Shohreh Ariaeenejad - Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran- Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran
Kaveh Kavousi - Laboratory of Complex Biological systems and Bioinformatics (CBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
Ali A Moosavi-Movahedi - Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran

Evolution involves a change over time in organisms including anatomical, biochemical or behavioralcharacteristics. The natural selection and genetic drift are known as two main causes of evolution. Fishesare diversified and complicated with a huge variety of adaptations. A common classification of fishessuggests that they can be divided into three different classes including Cyclostomata, Chondrichthyes, andOsteichthyes (bony fishes). In this study, globin proteins are investigated to elucidate structure-functionrelationships and illuminate the trend of evolution in globin proteins. The complete gene and proteinsequences of all available fish α-globin sequences were analyzed to reveal their phylogenetic relationshipsand shed light on the speciation process. Estimating the divergence time of α-globin genes for differentfish families can be done by building molecular evolutionary trees scaled to time based on the α-globinexons. The results support the hypothesis of concurrency between time of morphological speciation andα-globin divergence and this concurrency can be interpreted as a sign of struggling to acquire more fitnessto changing environment. Investigation on the fish globins as well as the evolutionary studies andcomputational analysis of available globin proteins reveals that the hydrophobicity has a key role in theevolution process of fish hemoglobins. Our findings confirm the existence of a strong relationshipbetween the evolutions of fish globin proteins with their hydrophobic properties. It has been shown thatdifference between the structural properties of Hbs is related to their adaptation with habitatenvironmental conditions such as depth, partial oxygen pressure, temperature and salinity.

α-globin, hemoglobin, molecular phylogenetic, hydrophobicity