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I Have A Dream...
Was 50 Years Ago Today 
Martin Luther King Jr.
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Martin Luther King Jr.
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"I Have a Dream" is a public speech
Delivered to over 250,000 civil rights supporters
from the steps of the Lincoln Memorial during the March on Washington for Jobs and Freedom,
the speech was a defining moment of
the American Civil Rights Movement. (Wikipedia) |
The Assassination Of Martin Luther King Jr.
April 4, 1968 |  |
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Salif Keita
 Happy Birthday To
The Golden Voice of Africa
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He was born on August 25, 1949
in the village of Djoliba. 
The direct descendant of
Sundiata Keita the founder of the Mali Empire |
Moussolou
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Souareba is a tribute to the mansas (kings) of the Mali Empire
Souareba was released on the album "Soro" in December 1987
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   Since 2006, Salif Keita has personally donated hundreds of thousands of dollars to purchase sunscreen lotions and make other donations for the aid of people with albinism in Mali. He has acquired land for his foundation to build a school and health clinic for albinos in Bamako, Mali. Private and public funds have also been allocated for use in Mali for lotions and sunglasses for people with albinism. 
to know more about his Foundation.
Salif´s music and extremely moving voice are musical treasures of my memories of 1987 when I first heard his album Soro and even though his words where in mandinka dialect, I was so moved by it I just had to have more.
HAPPY BIRTHDAY
SALIF!
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Salif Keita - Cono
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Warning! Colors!
Part 3:
Evolution of Coral Snakes
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Coral snakes are usually live in forests, but are also found in grasslands and deserts. Their distribution ranges throughout the tropical, subtropical and neotropical regions in the world. Like virtually all snakes, with the exception of cobras, (which are arrogant) they are secretive and have a docile disposition. They generally don't bite unless truly threatened such as by being stepped on.
 The coral snake is really several species all belonging to the genus Micurus of the cobra family, the Elaphidae. They are generally small (maximum recorded size five feet) with a common length between eighteen inches and two feet.
All coral snakes are diurnal (active in the day-time) predators, thus they have round eyes for the daylight. This condition is similar to the eyes of non-poisonous snakes. The coral's eyes are very different from the oval eyes of nocturnal (active in the night-time) snakes and most other poisonous snakes. However, coral snakes also have similar oil droplets in their eyes as do some birds. This oil droplet appears to aid their color vision by filtering out certain wave-lengths of light.
The head of all coral snakes is blunt, the scales smooth and glossy. The body shape is narrow, tapering to a sharp tail. The body is banded in triads (in threes), that may be narrow or wide. They have alternating strips of red and black always separated by yellow. This is typical and most species have this although there are variations in proportions or intensity of color. Some species have shown melanism (tending darker) and others albinism (tending lighter).
 The triad red, yellow and black banding is the general rule. However, there are also exceptions to this banded body pattern in certain parts of the world. Instead of banding across the body it may be along the body length-wise, or in unusual cases it may have a different pattern. An example of this is the blue coral from Asia. The blue coral snake is noted for its conspicuously bright red head and tail. Although the blue color may not be a common color in the corals, this species is still aposematic. Like all snakes, corals snakes are exclusively carnivore. They are extremely quick and nimble, preying specifically on other snakes. They may also take lizards and other reptiles. Prey are killed by venom only if the prey is dangerous to the snake. The venom is highly toxic though small in quantity.  Coral snakes have two enlarged, tubular, maxillary teeth in a fixed anterior position in the upper jaw of the mouth. New fangs are continuously replacing older ones. These tubular fangs are hollow. Each one is individually connected to a duct that is in turn connected (only during discharge) to a venom gland. |
| Whether the development of color in the species occurs first, after noxiousness, or simultaneously, the predator-prey model asserts that at least some conspicuously colored prey will be sacrificed in order for a predator to learn and make the association of the pleasant experience with that color and pattern of animal. The unpleasant experience itself must be just noxious enough to deter further attack and thus reinforce learning, but ultimately not kill the predator outright. Still, it must deter with a minimum number of trials so as to allow the prey density to be relevant. The second point is one that is often draws the questions that most people have difficulty to grasp. If it has no previous experience of the prey's threat or danger, how does a predator know to avoid it? This point will also lead to other questions. How can it benefit the warning prey if the predator does not initially know the warning signal? Put another way, how can the trait be selected for and preserved, if the snake is killed or fatally injured during the predator's first learning experience? Then again, there is the similar but converse point. How can a predator learn about the prey's danger and avoid the prey, if it's dead after its first encounter? How can this be adaptive or help with fitness? The third point address the fact that a hungry predator might still be tempted to "go for it". The warning signal must in fact be backed-up with something that is strong enough to illicit the avoidance reaction. The proverbial stick in the saying "Walk softly but carry a big stick." has to really be there and it must be a pretty big stick, even a deadly one! |
The individual is marked in a clear manner.
