ABSTRACT
We assessed the spatial pattern of genetic structure of smooth hammerhead shark Sphyrna zygaena in 10 localities from the Northern Mexican Pacific. A total of 35 haplotypes were identified in 129 sequences of the mtDNA control region. The results showed slight but significant genetic structure among localities (ΦST = 0.044, P < 0.001). In addition, the localities with highest number of juveniles were genetically different (ΦST = 0.058, P < 0.024), which may be representative of nursery areas. The genetic differentiation pattern can be associated to female philopatry and preference for particular birthing sites. Finally, historical demography shows that S. zygaena populations present a recent demographic expansion that occurred during glacial events in the late Pleistocene to early Holocene.
Subject(s)
Genetic Variation , Homing Behavior , Sharks/physiology , Animals , DNA, Mitochondrial/chemistry , Female , Haplotypes , Mexico , Pacific Ocean , Phylogeography , Reproduction , Sharks/geneticsABSTRACT
The hammerhead shark (Sphyrna zygaena) is listed as a "Vulnerable" species for the International Union for Conservation of Nature (IUCN). Here we report the complete sequence for the mitochondrial genome of the hammerhead shark of a specimen collected from the eastern Pacific Ocean. The genome structure is quite similar to other reported mtDNA shark species. It has a total length of 16,731 base pairs (bp); the base composition was A (31.54%), T (30.23%) C (25.03%) and G: 13.20, contains 13 protein-coding genes, 2 rRNA genes; 21 tRNA genes. In addition, most of the starting (ATG) and ending codons (TAA) for the mtDNA gene regions were registered.
