Monthly Archives: February 2017

Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions. Bird, bat and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions.

The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to but different from parallel evolution. Parallel evolution occurs when two independent but similar species evolve in the same direction and thus independently acquire similar characteristics; for instance, gliding frogs have evolved in parallel from multiple types of tree frog.

Many instances of convergent evolution are known in plants, including the repeated development of C4 photosynthesis, seed dispersal by fleshy fruits adapted to be eaten by animals, and carnivory.

In morphology, analogous traits arise when different species live in similar ways and/or a similar environment, and so face the same environmental factors. When occupying similar ecological niches (that is, a distinctive way of life) similar problems can lead to similar solutions.[1][2][3] The British anatomist Richard Owen was the first to identify the fundamental difference between analogies and homologies.[4]

In biochemistry, physical and chemical constraints on mechanisms have caused some active site arrangements such as the catalytic triad to evolve independently in separate enzyme superfamilies.[5]

In his 1989 book Wonderful Life, Stephen Jay Gould argued that if one could "rewind the tape of life [and] the same conditions were encountered again, evolution could take a very different course".[6]Simon Conway Morris disputes this conclusion, arguing that convergence is a dominant force in evolution, and given that the same environmental and physical constraints are at work, life will inevitably evolve toward an "optimum" body plan, and at some point, evolution is bound to stumble upon intelligence, a trait presently identified with at least primates, corvids, and cetaceans.[7]

In cladistics, a homoplasy is a trait shared by two or more taxa for any reason other than that they share a common ancestry. Taxa which do share ancestry are part of the same clade; cladistics seeks to arrange them according to their degree of relatedness to describe their phylogeny. Homoplastic traits caused by convergence are therefore, from the point of view of cladistics, confounding factors which could lead to an incorrect analysis.[8][9][10][11]

In some cases, it is difficult to tell whether a trait has been lost and then re-evolved convergently, or whether a gene has simply been switched off and then re-enabled later. Such a re-emerged trait is called an atavism. From a mathematical standpoint, an unused gene (selectively neutral) has a steadily decreasing probability of retaining potential functionality over time. The time scale of this process varies greatly in different phylogenies; in mammals and birds, there is a reasonable probability of remaining in the genome in a potentially functional state for around 6 million years.[12]

When two species are similar in a particular character, evolution is defined as parallel if the ancestors were also similar, and convergent if they were not.[a] Some scientists have argued that there is a continuum between parallel and convergent evolution, while others maintain that despite some overlap, there are still important distinctions between the two.[13][14][15]

When the ancestral forms are unspecified or unknown, or the range of traits considered is not clearly specified, the distinction between parallel and convergent evolution becomes more subjective. For instance, the striking example of similar placental and marsupial forms is described by Richard Dawkins in The Blind Watchmaker as a case of convergent evolution, because mammals on each continent had a long evolutionary history prior to the extinction of the dinosaurs under which to accumulate relevant differences.[16]

The enzymology of proteases provides some of the clearest examples of convergent evolution. These examples reflect the intrinsic chemical constraints on enzymes, leading evolution to converge on equivalent solutions independently and repeatedly.[5][17]

Serine and cysteine proteases use different amino acid functional groups (alcohol or thiol) as a nucleophile. In order to activate that nucleophile, they orient an acidic and a basic residue in a catalytic triad. The chemical and physical constraints on enzyme catalysis have caused identical triad arrangements to evolve independently more than 20 times in different enzyme superfamilies.[5]

Threonine proteases use the amino acid threonine as their catalytic nucleophile. Unlike cysteine and serine, threonine is a secondary alcohol (i.e. has a methyl group). The methyl group of threonine greatly restricts the possible orientations of triad and substrate, as the methyl clashes with either the enzyme backbone or the histidine base. Consequently, most threonine proteases use an N-terminal threonine in order to avoid such steric clashes. Several evolutionarily independent enzyme superfamilies with different protein folds use the N-terminal residue as a nucleophile. This commonality of active site but difference of protein fold indicates that the active site evolved convergently in those families.[5][18]

