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79

Do they exist? Yes What are they called? Marilyn Roossinck calls them viral mutualistic symbiotes. She has an excellent review here. What are some examples? My personal favorite is GB-Virus C, or Hepatitis G, which appears to slow the progression of HIV using a number of different mechanisms: Box 1. Summary of the effects of GBV-C infection in HIV-...


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Another good virus would be a Bacteriophage, a virus that infects and kills illness-causing bacteria. From Wiki: A bacteriophage also known informally as a phage, is a virus that infects and replicates within Bacteria and Archaea. The term was derived from "bacteria" and the Greek φαγεῖν (phagein), "to devour". Bacteriophages are ...


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We have engineered a few good viruses to treat certain diseases Per my comment and response: The most current example (at this time and based on my recollection) is the virus we have engineered to treat a certain type of macro degenerative eye condition: Scientists Have Reversed Age-Related Blindness by Deliberately Infecting Eyes With a Virus There are a ...


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I would say that if any "good" viruses exist, they are already within us. Retrotransposons are genetic elements in our DNA that were likely ancient viruses and they move around from time to time either by excising themselves and moving somewhere else or by making a copy and inserting it somewhere else in the genome. Even though we are born with them, their ...


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Cowpox and smallpox viruses structurally similar, and catching one confers immunity to both by immune system response, but one was a deadly disease and the other almost harmless. Once this was discovered, the days of smallpox were numbered. We had the means and the motivation to stamp it out. On my last check a few years ago, we are deliberately keeping ...


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Introduction The system that regulates body energy store consumption is hugely complicated, but is mainly a cooperation between hormones released by the pancreas (insulin - lowers blood sugar and glucagon - raises blood sugar) and the liver (as the bodies main glycogen store and factory for various energy related tasks). Fed State In the fed state (high ...


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From your profile, I see that you have some knowledge in computer science so I will try to use some terms from the field of machine learning! Natural Selection Natural Selection (NS) can only lead a population toward local optimum. In other words, NS is like a greedy algorithm. Mutations and genetic drift do not behave like a greedy algorithm. Genetic ...


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It isn't burning of the calorie you should consider as once digested different calories are stored in the same manner, it is actually the digestion itself. Proteins are by far the most energy requiring foods to digest such that around 20% of the calories in proteins are used in extracting them. In comparison carbohydrates are much easier at around 5-10% ...


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how can kin selection be altruistic? Part of you confusion is purely semantic. Kin selection cannot be altruistic. Kin selection is an evolutionary process. Altruism is a behaviour. Saying "kin selection is altruistic" is like saying "natural selection is flying" (when thinking of selection for flying abilities in, say, flying squirrels). Altruism ...


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That definition in the wikipedia is misleading at best. Contrary to what it seems to suggest there, absolute fitness is computed across a single generation, not within a single generation. For simplicity, let's look at an example using asexual haploids with discrete non-overlapping generations. If individuals with the A genotype produce an average of 3 ...


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Evolutionary tools that are not needed for increased survival rate of offspring of a certain lineage deteriorate with time. The deterioration might have a form of gene expression changes or mutation accumulation. For example, gene MYH16 encodes a protein that facilitates strong jaw muscles in primates, but humans carry a mutated gene that had lost its ...


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Yes, you can decrease your own heart rate very simply by stimulating the vagus nerve in what are called 'vagal maneuvers'. If you stick your thumb in your mouth, wrap your lips tightly around your thumb, and blow on your thumb like you are blowing up a balloon, you will stimulate the vagus nerve and decrease HR. This technique is often used clinically, and ...


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Relatedness measures a specific type of genetic similarity. In particular, it measures the genetic similarity relative to the rest of the population. When $r>0$, the recipient carries the actor's genes at a higher frequency than the population. When $r=0$ it doesn't mean that the actor and the recipient do not share genes; it only says that the recipient ...


