background preloader

Evolution - Year 12 Biology

Facebook Twitter

Natural Selection: How Evolution Works. December 2004 What is natural selection, and how is it central to the theory of evolution?

Natural Selection: How Evolution Works

Natural selection is how species evolve by adapting to their environment. Natural selection explains design in nature. Charles Darwin studied beak variation of finches on the Galapagos Islands as evidence of natural selection. Illustration from BSCS, Biological Science: Molecules to Man, 1963. Futuyma: Natural selection is the process by which species adapt to their environment. The reason that natural selection is important is that it’s the central idea, stemming from Charles Darwin and Alfred Russel Wallace, that explains design in nature. Mapbiologicalevolution2.pdf. Evolution of the Australian Flora. Australia is an island continent with a distinctive and unique flora unlike that found on any other land mass.

Evolution of the Australian Flora

The evolution of its plants was a result of Australia's long isolation from the other continents. The story starts in the cretaceous period (136 Ma) when the flora of the world began localising, particularly in the southern continents (Australia, Antarctica, India, South America and Africa) due to the splitting of Gondwana. (See the section on continental drift). In Australia, there was a great flood during the Cretaceous period which broke the continent into four distinct islands.

Between these islands were shallow seas, which supported extensive marine life. Direct evidence for this island theory comes from the fact that many molluscs and other fossilised sea creatures have been found in outback Australia, as well as the acid nature of the soils. During the massive floods, the flora on each island diversified and evolved, each island developing its own unique flora.

Mind of Plants : Documentary on The Intelligence of Plants. What is Evolution - history and definitions. Evolution is a scientific theory that essentially states species change over time.

What is Evolution - history and definitions

Evolution of Plants. Plant Evolution. Darwin's Theory of Evolution. Evolution (scientific theory) Evolution, theory in biology postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations.

evolution (scientific theory)

GCSE Bitesize: Darwin's theory of evolution. Phylogeny: Rewriting evolution. Kevin Peterson has kicked many mammals, including the Alaskan Brown Bear, off their traditional perch on the evolutionary tree.

Phylogeny: Rewriting evolution

Kevin Peterson grabs a pen and starts to scribble an evolutionary tree on the paper tablecloth of a bar in Hanover, New Hampshire. Drawing upside down to make it easier for me to see, he maps out the standard phylogenetic tale for placental mammals. First, Peterson scratches a line leading to elephants, which branched away from the rest of the placentals around 90 million years ago. Then came dogs, followed by primates (including humans) and finally rodents — all within a frenetic 20 million years.

This family tree is backed up by reams of genomic and morphological data, and is well accepted by the palaeontological community. “I've looked at thousands of microRNA genes, and I can't find a single example that would support the traditional tree,” he says. Peterson didn't set out to rewrite textbooks. Fossil find. Evolution: 24 myths and misconceptions - life - 16 April 2008. If you think you understand it, you don't know nearly enough about it It will soon be 200 years since the birth of Charles Darwin and 150 years since the publication of On the Origin of Species, arguably the most important book ever written.

Evolution: 24 myths and misconceptions - life - 16 April 2008

In it, Darwin outlined an idea that many still find shocking - that all life on Earth, including human life, evolved through natural selection. Darwin presented compelling evidence for evolution in On the Origin and, since his time, the case has become overwhelming. Countless fossil discoveries allow us to trace the evolution of today's organisms from earlier forms. DNA sequencing has confirmed beyond any doubt that all living creatures share a common origin. And yet despite an ever-growing mountain of evidence, most people around the world are not taught the truth about evolution, if they are taught about it at all.

Timeline: The evolution of life - life - 14 July 2009. Read full article Continue reading page |1|2|3|4 There are all sorts of ways to reconstruct the history of life on Earth.

Timeline: The evolution of life - life - 14 July 2009

Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the "molecular clocks" in the DNA of living organisms. There are problems with each of these methods. Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species.

These difficulties mean that the dates in the timeline should be taken as approximate. 3.8 billion years ago? This is our current "best guess" for the beginning of life on Earth. . , and was probably based on RNA rather than DNA. At some point far back in time, a common ancestor gave rise to two main groups of life: bacteria and archaea. 3.5 billion years ago 3.46 billion years ago. Introduction: Evolution - life - 04 September 2006.