Convergence occurs at the level of DNA and amino acids. In 2013 the first genome-wide study of convergence was published. Comparisons of the genomes of echolocating bats and the dolphin identified numerous convergent amino acid substitutions in genes implicated in hearing and vision.[19]

Swimming animals including fish such as herrings, marine mammals such as dolphins, and ichthyosaurs (of the Mesozoic) all converged on the same streamlined shape.[20][21] The fusiform bodyshape (a tube tapered at both ends) adopted by many aquatic animals is an adaptation to enable them to travel at high speed in a high drag environment.[22] Similar body shapes are found in the earless seals and the eared seals: they still have four legs, but these are strongly modified for swimming.[23]

The marsupial fauna of Australia and the placental mammals of the Old World have several strikingly similar forms, developed in two clades, isolated from each other.[7] The body and especially the skull shape of the thylacine (Tasmanian wolf) converged with those of Canidae such as the red fox, Vulpes vulpes.[24]

As a sensory adaptation, echolocation has evolved separately in cetaceans (dolphins and whales) and bats, but from the same genetic mutations.[25]

One of the best-known examples of convergent evolution is the camera eye of cephalopods (such as squid and octopus), vertebrates (including mammals) and cnidaria (such as jellyfish).[27] Their last common ancestor had at most a simple photoreceptive spot, but a range of processes led to the progressive refinement of camera eyes with one sharp difference: the cephalopod eye is "wired" in the opposite direction, with blood and nerve vessels entering from the back of the retina, rather than the front as in vertebrates. This means that cephalopods do not have a blind spot.[7]

Birds and bats have homologous limbs as they are both ultimately derived from terrestrial tetrapods, but their flight mechanisms are only analogous, so their wings are examples of functional convergence. The two groups have powered flight, evolved independently. Their wings differ substantially in construction. The bat wing is a membrane stretched across four extremely elongated fingers and the legs. The airfoil of the bird wing is made of feathers, strongly attached to the forearm (the ulna) and the highly fused bones of the wrist and hand (the carpometacarpus), with only tiny remnants of two fingers remaining, each anchoring a single feather. So, while the wings of bats and birds are functionally convergent, they are not anatomically convergent.[3][28] Similarly, the extinct pterosaur also shows an independent evolution of vertebrate fore- and hindlimbs to wing. An even more distantly related group, the insects, have wings that evolved separately from different organs.[29]

Flying squirrels and sugar gliders are much alike in their body plans with gliding wings stretched between their limbs, but flying squirrels are placental mammals while sugar gliders are marsupials, widely separated within the mammal lineage.[30]

Insect mouthparts show many examples of convergent evolution. The mouthparts of different insect groups consist of a set of homologous organs, specialised for the dietary intake of that insect group. Convergent evolution of many groups of insects led from original biting-chewing mouthparts to different, more specialised, derived function types. These include, for example, the proboscis of flower-visiting insects such as bees and flower beetles,[31][32][33] or the biting-sucking mouthparts of blood-sucking insects such as fleas and mosquitos.

Opposable thumbs allowing the grasping of objects are most often associated with primates, like humans, monkeys, apes, and lemurs. Opposable thumbs also evolved in pandas, but these are completely different in structure, having six fingers including the thumb, which develops from a wrist bone entirely separately from other fingers.[34]

Convergent evolution in humans includes blue eye colour and light skin colour. When humans migrated out of Africa, they moved to more northern latitudes with less intense sunlight. It was beneficial to them to reduce their skin pigmentation. It appears certain that there was some lightening of skin colour before European and Chinese lineages diverged, as there are some skin-lightening genetic differences that are common to both groups. However, after the lineages diverged and became genetically isolated, the skin of both groups lightened more, and that additional lightening was due to different genetic changes.[35]