It warns potential predators of harm or danger.
The predator must know the warning.
Or the predator must have some way of learning it.
The warning must be enough for deterence.
The predator should actually avoid a direct encounter.
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Determinants to Conspicuousness
 The source of light, time of day, as well as clouds or other cover.  Light absorption-color reflection and type of material or texture.  Dark or light and simple or complex backgrounds. | The loss of life that is risked or incurred by the individual for a predator's learning curve can be compensated for by inclusive fitness. An adaptation by inclusive fitness means that any inherited trait that increases the individual's genes in the population is fit by Darwin's definition. The trait then, will enhance the organism's chances of perpetuating its genes by the survival of its kin. It is not necessarily the individual's survival that bestows fitness and the survival of a species. A trait may be adaptive by kin selection. This can be done through the number of kin and the genes in common with its surviving relatives. Hamilton’s rule, the central theorem of kin selection, states that an altruistic trait can increase in frequency if the cost of the trait to the actor in terms of individual fitness is offset by that individuals gain in inclusive fitness. Hamilton’s rule may be expressed as rb - c > 0, where r is the genetic relatedness of the actor to the recipient, b is the benefit to the recipient, and c is the cost in fitness to the individual. The trait is fit by increasing the individual's genetic contribution to future generations. There is another effect that may come about in the process of educating a predator. If the genes expressing for the phenotype are carried even by non-related individuals then the trait may still be adaptive by a kind of green-beard selection. A green-beard is an expression to indicate a genetic marker, something that identifies another individual as having some similarity. In this type of selection it is the phenotypic similarity between the actor and the recipient, rather than the genetic relatedness by descent that is selection is acting on. Therefore, despite the lack of assurance of survival to the individual the trait for conspicuousness and indeed the warning color will be adaptive under several scenarios. The dominant colors seen for aposematic coloration are varying shades of red, yellow and black. The conspicuousness of color concerns the question of not only what color but also the use of color in pattern. In considering the visual aspects of certain colors and patterns in coral snakes, a general outline is useful. Accordingly, there are three principle elements in conspicuousness listed below: |
| The chief predators of coral snakes are diurnal birds, king snakes, and some mammals. It is presumed that, in fact, color vision mechanisms are adapted to the priorities of food location, mating and predator detection in these animals. Logically then, it can be seen that coloration will take advantage of these characteristics. Oil droplets in the retina, specifically in the cones of some animals, have been long known to be effective cut-off filters. They are only found in such animals as; amphibians, reptiles, birds and marsupials. These oil droplets act as filters to short wave-length light and transmit the long wave-lengths of red and yellow. Of the bright colored oil droplets, red has only been found in turtles and birds. It is widely known and accepted that plant flowers pollinated by birds, various fruits whose seeds are dispersed by birds as well as many noxious and presumed aposematic animals are most often colored combinations of red and/or black, yellow and/or black, or red, yellow and black. Incidentlaly, the black makes an excellent contrast and so enhances the other color next to it. It is appears that natural selection favors individuals that recall only one or two important clues for that is the prevalent trait in a wide range of animals in the world. Animals learn to associate food with any visual clue that fosters storage or those where the association is forgotten slower than other clues. It is found that many animals will never touch a potential food item if it is associated with a noxious experience, even when there is a delay in the negative experience and even if the noxiousness is from an external source. Each species is programmed to identify the good or forbidden food encountered in the future by its own set of rules. There is much research pointing to aposematic colors playing a large role. Despite the opportunities for escape and learning, over evolutionary time, there appears to be selection pressure for innate avoidance due to fatal encounters. An insect eating monkey when offered over 200 different species of insects will accept 83% of cryptically colored (camouflaged) species but only 16% of conspicuously colored ones. This was found to be so, even though many of the insects belonged to species that the monkey had previously never encountered. It seems that conspicuous colors of aposematic animals are very effective as a means of not being eaten. Many studies show that some mammals have clearly negative responses to coral snake patterns. This avoidance reaction occurs even in those species that were never exposed to coral snakes in their lifetime, but it seems in the past their ancestors would have encountered coral snakes. |
What is good or bad in getting food is important
It is remarkable that many young animals
are very alert to the feeding habits of others.
