/r/evolution
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On the Origin of Species
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Sharks' skeletons have very similar structures to that of animals with bones. So did sharks have bones at some points and then transformed them into cartilages? Or is it the other way around and other animals had cartilages that turned into bones? Or did we both evolve from animals with neither bones nor cartilages and our skeletons just converged to have similar structures?
Why did it evolve before chloroplasts? How do we know?
Anyone who's had a cat knows that felids have rough tongues due to tiny tooth-like structures on their tongues called papillae, which serve two evolutionary purposes: to assist cats with grooming and to scrape flesh off of the bones of their prey. It seems like there are plenty of other mammals, especially carnivora, that could benefit from this; canids, for example, also lick themselves and the members of their pack, and they could also have a need for scraping flesh off of bones, yet their tongues are smooth. As far as I know felids are the only animals who exhibit this trait. Why is this?
So if Humans and Apes are on a huge bush of a family tree, then wouldn’t there be a mass amount of other species? Like are mythological species like Elves and others. Were those human species? Did we kill them off to gain dominance?
Secondly if the creation of species is all about luck mutations, then how accurate is it to say we couldn’t come from apes, not saying that generally we did but if it’s a mutation thing why couldn’t a ape lineage slowly become like humans literally?
If skin colors evolved as a response to sunlight levels/distance from equator, why did we evolve cool vs warm tones of skin? Does the undertone (warm, cool, neutral) affect vitamin D absorption?
I want to learn more about evolution and I´m wondering if anyone knows some good ways of learning evolution in a comprehending way. Books, youtube, websites, anything.
it really murders idealism
It is to be expected that in thousands, tens of thousands, millions of years, evolution will take us to a taxonomically distant place from where we are.
Every day we see articles about the effects of evolution such as the absence of wisdom teeth, the appearance of epicanthic folds, lactose tolerance, etc. At some point these changes will accumulate until we can consider ourselves another species.
Even though there is no first being of this "next species", we now have ways to record our evolution. We have photos, videos, books. We would no longer need to compare fossils, we would have the evolutionary process practically in real time.
How do you believe this process will take place? How long do you think it will be "being another species" before someone says, "Hey, I guess we're not human anymore"? And in the case of evolution in isolated groups, how controversial would it be to say that a certain group is "no longer human"?
Through antibiotics that doesn’t work anymore because the bacteria evolves to withstand the harm antibiotics do to them and we have so much in common with apes and have a common ancestors and are the only primates that can both swing for a long time and looking back at earlier humans we look even more like apes then too and I feel like saying apes aren’t our common ancestors is like saying peoooe don’t have cousins it’s just that we’re far separated now we don’t look a like. I don’t know how people can deny evolution just based on those points alone and I feel like we can see evolution just based on those points. What do you think ?
From what I've read, it has occured at least 20 times. This includes plants and animals, which I've read have a unicellular common ancestor.
It just seems strange to me that life spent more than 3 billion years as single cells, but then made the jump to multicellular complexity many times, when it seems like it would be a very "difficult" jump, just based on the amount of time it took.
Can anyone explain what the selection differential (S), response to selection (R), and narrow sense heritability (h^(2)) mean?
I understand the basics and that if h^(2) <0.5 the majority of change is environmental and not genetic. But does that mean that since the changes aren’t heritable no evolution is occurring despite changes in a allele frequencies?
Also, I haven’t been able to find much information about what a negative or positive values for S or R mean.
I’m working on an assignment (for second year evolution) now, and I’m totally lost, any help would be greatly appreciated!
Hello everyone. This question has been calling my attention for several days. Yes, I know that by spending several hours rummaging through the existing literature I could probably get some insight into the issue, but lately I have little time. Likewise, I thought that maybe someone in this sub has worked/is fond of whale evolution, so his assessment might be much better than mine (STEM student, but not evolutionary biology).
By the way, I also know Hans Thewissen's work with embryos, and no, I am not referring to those types of studies. To the point: I wanted to know if in recent times (by this I mean from the ~2000's onwards) any case of an adult cetacean with apparent rudimentary development of the hind limbs has been reported and studied?
Of course, I know there are much older reports (e.g Andrews., 1921; Ogawa and Kamiya., 1957; Ohsumi., 1965). Although none seem to be as detailed, not even with a histological evaluation. The limitations of the time also did not allow a genetic evaluation, at least for the first case and similar reports.