Lemurs and humans are both primates. Ancestral primates had brown eyes, as most primates do today. The genetic basis of blue eyes in humans has been studied in detail and much is known about it. It is not the case that one gene locus is responsible, say with brown dominant to blue eye color. However, a single locus is responsible for about 80% of the variation. In lemurs, the difference(s) between blue and brown eyes are not completely known, but the same gene locus is not involved.[36]

While convergent evolution is often illustrated with animal examples, it has often occurred in plant evolution. For instance, C4 photosynthesis, one of the three major carbon-fixing biochemical processes, has arisen independently up to 40 times.[37][38] About 7,600 plant species of angiosperms use C4 carbon fixation, with many monocots including 46% of grasses such as maize and sugar cane,[39][40] and dicots including several species in the Chenopodiaceae and the Amaranthaceae.[41][42]

A good example of convergence in plants is the evolution of edible fruits such as apples. These pomes incorporate (five) carpels and their accessory tissues forming the apple's core, surrounded by structures from outside the botanical fruit, the receptacle or hypanthium. Other edible fruits include other plant tissues;[43] for example, the fleshy part of a tomato is the walls of the pericarp.[44] This implies convergent evolution under selective pressure, in this case the competition for seed dispersal by animals through consumption of fleshy fruits.[45]

The emergence of seed dispersal by ants (myrmecochory) has evolved independently more than 100 times, and is present in more than 11,000 plant species. It is one of the most dramatic examples of convergent evolution in biology.[46]

Carnivory has evolved multiple times independently in plants in widely separated groups. In three species studied, Cephalotus follicularis, Nepenthes alata and Sarracenia purpurea, there has been convergence at the molecular level. Carnivorous plants secrete enzymes into the digestive fluid they produce. By studying phosphatase, glycoside hydrolase, glucanase, RNAse and chitinase enzymes as well as a pathogenesis-related protein and a thaumatin-related protein, the authors found many convergent amino acid substitutions. These changes were not at the enzymes' catalytic sites, but rather on the exposed surfaces of the proteins, where they might interact with other components of the cell or the digestive fluid. The authors also found that homologous genes in the non-carnivorous plant Arabidopsis thaliana tend to have their expression increased when the plant is stressed, leading the authors to suggest that stress-responsive proteins have often been co-opted[b] in the repeated evolution of carnivory.[47]

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Convergent evolution - Wikipedia

Autism genes may have been conserved during human evolution because they make us smarter, say scientists.

More inherited genetic variants linked to autism have been naturally selected than would be expected by chance, a study has shown.

The same variants were associated with traits linked to brain performance, such as molecular functions involved in the creation of new neurons.

Lead researcher Dr Renato Polimanti, from Yale School of Medicine in the US, said: We found a strong positive signal that, along with autism spectrum disorder, these variants are also associated with intellectual achievement.

Under the laws of natural selection outlined by Charles Darwin, evolutionary variants that have a negative impact on reproductive success are quickly eliminated from a population.

But those providing a better chance of survival tend to remain for generation after generation, if their advantages outweigh their adverse effects.

Meet the Labrador changing the life of a little boy with autism

Study co-author Professor Joel Gelernter, from Yale University, said: It might be difficult to imagine why the large number of gene variants that together give rise to traits like ASD (autism spectrum disorder) are retained in human populations.

Why aren't they just eliminated by evolution?.

The idea is that during evolution these variants that have positive effects on cognitive function were selected, but at a cost - in this case an increased risk of autism spectrum disorders."

The scientists, whose findings are published in the journal Public Library of Science Genetics, studied more than 5,000 cases of ASD and conducted an analysis of evolutionary gene selection.

PA

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Autism genes conserved during human evolution to make us ... - The Independent

BOSTON In humans mysterious journey to become intelligent, socializing creatures like no other in the animal world, one innovation played an essential role: religion.