Imprinting, especially in birds is well documented.
Important in the motivation for learning:
Nutrient procurement
Safety and survival
Mating and reproduction
Elements of learning itself:
Perception and cognition
Storage of information
Recall of information
 There is a definite avoidance of coral snakes. There is ample evidence of predators learning to avoid dangerous snakes by witnessing an attack, and this empathic type of learning need not be restricted to social animals. Innate avoidance to the coral pattern may not be generalized to all birds however, those species from tropical zones that would have contact with them demonstrate a strong avoidance. There is data to show that when presented with painted wooden dowels, some birds would attack only the portion of the dowel painted with coral snake colors. |
 | It would seem quite evident that the color patterns of coral snakes can certainly be recognized either by learning or as innate signals to stay away. Since these colors do in fact serve to warn potential predators of a true fatal threat or highly undesirable encounter, they certainly fit the criteria for being aposematic. |
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Warning!
Colors!
Part 2:
Evolutionary Explanations
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Selection for Being Conspicuous
The first to suggest that the conspicuous color of some animals might have evolved through natural selection as a warning to predators was Alfred Russel Wallace. This was in reply to a letter from Charles Darwin in 1866. Darwin's enthusiastic response to Wallace prompted Wallace to request data that could be used to test the hypothesis at a meeting of the Entomological Society of London. It was this that lead John Jenner Weir to conduct experiments for 2 years with brightly colored caterpillars and birds that prey on them. His results provided the first experimental evidence for warning coloration in animals. The term aposematism itself was introduced by Edward Bagnall Poulton, a friend of Wallace, in The Colours of Animals (1890).
The significance of aposematic coloration has numerous and broad implications in ecology. For example in visual perception, communication and learning in predator/prey interactions, the mechanisms and environmental conditions in natural selection, insight into the convergence of traits, and the paradox of a fatal prey model in mimicry, just to mention a few.
