Complete mitochondrial genome of the blacktip reef shark Carcharhinus melanopterus (Carcharhiniformes: Carcharhinidae).

The complete mitochondrial genome of the blacktip reef shark Carcharhinus melanopterus is determined for the first time in this study. The gene composition and order in the mitogenome of C. melanopterus is identical to most vertebrates. The overall base composition is 31.3% A, 25.3% C, 13.3% G and 30.1% T. There are 29 bp overlaps and 21 bp short intergenic spaces in the mitogenome. Two start codons and three stop codons were found in protein-coding genes. The dihydrouridine arm of tRNA-Ser2 was replaced by a simple loop and the other tRNAs could be folded into the typical cloverleaf structure. The termination associated sequence (TAS) and the conserved sequence blocks (CSB1-3) are found in the control region.

The updated phylogenies of the phasianidae based on combined data of nuclear and mitochondrial DNA.

The phylogenetic relationships of species in the Phasianidae, Order Galliformes, are the object of intensive study. However, convergent morphological evolution and rapid species radiation result in much ambiguity in the group. Further, matrilineal (mtDNA) genealogies conflict with trees based on nuclear DNA retrotransposable elements. Herein, we analyze 39 nearly complete mitochondrial genomes (three new) and up to seven nuclear DNA segments. We combine these multiple unlinked, more informative genetic markers to infer historical relationships of the major groups of phasianids. The nuclear DNA tree is largely congruent with the tree derived from mt genomes. However, branching orders of mt/nuclear trees largely conflict with those based on retrotransposons. For example, Gallus/Bambusicola/Francolinus forms the sister-group of Coturnix/Alectoris in the nuclear/mtDNA trees, yet the tree based on retrotransposable elements roots the former at the base of the tree and not with the latter. Further, while peafowls cluster with Gallus/Coturnix in the mt tree, they root at the base of the phasianids following Gallus in the tree based on retrotransposable elements. The conflicting branch orders in nuclear/mtDNA and retrotransposons-based trees in our study reveal the complex topology of the Phasianidae.

Parallel evolution of IDH2 gene in cetaceans, primates and bats.

Cetaceans and primates both have large brains that require large amounts of aerobic energy metabolism. In bats, the cost of flight makes locomotion energetically demanding. These mammalian groups may represent three independent evolutionary origins of an energy-demanding lifestyle in mammals. IDH2 encodes an enzyme in the tricarboxylic acid cycle in the mitochondrion, which plays a key role in aerobic energy metabolism. In this study, we cloned and sequenced this gene in two cetaceans, and 19 bat species, and compared the data with available primate sequences to test its evolution. We found significant signals of parallel evolution in this gene among these three groups. Parallel evolution of this gene may reflect their parallel evolution towards a higher demand for energy.