability in pen colors as the other colors will slowly disappear. If you allow for mutation to occur you will recreate blue and ...


1

Was it necessary for the common ancestor with fused chromosome 2 to mate with another creature whose 2 chromosomes fused in a similar manner? Of course not. People with balanced translocations have kids with people with the wild-type chromosome arrangement all the time. Such people have some fertility problems, due to problematic meiosis leading ...


6

Several issues here that make your question unanswerable: Intelligence is not defined. How would you define it? What kind of relationship are you exactly looking for? Comparing average intelligence between groups or trying to fit a regression with intelligence on the Y-axis and relatedness to human on the X-axis? The general issue hidden behind methods of ...


1

Could not fit in a comment… What kind of observations will you accept to be an observation? If we can demonstrate showing genetic data that two current species where actually only one some time in the past would it represent an observation to you? Or does it has to be a lab experiment (experimental evolution)? Experimental evolution with big animals take ...


1

Rh is just a proteinous(antigenic) factor in red blood cells; not a DISEASE.If it is present in blood you are Rh positive. If not Rh negative.An Rh negative person if exposed to Rh positive blood will form specific antibodies against the Rh antigens. In case of pregnancy, Rh antigens of the foetus do not get exposed to the Rh negative blood of the mother ...


2

What are the evolutionary explanations for why women are weaker than men (on average), and is this difference adaptive? All of the theories surrounding this fact are speculative; it would be difficult to prove "why" men are, on average, stronger than women. One contributing theory is Female-Choice - basically that women had (or has) the ability to be ...


0

I understand the question as "can you get any animal to have heritable traits selected by humans?" This definition of domestication implies that a population of animals can be bred for a sufficiently long period of time, so that humans can select hereditary traits that fit their needs. Humans could provide selective pressure that creates a new variety with ...


3

There's an issue with what you mean when saying "cold blooded". The correct words you may want to use are homeotherm, poikilothermic, ectotherm, and endotherm. In short… Source of heat endo = inside exo = outside Variance in warmth Poikilo = varies homeo = does not vary Any combination of these two axes exist. For example: If the temperature ...


1

Cypress swamps are an example of tree like plants in lakes. There is even a lake in Louisiana called Cypress Lake


0

Ants, slime molds, and brains. Ants and slime molds use simple rules to generate pretty good transportation networks in an emergent way, and brains wire and rewire themselves constantly(adding/removing edges, but not usually nodes). Evolutionary networks, metabolic networks, and ecological networks are much harder to get concrete data sets from, because ...


2

You will find here a very good overview of the main hypotheses that explain senescence. I am not sure I will answer your question but here are some reactions to your post.. What you say has to do with species selection. Selection selects between various objects/units that differ. These objects may be genes, individuals, populations, species, etc… In other ...


1

The question of 'why are there no/few aquatic trees' can be approached in two ways. 1) Why are land trees tall? 2) Is it harder to be tall in a lake? Land trees are tall to shade competitors and spread their seeds and fruits. To get tall, they need extensive root structures to anchor and provide enough water to the trunk. If there are no competitors to ...


1

Remi.b's answer is great, but here's something less technical if that's what you're looking for: Genetic mutations happen ALL THE TIME. Every time a cell divides, there is an error rate of about one per billion. That's a very low error rate per division, but when you multiply it by the number of divisions, times the number of cells, times the number of ...


2

This reply needs to contain a number of links to qualify each of my claims. Unfortunately this site won't allow me to include more than two links because I am a new user. Please see this post which contains the same response and all the necessary links as well. I would be very careful trusting any claims published by the young earther Jeffrey Tomkins. In my ...


2

In your 5 points you basically cover several concepts of evolutionary biology. 1) The number of mutations depend on mutation rate. The mutation rate varies along genome sequences, species and individuals. According to the recent DECODE study (Kong et al., 2012) a human mother transmit on average 15 mutations to her offspring and a human father transmit on ...



Top 50 recent answers are included