Thats the theory that a preeminent evolutionary scientist is setting out to prove.

You need something quite literally to stop everybody from killing everybody else out of just crossness, said Robin Dunbar. Somehow its clear that religions, all these doctrinal religions, create the sense that were all one family.

[Fear of a vengeful God may explain humanitys global expansion]

Dunbar, an evolutionary psychology professor at Oxford University, gained some measure of fame more than 20 years ago for his research on the size of animals social networks. Each species of primate, he found, can manage to keep up a social bond with a certain number of other members of its own species. That number goes up as primates brain size increases, from monkeys to apes.

Humans, Dunbar found, are capable of maintaining significantly more social ties than the size of our brains alone could explain. He proved that each human is surprisingly consistent in the number of social ties we can maintain: About five with intimate friends, 50 with good friends, 150 with friends and 1,500 with people we could recognize by name. That discovery came to be known as Dunbars number.

And then Dunbar turned to figuring out why Dunbars number is so high. Did humor help us manage it? Exercise? Storytelling? That riddle has been Dunbars quest for years and religion is the latest hypothesis hes testing in his ongoing attempt to find the answer.

Most of these things were looking at, you get in religion in one form or another, he said.

[Harvard Medical School professor says faith-based miracle cures could be real]

Dunbar is just one of a recent wave of scientists who are interested in how religion came to be and how people have benefited from it. For most of Western intellectual history since the Enlightenment, religion has been thought of as ignorant and strange and an aberration and something that gets in the way of reason, said Christian Smith, a sociologist at the University of Notre Dame who studies religion. In the last 10 or 20 years on many fronts, theres been a change in thinking about religion, where a lot of neuroscientists have been saying religion is totally natural. It totally makes sense that were religious. Religion has served a lot of important functions in developing societies.

In the case of Dunbar and his colleagues, they already published research demonstrating that two other particularly human behaviors increased peoples capacity for social bonding. In the lab, they showed that first, laughter, and second, singing, left research subjects more capable of forming connections with other people than they were before.

Religion is the remaining key to explaining humans remarkable social networks, Dunbar thinks. These three things are very good at triggering endorphins, making us feel bonded, he said last week at the American Association for the Advancement of Sciences annual meeting, where he presented his teams research on laughter and singing and introduced the forthcoming research on religion.

[Religion doesnt necessarily influence Americans views on science, with two big exceptions]

Religion includes numerous elements of Dunbars earlier studies on endorphin-producing activities. Lots of singing, to start. Repetitive motion triggers endorphins, he said, noting that traditions from Catholicism to Islam to Buddhism to Hinduism make use of prayer beads.

Plus, researchers have shown that doing these activities in synchronized fashion with other people drastically magnifies the endorphin-producing effect: Picture the coordinated bowing that is central to Muslim, Jewish and Catholic worship.

And Dunbars most recent published research demonstrated the effectiveness of emotional storytelling in bonding groups of strangers who hear the story together again, a fixture of religious worship.

What you get from dance and singing on its own is a sense of belonging. It happens very quickly. What happens, I suspect, is that it can trigger very easily trance states, Dunbar said. He theorizes that these spiritual experiences matter much more than dance and song alone. Once youve triggered that, youre in, I think, a different ballgame. It ramps up massively. Thats whats triggered. Theres something there.

Dunbars team will start research on religion in April, and he expects it will take three years. To begin, he wants to map a sort of evolutionary tree of religion, using statistical modeling to try to show when religious traditions evolved and how they morphed into each other.

Of course, religious people themselves might find Dunbars theory odd most dont think of religion existing to serve an evolutionary purpose, but of their faiths simply being true.

But Smith thinks one can easily have faith in both Gods truth and religions role in human development. From the religious point of view, you can say this . God created humans as a very particular type of creature, with very particular brains and biology, just so that they would develop into the type of humans who would know God and believe in God, Smith said. Theyre not in conflict at all.