| Under certain circumstances conspicuous coloration and pattern may in fact be cryptic. A predator not tuned for colors that are easy to distinguish or a background where these colors blend or even a disruptive pattern can serve to camouflage an individual. There are pigments that due to their structure show remarkable color change in different light intensity or angle. In various lighting conditions the radiance and reflective transmission of color can be dramatically decreased. And this can be coupled with the loss of contrast on a similar background or even by interference. These pigments have a remarkable color change in different light intensity or angle, due to their structure.  As well, bars or bands at certain spatial frequencies are in fact cryptic. An example of this are a zebra's stripes. At twilight they actually make a zebra well hidden even at close range. In other situations, the combination of quick movement and banded patterns may appear an achromatic grey blur to animals due to a well known optical effect in perception. |
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 The basic premise of aposematic coloration is that the usefulness or adaptive quality of these phenotypes is that they function in some way for predator avoidance of the individual. Predator-prey interactions will for the sake of predator avoidance, select for evolutionary compromises based on the strategy of an investment made to make predation difficult, since it is unlikely to be made impossible. Such an individual is marked in a manner which as a first line of defense warns potential predators of it's second line of defense, namely the genuine risk of harm to the predator. The risk of loss of life by standing out is compensated by the advantages of these traits such as increasing the chances for that individual's survival, but also its' offspring or its' relatives. Whether color occurs first, after, or simultaneously with being noxious being this scenario asserts that some conspicuous phenotypes will be sacrificed in order for a predator to learn and make an association of the unpleasant experience with the color pattern. The experience itself must be noxious enough to deter further attack and reinforce the learning but with a minimum number of trails so as to allow the density of prey to be relevant. This will have selective pressures on the predator to have a high motivation for learning certain color patterns well (and quickly). In some cases, as in long established or fatal prey interactions, an innate reaction of avoidance would be expected as is often seen. In this case, the prey is expected to be selected for a striking and unambiguous signal that would be clearly identifying the sender. The result would tend to a stabilizing selection for the color pattern and lower the variation in the trait used by the receiver's optical system. The effect of this would be greatly enhanced if the signal is fixed and "always on", so that attacks by predators will be discouraged regardless of whether the prey is aware of the predator. Important in this, is the relationship between the advertised color and its visual perception by the predator as well as the convergence of aposematic patterns and their relation to the environment such as free exposure, diurnal activity and the organism's behaviors. Important in being conspicuous are 3 the factors of available light, the background and the transmissivity. These factors in the conspicuousness of animals reveal a tendency for increased motion, that is in particular directional, repetitive and usually of sudden on set. In the patterns there is generally geometric regularity and surface contrast especially with colors outlined in contrasting hues of red and yellow, as well as spacial repetition. |
| Conspicuous coloration doesn't necessarily need to start out being aposematic. It is possible that if other functions of these colors provide do advantages over crypsis or dull colors, then selection may have operated on several factors for this phenotype. A consequence of this would be the development of defenses in response to the increased predation brought on by being conspicuous. In coral snakes and its' related elaphids, it seems that this scenario may apply in so far as the development of defenses since the colors and patterns of coral snakes, cobras and other snakes do conver other advantages in their ecology. |
| Coloration may also be used for species identification, especially for mating. This can be extemely important since an encounter with a similar colored aggressive mimic predator could be fatal. In the case of coral snakes, there are species of king snakes that range in coral snake regions. King snakes are not venomous, they are constrictors and as their name may suggest, they prey on other snakes. King snakes have the interesting adaptation of being immune to most types of snake toxin, they are also quick and strong and can even take on (and regularly eat) rattlers. Although they are less immune to elaphid venom they are also extremely good mimics of coral snakes. | I've owned a California King snake as a pet. I got him as a hatchling and raised for over 10 years. |
   | Thermoregulation is another possible function of color. Black can exaggerate heat gain. There are many short and long term benefits to this. Let's say for example... a reptilian predator that hunts early in the morning. A black color would be an advantage if this allowed the predator to warm its' muscles a little sooner and get jump on its' prey. In poikilotherms, developmental processes are also temperature dependent. An increased metabolic rate would always foster growth but this is especially useful for predators that rest for digestion that would be helped by passive heat absorption. Even only slightly warmer animals in a population of poikilotherms can increase the rate of other metabolic processes and thus confer higher fecundity.  Other advantages to black coloration is seen in diurnal desert reptiles. Here there is the added benefit of protection from ultraviolet rays that penetrate tissue and cause dimerization in DNA. These induced mutations as well as other structural damage can be mitigated by melanin. Melanin is noted for maintaining the rigidness of structures in which it is deposited. There is also evidence that melanin pigments reduce water loss and thus give some protection against dessication. But black and melanin pigments aren't the whole story. (I'm resisting the urge to pun orange is the new black...) Carotenoids are responsible for red and yellow pigments. They may also serve as protective coloration and have been suggested to function against excessive radiation as well as visual signals. |
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Warning!
 Colors! Part 1: An Introduction to Aposematics and Coral Snakes |
| Aposematic Coloration
The term aposematic is a word whose Greek origin means keeping away and connotes eliciting a distaste for food. Using the term coloration in relation to the aposematic trait may be incomplete since the coloration of the animals with this attribute is mostly in association with patterns as well.
