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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
What process forms new seafloor?
New seafloor is formed through a process called seafloor spreading, which occurs at mid-ocean ridges. Magma rises from the mantle and solidifies to create new crust as tectonic plates move apart. This continuous process results in the creation of new seafloor and plays a key role in plate tectonics.
Where on earth would you find the greatest biodiversity?
In general, biodiversity globally is high in the Tropical World
of the humid tropics (most especially in tropical rainforests where more than half of all species are found) and in the extremely infertile Unenriched World
of the ancient arid landmasses of Australia and Southern Africa. Biodiversity is much lower in the geologically young and cool Enriched World
which basically corresponds to the extratropical northern and western hemispheres, plus New Zealand (which can very easily be thought of as part of the Western Hemisphere though it is on the other side of the International Date Line).
Although it is popularly though that high biodiversity relates to the more “benign†and less demanding environment in hot climates, recent research by Michael Huston of the University of Texas in “Biological diversity, soils, and economics†and “Precipitation, soils, NPP, and biodiversity: resurrection of Albrecht's curveâ€, Australian ecologist Tim Flannery in The Future Eaters
plus Jason Weir and Dolph Schluter in “The latitudinal gradient in recent speciation and extinction rates of birds and mammals†show that these are misconceptions.
Flannery and Huston both demonstrate that owing to the roughly four orders of magnitude greater age of their soils (except in the volcanic regions of the Pacific Rim), the productivity of the Tropical and Unenriched Worlds is very much less than those of the Enriched World of the extratropical northern and western hemispheres. Weir and Schluter show that speciation rates are much lower in the Tropical World than in the depauperate fauna of the Enriched. One would presume that with their extreme geological stability the Unenriched World of Australia and Southern Africa would have still lower speciation rates than the humid tropics
. This is especially true when one considers that many birds and mammals in Australia and Southern Africa require so much labour for reproduction that most adults must serve as “helpers at the nest†rather than reproduce on their own, which acts as an extremely severe limiter on potential dispersal.
All these indicators point to the higher diversity of the Tropical and Unenriched Worlds as being due to reduced interspecific competition
compared to the young and highly productive Enriched World. Soils of an infertility universal in all of the Unenriched and most of the Tropical World are exceedingly rare in the Enriched World - occurring only in a few areas of exceptionally nutrient-poor parent materials
like ultrabasic rocks (serpentines, peridotites) - and then only outside of glaciation limits within which intrazonal parent materials are converted to highly fertile zonal soils. (In this context, it’s notable that the most northerly major biodiversity hotspot in the Klamath Basin is one of the major occurrences of serpentines in the world, as is the very rich tropical hotspot of New Caledonia).
In the Tropical and Unenriched World resources are so scarce in unfertilised environments that co-operation rather than competition tends to be the rule to allow plants to obtain the minimal nutrition possible on these soils. The absence of competition reduces extinction rates to a fraction of the level observed throughout the Enriched World: in essence, the creation of biodiversity occurs in the Enriched World, but it is rapidly pooled into reservoirs in the Tropical World, and the Unenriched retains older species (marsupials, mousebirds) dating from periods when its ecological conditions were globally general.
This process is called natural selection. It is the mechanism by which traits that provide a survival or reproductive advantage to an organism become more common in a population over time.
What are the sites of gametogenesis?
Gametogenesis occurs in the gonads (ovaries in females and testes in males). In females, oogenesis takes place in the ovaries, where oogonia develop into primary oocytes. In males, spermatogenesis occurs in the testes, where spermatogonia differentiate into sperm cells.
What did the sparks in miller and urey's experiments stimulate?
They simulated lightning in the early earth's atmosphere. The reasoning being that the reactions required some form of energy input to begin, and that lightning would have almost certainly been present.
What type of evolution studies changes in living things?
Biological evolution studies changes in living things over time, including how species adapt, diversify, and evolve through natural selection and genetic variation. It seeks to understand the mechanisms driving these changes and their impact on biodiversity and the development of life on Earth.
No, the process of speciation occurs over many generations through evolutionary changes in a population. It is not a sudden event resulting from the mating of two individuals from different species. Speciation involves gradual divergence in traits and genetic makeup that eventually lead to the formation of a new species.
Joins together the ideas of modern genetics with Darwin's theory of natural selection?
Modern genetics has provided evidence to support Darwin's theory of natural selection by showing how variations in genes can lead to differences in physical traits among individuals of a species. Genetic research has also demonstrated how the process of natural selection acts on these genetic variations to drive evolutionary changes in populations over time. By understanding how genes and natural selection interact, scientists can better explain the mechanisms behind the diversity of life on Earth as proposed by Darwin.
RNA polymerases are transcripted by which enzyme?
You seem confused. RNA polymerase is the enzyme that transcribes DNA into pre mRNA. So, the enzyme would transcribe the messenger RNA for its own protein construction.
True or false Mutations are not capable of altering allele frequencies?
