Genetic Diversity of Mute Swans and Egg Clutch Size
Tuesday March 1st 2011
Researcher Anne Charmontier, from England, has devoted most of her professional career investigating Genetic Diversity of Mute Swans as a wild and avian bird population. Along with other researchers Charmontier published in American Naturalist a 25-year study regarding Egg Clutch Size entitled “Mute Swan Population Helps Explain Evolutionary Question.” In this study the scientific question was – Why does a population’s average clutch size differ from the most productive clutch size ? Charmontier and the other researchers hypothesis was supported in this study results that (a) recent relaxation on food constraints, and, (b) an increase of protection from predators, both may have helped the Mute Swans to Evolve towards a Larger Clutch Size. In her work, Charmontier has studied and published data on (1) Evolutionary response to egg clutch size, (2) Individual variation in rates of Senescence: Natal Origin Effects in wild bird populations, (3) Seasonal Changes in Male/Female Mute Swans, (4) Climate Changes in wild bird population; (5) Genetic Models of Mate Choice in the wild; (6) Variations in Breeding Behaviour; and, her current work in 2,011 is entitled (7) “Age-Dependent Genetic Variations in the Life-History Traits of Mute Swans.” Other researchers measured the eggs and hatching mass in birds and reptiles. They found in birds the most important factor affecting hatching mass (HM) was the initial egg mass (IEM) at laying the egg.
They also found a physiological link between (IEM) and (HM) which contrast the observed relationship between egg mass and the incubation period. The results of this study, for birds and reptiles, showed “significant implications for the interrelationships between (IEM) and Embryonic Growth (of the Cygnet within the egg in swans).” Another study of 1,525 bird species and 201 reptile species investigated initial egg mass (IEM) and incubation period (IP). Their statistical ANOVA tables demonstrated that for bird eggs incubation period is NOT determined in large part by egg mass. And this study’s results allowed for new scientific questions to be proved by researchers. Two of these questions include (1) Ecological and Physiological Factors affecting the Length of Incubation Period, and, (2) The Rates of Embryonic Growth for different taxa (animal kingdoms) and habitats. In light of these studies considering Embryonic Growth within the Mute Swan’s egg, how do you feel about some people spraying the eggs with corn oil so they won’t grow and the pen Mute Swan would sit on those eggs forever with no cygnets hatching ?
Heterozygosis is dissimilar pairs of Genes or in a Cell the loss of normal function of one allele (different forms) of a Gene. Genetic variations from Genes are important in zoology and nature in general ! In Mute Swans and other animals body proportions can change depending where particular master Hox Genes are active. The same Hox Gene – Hox C6 – switches on at different points along the body. The Hox Gene marks the beginning of the Thorax, therefore, different species end up with necks of varying lengths…a long neck in the goose…and a much longer neck in Mute Swans, according to National Geographic’s “Fins to Wings.” In the Journal of Zoology March 2,011 issue includes a study on “Genetic Diversity in Birds associated with (1) Body Mass (BM), and (2) Habitat Type (HT) [aquatic or terrestrial] in 76 Avian Bird Species.” These variables were chosen because (BM) and (HT) are predictors of Genetic Variation which is very similar in birds. The results of this study show Terrestrial birds have a greater Genetic Diversity than Aquatic species. And, these results were interpreted from published data of other vertebrates that suggest the “Patterns of Genetic Diversity in Birds” depends on two relationships, namely (1) Bird Evolutionary effective POPULATION SIZE , determined in part by Ecological and Environmental features, and, (2) on the Rate of Molecular Evolution. J. L. Quinn stated in the Journal of Evolutionary Biology that “Evolutionary Biologists increasingly use pedigree-based quantitative Genetic Methods to address questions about the Evolutionary Dynamics of Traits in wild bird populations: data depth (number of years) and completeness (number of observations). The results of J.L. Quinn’s study showed by using long-term studies of the Great Tit and Mute Swan Estimated Breeding Values in the Great Tit were NOT influenced by data depth; but, Breeding Values WERE INFLUENCED by data depth (number of years) in the Mute Swans. This influence in Breeding Values by Data Depth was probably due to the differences in pedigree structure between the Mute Swan and Great Tit. At Chicago’s Field Museum of Natural History, Sushma Reddy published in Science “Genetic Sequence of 169 Birds.” In the study results Reddy indicated “Flamingoes and some other aquatic birds did not evolve from water birds, instead, they adapted to life on the water.” Along the same line of thinking, Evolution Diary states “New bird family tree reveals same odd ducks.” The Mute Swan (Cygrus olor) is a species of swan, and thus a member of the duck, goose and swan family Anatidae. E. Marjorie Northcote, Cambridge University, England study indicated “Limb bones of Mute Swans from Neolithic [the last part of the Stone Age – not a time frame, but state of the culture] to the Bronze Age in Cambridgeshire PEAT were larger than that of a recent sample when compared biometrically.” That means, a study of biological phenomena, such as, measuring physical characteristics, such as, Limb Bones of Mute Swans.
Mute Swans 6,000 years old are found in post-glacial PEAT beds at East Anglia in England. Despite the Eurasian origin of Mute Swans, its closest relatives are the Black Swan of Australia and the Black-Necked Swan of South America. The Mute Swan is constantly criticized for stealing Trumpeter Swan, native to Canada, nesting sites. Conversely, in a List Of Animals Displaying Homosexual Behaviour it included Black Swans. This listing stated: “The Black Swan (Cygnus Atratus) is a large waterbird that breeds mainly in the southeast and southwest regions of Australia. An estimated 1/4 of all Black Swan pairings are homosexual and they STEAL NESTS, or form temporary threesomes with females to obtain eggs, driving away the female after she lays the egg.” The Stealing of Nests seems to be a family trait in both Mute and Black Swans. . For many years Black Swans have been on the River Thames in Stratford, Ontario and there were a pair at White Chapel Pond in Hamilton, Ontario. The International Union For Conservation Of Nature (IUCN) founded in 1963, Red |List or Threatened Species is the world’s most comprehensive inventory of the global conservation status of plant and animal species. The (IUCN) is also the world’s main authority on the conservation status of species. A series of Regional Red Lists are produced by countries or organizations, which assess the risk of extinction to species within a political management unit. Joseph Travis, Presidential Address of the American Society of Naturalists stated: “Ecology and Evolutionary Biology are fundamental processes that unfold from a variety of histories. The task of our science is to match the question to organisms, or systems. For many scientist, the organism leads to the question when we observe (participant observation) some of nature’s striking phenomena.”
Sources: Journal of Zoology, National Geographic, Journal of Evolutionary Biology, Science, American Naturalist, Evolution Diary, American Society of Naturalists
Doug Worrall Photography