Plumage determines sex of offspring in Gouldian Finches Over eighty per cent of Gouldian finch chicks will be male if their mother sees that the father has a different coloured head. These colourful Australian native birds have three possible head colours-red, yellow and black. Daughters produced from mixed matings-where parents differ in head colour - suffer from genetic incompatibilities between their parents that cause about 84 per cent to die young. Magellanic penguins swim further for food Magellanic penguins are breeding in large numbers off the Argentinian coast. They are a huge tourist attraction. The birds are spread over a large area. But they need to travel further for their food. This burns up more energy and the mate and chicks need to wait longer between feeds. Penguins can change the pH of their stomach, storing the food longer. The penguins are racing against time when they return. They swim at the same speed day and night. Radio ID tags reveal how long the penguins are away and how much food they´re bringing back. Self-cleaning glass Meera Senthilingam visits St Pancras International Railway Station in London. The roof is made of glass and is self-cleaning due to a very thin film of titanium dioxide. Ian Parkin explains the biological and physical actions which keep the glass clean. Stromatolites and phosphorus Stromatolites are laminated remains of a micro-organism of the past. They contain micro-algae and carbohydrates and some inorganic materials. Some are living. The Chihuahuan desert in Mexico has some beautiful stromatolites growing in the water of springs. Phosphorous is an important element in stromatolies as it is in bones and cells where it plays an important role in energy transactions. It forms nucleic acids such as ATP and RNA. Phosphorous is bound up in rocks and is released by weathering and erosion. It´s a slow process. Some people are concerned that our supply of phosphorous, which is used in agriculture is in short supply, and will be the limit of human sustainability. North American Indians of the Navada high desert David Hurst Thomas works in the high desert of Navada. He studies human ecology. Many Indians lived in the Navada high desert over a period of 12,000 years. The area supplies dense archaeology. David Hurst Thomas says the people were not specialised and thus were adaptable to change, be it change in climate, vegetation or the people with whom they interacted. This allowed the group to survive for so long. How bones react to mechanical activity For over a century people have wondered how it is that bones react to mechanical activity. Walking and running firms bones. Bones not under stress, such as those of astronauts thin. Sheldon Weinbaum studied bone cells and noted fluid motion in tiny tubes. He describes it as a flow induced system of mechano-induction.

[ Sat, 28 Mar 2009 00:00:00 +1000 ]

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