Evolution

The theory of evolution is the overarching scientific framework that explains how biological evolution occurs. Biological evolution refers specifically to the change in inherited characteristics of populations over generations. Biological evolution is the observed process that supports the theory of evolution.

Both gradualism and punctuated equilibrium are theories of evolutionary change that emphasize the idea of species evolving over time. Both theories assert that species do change and evolve, but they differ in the pace and pattern of that change: gradualism suggests a slower, steady accumulation of small changes over time, while punctuated equilibrium proposes that evolutionary change occurs in rapid bursts followed by long periods of stability.

A model of evolution showing slow change is gradualism. It proposes that evolution occurs slowly and steadily over time, with species gradually diverging from common ancestors through small, incremental changes. This contrasts with punctuated equilibrium, which suggests that evolution occurs in relatively rapid bursts of change separated by long periods of stability.

When an organism is in Hardy-Weinberg equilibrium there is no evolution. There is no mutation, mating is random and thus no natural selection. Naturally, outside of labs this condition is never seen.

Charles Darwin is the scientist known for proposing the theory of evolution through natural selection in his book "On the Origin of Species" published in 1859.

You have to have variation in order to be able to have more successful variations, which succeed in evolutionary terms, and less successful variations which fail. If there were no variation in a species, there would be no natural selection.

Budding , mitosis and regeneration have no link with genetic variation.All variations in human being and other organisms are produced by MEIOSIS. During meiosis following important processes take place which include 1; crossing over in Prophase I ; Independent assortment of chromosomes and genes during Metaphase I , both of them result in reshufling of genes which is base of variation. Another source of variation is MUTATION.

One of the key contributions of the punctuated equilibrium model is that it helps explain the pattern of evolution where long periods of stasis are interrupted by short bursts of rapid change. This model helps to account for the gaps and jumps in the fossil record by proposing that species experience most of their evolutionary change during speciation events, rather than gradually over time.

Following characteristics of mitochondria and chloroplast led Margulis (1983) and other scientists to hypothesized that mitochondria and chloroplast were Bacteria and Cyanobacteria that were engulfed by Amoeboid Eucaryotic cells and became symbiotic organelles.

1; Both mitochondria and chloroplast (M&C) are self replicating.

2; Both possess small circular DNA molecule similar to Plasmids.

3; Both possess an outer membrane similar to eukaryotic cell membrane.

4; Both possess an inner membrane simillar to prokaryotic cell membrane as it lacks sterols.

5; Both possess ribosome similar to prokaryotes and smaller than eukaryotic ribosomes.

6; Both produce their own m RNA and some proteins .

7; Both can produce their own ATP.

8; Both are semidependent on animal or plant cell.

this hypothesis is called Endosymbiont hypothesis,

Molecular evidence can be used to establish evolutionary relationships by comparing similarities and differences in DNA, RNA, or protein sequences among different species. The more similar the sequences are between two species, the more closely related they are believed to be in terms of their evolutionary history. This helps scientists create phylogenetic trees to show how species are related to each other through common ancestry.

Charles Darwin's theory of evolution upset people because it challenged traditional religious beliefs about the origin of life and the role of humans in the natural world. It also posed a threat to established scientific theories of the time. Additionally, the idea that humans shared a common ancestor with other species was seen as controversial and unsettling to many people.

In 1858, Darwin received a short essay from Alfred Russel Wallace, a fellow naturalist who had been doing field work inMalaysia. Summarized in his essay was thoughts on evolutionary change that Darwin had been mulling over for almost 25 years! Suddenly, Darwin had n incentive to publish his own work.

The Red Queen's Hypothesis was proposed by Leigh Van Valen in 1973 as a way to explain the coevolutionary dynamics between species where constant adaptation is necessary to maintain relative fitness.

It is made up of diverse colonies which better enable it to respond to environmental threats more adequately. It diversifies the defense mechanisms. it also acts as a collective group in which it can place persister colonies toward the center where there is better protection.

Oxygen became a significant part of Earth's atmosphere due to the evolution of photosynthetic life forms, such as cyanobacteria and plants. These organisms produce oxygen as a byproduct of their metabolic processes, leading to the rise of oxygen levels in the atmosphere over time.

The origins of life on Earth are still a subject of scientific investigation and debate. One prominent theory is that life originated through a process called abiogenesis, where simple organic molecules combined to form more complex molecules that eventually led to the first living organisms. Other theories suggest that life might have originated from elsewhere in the universe and arrived on Earth through meteorites or other means.

The condition necessary for genetic drift to have a significant effect on a population is when the population size is small. In smaller populations, genetic drift can lead to random changes in allele frequencies, impacting the overall genetic diversity of the population.

The individuals of a species that live in a particular area are called a population.

Mutations serve up the variations in organisms to natural selection. The reproductively successful variations pass on these successful traits to progeny and allele frequencies change because of this and this is evolution.

For natural selection to occur, there must be genetic variation present in a population, some of which is heritable. This variation must lead to differences in survival and reproduction (differential fitness). Individuals with advantageous traits must pass those traits on to their offspring. Over time, these advantageous traits become more common in the population.

Evolution can occur slowly over long periods of time, as changes accumulate in a population's genetic makeup. However, some evolutionary changes can also happen relatively quickly in response to environmental pressures or other factors, such as in the case of adaptive radiation or rapid genetic mutations.

Acquired characteristics are traits that an individual develops during its lifetime, such as a tan from sun exposure, and are not passed down to offspring. Adaptations are heritable traits that increase an organism's fitness in its environment and are passed down through generations. Acquired characteristics do not involve genetic changes, while adaptations are the result of genetic variation and natural selection.

Darwin's theories were revolutionary because they proposed a mechanism, natural selection, by which evolution could occur through the adaptation of populations to their environment. This was different from the prevailing idea of fixed species created by a divine force. Darwin's focus on variation within a population and the importance of competition and survival for shaping evolution set his theories apart from his predecessors.

The three evolutionary levels of the brain are the reptilian brain (responsible for basic survival functions), the limbic system (associated with emotions and memory), and the neocortex (involved in higher cognitive functions such as reasoning and problem-solving).

The bases in Dna are read three at a time - these are known as triplet-codons.

Each triplet-codon codes for a specific amino-acid.

The order [or sequence] of amino-acids in the resultant protein will and does determine its 'particular features'.