Introduction
Otters are mammals of the class amphibians that are mostly aquatic and feed on fish. Their bodies are generally slim with short limbs. They have characteristic long muscular tails. They are also known for their webbed toes that end in sharp claws adapted for their feeding habits. They are found almost in all parts of the world.
This genetic review will focus on both the diversity of river otters and sea otters.
River otters ( Lutra Canadensis)
Lutra canadensis commonly found in North America like rivers with transparent waters with a high rate of flow and well-vegetated riverbanks. They enjoy living in mature trees deciduous trees alder, scrub and woodlands. In terms of habitat and diet, this species is opportunistic in nature and has to utilize a wide area of the river so as to meet the metabolic demands of the body. This species population has been known to be on the decline due to factors that include habitat destruction and unregulated fur harvest. Issues of pollution and trapping have also contributed to the loss of genetic diversity in this group of animals.
Researchers have undertaken studies on river otters to determine diversity. For instance the introduction of 279 river otters in western New York between the long period of 1995 and 2000. Studies have been done on the faeces of the otters so as to determine dietary and genetic characteristics. For the reintroduced river otters genetic diversity can be determined using the technology of molecular scatology. The DNA material obtained from the faeces can be used for analysis to obtain the required information for genetic variability. The river otters are opportunistic feeders with their food mainly comprising of crayfish, frogs and aquatic insects. (Serfass, 26 1995)
Breeding patterns in these species can be determined using the technology of scatology. The DNA materials were obtained from the faeces of those individuals who were reintroduced into the river. This DNA can then be subjected to laboratory tests. This method is good because it has no effect on the otters and to be particular their natural behaviour. In the group, the molecular technology can be used to determine where an individual otter came from therefore establish if there are instances of inbreeding. If inbreeding is noted in the analysis then measures can be put in place to prevent The phenomenon from occurring.
Inbreeding can cause can give rise to weaker individuals in the population who cannot compete effectively with the rest. Therefore if instances of inbreeding are reduced in the breeding of the river otters then this will be a big step towards conserving the group and maintaining genetic diversity. The presence of raccoons in the population has also led to studies to determine if there exists a relationship between them and the river otters. Genetic similarities between the two species can be determined using molecular technology. (Amos, 87 2001)
Suitable methodologies have been designed in such a way that possible visual cues can between the river otters and the raccoons can be determined.
The genetic sample analysis can also be useful in determining if there exist differences between the river otter and the raccoon’s microsatellite sequences.
From such studies, scientists will be in a better position to know whether to introduce more river otter species in the various samples so as to maintain high genetic diversity within the entire population and prevent the threat of extinction. Mitochondrial DNA is a very vital component that can be utilized in the conservations aspects of river otters. Mitochondrial DNA is passed to the offspring from the parents because the mother contains a large number of chromosomes.
The sperms from the male parent do not contain these cells therefore it follows that mitochondrial DNA is inherited maternally. Koepfli and Wayne (2003) through their works came up with the mitochondrial DNA cytochrome b sequence for the North American river otter (Lontra Canadensis). If such studies are undertaken on the populations of river otter species the success rates are high and this conforms the way forwards towards utilizing genetics to create more varieties of the same species which can withstand the habitat challenges.
The sea otter (Enhydra lutris )
Large scale hunting for commercial purposes of the sea otter started to be a threat to this species in the early 20th century. Sea otters play an important role in the natural ecosystem. They are also important to the human being as far as aesthetic value is concerned. This then sparked off efforts to conserve the remaining population and prevent the extinction that was eminent. Between the 18th and 19th century there was widespread trade in fur which mostly came from this species. This so a significant reduction in the population of sea otters during that period.. The existing populations suffered most as s result of the fur trade and it so the urgency of using genetics to initiate conservation measures so as to prevent extinction.(Wilson,72 1991)
Oil spills were also a major cause of mortality increase in the population of sea otters.
Low levels of genetic variance have been observed between extant populations and translocated sea otters. Genetic variation has been noted in the extinct sea otter populations. This revealed variations in the mitochondrial DNA loop and the nuclear microsatellite. This was evident in both translocated and remnant populations.
Early conservation measures for this species of otter mainly utilized translocation approaches whereby otters were moved from one point to another. This took place around 1987. Sea otters were translocated from parent range to San Nicholas Island found in the Channel Islands. Scientists believed that the second population will prevent the southern sea otter population from being eliminated by oil spills.
Translocation was also important for the purpose of cross-breeding different varieties of this species and introducing a more superior variety of sea otters that is capable of overcoming the mortality factors Sea otters in California (Enhydra lutris genes) have experienced a decline in population in recent years. This has been caused by high mortality rates in young adults and adults. The cause of most of the deaths has been attributed to cardiac infections coming from the parasite called Toxoplasma gondii. This is the case because antibodies of the parasite were detected in the bodies of some sea otters which were studied.
Why cardiac disease is more vulnerable in California than in populations in other parts of the world, can be attributed to low genetic variability within this particular population. This follows that the solution to preventing the extinction of the sea otter species in California lies in creating genetic variation within the group so as to develop a resistant variety that will not succumb to the infections by Toxoplasma gondii. Research also established through examination of sea otter carcasses that their mortality is also caused by an infectious disease. The disease is found in shorebirds who acquire it from the sand crabs. Fortunately, the sea otters have been observed not to prefer sand crabs as their prey. The parasite responsible for the disease is not fatal to the shorebirds as it is on the sea otters.
Sea otter conservation by use of genetics is mainly focused on increasing variability within the population so as to establish superior varieties which are capable of adequately utilizing their habitats and developing resistant to the main diseases that are significant in increasing the mortality rates within the population. Reintroduction of new species can also be utilized in the conservation of sea otters with new species having suitable adaptations that can be used for the purpose of population build-up and therefore conservation of the group to reduce the threat of extinction. (Cheney, 59,1995)
In conclusion, it is therefore important to note that there’s has been a considerable effort towards employing genetics in the conservation of both river and sea otters. There is still much left to be explored for instance issues that touch on the breeding of the sea and river otters. If this area is well explored it could be a great move towards population build-up and therefore conservation of these very important animals in the ecosystem.
References
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Cheney LC (1995) An Assessment of Genetic Variation Within and Between Sea Otter(Enhydra lutris) Populations off Alaska and California Moss Landing Marine Laboratories, California State University, San Jose, CA.
Serfass, T. L., M. T. Whary, R. L. Peper, R. P. Brooks, T. J. Swimley, W. R. Lawrence, and C. E. Rupprecht. 1995. Rabies in a river otter intended (Lutra canadensis) for reintroduction. Journal of Zoo and Wildlife Medicine 26:311-314.
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