In 2006, the capture (alive) of a 'hindlimbed' bottlenose dolphin in Taiji, Wakajama (Japan) appeared in the popular press. Many probably know him, he was quite famous at the time. However, the only more or less formal report that I could find on the AO-4 (the hind limbed dolphin) case is Ohsumi and Kato (2008). They say that:
For the time being, our first priority is to keep AO-4 and AO-1 healthy. In order to conduct wider interdisciplinary research, we wish to organize a project team to study the comparative morphology, genetics, physiology, and life history of these two dolphins involving interested scientists from various research fields. We believe that keeping AO-1 and AO-4 together will be useful for comparative studies and to maintain the long-term mental health of this unusual dolphin.
However, there is almost no information about what happened to this specimen (and not even an X-ray), beyond the initial reports. Some sites mention that she died in 2013, although I did not find any official source to comment on this.
So, to summarize, is there currently any case similar to that of AO-4, or that of the whales reported in the early and mid-20th century that has been or is being studied in detail? Or am I simply overestimating here the importance of a possible atavistic dolphin for our knowledge of the evolution of cetaceans?
Thank you so much!
Today I came across a Royal Institution public lecture by evolutionary biologist Andreas Wagner, and intrigued by the topic he discussed (robustness and randomness), I checked his Wiki page:
Wagner showed that robustness can accelerate innovation in biological evolution, because it helps organisms tolerate otherwise deleterious mutations that can help create new and useful traits.[8] In this way, robust transcription factor binding sites, for example, can facilitate the evolution of new gene expression.[9] [more on his work ...] Wagner has argued that robustness can also help resolve the long-standing neutralism-selectionism controversy [...]
[From: Andreas Wagner - Wikipedia]
That "controversy" is also new to me. So, if it is such, how well is Andreas Wagner's work accepted, and what alternative, perhaps better accepted, solutions are there?
Thanks!!
We wound up accidentally skipping Paper of the Week last week, so to make up for it, here's two papers for the price of one. In this first paper, a team of scientists has discovered a way to mimic the initial stages of evolving plant carnivory, potentially giving insight into how it's arisen so many times.
Leaves vary from planar sheets and needle-like structures to elaborate cup-shaped traps. Here, we show that in the carnivorous plant Utricularia gibba, the upper leaf (adaxial) domain is restricted to a small region of the primordium that gives rise to the trap’s inner layer. This restriction is necessary for trap formation, because ectopic adaxial activity at early stages gives radialized leaves and no traps. We present a model that accounts for the formation of both planar and nonplanar leaves through adaxial-abaxial domains of gene activity establishing a polarity field that orients growth. In combination with an orthogonal proximodistal polarity field, this system can generate diverse leaf forms and account for the multiple evolutionary origins of cup-shaped leaves through simple shifts in gene expression.
Plant carnivory is something which has evolved dozens of times across multiple plant lineages, and often takes the form of foliar feeding. Examples include the central leaf pit of Bromelia, which fills with water and digestive enzymes; pitcher plants constitute a variety of species across multiple plant families within different eudicot lineages; the sticky leaves of Sundews; Venus Fly Traps; the leaves of Butterworts; Drosophyllum (which superficially look like a fern, but are more closely related to cacti); and Bladderwort, an aquatic carnivorous plant that eats fungus gnats and aquatic algae, all to name a few. The common link between them is that they and others have evolved foliar feeding in response to the nitrogen poor soils of their homes.
Stickiness of vegetative tissues has evolved multiple times in different plant families but is rare and understudied in flowers. While stickiness in general is thought to function primarily as a defense against herbivores, it may compromise mutualistic interactions (such as those with pollinators) in reproductive tissues. Here, we test the hypothesis that stickiness on flower petals of the High-Andean plant, Bejaria resinosa (Ericaceae), functions as a defense against florivores. We address ecological consequences and discuss potential trade-offs associated with a repellant trait expressed in flowers that mediate mutualistic interactions. In surveys and manipulative experiments, we assess florivory and resulting fitness effects on plants with sticky and non-sticky flowers in different native populations of B. resinosa in Colombia. In addition, we analyze the volatile and non-volatile components in sticky and non-sticky flower morphs to understand the chemical information context within which stickiness is expressed. We demonstrate that fruit set is strongly affected by floral stickiness but also varies with population. While identifying floral stickiness as a major defensive function, our data also suggest that the context-dependency of chemical defense functionality likely arises from differential availability of primary pollinators and potential trade-offs between chemical defense with different modes of action.
A flower that grows in my region is Bajaria racemosa, aka "Tarflower", which traps insects with sticky secretions on its flowers. It's believed that insects decompose on the petals and provide nutrients for developing into fruit later. As a weird tie in to the first paper, flowers are actually modified leaves. According to the ABC Theory of Floral Whorl Development, there are A, B, and C genes associated with the development of the different parts of a flower, and depending on which ones are active determine which parts form. Plant breeders can sometimes utilize this information to make extra showy flowers, so that plants which normally produce a lot of anthers produce a lot of petals instead, like roses and peonies. If A, B, and C genes are all knocked out, all that forms are leaves. So technically, B. racemosa, B. resinosa, and other flowers with this habit also sort of do foliar feeding.
