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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
What dangers might travelers face in the devonian period?
A traveler should watch out for armored placoderms. If the traveler is in the Early Devonian, these fish did not have teeth, but plates in their jaws that acted as teeth. By the late Devonian though, they had developed jaws that could measure up to 33 ft. The only thing a traveler should worry about on land is insects, because no other animals existed during this period. The traveler should watch out if they are visiting the Late Devonian because of the high levels of carbon dioxide in the atmosphere, colder temperatures, and meteorites striking the earth,
Who formulated the theory of evolution?
Jean-Baptiste Lamarck was the first person to clearly formulate and present a plausible theory of evolution. Lamarck was a French naturalist who lived from 1744 to 1829.
Why evolution should not be equated with progress?
Evolution is simply the generation of diversity and the shaping of the diversity by environmental selection. Species adapt to the conditions available in their environment. Some older and simple species live on quite effectively. The only progressive trend in evolution seems to be that more and more complex body designs have emerged over time.
In fact, one of the simplest life forms like bacteria - inhabit the most inhospitable habitats like hot springs, deep-sea thermal vents and the ice in Antarctica.
This is the reason why evolution in not equated with progress.
What is transfer of the water from leaves of plants into the air is called?
Transpiration - see here
http://en.wikipedia.org/wiki/Transpiration
What did bilateral symmetry lead to the evolution of?
It allows different parts of the body to become specialized in different ways. This is called cephalization.
Where is Tiktaalik and is it open to be viewed by the public?
Key finds, especially if they are rare specimen, are not usually themselves put on public display. Rather, casts are made and distributed to researchers and musea around the world, while the fossils themselves are kept secure in laboratoria and archives, in a controlled climate.
Casts of Tiktaalik may be found in various natural history musea, such as the Harvard Museum of Natural History.
Can someone help you compare and contrast natural selection and evolution any help would be great?
Evolution is simply genetic change within a poulation. That change can occur in several ways. One is immigration/emigration: individuals moving in or out of a population bring in or take out their alleles with them. Another is genetic drift, or chance events which cause the frequencies of alleles in a population to fluctuate. New mutations can change the allelic frequency as well. Finally, natural selection can cause some alleles to become more common at the expense of others. In short, natural selection is one of several mechanisms that can bring about evolution.
the actions of organisms as they use or fail to use body structures.
What are the five main items used to support the theory of evolution?
I don't know about there being five things used in favour of evolution, but there are many nonetheless. Below are some supports for Darwin's Theory of Evolution.
Comparative anatomy: The bones of vertebrate forelimbs are 'homologous'. They have common ancestry. You can identify the same bones in the hand of a bat as there are in the hand of a human, the leg of a horse, the flipper of a whale or the paw of a cat. Evolution does not start from scratch all the time but adapts what is already present. Thus once evolution was equipped with forelimb bones, it simply stretched them to support a wing (in bats), strengthened them for beating down water (in whales) or warped their agility to the gripping ability of a human hand.
There are also 'vestigial' anatomical structures which are seen as very convincing of evolution. Whales evolved from hoofed terrestrial herbivores. Whales have foreflippers but not hindflippers. There are however vestigial bones in the hindquarters, which are the left overs of the ancestral terrestrial artiodactyl. Pythons are snakes (thus legless) but evolved from limbed lizards (varanids may be the closest lizard relatives to snakes). Pythons have vestigial hindlimb bones too.
Comparative genetics: Modern science can, incredibly, sequence whole sections of an organism's genome or indeed the whole genome. The genome is composed of DNA, and what is 'sequenced' are the bases of that DNA. DNA bases are abbreviated A, T, C and G. Say you select a frog, a snake and a dog as representatives of amphibians, reptiles and mammals. Now you sequence a gene that each of them share and compare the sequences.
Hypothetical sequences:
Dog: AAAGCGGGGTAG
Snake: AAAGCCGGGTAC
Frog: AAGCCCCGGAAC
You would expect the sequences to show a pattern like the one above, where the most sequence differences are between most distantly related organisms. Evolution would predict that a dog is more closely related to a snake than to a frog. If you come up with a sequence like the above, there are a greater number of AGCT (base) differences between the dog and the frog than between the dog and the snake. This would confirm the idea that snakes and dogs are more closely related than frogs and dogs. Such sequencing has been done and the results have confirmed all of the Theory of Evolutions's predictions.
The fossil record: The fossil record provides many extinct transitions between major taxa. Archaeopteryxrepresent a reptilian-avian transition. Tiktaalik and Icthyostega and relatives give clues as to the sarcopterygian-amphibian transition. Early hominid skulls are representations of transitions from Australopithecus and early Homo to our present species Homo sapiens.
There are also modern (extant) animals and plants that give clues as to transitions. These extant examples are remnants of lineages of ancient organisms that have survived to the present. Platypuses show the reptilian-mammalian transition. Some plants like Welwitschia and other gnetophytes give clues to gymnosperm-angiosperms transitions.