In the strict sense, no. Mutations happen to individuals and are only heritable in the germ line. Populations have allele frequencies in their gene pools. So, the mutation must be beneficial, lucky enough that it original carrier passes it on intact and that it is driven into the populations gene pool in sufficient number, by having reproductive success, to change allele frequencies.
One similarity between natural selection and genetic drift is that both events change what?
Both change the availability of certain alleles in the gene pool.
Natural selection is a natural process resulting in the evolution of organisms best adapted to the environment. ie predators eat the slower prey, so faster genes survive to spread to the next generation.
Random fluctuations in the frequency of the appearance of a gene in a small isolated population, presumably owing to chance rather than natural selection. ie 50 people move from America to a small island in the Caribbean, and stay isolated there for many centuries. If maybe 20 of those original 50 people carried a gene for say, early onset male baldness, that would not mean that 20 out of every 50 people in US have that gene, that just means that this happened by chance. If they inbreed for centuries, eventually most or all of them will carry this gene. This is why it is important that our gene pool does not become stagnant.
Source: Way too much biology for nursing!
Mutations are changes in the DNA sequence of a gene. They can occur spontaneously during DNA replication or due to external factors like radiation or chemicals. Mutations can lead to genetic diversity and evolution, but they can also cause genetic diseases if they disrupt normal gene function.
What level of organization is acted upon by natural selection?
The individual or his/her (assuming a sexed species) genes. Still a bit of a ' bone of contention in biology between these two levels; the gene and the individual. The only truly marginalized position as to ' target ' of selection is the group.
What can result in the immediate creation of a new species?
That depends on what you mean by 'immediate'. Drastic rates of evolution are possible in many species, where mutations are either relatively very common or where the environment results in harsh selection.
But nothing will make one species "immediately" evolve into another in one generation, or even two or ten.
According to Darwin's theory of evolution differences between species may be the result of?
Evolution may have been caused according to Darwin's theory, by different locations of the animals. according to what they eat and how they live their lifestyle depends on how they evolve. for example: over time girraffes had to have a long neck to consume leaves off of tall trees. another example would be wood peckers developing a sharp beak to hammer through tough bark on trees.
Stabilizing selection is the type of natural selection that acts against extreme forms of a polygenic trait to reduce genetic variation and maintains the average value of the trait within a population. It favors the intermediate phenotype, leading to a narrowing of the range of variation for that trait over time.
Yes, antibiotic resistance typically arises through a combination of random mutations in bacteria's genetic material and natural selection favoring those bacteria that have mutations conferring resistance to antibiotics. Over time, these resistant bacteria survive and multiply, leading to the emergence of antibiotic-resistant strains.
How does natural selection operate to cause a change in population?
Natural selection operates by favoring individuals with advantageous traits that increase their survival and reproduction rates. Over time, these individuals pass on these advantageous traits to their offspring, leading to a change in the population's characteristics as the frequency of these traits increases. This process results in the adaptation of the population to its environment.
Is the spoils system a good idea in today's America?
The spoils system is a system when the elected appoints his friends to offices based on their support, not skill. Does that sound like a good idea? The only way i could argue this to be a good idea is if you take into account that like-minded government officials are more likely to accomplish change as compared to battling political minds (But then again, the Democrats certainly have failed despite controlling presidency and Congress from '08-'10)
Source: My mind
Cuckoo and cowbirds are studied for determining evolutionary relationships among bird families. These brood parasites lay their eggs in the nests of other bird species, enabling researchers to understand host-parasite relationships and evolutionary histories within avian families.
How did organisms change 1.2 billion years ago?
1.2 billion years ago, organisms experienced significant changes such as the development of multicellularity in certain lineages and the emergence of more complex forms of life. This period marked the diversification of eukaryotic organisms, leading to the evolution of various new body plans and adaptations. Additionally, the first evidence of sexual reproduction and the appearance of eukaryotic algae and fungi occurred during this time.
Can theories change over time?
yes, as more things are learned theories can be modified (theory of evolution) also sometimes theories can be thrown out (the theory that the earth is flat)
How can fads lead to shortages?
Fads can lead to shortages by causing sudden spikes in demand for specific products. Manufacturers may not be able to adjust production quickly enough to meet this increased demand, leading to shortages in supply. Additionally, hoarding by consumers who want to stock up on the trendy item can further exacerbate the shortage.
When studying evolution the term isolation means one?
Isolation in evolution refers to the separation of a population from the rest of its species, leading to reduced gene flow between different groups. This isolation can be geographic, reproductive, or behavioral, and can ultimately result in the development of distinct species through the process of divergent evolution.
What were the long term consequences of Darwin's theory?
Darwin's theory of evolution by natural selection revolutionized the field of biology by providing a comprehensive explanation for the diversity of life on Earth. It led to the development of modern evolutionary biology and has had profound implications for various scientific disciplines, including genetics, ecology, and anthropology. Additionally, Darwin's theory has influenced societal perspectives on our place in the natural world and continues to be a topic of debate in discussions about science, religion, and ethics.
