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How has natural selection happen over the years?

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How has natural selection happen over the years?

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This article is about a mouse that had evolved immune to mouse poison.

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How has natural selection happen over the years?

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How has natural selection happen over the years?

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This salamander evolution in action!!!!

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How has natural selection happen over the years?

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How has natural selection happen over the years?

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This an article with 12 examples of natural selection. I learned all about how these animals evolved over the years.

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ForestWander/WikiMedia Commons
So much for high school biology.

And we are it's primary drivers.

Bedbugs are becoming a new species of nightmare insects.

While you might be familiar (a little too familiar, you might say), with bedbugs, they didn't always used to be the terrifying critters we know today.

Thousands of years ago, our cave-dwelling ancestors got along perfectly fine with bedbugs - mainly because they were nearly an entirely different species back then. Unfortunately, as humans migrated out of caves and into cities over thousands of years, they brought bedbugs along for the ride. The insects with traits that made them better able to survive their new urban lifestyle - such as being more active at night, when humans sleep, and having longer, thinner legs for hopping away from us quickly - outlived their less-evolved bedbug friends.

In just the last few decades, these city-dwelling insects have become almost an entirely separate species from their cave-dwelling cousins. In addition to their new penchant for the nightlife, today's urban bedbugs have also evolved resistance to pesticides: They have thicker, waxier exoskeletons (to shield them from toxins) and faster metabolisms (to beef-up their natural chemical defenses).

Two distinct species of mice are mating and their hybrid mice pups are immune to pesticides.

Typically, members of two different species can't mate with one another - and if they do, the offspring they produce are often infertile or so weak they die before they can produce any babies.

In mice, at least 50% of hybrids are sterile. But sometime in the past 50 years, when wandering Europeans brought together the Algerian mouse ( Mus spretus) and the common house mouse ( Mus musculus), the two species got to mating.

Miraculously, their mice pups were fertile. Although rare, this sort of thing can happen every so often with just the right combination of genes. In addition to their baby-making capabilities, the hybrid mice got another gift from their parents: a chunk of genes that makes them immune to the poison warfarin, meaning they can't be killed by pesticides.

Unlike the house mice, the Algerian mice had this poison-resistance gene naturally - they likely evolved it as an adaptation to a vitamin-K diet (the same gene that's responsible for warfarin-immunity manages vitamin K in the body.)

Clepto sea slugs steal genes from their food and incorporate them into their own DNA.

How to adapt to survive for months on nothing but sunlight? Try taking a cue from plants. Better yet, steal a few of their genes.

When food in the chilly coastal waters where they live runs scarce, the bright green sea slug snatches chunks of DNA from the algae they eat. Coupled with tiny energy-producing powerhouses called chloroplasts (which the sneaky slugs also pilfer from their algeae meals), the stolen genes are enough to allow the slugs to survive on nothing but sunshine for days.

The best part? The algae genes get passed onto the next generation of slugs.

Although future slugs will then come pre-equipped with the algae genes in their DNA, they'll still need to snatch up new chloroplasts to keep the process going. This gene-swapping process is called horizontal gene transfer. By doing it, the slugs are effectively bypassing traditional evolution, which typically happens over thousands or millions of years. So far, these sea slugs are one of the only known examples of this process occurring between multicellular organisms.

Humans have used artificial selection to create crazy specific dog breeds.

There's nothing "natural" about the silky-smooth fur, distinctive coloring, or even the friendly personality we've come to associate with man's best friend.

Over the past 150 years or so, humans have been specifically mating dogs that look a certain way to create the animals we now keep as pets via a process known as breeding. This is artificial selection, where one species (humans) directs the traits that get passed down to future generations of another species (dogs).

It's important to keep in mind, though, that all our selective pressures still haven't resulted in any new dog species (cocker spaniels and poodles can still interbreed, for example) but merely a bunch of breeds. Nevertheless, our actions can be seen in the doggie genome, the collection of all of its genes. At least favoring traits from skin wrinkling (like that seen in the Shar-Pei) to coat and size. 155 different regions show evidence of strong recent selection

Plus, these changes are still happening, as breeders mix and match breeds to create pets like labradoodles (labrador retriever and poodle mixes), and cockapoos, (cocker spaniel and poodle mixes).

Stray dogs that have left human care are evolving more wolf-life traits.

Although dogs separated from their wolf ancestor around 18,000 years ago, several new groups of pups that are more genetically similar to wolves have begun to show up around the world sometime within the past 150 years.

