The Evolution Forum cubit

Quote of the week: "Intelligent life on a planet comes of age when it first works out the reason for its own existence." Richard Dawkins, The Selfish Gene. (pg. 1)

Articles:
The Role of Predators in Evolution
By Branden Holmes on September 6, 2010

The evolutionary arms race between predator and prey is virtually universal. As such, it is vital to have a grasp of how predators can drive evolution in prey species. Of course, the arms race is run in evolutionary time rather than real time; adaptation and counter-adaptation, separated by a lag of several or many generations in genetic response. Adaptation is a long and steady process of replacement: maladapted individuals give way to adapted individuals, and adapted individuals give way to better adapted individuals. But the adaptations that are beneficial to an individual which lives free from predators are, as we shall see, diametrically opposed to those that individuals which experience the constant threat of being eaten, find to help aid survival.

» Read the article

What is fitness?
By Branden Holmes on November 28, 2010

When evolutionary biologists speak of the "fitness" of an individual, what they usually mean these days is what is called reproductive success (RS): the extent to which some of their genes will still survive in the population x number of generations later. Because it is not enough just to only consider the contribution of offspring into the next generation. It is good that an individual may have many offspring, even twice as many as the average. But if none of those offspring are likewise endowed with fecundity, it doesn't matter how many offspring that individual has because they will not be disproportianally represented in terms of genes many generations later. How durable a species or gene is (the probability that that species or gene will still be extant after many generations) is what really counts in evolution. This is simply a temporal extension of reproductive success, where the period concerned is many, many generations later, and the entity concerned is the population as opposed to the individual, because individuals do not live for many generations. So, inheritability of fecundity is essential, otherwise the gene pool will simply be diluted and directional selection of fecundity will be impossible. But a number of other definitions for fitness are in wide use, somewhat confounding the problem of multiple definitions, which also partially overlap in meaning:

» Read the article

Genetic drift as cause of evolutionary change
By Branden Holmes on November 22, 2010

There are two ways in which evolutionary change may occur. The first is of course natural selection, made famous by Darwin in the Origin (he coined the phrase). The second process is random sampling, better known by its popular name genetic drift. Natural selection deals with advantageous and disadvantageous mutations, whereas genetic drift governs how neutral and nearly neutral mutations will be inherited from one generation to the next. However, genetic drift is only an evolutionary force in small populations. This is because it is the random changing of the frequencies of different alleles at a given locus, or position where a gene resides upon a chromosome. For alleles to become fixated (where every individual in the population possesses that particular allele) by coincidence is much more probable given a small initial population because there are less individuals for the allele to spread to.

» Read the article

» View all articles

» Common questions regarding evolution

There are 22 forums in this cubit:
Forum Who Last Post
Adaptation
LindaTX8 May 17, 2011 10:36 AM
Biogeography
Surroundx Jul 16, 2010 9:13 PM
Book reviews
Surroundx Jul 16, 2010 7:14 PM
Books
Surroundx Nov 28, 2010 1:39 AM
Charles Darwin
Surroundx Jul 13, 2010 5:51 AM
DNA and Genetics
Surroundx Jul 13, 2010 6:34 AM
Evidence
Surroundx Jul 16, 2010 7:17 PM
Evolution of Plants
Surroundx Jul 17, 2010 4:25 AM
Evolution of Sex
Surroundx Jul 18, 2010 5:28 AM
Evolutionary Development ("evo devo")
Surroundx Nov 28, 2010 12:57 AM
Extinction
Surroundx Jul 17, 2010 4:27 AM
Fossils
Surroundx Jul 18, 2010 5:29 AM
Human Evolution
Surroundx Nov 24, 2010 10:58 PM
Latest News
Surroundx Dec 3, 2010 3:31 AM
Main
bachngolf Jan 25, 2011 10:54 PM
Miscellaneous
Surroundx Nov 26, 2010 3:29 AM
Mutations
Surroundx Jul 13, 2010 5:45 AM
Natural Selection
Surroundx Jul 13, 2010 6:13 AM
Origin of Life
AlohaHoya Sep 5, 2010 11:12 PM
Sexual Selection
Surroundx Sep 8, 2010 9:27 PM
Speciation
Surroundx Jul 16, 2010 9:50 PM
Taxonomy, Cladistics, Phylogenetics etc.
Surroundx Jul 17, 2010 4:53 AM

Recent Threads:
New? Subject Area Date of last post
No Adaptation Forum Adaptation forum May 17, 2011 10:36 AM
No Sharing my news Main forum Jan 25, 2011 10:54 PM
No The disappearance of rainforests 300mya caused a major radiation of reptiles Latest News forum Dec 3, 2010 3:31 AM
No Untitled Article: The Myth of Darwin's Finches Nov 28, 2010 6:42 PM
No Free online books about evolution Books forum Nov 28, 2010 1:39 AM
No The vertebrate sequence Evolutionary Development ("evo devo") forum Nov 28, 2010 12:57 AM
No Four stages of whale evolution Evolutionary Development ("evo devo") forum Nov 28, 2010 12:51 AM
No Humans, chimps diverged 8 mya not 5 Latest News forum Nov 27, 2010 6:40 PM
No Oldest ground-axe found in Australia, 35,000 years old Latest News forum Nov 26, 2010 6:41 PM
No Oldest fossil shrimp uncovered Latest News forum Nov 26, 2010 6:40 PM
No First European farmers were from middle-east Latest News forum Nov 26, 2010 6:37 PM
No Cambrian explosion slower than thought Latest News forum Nov 26, 2010 6:35 PM
No Passenger pigeon finds place to roost on evolutionary tree Latest News forum Nov 26, 2010 6:34 PM
No 209 new molluscs described at once Latest News forum Nov 26, 2010 6:33 PM
No New monkey sneezes in the rain Latest News forum Nov 26, 2010 6:32 PM
No Proof that mammals grew after dinosaurs became extinct Latest News forum Nov 26, 2010 6:31 PM
No New species of ground parrot in Western Australia Latest News forum Nov 26, 2010 6:42 AM

The Evolution Forum

An online evolution resource with articles, the latest news, book reviews, databases, links and a forum.

» Home
» Forums
» Articles
» Database
» FAQ
» Links

Cubit owner: Surroundx

» Contact Admin: Surroundx

New Feature! A database of all popular books written on evolution since 1859.

Contact me: brndnholmes[at]gmail.com