He added: A lot of people assume, falsely, that science and religion are zero-sum games: that if science explains something, then religion must not be true. If you were God and wanted to set up the world in a certain way, wouldnt you create humans with bigger brains and the ability to imagine?

One more research finding onthe place of God in our brains remember Dunbars number, the five intimate friends and 50 good friends and 150 friends each person can hold onto? Dunbar says that if a person feels he or she has a close relationship with a spiritual figure, like God or the Virgin Mary, then that spiritual personage actually fills up one of those numbered spots, just like a human relationship would. One of your closest friends, scientifically speaking, might be God.

Want more stories about faith? Follow Acts of Faithon Twitteror sign up for our newsletter.

Jesus had a body. Heres why that matters for Lent.

How do you prick the conscience of an NFL fan? The problem with uncritical football fandom.

Engineering an advanced human? The more religious you are, the less likely youll want to.

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A scientist's new theory: Religion was key to humans' social evolution - Washington Post

For those in Pokemon GO about to evolve their Eevee into the first Espeon or Umbreon theyve ever had, pay attention. The most recent chart of Eevolutions, methods, and best potential outcomes has arrived. Barring all Pokemon GO hacks and whatnot, were having a look at the insides of the software to show you exactly whats possible for Eevee in the wild.

The first thing were going to do is list the most updated chart on whats possible with wild Eevee captures. This list includes the minimum CP and the max CP available for Eevee given power level. The minimum CP of any given Eevee is 10, while the max CP is 969. A max CP Eevee is extremely rare.

Eevee Wild Capture Stats: Max Wild Capture: 830 CP Global Spawn Rate: 2.75% Capture Rate: 30%+ Flee Rate: 10% Max Egg Hatch: 615 CP Egg Hatch Rate: 18%

As such, theres just under 3 Eevee hiding in every 100 Pokemon that pop up around the world at any given moment. The rarity of Eevee in general is dictated by the region in which the user is standing. Eevee is not a region-specific Pokemon, so theres nowhere where Eevee CANT pop up, but itll be more common in places like Residential Neighborhoods and University Campuses.

For those that wish to power up an Eevee before evolving dont even. Using Stardust to power up an Eevee costs the same as an Eevee as it does in any evolved form. It does not matter what evolution the Eevee is at any given time.

Pokemon have a hidden Level which dictates their minimum and maximum CP. Every Pokemon is always a Level between 1 and 40, and each time Stardust is given to a Pokemon, it grows 0.5 level. To raise the level of an Eevee from level 21 to level 21.5, itll cost a trainer 3000 Stardust. To raise the level of any evolved form of Eevee from level 21 to level 21.5, itll cost a trainer 3000 Stardust.

When evolving a Pokemon any Pokemon trainers should ALWAYS wait until the full evolution is complete before deciding to add Stardust. The final evolution will show what moves the Pokemon can do and theyre not always great. For Eevee, the final evolution can be one of five entirely different Pokemon that each have their own unique set of possible moves. Leveling up an Eevee before evolution is not a great idea.

In general its best to wait until finding an Eevee thats as close to maximum level as possible before evolving. Maximum level for Eevee in the wild is 30 thats the same for every Pokemon in the Pokemon GO universe. As such, the max WILD CAPTURE for Eevee is 830 CP.

SEE TOO: How to get Espeon or Umbreon in Pokemon GO

The best Eevee available in the wild will be between 642 CP and 830 CP. Once that Eevee is captured, it can be leveled up with Stardust up to level 40, where its max CP will be between 749 and 969. Again, dont DO that see Section 2. But thats the range youre dealing with.

Eevee Worth Evolving Minimum: 200+ CP* Maximum: 830 CP

*This is our opinion anything less than this and the Eevelution isnt going to be a worthy Gym attacker or defender. This is really up to you, when it comes down to it especially if youre targeting Pokemon types with types that are strong against certain types. If youre battling another Vaporeon, for example, you could potentially beat a level 2,000 with a Jolteon of level 1,000 since water is weak against lightning.