This is a good example of what happens when a strong evolutionary pressure, like humans' intensive practice of breeding dogs for favorable traits, is suddenly removed.

Stray dogs in Moscow, for example, who've been living largely separate from humans for the past several hundred years, have evolved to be expert beggars. Because the survival rate in the wild for these animals is so low, their evolution has happened at a superfast pace: the strays who have the traits that help them survive (they're unfriendly toward humans, feeding only on their trash, they have superior navigation skills, etc.) pass those traits onto their pups.

Moths living around dirty humans evolved darker wings to blend into their sooty surroundings.

The peppered moth can most easily be spotted on a dark surface: its distinctive off-white wings, speckled with tiny dark spots, make it stand out.

During the industrial revolution in Britain and the US, when humans started pumping their air full of pollutants, that dark soot fell on trees, darkening their bark and endangering the moth, who'd easily be picked out by predators on a shadowy tree. Over several generations, as the lightest moths were eaten and the darker moths tended to survive, the majority of moths in the region became dark via a process called natural selection.

But when pollution control laws in both countries started to scale back the amount of soot in the air in the 1970s, dark moths again became more prone to getting eaten. Today, most moths have returned to their original light color.

Humans created a new top predator that is taking over the Northeast.

And you thought coyotes were terrifying.

A new hybrid of the coyote and the wolf, or coywolf, that first emerged in the last few decades is now coming out in droves in the Northeastern US. About 2/3 of the coywolves' DNA is from wolves, while another 1/4 is from coyotes. The remainder is from domesticated dogs.

But nothing about these animals is domestic. They're even bigger than either their wolf or coyote ancestors, weighing in at as much as 140 pounds. They're also social, like wolves, meaning they tend to hunt in packs.

Coyotes and wolves would likely have never come together in the first place if not for human farming and hunting practices, which drove the wolf north and coyotes east. But they're definitely here to stay - the coywolf's unique genetic makeup appears to be particularly appropriate for its northern habitat - moreso, even, than either of its parent species, meaning the hybrid genes will likely keep getting passed down to future generations. While the DNA from the wolf appears to allow the coywolf to hunt larger prey, the coyote DNA helps it adapt rapidly to urban areas.

Bacteria have evolved to outsmart our antibiotics - and we're on the cusp of an "apocalyptic scenario."

National Institute of Allergy and Infectious Diseases/Flickr

Doctors commonly treat bacterial infections with antibiotics . When one drug doesn't work, they try another. But now, physicians are finding that some of our infections are resistant to even our strongest drugs. The bacteria have, genetically speaking, outsmarted us. Those with traits that allow them to survive in antibiotic-rich environments pass them onto future generations, making each successive strain more resistant to our drugs than the last.

Last year, 23,000 Americans died from bacterial infections that didn't respond to antibiotics. Certain strains of "nightmare bacteria" kill up to half of the patients they infect, and cases are becoming increasingly common across 42 states.

The problem isn't exclusive to the US, though. Because of our global overuse of these drugs - and our increasing reliance on them - antibiotic-resistant bacteria could kill up to 10 million people worldwide each year by 2050, according to a recent report from the Healthcare Infection Society.

A special fish managed to beat the toxic pollution of New York City's dirtiest river.

Normandeau Associates, Inc./Mark Mattson

When New Yorkers started dumping PCBs (a type of industrial toxin) in the Hudson River in 1929, they wiped out a large majority of its wildlife.

But at least one species survived - and thrived. Over the span of a few decades (PCBs were banned in 1979) a fish called the tomcod evolved to resist the poison via natural selection.

Fish with a special set of genes that make a key poison-shielding protein were the only critters to survive the toxic onslaught. They, in turn, passed their protective genes onto their offspring.

Happy fishing!

An evil-looking amphibian took over Australia's east coast, harming other plants and wildlife.

About 75 years ago, the Australian sugar bureau decided to lug a handful of South American cane toads from Hawaii to Australia with the idea that they'd rid the country of the sugar-cane-devouring cane beetle. On their new continent, where they lacked their natural predators, the toad population immediately exploded.

Typically when an invasive species is first introduced to a new continent, its population levels stay low for a few decades before growing exponentially.

But these toads expanded rapidly, likely because of several adaptive traits that allowed them to travel faster and farther. Compared with their pioneering ancestors, the toads in Australia today have longer legs and hop much quicker, since they were able to move faster and were always at the forefront of an invasion into a new area. When they mate, they pass their longer legs onto their offspring.

