Numbering the game
SCIENTISTS from the Natural Environment Resource Council (NERC'S), Institute of Terrestrial Ecology at Banchory, and the department of zoology at the University of Aberdeen - both in Scotland - have embarked on a novel method to study population ecology. The programme called Molecular Genetics in Ecology (MGE) Initiative, Uses DNA fingerprinting and has been in operation since September, 1994. The team is working towards developing DNA markers known as microsatellite primers that will help establish the animal's individual and group identity (NERc news, No 34).
Population ecology is a field which specialises in collecting data on individual animals, paying attention to such details as their life expectancy, the number of offspring produced by them, their habitat area and the causes of their death. This exercise helps determine whether or not a certain isolated population will survive in the face of unfavourable conditions.
Certain groups of animals like birds can be trapped easily and marked unobtrusively, and then re-captured or resighted to obtain the necessary information. But there are animals which are difficult to catch and observe" making population studies on them an awesome task. Scientists hope to overcome these problems by applying the DNA fingerprinting technique, so that each individual would have a unique identity. Trace quantities Of DNA which can be retrieved from the individual's hair, feathers, egg membranes and even droppings, would be sufficient to establish the animals' identity. Moreover, the use of this technique does not call for the capture of the animals. The team has used the technique to study the population dynamics of otters, re@ -grouse, water-voles and winter moths.
The Eurasian otter - a secretive and endangered carnivore - is extremely difficult to spot in the wild and as difficult to capture. The MGE team collected otter droppings (spraints) and extracted reasonable amounts Of DNA from it. If successful, the researchers shall be able to track the movement of individual otters and trace their relation to others in the local population.
Populations of the red grouse - a common bird found in the British moorlands - are known to fluctuate every five to 12 years. The reasons for these changes are attributed to the tendency of these creatures to inbreed, and the harm caused by the parasites harboured by them. The degree of relatedness among the red grouse - which normally prefer kin as neighbours and mates - tend to change as their population begins wavering. The study has so far focused only on a small population of grouse. Now the MGE team is working towards developing primers specific to the red grouse.
Water-vole populations in the UK are rapidly declining. The species' survival now depends on the animal's ability to disperse and re-colonise. Dispersal on the basis of the sex of the animal results in the males moving out and the females staying back. The success of re-colonisation therefore, depends on the movement of both sexes to the new site. The'MGE initiative - through mitochondrial DNA and microsatellite markers - plans to study the movements of the animals between dispersed populations, and also discover whether or not sex-specific dispersal affects population viability. Such knowledge will help in devising conservation- strategies for the water-voles.
The MGE initiative is also developing DNA markers to differentiate between the different types of winter moth which feed on different plants. The moths are known to share host-parasite relationships with broad-leaved trees like oak and birch, but now their range seems to have extended to other plants such as the unpalatable Sitka spruce and heather. Preliminary results indicate, that different genetic types are associated with different hosts, and that there is lesser genetic variation within the group feeding on heather and-Sitka spruce.
The work conducted through the MGE initiative has proved significant not only to study population dynamics of species, but also to develop effective conservation strategies to save these animal populations.
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