Population Characteristics and Dynamics
Population Distribution:
The Blanding's Turtle can be found in Canada and the United States of America. In Canada, there are two distinct populations, based on location: the Great Lakes and St. Lawrence population and the Nova Scotia population (14). The majority of this species found in Canada live in the provinces of Ontario and Quebec, in the Great Lakes and St. Lawrence population. The Great Lakes and St. Lawrence population is located throughout southern Ontario and extending eastward across the provinces of Ontario and Quebec to southwestern Quebec (8). The Ontario population distribution is not continuous, while the Quebec population is concentrated in areas close to the Ontario border (8). The Blanding's Turtle population in this region, the Great Lakes and St. Lawrence, is considered random. These populations are isolated from each other (8). They do not thrive in groups of individuals as seen in the clumped distribution, and they do not mark out their own territory as seen in a uniform distribution. In a random population distribution, the resource distribution is uniform, there is an abundance of resources, and the interactions between members of the same species is neutral. |
Population Density:
Blanding's Turtles are typically found isolated from each other, with a very low population density. It has been estimated that the population density could be as low as one adult per square kilometer (8).
Population Size:
Focusing on the species of the Blanding's Turtle in the Great Lakes-St. Lawrence population, the estimated current size of this population is 10,000 individuals (8). There are no estimates given for the Quebec population or the Nova Scotia populations, but these are thought to be very small (8).
Environment's Carrying Capacity:
The environment's carrying capacity for this species is much greater than what the population density values would suggest. Like many other reptiles, because the Blanding's Turtle does not require care and support from other member's of its species, the minimum viable size of this population is lower than most other animals.
Genetic Diversity in the Population:
One of the main reasons why the Blanding's Turtle was deemed threatened by COSEWIC is because of the population's uneven age structure. This means that the distribution of the turtle's ages within the population is not constant. Because the population is declining, this is an indication of low numbers of juvenile turtles.
Another major reason why the Blanding's Turtle is threatened in general is because a lack of genetic diversity. However, studies show that the Nova Scotia population of the Blanding's Turtle could be a significant key to the survival of the species, as those turtles have slightly different genetic variation.
The main range populations of Blanding's Turtles includes those found in Ontario, Quebec, Wisconsin, Illinois, Michigan, Ohio, Minnesota, Iowa, Indiana, Nebraska, and Pennsylvania (13). Isolated populations of the Blanding's Turtle include those found in Maine, Massachusetts, New York, and New Hampshire (13).
A preliminary study was conducted by Acadia University to examine the genetic diversity within the Blanding's Turtle species. The turtles in the Nova Scotia populations have different shell sizes and carapace colours that these turtles from the main range, which are phenotypic differences that may result from genetic diversity (13).
The deoxyribonucleic acid (DNA) was extracted from these turtles in the Nova Scotia population. These turtles' DNA was then compared with the DNA from the Blanding's Turtles in other populations. The Nova Scotia population has believed to have been isolated from the mainland populations for between four thousand and eight thousand years (13). It was shown that there is a thirty-four percent variance between the Nova Scotia population and the main range populations of the Blanding's Turtle species (13).
The results of this study suggest that the Nova Scotia population of Blanding's Turtles could be crucial in maintaining genetic diversity within this species. This is the case because this population is a large contributor to the genetic diversity within this species. The Nova Scotia population may be an important evolutionary unit of the species (13).
http://www.theweathernetwork.com/insider-insights/articles/endangered-species-the-blandings-turtle/17743/
http://blog.cwf-fcf.org/?m=201408
http://www.saveostranderpoint.org/ode-to-a-turtle-a-poem-by-david-simmonds/#sthash.Rn91C15i.dpbs
http://blog.cwf-fcf.org/?m=201408
http://www.saveostranderpoint.org/ode-to-a-turtle-a-poem-by-david-simmonds/#sthash.Rn91C15i.dpbs