A pest that thrives on one of our favorite foods is developing immunity to the toxins we use to keep it at bay.

Corn is one of the staples of American cuisine. It's derivatives are in everything from candy and soda to hamburger patties and fast-food taco meat. To soothe our corn sweet tooth, we've begun growing the crop in massive quantities, making powerful pesticides necessary to kill of pests that feed on the increasingly vulnerable plant.

Unfortunately, our overuse of pesticides have, in turn, spurned genetically stronger pests.

When the western corn rootworm, for example, developed a resistance to the chief pesticide in Monsanto's GMO corn (a gene designed to produce a special protein to destroy the worm's digestive tract), the company responded by switching up the pesticide in its corn to another type of protein. The worms evolved to resist it that as well.

Plants developed perfect bird perches to lure their potential pollinators.

This South African flower, whose gorgeous red tubular flowers blossom close to the ground, looks upside down.

In a sense, it is. The type of birds that typically polinate the plant are relatively scarce in the western portion of the country, and they avoid the ground, where they make easy prey for predators.

As a result, natural selection favored the versions of this low-lying plant that featured stems shooting upwards from the ground - skittish, ground-shy birds would perch on those plants to feed, and the pollinated upside-down plants outlived the non-pollinated stemless plants.

How do scientists know this is evolution at work and not simply some weird-looking plant?

In the East, where there's a bigger variety of birds looking for potential sources of food, the stalk has receded over many generations, a process scientists call relaxed selection. As a result of this process, traits that were once useful gradually fade away in subsequent generations as they lose their utility.

Now that you've seen how we're creating risky changes to the plants and animals around us...

More: Biology Evolution Animals Genetics

For you

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12 examples of evolution happening right now

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So much for high school biology. And we are it's primary drivers. Bedbugs are becoming a new species of nightmare insects. While you might be familiar (a little too familiar, you might say), with bedbugs, they didn't always used to be the terrifying critters we know today.

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What would happen if there was no natural selection?

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What would happen if there was no natural selection?

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Tis article talks about what happens if there is no natural selection.

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" Nothing in biology makes sense except in light of evolution"

WHAT ARE SOME EMPIRICAL EXAMPLES OF THESE CONDITIONS FOR NATURAL SELECTION?
Differences in rates of survival and reproduction are the driving force behind natural selection, and they usually vary greatly among organisms in the natural world. The Atlantic cod (Gadus morhua) is a dramatic illustration of this. The average female cod produces 2 million eggs in a single spawning, which would clearly lead to billions of cod very quickly if each and every one survived. However, 99% of these eggs die in their first month, and 90% of those remaining after the first month will die before their first year. This means that only about 200 of the original 2 million cod survive to age one, and by the time the cod get to their reproductive age of 2-4 years on average only 2 of the original 2 million are still alive. It is quite clear that those two cod would have their genes represented disproportionately in the next generation, and therefore any heritable traits that allowed those two fish to survive and reproduce would have strong selective pressure.

Large mammals in the wild also generally display considerable variation in survival and reproduction, although perhaps not quite as dramatic as those seen in fish. Red deer are found in Europe and are closely related to the American elk. The reproductive success of females in a red deer population were carefully tracked over the entire lifetime of the animals (Fig. 5.2). As you can see in the figure, the most common outcome is that a female red deer does not manage to produce even a single offspring that lives to its first birthday. Among those red deer that do produce offspring that live to one year, the median number of offspring is only 4.5 per lifetime, while a small percentage of females manage to produce a dozen or more offspring that live to their first birthdays. As with the cod, it is readily apparent from these data that a relatively small number of organisms are passing down a disproportionate amount of the genetic material that comprises the subsequent generations.

While measuring variation in survival and reproduction strongly suggests that natural selection is in effect, fully verifying the conditions necessary for natural selection also requires linking these differences in survival and reproduction to a heritable trait. This was done in a classic 1950s study with a land snail, Cepea nemoralis, in Oxford England. The shells of these snails are highly variable, with some snails being solid in color and others have strong stripes or bands. Predation by birds is a major source of mortality for the snails. Censuses found that while 47% of the snail population was banded, 56% of the snails eaten by birds were banded. Clearly birds were preferentially eating the banded snails, perhaps because the unbanded snails were harder to see. This variation in survival would clearly cause selection for the spread of the genes for unbanded snails. The fact that there still remains so many banded snails in the population suggests that there are also other processes at work in the ecosystem that favor banded snails over the unbanded snails.

