KEGS Biology Blog


Monday 19th November Section 2
November 19, 2012, 8:44 pm
Filed under: Uncategorized

Darwinism and evolution articles.

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20 Comments so far
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Great article Hinali, loads of stuff here for the AS level spec!! Binomial classification, natural selection, observations of anatomy and physiology!

Comment by kegsbiology

Darwinism and Evolution

Charles Darwin, when travelling in the Galapagos Islands, made 4 key observations:
1) Offspring are similar to their parents
2) There is variation within the offspring – no two individuals are identical
3) Organisms produce more offspring than can possibly survive
4) Populations fluctuate but remain fairly stable

From this we can make the following conclusions:
1) Parents pass on their genes to their offspring, giving them similar characteristics
2) Variation is needed for survival – if all offspring are the same they will die out as there is not enough food for all and none of the offspring will have traits that make them better suited for survival
3) This causes a competition for food, meaning that adaptations take place that lead to a better suited species – if all of the offspring survived there would be no need for adaptations
4) Again this shows a competition for survival – the birth and deaths of species occur at a similar rate

Difference between survival of the fittest and survival of the organisms that can adapt the best:
Survival of the fittest is on a shorter term basis i.e. over one generation, while adaptation occurs over several generations

Why do adult mice have the same tail length?
Across several generations, those with too long or too short tails have died out before passing on their genes due to the disadvantageous nature of their tails, so eventually all mice have the same, most advantageous tail length.

Why do snails have brown shells and not pink?
Brown allows for better camouflage and so are less likely to be eaten by predators. Those with pink shells are more conspicuous and so are eaten and die before reproducing and passing on the gene, meaning eventually only brown snails are left.

Why are leaves at the bottom of a tree bigger?
They need a bigger surface area to absorb more sunlight as less reaches the lower branches due to the increased shade.

Comment by hannahgooch

Good work Hannah, what about Speciation?

Comment by kegsbiology

http://www.bbc.co.uk/news/science-environment-19250778

Comment by gautammenon1

A great article Gautam, can you provide a quick synopsis of the article?

Comment by kegsbiology

http://www.bbc.co.uk/news/science-environment-19184370
The article is about the difficulties of a theory of a “march of progress” type evolutionary path because of new fossils of a presumably entirely new species of human co-existing in Africa with an already known species of early human. The article is especially relevant considering the work done on environmental factors, random mutation and survival of the fittest / most easily adaptable species.
A VERY INTERESTING READ 🙂

Comment by matthewbesley

An ‘interesting’ article, can you provide a synopsis of the article and highlight any areas that link into the spec?

Comment by kegsbiology

Candidates should be able to: “(b) discuss the fact that variation occurs within as well as between species;” – The article shows that humans have had different types of and paths of variation in forms of homo erectus, homo habillis and homo rudolfensis each of which have varying characteristics importantly in terms of brain size in this specific case.

“(h) discuss the evidence supporting the theory

of evolution, with reference to fossil, DNA
and molecular evidence”
This speaks for itself, this is fossil evidence which can be compared and contrasted with modern humans and older species of humans skulls. Similarities and differences and be drawn such as brain capacity and the unusual “flat face” that this specific skull has

Comment by matthewbesley

http://news.bbc.co.uk/1/hi/6057734.stm

Comment by yuansun

http://www.nhm.ac.uk/nature-online/evolution/index.html

This talks about evolution in detail. How evolution developed, the evidence for it, how the evolutionary theory developed, human evolution and the tree of life (evolutionary tree).
it’s got reallly good quick videos to demonstrate alll this stuff as well so i urge you guys to check it out.

Comment by halima101

Article on crocodile’s jaws: http://www.bbc.co.uk/nature/20222022

Comment by nisithadissanayake

http://dinosaurs.about.com/od/otherprehistoriclife/a/prehistoric-sharks.htm
does not include much detail about why sharks evolved from fish to be structured from cartilage rather than bone, but interesting to read about the competition from ancient predators and why this caused it to evolve!

Comment by alexgurton

http://www.dailymail.co.uk/sciencetech/article-2236373/Birds-evolved-wings-warmth-flight-new-findings-suggest.html?ito=feeds-newsxml

Article about bird’s wings and how they were originally developed for warmth and camouflage, and it is only as result of millions of years of variation that they have ended up resembling what we see today. The findings were based on research into two different species, by comparing their similarities and differences.

Comment by jakepalmer1

http://news.sciencemag.org/sciencenow/2012/06/mantis-shrimp-smash.html

http://mantisshrimp.wordpress.com/tag/mantis-shrimp-evolution/

The first article describes some of the potential uses for the unique mantis shrimp’s claws, and the second article describes in more detail some of the unusual feature mantis shrimp have, and how they would have benefited from them evolutionarily.

Comment by spencerfinch

http://www.newscientist.com/article/dn17453-timeline-the-evolution-of-life.html

An article showing the timeline of evolution throughout history looking at the genetics of evolution. The whole site is pretty useful as it has links about some case study examples.

Comment by danialnaqvi

http://www.nytimes.com/2006/12/11/science/11evolve.html
http://www.sciencedaily.com/releases/2005/06/050602012109.htm
2 articles leading on from the conference about the history of drinking milk, linked in with evolution. Quite interesting how difference in environment caused a such a significant variation in one species.

Comment by mehleen

http://www.bbc.co.uk/sn/prehistoric_life/human/human_evolution/food_for_thought1.shtml
Information on part of the evolution of man, discusses how natural change in the Earth helped to cause variation in human lineage, only adapted species were to survive etc.

Comment by phillipmarriage

http://www.bbc.co.uk/nature/20413665
article on adaptations by a herbivore, linked with evolution, and how fossil evidence eventually led scientists to reconsider its nutrition from carnivore to herbivore.

Comment by candicetam

http://www.bbc.co.uk/news/world-asia-20178399

Interesting article that covers malarial drug – resistance through natural selection and how it could be a global crisis if not contained to south east asia and some interesting statistics

Comment by helenquah




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