The significance of this phenomenon
has numerous and broad implications
in ecology and evolution
The notion of coloration as an adaptive trait and its importance as a phenotype for natural selection hasn't always been universally accepted (even after the publication of On the Origin of Species). A. F. Shull in "Evolution" (1936) suggests traits such as sexual selection, warning color and mimicry are insignificant and irrelevant to the point of being excluded from the doctrine of natural selection. Today, as Darwin originally did, biologists see the convergence of colors (and in some cases patterns) in clear association to ecological conditions as evidence for its role as a selected phenotype in a multitude of organisms.
While there are many animals that have warning colors, coral snakes are a vividly colored and a perfect example of the adaptive value of being conspicuously colored and in effect honestly advertising or warning potential predators of an unpleasant, harmful or deadly counter attack.
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 Part 1: Intro to Aposematics and Coral Snakes Part 2: Evolutionary Explanations Part 3: Conspicuous Coral Snakes |
Cobras are very present in Hindu lore,
especially as kingly protectors.
Pouring milk over a cobra
during the Nag Panchami festival.
AFP PHOTO/NARINDER NANU
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Eastern cultures have since ancient times revered snakes as immortals, protectors and especially as symbols of wisdom. The mythology of western cultures especially those of the Judeo-Christian, abound with references to the deceptiveness and threat of snakes. Without delving into the anthropological reasons as to why this is so, here's a well known expression to illustrate the point... The phrase "a snake in the grass" for most people conjures up an image of a sadistic creature disguising itself in order to inject venom into its hapless victim. That is to say, not for self-defense, not for food, but for evil pleasure. We even further emphasize the attitude, since they are poikilotherms, by calling this type of behavior 'cold-blooded".
 But, this is a cultural bias and just not true of nature. If fact we don't seem to be born with an instinct to fear snakes. it appears that is learned. Although I'll warrant that any snake will bite if only not to get stepped on. there is the ecological and evolutionary unsoundness of this sneaky snake scenario. There are many reasons why they don't really act this way, such as the energy costs of poison production, the lack of survival benefit, not to mention the potential loss of teeth and risk of infection just to name a few. The fact is, most snakes survive with the completely opposite strategy.
Quetzalcoatl The Feathered Serpent
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| Meet Mr. Coral Snake & Family
The coral snake is really several species all belonging to the genus Micrurus, of the cobra family Elaphidae. The are generally small (maximum recorded length about 5 feet) with a common length between 18 inches and 2 feet.
Their distribution ranges throughout the world in tropical, subtropical and neotropical regions. They usually live in forests but are also found in grass lands and deserts. Like virtually all these kinds of snakes (with the exception of a few cobras, which are arrogant) they are secretive and docile. In fact they will generally not bite humans unless stepped on, picked up or disturbed.
All coral snakes are diurnal, thus they have round eyes similar to non-venomous snakes rather than the ovals of nocturnal (and most other venomous) snakes. Coral snake eyes also have similar oil drops as birds, aiding their color vision for certain wavelengths of light.
The head of all coral snakes is blunt, the scales smooth and glossy. Micurus flavius (eastern coral snake) of the United States are banded in triads with alternating wide bands of red and black separated by narrow stripes of yellow. It is from this coral snake that the infamous phrase "red touching yellow is a dangerous fellow is derived. The pattern and order generally hold true although there are variations in proportion and intensity. Some species of coral have demonstrated melanism and others toward albinism especially with the yellows tending to white in the western species. But remember, this order of colors only applies to these snakes in North America! On other continents coral snakes do not necessarily follow this pattern.
Like all snakes, coral snakes are carnivores. They are extremely quick and nimble, preying specifically on other snakes, yet they may take lizards and other reptiles. Prey are killed by venom only if the prey is dangerous. The venom is highly neurotoxic though small in quantity.
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 Coming up in future posts, more about coral snakes, how conspicuousness or cryptic their pigments can be and the evolutionary factors in their aposematic coloration. |