In the end it all comes down to what you want and what youre willing to wait for. For more information on HOW to get the Eevee evolution types youre wishing to get, including Jolteon, Vaporeon, Flareon, Espeon, or Umbreon, have a peek at the timeline below. Weve got more guides than youll know what to do with.

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Pokemon GO update: Eevee evolution charts tweaked - SlashGear

February 27, 2017 Credit: NASA, ESA and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics)

Thirty years ago, on 23 February 1987, the light from a stellar explosion marking the death of a massive star arrived at Earth to shine in Southern Hemisphere skies.

Located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, SN 1987A was the closest observed supernova to Earth since the invention of the telescope. Studying it for the last 30 years has revolutionised our understanding of the explosive death of massive stars.

In operation since 1990, the NASA/ESA Hubble Space Telescope has observed the supernova remnant many times, as highlighted in this montage. The images show its evolution between 1994 and 2016, and highlight the main ring that blazes around the exploded star.

A new wide-field image was also taken by Hubble in January 2017 to mark the 30 year anniversary.

By observing the expanding remnant material over the years, Hubble has helped to show that the material within the ring was likely ejected 20 000 years before the actual explosion took place.

The initial burst of light from the supernova initially illuminated the rings. They slowly faded over the first decade after the explosion, until a fast-moving shell of gas ejected during the supernova slammed into the central ring, sending a powerful shockwave through the gas, heating it to searing temperatures and generating strong X-ray emission.

This caused clumps of denser gas within the ring to light up like a string of pearls, seen as the increasing number of bright spots, which are now fading again.

As the shock wave continues to move through the shells ejected by the dying star in its final throes of life, who knows what new details will be revealed?

Explore further: The dawn of a new era for Supernova 1987a (Update)

Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following ...

(PhysOrg.com) -- Using the Hubble Space Telescope, astronomers are witnessing the unprecedented transition of a supernova to a supernova remnant, where light from an exploding star in a neighboring galaxy, the Large Magellanic ...

(PhysOrg.com) -- In 1987, light from an exploding star in a neighboring galaxy, the Large Magellanic Cloud, reached Earth. Named Supernova 1987A, it was the closest supernova explosion witnessed in almost 400 years, allowing ...

This NASA/ESA Hubble Space Telescope image captures the remnants of a long-dead star. These rippling wisps of ionized gas, named DEM L316A, are located some 160,000 light-years away within one of the Milky Way's closest galactic ...

(PhysOrg.com) -- The delicate shell, photographed by the NASA/ESA Hubble Space Telescope, appears to float serenely in the depths of space, but this apparent calm hides an inner turmoil. The gaseous envelope formed as the ...

Twenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery ...

Planets are thought to form in the disks of dust and gas found around young stars. But astronomers have struggled to assemble a complete theory of their origin that explains how the initial dust develops into planetary systems. ...

Evidence of planetary debris surrounding a double sun, 'Tatooine-like' system has been found for the first time by a UCL-led team of researchers.

When the universe was young, a supermassive black holebloated to the bursting point with stupendous powerheaved out a jet of particle-infused energy that raced through the vastness of space at nearly the speed of light.

(Phys.org)A team of astronomers led by Favio Faifer of the National University of La Plata, Argentina, has discovered the first ultra-compact dwarf (UCD) galaxy in an X-ray bright galaxy group designated NGC 5044. The ...

Hunting for habitable exoplanets now may be easier: Cornell University astronomers report that hydrogen pouring from volcanic sources on planets throughout the universe could improve the chances of locating life in the cosmos.

Astronomers based at the University of Sheffield have found evidence that stars are ripped apart by supermassive black holes 100 times more often than previously thought.

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Image: The evolution of supernova 1987A - Phys.org - Phys.Org