Evolution

No. You can't define the evolution of a single species as convergent. Rather convergent evolution is a comparison of the evolution of two or more groups of organism, which independently evolve similar adaptations. The evolution of birds, bats, and pterosaurs is an example of convergent evolution: in all three groups the forelimbs developed into wings.

Birth weight in human babies is one good example. Too small and babies lose heat rapidly and are also prone to infectious disease. Too large and they endanger themselves and their mothers by the great difficulty they have passing through the birth canal. So, a small range of birth weights have been selected for and this remains stabilized by the constraints listed above.

Evolution depends upon genetic variations selected by natural selection each generation, so the species which reproduce the fastest generally evolve the fastest - those would be germs, viruses and other microscopic lifeforms.

Cancer cells evolve pretty fast too, unfortunately.

Luckily their adaptations are not cumulative, since they cannot reproduce outside of the patients' body and go on evolving for hundreds of years.

Evolution was not discovered. It started as an explanation by Charles Darwin, in 1838, to explain the differences between animals on the mainland with animals he encountered on islands that were VERY similar with their mainland cousins but had modified traits and characteristics to allow them to survive in environments that their mainland cousins could not. Ex. A hummingbird on an island very similar to one on the nearby continent but with a very long curved beak to reach nectar in the bottom of a long necked flower that only grew on that island. Their short beaked cousins would have never reached the nectar.

Charles Darwin admitted that he didn't know what mechanism existed that permitted these changes or govened their development. However, with the discovery of DNA, that mechanism was indeed discovered.

The characteristic within the population that causes natural selection to occur is that individuals within a given population are not all identical because they vary. The other characteristic that causes natural selection to occur is that some variants are better than the others.

Adaptation

(I'm studying the same thing ;)

Comparative anatomy is the investigation and comparison of the structures of different animals. Scientists use comparative anatomy to study the difference between species and how they are alike in other ways.

~ann :]

Variations arise due to recombinations(gene rearrangements) ,mutations etc.The former is the principal source of variation in sexually reproducing organisms and the latter is the source of variation in asexual organisms.According to Darwin variation arises due to chance since all the above mentioned process occur in nature spontanuously all organisms show variation

All fossil found to date were missing link. Missing link is a non-scientific term describe new found transitional fossil. Any single fossil found and placed along the line of evolution would yield 2 new missing link mathematically.

NO. Both artificial and natural selection are forms of Evolution in general. Both cause variation by selection within a particular population. The only difference is who is doing the selection, humans or nature.

Evolution is defined as genetic change inherited by offspring. The study of genetics and population genetics provides insight into the mechanisms of evolution.

Imagine a very complicated piece of machinery, such as a computer, and imagine that you alter the internal circuitry purely at random; will the machine be likely to work better? The machine is intricately and meticulously designed to do what it does; almost any change you make would almost certainly interfere with that functioning. Biochemistry is quite similar. It has evolved over billions of years, it is enormously complex and intricate, and every aspect of it is interconnected with every other aspect in many different ways. A random change is very likely to make it worse. To put it another way, for every functional DNA arrangement, there are endless quadrillions of nonfunctional arrangements. Choosing one at random is like buying a lottery ticket; chances are your ticket is not going to win (sorry, folks).

Evolution is defined as a change in allele frequencies over time. Since individuals have only the set of alleles that they're born with, an individual cannot evolve. This leaves the population as the smallest unit that can evolve.

Charles Darwin observations and documentation was invaluable in unraveling the phenomena of natural selection and specie divergence and diversity. What Darwin did not have at the time was an understanding of genetics and DNA, which was not even imaged until 1953 by James Watson and Francis Crick.

Cyanobacteria > Red Algae > Green Algae > Land Plants

1)Eye colour, skin colour, blood group etc..

2) Actually, answer 1 is not accurate. Discontinuous variation is variation which occurs as a result of very few genes. Environmental factors have very little impact. Discontinuous variation is when individuals can be clearly categorised into 2 or more very DISTINCT groups (you are either one group or another, you do not fall somewhere in between). Therefore, better examples would be;

Blood Group

Gender (male/female)

And to be a bit whimsical, the ability to roll your tongue (you either can or you can't)

Eye colour and skin colour are examples of continuous variation as there can be many varying shades. I for one neither fit into the brown eyes or green eyes group, instead I am somewhere in between. My skin colour is fairly pale but has olive tones, meaning I don't burn easily but I don't tan either. Both are good examples of not really fitting into any pre-defined box. I also know someone whose eyes change colour.

Good examples of continuous variation are;

Hair and eye colour

Height and weight

The size of your features (ears, nose, hands etc)

Recessive genes are replaced by dominant genes over time and unfavorable genes die out.

Natural selection needs competition in order to occur

According to Malthus, when food production is more than is needed by the population, the population increases; if population grows too much faster than food production, the population growth is slowed by famine, disease, and war.

pigmentocytes are just color changing cells that some organisms have, not confused with chromotophores

Darwin was able to observe how a few basic creatures evolved and specialized in different roles.

nertic sediments

In 1858, observed cells dividing under the microscope & deducted that ALL cells come from other living cells. Who ever put this answer was completely wrong.

He helped contribute to it because he was examing the inside of the cork also known as the cell walls. He couldn't figure out what a real cell looked like because the cork cells were all dead.

Specialization occurred during the process that moved from unicellular organisms to multicellular organisms. Selection pressures favored having numerous distinct cells that work in tandem over individual cells that did not and then further cells that were in complete union with each other over those that work in tandem. There are a number of intermediate steps between unicellular and multicellular organisms. Probably the most clear "midway" point is the colonial organism of which the extant Volvox is one of the best examples. (Admittedly Volvox itself is only 200 million years to present old, so it is not a remnant of this transition, but is similar to what scientists surmise was part of the transition that led to the development of multicellular organisms.) In a colonial organism, numerous unicellular organisms work in tandem to achieve goals (similar to how geese fly in flocks even though each is autonomous). The required communication would select cells that more effectively communicate with each other, leading to cells that can function as part of the same organism. In Volvox, we also already see small degrees of specialization. There are distinct somatic cells which perform day to day activities such as motion and photosynthesis and germ cells which are primarily responsible for replication. Since no cell could adequately perform both functions well, this partial specialization is favored. In organisms performing more complex tasks, this differentiation in tasks would naturally be selected for enlargement. You can read more about it in the Royal Society report below.