Evolution

It is the reproductive isolation between populations that allows divergence between populations, and ultimately speciation, to occur. Often this reproductive isolation is the result of geographical isolation, for instance when part of a population migrates to new territories.

Charles Darwin, contrary to popular opinion, did not formulate the theory of evolution, but he did refine it. The theory had been developed and added to by numerous scientists through the years. Darwin simply added to evolutionary theory.

Non-random mating is otherwise known as sexual selection. Some see this as distinct from natural selection, but I think that sexual selection is merely a form of, or perhaps more a complication of natural selection. Selection, natural or sexual, is the effect that "guides" evolution, that allows evolution to produce populations suited to their environment.

The theory that states organisms evolved from a common ancestor is the theory of evolution proposed by Charles Darwin in his book "On the Origin of Species" published in 1859. Darwin's theory of evolution by natural selection explains how species change over time through the process of adaptation to their environments.

Physiology can provide evidence of evolution by showing how certain traits or adaptations have evolved over time to enhance survival and reproduction. For example, studies on the physiological differences between closely related species can reveal how changes in gene expression or protein function have allowed for adaptation to different environments. By comparing physiological traits across different species, scientists can infer evolutionary relationships and the processes that have shaped them.

Balancing chaos and order allows for creative thinking while maintaining structure. Similarly, balancing evolution and revolution enables progress while preserving stability. Striking a harmonious blend of these elements provides resilience and adaptability in complex systems.

By looking at the fossil records, scientists were able to say approximately when life began. They used radiometric dating of rock layers as one method.

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Alfred Russell Wallace and Charles Darwin both independently developed the theory of evolution by natural selection. They both proposed that species evolve over time through the process of natural selection, where individuals with traits better suited to their environment are more likely to survive and reproduce. However, Darwin's work is more widely known and recognized, as he published his theory first.

Answer 1

All DNA, somatic and germ line, mutates at an average rate in humans. So, one picks up deletions, neutral base pair mutations and even more serious frame shift mutations. All mutations are just a discrepancy, copying error, in the DNA replication.

Answer 2

Another important change progressing with age is the length of the telomeric sequences. Telomeric sequences (which, if I am remembering correctly, is made up of something akin to LTR, or long, terminal repeat sequences) are sequences of nucleotide basepairs at the ends of the chromosomes. They do not code for proteins, but 'tie together' the ends of the molecular huge double helix that is a chromosome, and presumably play some role in preventing the random fusion of separate chromosomes. With each cell mitotic division in somatic tissues, a chromosome may lose a part of its telomeric sequences. If no telomeric bands remain, a chromosome may start to 'unravel', leading to apoptosis, the self-destruction of the cell. It is speculated that the loss of telomeric sequences plays some part in the aging process.

Natural selection acting on a single-gene trait can lead to changes in allele frequencies within a population. If individuals with a certain allele have a selective advantage, they are more likely to survive and reproduce, leading to an increase in the frequency of that allele in the population over time. This process is known as directional selection.

James Hutton, often regarded as the father of modern geology, proposed the principle of uniformitarianism in the late 18th century. This principle states that the same geological processes we observe today, such as erosion and volcanic activity, have been at work shaping Earth's features over long periods of time. This idea laid the foundation for understanding the gradual changes that have occurred in Earth's geological history.

Answer 1

The most important directional "force" in evolution is natural selection, or differential reproductive success.

Under natural selection I include sexual selection. Note that other people may list these two forms of selection under separate headers. Sexual selection is when organisms display preferences for mates with specific attributes, such as a colourful plumage, or broad hips and large mammaries.

Answer 1

If you have group of a species with dark skin and another group with light skin in an environment with much direct sunlight, the dark skinned gene group will be selected as the dark skin (with more melanin) is protective in that sunlit environment. If the environment is northern, the lighter skin gene will become more common. This variation will be a help in natural selection.

Answer 2

Genetic variation, or reproductive variation, are the mechanisms that cause one sibling to be slightly different from another. It is this difference that allows natural selection to work, for there may be various reasons, to do with these differences, why one sibling is more successful in producing offspring than the other.

Gene flow is the movement of genes between populations, which can introduce new genetic variations and prevent populations from diverging into separate species. It can increase genetic diversity, reduce differences between populations, and potentially lead to the spread of beneficial traits throughout a species. Gene flow is important in evolution as it promotes genetic exchange and maintains the genetic cohesion of a species.

Punctuated equilibrium describes evolution happening in rapid bursts rather than gradually over time.

Answer 1

Many churches of the time posited that god created all the organisms of earth at one time, so that no organism was related except to vary from it's created kind. Darwin showed that through the process of natural selection new species were constantly arising from related organisms.

Answer 2

Theism rationalizes its beliefs in deities by pointing to the organized nature of nature, claiming that such complexities could not have come about through unguided natural processes. Darwin, with his theory of natural selection, provided just that: an explanation for natural complexities in terms of unguided processes. Basically, while Darwin's theory does not claim that no gods are involved in nature, it did away with the need for any gods to explain the diversity of life.

Answer 1

One species can evolve from two species if the two bypass the barriers between them. These barriers can be physical. For example, mountains or if they are similar in type. A plant can not breed with a human, there are too many genetic differences. If their offspring can interbreed or have offspring of their own they can form a new species. Horses and donkeys are close in genetic type but their offspring are mules and they are infertile and can not have offspring of their own.

Answer 2

As noted above, a new species may emerge from a hybridisation between two closely related existing species. This is not seen very often in the more complex animals, but happens frequently in plants and may occasionally occur in insects or even birds.

The slow process that results in new species is called speciation. This occurs when a population of a species becomes isolated from the rest of its species and over time, genetic mutations and natural selection cause it to evolve into a distinct species. This process can take thousands or even millions of years to be completed.

Darwin's theory is no longer just Darwin's theory. In the 150 years + that the theory has been around it has been modified and strengthened by repeated testing and has made myriad predictions and generated a plethora of testable hypotheses.

No, the theory of evolution by natural selection is not expired.

Mutations in an individuals germ line can be passed into progeny and if these mutations are beneficial then the allele frequency in the individuals population can change which is evolution. Over time and with many beneficial mutations against a favorable environment a population, or populations, most often geographically isolated, can change alleles so much that the two split populations can no longer interbreed and you have a new species; macro-evolution.

In biogeography studies, similar animals that seem

to be closely related are adapted to different environments

in nearby areas. Also, in areas that are

widely separated animals that seem to be unrelated

are observed to have similar adaptations to

similar environments in the separate areas.

No, development and evolution do not have the same meaning in physiology. Development refers to the process through which an organism grows and matures from a single cell to a fully formed individual, while evolution refers to changes in a population of organisms over generations through the process of natural selection.

Biochemical evidence of evolution is considered indirect because it does not provide direct evidence of specific evolutionary events or transitions in the fossil record. Instead, it demonstrates similarities in molecular structures or sequences across different species, which support the idea of a common ancestor but do not directly show the process of evolution occurring.

Gradualism is the concept but I would not give it the ranking of scientific theory. It is more a subset of the theory of evolution by natural selection and was first formulated into that theory by Darwin.

Genetic variation drives evolution by providing the raw material for natural selection to act upon, allowing organisms to adapt to changing environments. Environmental factors can influence which traits are favored, shaping the direction of evolution. Together, genetic variation and environmental factors contribute to the diversity of life on Earth through the process of evolution.