Additionally there is a lot of molecular and chromosomal work done. Origins of species are sometimes demonstrated by this investigation. Apparently an single species of Aethomys mouse was investigated and it was found that the sperm cells of one group were incompatible with the egg cells of another. The two groups were sympatrically and reproductively isolated and were thus separate species.
Chromosomes can fuse together. This reproductively isolates populations and thus promotes speciation. Chromosomes fused somewhere in the lineage between the Chimpanzee-Human common ancestor and modern Homo sapiens. Chromosomes fuse and split all over the place across the animal kingdom. Plant chromosomes merge due to imperfect meiosis probably and produce nondiploid polyploid individuals. All of this promotes reproductive isolation and thus speciation and speciation is the way evolution makes progress.
Describe 2 hypothesis for the evolution of play behavior?
Practice Hypothesis- playing is a type of learning that allows animals to perfect behaviors needed in functional circumstances, such as a kitten stalking brothers and sisters which it will do later in life.
Exercise Hypothesis- playing keeps muscular and cardiovascular systems in top conditions, esp. when young aren't doing strenuous activity to keep active. Recent studies, however, have shown that beluga whales and multiple dolphin species play as adults, at least when in captivity.
1 . The animals are bilaterallysymmetrical , triploblastic and have coelem .
2 . They have a notochord , at least some stages during their lives . The notochord run along the back of the animal separating the nervous tissue from the gut . It provides support and a place for muscles to attach .
3 . Protochordates are marine animals . Examples are Balanglossus , Herdemania , Amphioxus , etc
Why is there a gap of time between the evolution of algae and trilobites?
There isn't, of course, a gap in time. There are, however, very few fossils intermediate between simple stromatolites (the first more or less multicellular organisms) and the first complex organisms found just before the Cambrian Explosion. This gap most likely exists because while predation already existed (organisms consuming other organisms), no organisms had yet developed an internal or external skeleton that could have been preserved at death. The very few organisms from that era that were preserved despite of this, were preserved in the form of molds and casts.
How do you install moonshell for the cyclods evolution?
FOR ME IT ONLY WORKED WHEN I PUT IT INTO THE SAME AREA AS THE ROMS ON MY MICRO SD CARD, NOT WHERE IT SAYS TO PUT IT ...I.E IN THE ROOT FILE
What is the overriding political question through the evolution of congress?
The distribution of powers within Congress.
In natural selection what must be true in traits that are passed down through generations?
They must help the organism in it'senvironmentso it may survive andreproduceand pass the trait down. If the trait is undesirable or useless the trait is selected against. Like if the desert was covered in snow, and all the 'prey' animals were out and wondering around. They can see if a 'predator' is coming, because of their orange-light brown color cause it doesn't blend in with the surrounding it isn't goodcamouflage.
What are five strong points on evolution?
Darwinism
Religious Execution
Natural Selection
Atheism
Richard Dawkins
The evolution of predators to be more cunning and prey to be faster runners is an example of?
you must got merhzad as yo teacher for biology . i dnt knoe the answer neither .
What are some reasons rapid evolution may occur after long periods of equilibrium?
Here are a couple of possiblilties (there are more): * The population can develop isolated subpopulations on its periphery. Evolution is much more rapid in small isolated populations. * Changes in the environment can lead to rapid evolution. Variation that was once neutral may now become beneficial and increase in frequency, while variation that may have been adaptive in the previous environment may now be deleterious and selected against.
Why can't intelligence be evidence of evolution?
Intelligence is merely a property of some lifeforms. It has no direct relationship to evolution and can say nothing either way, although the apparent development of intelligence combined with otehr mechanisms (e.g. suitability, usefulness) may be considered evidence.
How is evolution scientifically disputed?
It is NOT scientifically disputed as the overwhelming number of scientists accept evolutionary theory. Those scientists, and others, that do not accept the theory do so for religiously ideological reasons, though they try to rationalize this by pseudo scientific proposals.
Why are fossils important to evolution?
Fossils give a record as to what organisms lived throughout different time periods. Generally speaking, the lower layers of soil show the oldest fossils, which aids scientists in following the progression of evolution of an organism. Also, radioactive carbon dating is used in dating how old a fossil is by finding the amount of carbon^14, and then calculating how many half lives have passed to reach this amount.
Difference between genomic library and cdna library?
A cDNA (complementary DNA) library is a DNA library that has been created from mRNAs that are present in the cell. Since a cDNA is created from mRNA transcripts, that means that in Eukaryotic organisms there will be no introns or transcriptional factors present in the cDNA library, only exons. Only protein coding regions will be present in a cDNA library. This also means that a cDNA library is often times tissue specific. Since the expression of mRNAs will be different in different tissues of the organism it will appear different then a genomic library. Often times to offset this problem a cDNA library will be composed of different tissues (brain, liver, heart) to encompass a greater variety of the proteins that are expressed. A genomic library will contain all the exons, introns, and transcriptional factors that are not found in the cDNA library.
**2/24/2011**
cDNA library does contain exons, which is the protein coding regions.
