The traditionally accepted relationships among basal jawed vertebrates have been challenged by some molecular phylogenetic analyses based on mitochondrial sequences. Those studies split extant gnathostomes into two monophyletic groups: tetrapods and piscine branch, including Chondrichthyes, Actinopterygii and sarcopterygian fishes. Lungfish and bichir are found in a basal position on the piscin...

The relationship between the Chondrichthyes (cartilaginous fishes), the Actinopterygii (ray-finned fishes), and the piscine Sarcopterygii (lobe-finned fishes) and how the Tetrapoda (four-limbed terrestrial vertebrates) are related to these has been a contentious issue for more than a century. A general consensus about the relationship of these vertebrate clades has gradually emerged among morph...

Recent interest in sperm competition has led to a re-evaluation of the ‘cheap sperm’ assumption inherent in many studies of sexual selection. In particular, mounting evidence suggests that male sperm availability can be increased by the presence of females. However, there is little information on how this interacts with male traits presumably affected by female mate choice, such as larger size....

pond aquaculture is the most significant fish production method in central europe, approximately 70% of the total fish production is originated from traditional fish ponds in this region, which is a resource-saving, ecologically sustainable production method. however, the growth of this sector is not expected because of the low production capacity of valuable fish species and the relatively hig...

fish including; barbus spp, cyprinus carpio, liza abu and aspius vorax have very important role in the economic condition of the rural areas of khuzestan province. these fish have been consumed as fried or roasted. inadequately cooked fish, could be served as a source of infection in these communities. for this reasons, 701 fish were trapped from 4 lagoons (atash, sobhanieh, al-hai, houfel) and...

Sharks have a distinctive shape that remained practically unchanged through hundreds of millions of years of evolution. Nonetheless, there are variations of this shape that vary between and within species. We attempt to explain these variations by examining the partial derivatives of the cost of transport of a generic shark with respect to buoyancy, span and chord of its pectoral fins, length, ...