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Patas monkeys exhibit "sneak mating" where a male other than the resident male sires offspring. Resident males do sire more offspring than sneaker males, but both strategies do co-occur. I'm pretty sure there are other species that have a similar mating strategy as well.


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The concepts are very similar but there are a few differences. Firstly, fitness is usually applied to alleles or genotypes, reproductive success to individuals. Secondly (and partially as a consequence of this), fitness is an average or idealised/expected property across a population; but actual reproductive success per individual is stochastic. ...


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By experience, most of the time, authors are talking about relative fitness. To confirm my feeling, I looked at the three randomly chosen theory papers from the first page of results that Google Scholar returned when searching for fitness landscape and they all use fitness as a relative measure. The papers are Derrida and Peliti (1991), Merz and Freisleben (...


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Why natural selection leads to selfishness Imagine a population of individuals. At a given locus, some individual carry the A allele and some others can the S allele (A for altruistic and S for Selfish). For simplicity, we will assume organisms are haploid. Individuals carrying the S allele are selfish and will take care of themselves only. The A allele are ...


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As you point out, people have sampled other terms like "aptation" but these terms are not commonly used. In order to not imply anything about the evolutionary history, since it is unknown, I think it makes most sense to refer to these simply as traits or phenotypes (or genotype for that matter, depending on the approach you are taking). If you wish to ...


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I believe this page from Khan academy explains pretty decently why temperature is important to living organisms: https://www.khanacademy.org/science/biology/principles-of-physiology/metabolism-and-thermoregulation/a/endotherms-ectotherms It comes down to biochemistry. Temperature affects the molecules that make up our bodies and do everything in it. At ...


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Kin selection explains a violation of the assumption that individuals will always selfishly promote their own reproduction. (Lemmings jumping into the sea is a myth that does not happen). Every individual is supposed to work toward sending its own genes into the next generation. In your example, you say that the queen should just pump out workers to serve ...


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The amount (percentage) of eggs to mature varies greatly and depends on many factors and off course varies by season. The correct (but not really satisfying) answer is that from every 100 eggs, between 0 and 100 eggs will mature. On average, this number is greater than 1 (otherwise the species would go extinct), and much smaller than 100 (otherwise the ...


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Welcome to Biology.SE! Possible confusion When talking about growth rate as a proxy for fitness, most authors think of population growth rate (whether in terms of the Malthusian parameter or the net reproductive rate). Such methods are typically used for unicellular that have very short generation time. You seem to be referring to the individual growth ...


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So the dataset is this: id x3 x4 2 1 1 3 1 1 4 1 1 5 1 0 Lets assume that we caught the entire population so that we know that a 0 is really a dead organism (the estimate is proportional to lifetime fitness). Furthermore, there is no density-dependent selection and the generations are non overlapping. The survival ...


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That definition is problematic and incomplete. Absolute fitness can be used in different ways, and can be calculated at different levels of organisation (individuals, genes etc). However, absolute fitness always relate to actual growth rate, actual numbers of offspring or other measures of fitness (so an absolute measure), while relative fitness is ...


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Hypothesis testing in evolutionary biology Pretty much any paper of empirical evolutionary biology tests hypothesis. If you go on google scholar and look for any empirical paper in the field of evolutionary biology such as "does sexual selection has antagonist effect to natural selection", "evolution of range limits", "evolution of mutational robustness" or ...


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This paper uses 4 metrics for discreet landscapes. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3240586/ Deviation from additivity: How much your genes interact (normalized). Fitness in a purely additive landscape with three genes, for example, is F=f(x)+g(y)+h(z) where f,g, and h are each functions of one variable (the x,y, and z "genes"/coordinates). ...


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I haven't done LRS but I don't see a reason why you couldn't make that measurement over only a few days, if you keep this method consistent through out all your populations. Just as a control you might have to do a complete LRS to see if you get any patterns in their egg laying behaviour, which I assume/believe is a decreasing pattern over time but just ...


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