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Link to the previous Paper of the Week post
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Hi everyone. Long time lurker, first time poster. I started learning a bit more about taxonomy and cladistics recently in an attempt to trace our evolutionary history. Just for fun, lol.
Well, when I finally meandered down to Chordates, I was a little shocked to discover that, within the class Osteichthyes (bony fish), nested all the tetrapods--amphibians, reptiles, birds, and mammals.
Now, I know the difference between paraphyly and monophyly, and can accept that perhaps "fish" could be considered (monophyletically) to be the ray-finned fish or, considering coelacanths and lungfish, to be (paraphyletically) all non-tetrapod Chordates of the class Osteichthyes. That would be satisfying to me. But then what about sharks? I've heard people consider sharks fish too. But then they don't consider rays fish, and both sharks and rays nest within Chondrichthyes. If all of Chondrichthyes are fish, and all of Osteichthyes are fish, then all gnathistomata are fish, right? But then what about superclass Agnatha? Are hagFISH and lampreys fish too? If they are, then all vertebrates/craniates must be fish too (monophyletically speaking). What about the tunicates? They don't LOOK fishy, but lancelets kind of do. If we consider lancelets fish, then (again, monophyletically), ALL of Phylum Chordata must be considered fish. Is it fish all the way down?
In short, what is a fish? In the most broad terms possible. Please! Colloquially or scientifically--and I don't care how paraphyletic the definition might be--I just want to know what a fish IS. Thanks, all. Learning more about biology and evolution is a loooooong process for someone that barely has a bachelor's he's not actively using.
NOTE: For my own sake, my armchair research into this stuff has been focusing on extant clades and species. Tiktaalik is fascinating, as are many other extinct creatures, but including them will just serve to confuse me more at the present stage.
Not sure if this is the correct sub but this is a question that I'm wondering. I think this is kind of related with evolution as it is basically artificial selection.
I don't know too much about genetics but as far as I know, DNA is like a map of our phenotype which plans our caractheristics. Some "desviations" can happen because of problems during pregnancy. Some of them can be because of problems during fecundantion and then it can be genetic but not neccesary heritable.
How do they know if that desirable caractheristic they want to breed is heritable?
I know that not all cave dwelling salamanders have troglobite traits (lack of pigment, loss of eyesight, etc) however, there are a distinct handful that do. Notably the Olm, Georgia Blind Salamander, and the Texas Blind Salamander all express troglobite traits, with them all being completely white and completely blind. Yet not one out of the two frog species I could find that actually live in caves express any of these traits. The Cave Tree Frog (Ranoidea cavernicola) and the Puerto Rican rock frog (Eleutherodactylus cooki) are both brownish green colors and have large eyes. Completely opposite to the salamanders. Why is this? The frogs and the salamanders both share similar habitats yet don’t share any of the traits. Could the frogs just be new to cave life and haven’t evolved those traits yet? Or is it something different?
Surely it’s nonsensical to have one hand or limb you prioritise using. In the wild as what would you do if you lost that limb, or couldn’t use it? E.g. throwing spears, using swords etc?
Before wings evolve to the point where the creature can fly, surely they'd just weigh the creature down or get in the way, and so be bred out through natural selection?
Edit: Thank you so much to everyone that's responded; I've been reading through all the comments, and there's so many interesting theories!
Some people have mentioned that my question comes across as a little uneducated, and unfortunately it probably does, because I am, in fact, very uneducated on this topic! Home education and Christianity will do that to you.
I really appreciate everyone who's taken my question seriously and helped to broaden my understanding!!
Somebody has good and complete references(books, articles) for the mathematical models of evolution? (Also I you know some good mathematical model of extended synthesis). :) Edit: I mean the basic models, like the one you could do in a course of evolutionary theory
https://scienceillustrated.com/humans/you-are-the-result-of-inbreeding
According to genetic research, all Europeans are one big family, if you go 1,000 years back in time. So, you are probably related to your husband, wife, or girlfriend.
Did larger living things come from so many cells eating each other or adhering together? How I picture it is that one cell swallowed another cell and the process kept going until there were so many cells bound together that it started creating larger organisms. I am trying to study and find information on how exactly larger living creatures came from cells. Everything I find pretty much ends right up to the point of a cell that separated and cloned itself or a prokaryotic cells that swallows another cell.