Per Ericson, a leading scientist at the Swedish Museum of Natural History, is making fascinating discoveries about species of birds from all over the world that will help conservation in the future - not only of birds but also of flora and fauna in their habitats.
Per Ericson, Director of Science at the museum in Stockholm, leads and develops research and collection activities and is a member of the museum's management team. He has been at the museum since 1991, when he was senior curator of ornithology. His research focuses on the early evolution of birds and higher-level relationships between them. In his work morphological data on living and fossil birds (such as the Presbyornithidae, a family of late Cretaceous and early Tertiary birds) are combined with molecular data. Ericson is also studying intraspecific variation and speciation processes, especially in tropical and subtropical birds.
"Birds as a group are much older than we thought" says Dr Ericson, "and certain groups that we had assumed were recently evolved, like passerines, did in fact evolve already in the Late Cretaceous. In birds the morphological variation is rather limited because of the many constraints put on birds due to their adaptations to flying", says Dr Ericson.
"The skeleton and other parts of their morphology simply becomes similar and morphologists have long struggled to find out which features are inherited and which are due to adaptation to similar life-styles. The use of genetic data often helps to resolve these issues. In my research we look at all groups of birds in the world - how they evolve, where they originate from. With many groups there is no fresh tissue or blood available, so we are forced to work with old museum skins. It is hard work but if you succeed you will have access to specimens from all over the world. "The work with degraded DNA from museum material has been really successful at our museum. We have four or five people working on this here now" says Dr Ericson.
The main threat to DNA, he says, is from heat and moisture. "If you have a 19th century specimen of a bird that was properly dried soon after preparation, it most often will be useful. Mitochondrial DNA which is abundant in the cell has been rather easy to amplify from old specimens. Not until the past five years have we been able to amplify also the less abundant nuclear DNA. This has been a major breakthrough.
Money for conservation work is limited. One criterion for funding is systematic uniqueness. Small, isolated populations of otherwise rather widespread bird species thus rarely get protection. There are several examples where advances in DNA technology have found that such isolated populations indeed are genetically distinct and thus better be regarded as full species. This in turn may make them qualified for protection and making funds for conservation available.
Furthermore, birds are used as an indicator for highly valuable environments in conservation terms, he says. One assumes that if there are rare birds in an area, if you protect that area you will also protect rare butterflies, plants and so on. For instance, Dr Ericson did field work in Vietnam and collected blood from a population of birds which had been thought to belong to a species common in China but which was found to be from a quite distinct population. As a result that particular part of Vietnam was given a higher value in conservation terms. Dr Ericson says it is an ongoing project of his team to identify isolated bird populations across the globe in order to test their systematic uniqueness.
But how can one be sure about the quality and accuracy of collaborators' work? Is there not a danger of flawed findings or contaminated samples? "There is a risk in data sharing, including the sharing of tissue and DNA because of the problem of involuntary mislabeling and misidentification. We thus prefer to collaborate with people we have known for many years or who have a good track record," says Dr Ericson. "But errors do often correct themselves over the years because other groups are working on more or less the same scientific questions."
The Swedish Museum of Natural History is also engaged in the global effort to produce DNA-barcodes for all species, i.e. a short portion of DNA that is unique to a species. "The barcode is used for quick species identification but our task right now is to help building a reference library of all species in the world. This species identification tool is especially helpful for proper identification of food items or for legislative purposes (e.g., species identification of objects seized by Customs or the police)"
An interesting example of bird behavior is the population of blackcaps which split into two groups - those which flew to Britain over winter and those which left their central European breeding grounds to fly, as before, to Spain. Different characteristics evolved in the Britishwintering group, such as rounder wings and bills adapted for the garden feeder. Does DNA have a memory or do the chicks simply copy the adult birds in flying to Britain instead of to Spain? "It is true that birds may inherit a behaviour to migrate without the help of adults. As it is inherited, it is definitely part of the DNA. I would not say that the DNA itself has a memory."
Often mating patterns in birds indicate species because when a distinct and separate species is being formed members stop mating with and fighting off males from another group as they no longer see them as rivals for the female birds. "In many cases groups of individual birds are separated geographically and evolve independently," says Dr Ericson "After many, many years they may have evolved different mating strategies and morphologies, and thus no longer recognise each other as members of the same species.
This can rarely be tested, however, as the populations still are widely separated. It becomes a matter of subjective decision whether to regard them as separate species or not. Here, DNA analyses may show that similar-looking populations (regarded as subspecies) are in fact very different genetically and thus best regarded as full species."
What implications will Dr Ericson's discoveries will have for the science of humans? A recent study undertaken in Sheffield, England, into the zebra finch was said to have produced findings that would help researchers all over the world to understand biological processes in humans such as immunity and fertility. And a study of birds in the US was thought to have implications for reducing contamination in our food supply as well as for preventing collisions between aircraft and birds.
"Our research is curiosity-driven and not specifically aimed at resolving major human issues," Dr Ericson says. "Nevertheless our work is important since birds probably constitute the most popular objects of study in ecological and ethological research projects on vertebrates. In many of these projects, knowledge of the systematic position and evolutionary history of the studied species or group is a prerequisite for a correct interpretation of the results. One aim of our research is to provide a solid phylogenetic framework within which hypotheses about the evolutionary history and intra-relationships of a group can be tested. Our research also provides information that can be used to infer the importance of climate to speciation and geological distribution of species. This is made possible by interpreting the evolution of bird faunas over geologic time in a climatic context."
Dr Ericson, when asked whether it will be possible, as technology improves, to use degraded samples of DNA (not usable today) and whether laws should be drafted to protect samples in museums and ensure that none are discarded because they are thought to be unusable replied; "More and more degraded DNA will be useful for research thanks to improved techniques. Some museum specimens may still not yield useful DNA, but there is no risk they are discarded simply because of that. Museum collections in general are useful for numerous of other purposes and they constitute a source for research that is steadily growing in importance."
For more information, please contact Per Ericson -