HOW DOES NATURAL SELECTION RELATE TO EVOLUTION?
Evolution is defined as a change in the gene frequencies of a population through time. Natural selection can lead to evolutionary changes because it tends to raise the frequency of genes that increase the relative probability of survival and reproduction for the organisms that possess them in a population. Hence, natural selection causes changes in the frequency of genes through time and thereby causes evolution. It should be noted, however, that there are other causes of evolution as well. Migration, genetic drift, genetic mutation, and non-random mating can all change the frequency of genes in a population. However, natural selection is the only cause of evolution that results in greater adaptation. An adaptation is a feature of an organism enabling it to survive and reproduce in its natural environment better than if it lacked that feature. For this reason, natural selection is an especially important process in evolution.

As scientists we would like to point out that there is very little scientific controversy regarding evolution. The theory of evolution is supported throughout the field of biology by thousands of examples and studies with no convincing evidence to refute it. There are some creationists who seek to discount the certainty that scientists have in evolution by saying that it is "just a theory." This in part stems from the fact that to scientists the term theory means something quite different than it does in the culture at large. To scientists a theory is a clearly defined set of general principles that have been mathematically described and repeatedly validated with experiments and field data. For example, physicists describe gravity and electricity with "the theory of gravity" and "the theory of electromagnetism" not because they are uncertain about the existence of gravity and electricity, but precisely because they are highly certain about the nature of these phenomena. By the same token, biologists call evolution a theory because it is a clear, powerful idea that is well supported by evidence. Few ideas in science ever have the importance, clarity and validation to be called theories. Evolution happens continuously everywhere there is life. To deny it exists is to deny our ability to learn how the world works through observation.

HOW IS NATURAL SELECTION RELEVANT TO WILDLIFE ECOLOGY AND MANAGEMENT?
Natural selection is at work to some degree in all ecological systems at all times. For that reason it is inevitable that it will have an influence on the interactions between humans and wildlife. One example of such an interaction is a phenomenon observed in many fisheries; after humans begin to harvest a population, the size of the average fish declines. Harvesting by humans reduces the lifespan of the average fish in a population. This means that a fish is better off starting to reproduce when it is younger and smaller, because if it waits until it is older and larger it may get harvested first and not reproduce at all. A tradeoff generally exists for organisms between putting energy into their own growth and into reproduction, as indicated in the tule perch example. Heavy harvesting by humans selects for those individual fish that reproduce younger and put more energy into reproduction rather than growth, and hence results in the average fish becoming smaller in the harvested population.

An area in which natural selection bears directly on human affairs is in the evolution of resistance to pharmaceutical drugs and pesticides by microbes and insects. Malaria was nearly eradicated in the mid 20th century because the mosquito species that carries the Plasmodium parasites were highly susceptible to the pesticide DDT, and drugs were discovered that attacked the parasites in the human bloodstream. However, natural selection favored those few individual mosquitoes that happened to be resistant to DDT and other pesticides, so that now many mosquitoes are resistant to our pesticides, and consequently malaria is increasingly difficult to control. The evolved resistance of mosquitoes to pesticides has combined with the evolved resistance of the parasite itself to antibiotic drugs, helping to make malaria a widespread disease again; it is currently a major cause of death and illness in many tropical countries. There is some speculation that malaria may become more widespread in temperate regions such as North America with climate change, because the warm conditions necessary for the mosquitoes that carry malaria may begin to occur at higher latitudes. Thus, the consequences of natural selection have very real implications for you, your family, and your lifestyle.

Additional reading. A number of books have been published in recent years that attempt to convey the majesty and wonder of natural selection and evolution to non-hard-core scientists.

Two very good books that come to mind are:

Table of Contents

1. Roots of the modern environmental dilemma: A brief history of the relationship between humans and wildlife
2. A history of wildlife in North America
3. Climatic determinants of global patterns of biodiversity
4. Biodiversity
5. Natural selection
6. Principles of ecology
7. Niche and habitat
8. Conservation biology
9. Conservation in the USA: legislative milestones
10. Alien invaders
11. Wildlife and Pollution
12. What you can do to save wildlife

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" Nothing in biology makes sense except in light of evolution" WHAT ARE SOME EMPIRICAL EXAMPLES OF THESE CONDITIONS FOR NATURAL SELECTION? Differences in rates of survival and reproduction are the driving force behind natural selection, and they usually vary greatly among organisms in the natural world.

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This book helped me to understand the general concept of natural selection. (pages 39-40)

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This video helped me to understand the general concept of natural selection.