Pristis pristis
Abstract
Pristis pristis species belong to a family of sawfishes called the Pristidae. They also belong to genera Pristis. Currently, the species of sawfish are considered to be endangered species because of habitat loss, by-catch mortality, and direct exploitation. Due to these effects, Pristis zijsron, Pristis microdon and Pristis clavata have experienced an alarming decline in abundance. Consequently, they have been declared as an endangered species. Their demographic history was analyzed alongside other tests such as sampling and genetic testing in order to establish their populace genetics. The calculation used the equation τ = 2ut from the peak of mismatch distribution (s). u = μm^sub T^ and μm^sub T^ is the nucleotides figure sequence. According to this investigation, pristis pristis is indeed endangered and requires adequate conservation.
Pristis Pristis
The Pristis pristis species belong to a family of sawfishes called the Pristidae. They also belong to genera Pristis. This genus of fish is notable for their teeth- like denticles and large body size. According to Simpfendorfer (2000), the sawfish species are currently an endangered species having because of habitat loss, by-catch mortality, and direct exploitation (Peverell, 2005). As a consequence of these effects, the species have experienced an alarming decline in abundance. Subsequently, the International Union for Conservation of Nature has declared most of the fish in Pristidae family as endangered. Stevens et al., (2000) also consents that the sawfish species Pristis face the risk of extinction. However, Peverell (2005) adds that insufficient study and research is a stumbling block to adequate conservation plans for the Pristis species. Amos & Balmford (2001) note that information on Pristis phylogeographic makeup and genetic diversity must be investigated satisfactorily.
Information on the species population genetics has been extensively done. First, Watabe (1991) investigated the population genetics of sawfish species pristis miscrodon. Phillips et al. (2012) utilized the study by Watabe (1991) to examine the comparison of dehydrogenase isozyme. Research on population genetics of sawfishes is currently limited to a study by Watabe (1991), which compared the lactate dehydrogenase isozyme pattern in a total of 12 P. microdons from New Guinea (Papua) and northern Australia. The current study is, therefore, the first substantial investigation into the population genetics of any sawfish species. According to Thorburn et al. (2007), sawfishes have low productiveness, tardy maturity, high longevity, large body sizes and viviparous reproduction. Their body size suggests that adult sawfishes may have the aptitude to disperse over long distances (Peverell, 2008). However, Thorburn et al. (2007) suggests that the expected dispersal may or may have not been realized by adult sawfishes.
Pristis sawfish’s species were abundantly distributed with no extinction threat (Last & Stevens, 2009). Over time, this has greatly changed because these species distribution is now limited to northern Australia (Last & Stevens, 2009). Phillips et al. (2012) utilized mitochondrial DNA to analyze the population genetics of the species. This research was meant to aid in the preservation strategy of Pristis Sawfishes. Additionally in order to evaluate the genetic fitness of the sawfish populations, this information can be valuable. The natural science of Pristis species is considered to be analogous except for juvenile habitat users and adult size Pristis sawfish (Last & Stevens, 2009). The dispersal ability of the adult sawfish depends highly on its size. The size is instrumental because it influences its potential for dispersal. This in turn influences the population subdivision of the species (Jenkins et al., 2007). Pristis zijsron and Pristis clavata life cycles are largely typical and live most their life in marine waters.
Peverell, (2005) notes that Pristis zijsron and Pristis clavata spend their juvenile phase in mangrove areas and inshore waters. Alternatively, Pristis microdons spend their juvenile phase in estuaries and freshwater waterways. As adults, they subsist in the maritime waters (Thorburn et al., 2007). According to DiBattista et al. (2008), Pristis microdon exhibits stronger philopatry than its counterparts the Pristis zijsron and Pristis clavata. The overall study will enable the researcher to uncover the possibility of enhancing the preservation strategy of Pristis Sawfishes, in order to avoid possible extinction.
Methods
Demographic history
In order to determine the population genetics and the rate of the likely extinction of Pristis zijsron, Pristis microdon and Pristis clavata, their demographic history was analyzed alongside other tests such as sampling and genetic testing. Demographic history is essential in the determination of regional species distribution. According to Philips et al (2011), Tajima’s (1989) D and Fu’s (1997) F^sub S^ were utilized to determine conformity of each genetic diversity sample to the population and neutrality equilibrium expectations. Afterwards, all the values were compared with the anticipated distribution via simulations in ARLEQUIN to determine their statistical significance (Excoffier et al. 2005). Rogers & Harpending (1992) add that mismatch distribution and the goodness of fit were compared under the model of population growth with the expected distribution via sum of squares (SSD) (Excoffier et al. 2005).
After finding the consistency of the expected population growth and the mismatch distribution, the generation number since the expansion (τ) was calculated using the software DnaSP v5 (Librado & Rozas, 2009). The calculation used the equation τ = 2ut from the peak of mismatch distribution (s). u = μm^sub T^ and μm^sub T^ is the nucleotides number in the control region sequence (Rogers & Harpending, 1992). According to Peverell (2008), the period from expansion time was changed into generation time (years); Pristis zijsron 9 years, Pristis microdon and Pristis clavata 8 years.
Results
The timing for the growth commencement was estimated when population growth expectations and the mismatch sample distribution was consistent. The population expansion in Pristis zijsron began earlier on the west coast before the present Gulf of Carpentaria. These estimates are rough and suggest that population expansion in Pristis clavata are more recent than the distribution of the Pristis zijsron. The overall result is dependent on the rate of mutation and generation time. The results reveal that the species Pristis pristis is indeed endangered and requires adequate conservation.
Discussion
After investigation and research carried out on Pristis zijsron, Pristis microdon and Pristis clavata species of sawfish, this study has provided sizeable information. According to Phillips et al. (2011) study, all sawfish; Pristis zijsron, Pristis microdon and Pristis clavata have a high level population matrilineal structuring. This is restrained to low levels of haplotype and nucleotide variety, and around the Australian range.
Some secondary facets of the data sets such as fine-scale variation patterns were not interpreted sufficiently because of the inadequate sample size numbers and sampling locations. However, Thorburn et al. (2003) notes that Pristis pristis are rare and dwell in the remotest areas. Peverell (2005) consents that their scarcity of pristis zijsron, Pristis microdon and Pristis clavata makes it harder to obtain samples. The results of the study indicate that the distribution of the species and sample sizes compare favourably. Herein, the conservation criteria that can be utilized can compliment uniformly (Thorburn et al., 2003). Studies by Last & Stevens (2009) review that Pristis zijsron, Pristis microdon and Pristis clavata are all Pristis pristis.
Being an endangered species is dependent on their abundance, breeding patterns and distribution. Pristis pectinata also known as the small tooth sawfish is another species of the sawfish also listed as an endangered species. However, Simpfendorfer (2000) notes that the sawfish species are currently an endangered species having because of habitat loss, by-catch mortality, and direct exploitation. The distribution patterns of Pristis pectinata are vast in Florida, North Carolina, Texas as well as Australia.
Conclusion
In conclusion, the Pristis pristis species belong to a family of sawfishes called the Pristidae. They also belong to genera Pristis. The sawfish species are currently an endangered species having because of habitat loss, by-catch mortality, and direct exploitation. The Pristis pristis have experienced an alarming decline in abundance as a result of these effects. Consequently, the International Union for Conservation of Nature has declared most of the fish in Pristidae family as endangered. In order to determine the population genetics and the rate of the likely extinction of Pristis zijsron, Pristis microdon and Pristis clavata, their demographic history was analyzed alongside other tests such as sampling and genetic testing. The results reveal that the species pristis pristis is indeed endangered and requires adequate conservation.
References
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