Evolution is the change in frequency of the alleles in a gene pool over time; evolution is when a population of species gets more suited to its environment over time.
Evolution occurs with mutations and natural selection.
What happens is that in a population of species, not all of them are the same. For example, there is a whole colony of fish in a pond. Some of the fish are faster than the others. They reproduce and pass on their genes - these genes make their offspring fast as well. The other fish that aren't as fast, die out because they are not fast enough. The fast fish soon become more common, making the species as a whole faster. This occurs in several stages, where the slowest fish are removed each time, and the faster ones reproduce more often. Gradually, the fish get faster and faster as a group.
The second aspect is that these fish will often have differences in their genetic codes, called mutations. While bad mutations will normally result in fatality and not get passed on, some are useful and result in increased survival. When these mutations build up, the species we previously had may then become completely different from what is here now; the two groups cannot crossbreed, and have become different species.
Evolution is the change in frequency of the alleles in a gene pool over time; evolution is when a population of species gets more suited to its environment over time.
Evolution occurs with mutations and natural selection.
What happens is that in a population of species, not all of them are the same. For example, there is a whole colony of fish in a pond. Some of the fish are faster than the others. They reproduce and pass on their genes - these genes make their offspring fast as well. The other fish that aren't as fast, die out because they are not fast enough. The fast fish soon become more common, making the species as a whole faster. This occurs in several stages, where the slowest fish are removed each time, and the faster ones reproduce more often. Gradually, the fish get faster and faster as a group.
The second aspect is that these fish will often have differences in their genetic codes, called mutations. While bad mutations will normally result in fatality and not get passed on, some are useful and result in increased survival. When these mutations build up, the species we previously had may then become completely different from what is here now; the two groups cannot crossbreed, and have become different species.
Evolution is defined as changes in allele frequencies from one generation to the next. Therefore, anything that affects allelic frequencies in a population in fact causes evolution. Biological organisms - all of them - reproduce with genetic variation. Every new birth causes the tiniest shift in the number of times an allele occurs in the population. So technically, every new reproduction causes the population to evolve. Evolution happens when reproduction occurs.
Evolution occurs as two processes: mutation and natural selection.
Mutation: different genes get passed on, and some get altered so that they become something different. These are 99% harmless and make no difference. Sometimes they cause instant fatality or extreme disability (normally resulting in death in the natural world) but sometimes, they cause a useful change that eventually - through natural selection - makes it more common.
Natural selection: some genes make an organism more likely to survive. Those that do get the chance to pass such genes onwards to the next generation, where again, some are killed and a greater ratio survive. Eventually, these 'superior' genes are the majority of or even the only ones possessed in that population, making the population most able to survive in that environment. This occurs with every possible factor, and every gene that affects them.
Both require a long time to see any major difference; with very careful testing we can check for and find slight differences between several generations. When enough changes can accumulate, a new species may have emerged to replace or coexist with the original.
Evolution didn't "Happen" it is happening still. When a change in environment occurs some animals of a specific type cannot survive those animals will die. The animals that had a mutation, say we were talking about hummingbirds with a longer beak to reach necter, survived. So the hummingbirds that survived had longer beaks and therfore mated with other hummingbirds with long beaks and breated offspring with long beaks. Maybe when another change in environment occurs the hummingbirds with even longer beaks will survive again. The more this process goes on the longer the beak would get. Over time the hummingbirds could be considered a different species. Overpopulation Competition Variation Adaption Natural Selection speciation
it never did... God created everything you see. NOTHING started by chance; someone had to create and that someone was God the Creator himself. And the end of evolution will be the creation of God.
Answer
We don't entirely know how life started. Evolution (change by Natural Selection) can be regarded as concomitant with the concept of life. Once the first truly 'living' organism popped into existence we can assume that evolution had begun. In other words, where there be life, there be evolution.
Evolution (like life itself) must have started with simple and early (Precambrian) cells. Life these days is ruled by DNA. Today's cells are constructed by the 'instructions' in DNA. Today, before a bacterial cell divides, the DNA replicates so each daughter cell receives an identical set of 'instructions' on how to build a cell. Ah ha, not quite identical actually. The occasional error in DNA replication brings about mutations. If they remain in the population, then that population is variable. It would have been (in those Precambrian seas of early life) the origin of variation that got evolution going.
In those Precambrian seas, on the sea bed or under the first layer of rock of a rock or around a deep sea sulphur-spewing vent (we don't know where of course), life would have had to bear the terrors of variation in the environment. Just a few metres from those boiling sulphur-spewing vents the temperature might be just above freezing. What a change! The nature of nutrients from one square centimetre of ocean floor to another may vary too. So if life is to survive at all in its present surroundings, there needs to be variation.
Some may have survived better in the cold, some in the warm, some in saltier or sulphurier water than others. And those that outpopulate others in one square centimetre rather than another would have owed their success (then as today) to genetic variation. The genetic predisposition to cope with this or that that the environment throws at one. Some don't have that gene or gene variant. If not, they die or they don't fill up the land with their offspring as successfully as their kin and so are outcompeted.
Variation is the beginning of evolution. And variation that brings about the outreproducing of one's relatives is the next step. That is how evolution must have started. DNA, a molecule that can vary and so give its protein-made shadow the ability to survive. What has to happen in an organism's life (Precambrian or present) is to be able to survive from birth to reproductive age AND THEN STILL to produce more offspring than its competitors. Those successful offspring are then the product of this process, Natural Selection itself.
So, DNA is the key to it all, among the barely bacterial cells of the Precambrian (perhaps 3.8 billion years ago).
for ex: When The heat Gets rid of the liquid by turning it into a gas,wich is called evaporation.
Evolution results from natural selection preserving mutations that result in adaptations of a species to the environment.
They do Occur in SOLID,LIQUID and GAS
Thallium, discovered in 1861, does occur naturally, but not in its pure form.
For evaporation to occur you need the following: Heat (energy), and water.
Luciferin, and enzyme called luciferase. Bioluminescence does not occur in the absence of oxygen.
Many single-replacement reactions occur in an aqueous solution.
they can occur any where it has to occur with precipitation
of Occur
When and where did the dustbowl occur
They occur in the Mesosphere.
when does a disaster occur
How did the abacus occur?
"When does Hemoconcentration occur?"
They occur in the Mesosphere.
why financial crisis occur why financial crisis occur
they most likely occur in Florida or the mostly occur in Texas
The lithosphere is where earthquakes occur.
The chance that a given event will occur, usually expressed between the number 0 (will not occur) and 1 (will occur) is called probability.