Link to the Show / Show NotesEmails from East Anglia
Hundreds of emails between scientists at the University of East Anglia´s Climate Research Unit have been published. Do they question our understanding of climate? Fred Pearce investigated for New Scientist magazine.
Decline of birds in Victorian forests
Reports show birds are declining in national parks in Victoria. Two thirds of species have shown reduced numbers over 10 years. Reduced rainfall has resulted in less flowering in trees and fewer nest sites. Red Ironbark supplies honey and nectar but this important food species hasn´t flowered in two of the last eight years. Other effects on birds include loss of native vegetation. The concern is bird species are disappearing one by one.
Extra-retinal photo receptors
The birth rates of many birds and mammals vary with the season. In ancient times this was shown in people too, but in people the mechanism is unknown. Humans have receptors in the eye which set the biological clock with the local time of day. The push has been to understand the pathway of chemicals involved. Some ocular diseases impact circadian rhythms. Non-mammalian vertebrates have extra light sensitive cells. These can be deep within the brain. Genes for these light sensitive molecules have been isolated in some animals´ DNAs, such as the chicken. All mammals, placental mammals and monotremes have lost these extra-retinal photo receptors. This is part evidence for a nocturnal lineage. So it is suspected that birds' singing in the early spring morning and the activity of their reproductive systems are the result of light penetrating the brain and triggering photoreceptors there.
The musky rat-kangaroo - a living fossil
Benjamin Kear describes the musky rat-kangaroo of north-east Queensland. It is known as a living fossil: it existed 26 million years ago in a form similar to that found today. Now the animal is endangered as its habitat is replaced by houses and golf courses. The fossil record and modern DNA analysis shows the changes that kangaroos have gone through, including a great extinction 10 million years ago. It is thought this occurred as the result of a big drying of the environment when forests were replaced by dry grasslands.
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