Convergent Evolution

Convergent Evolution evolution of antifreeze proteins in Antarctic notothenioid fish and Arctic cod:

Convergent Evolution evolution of antifreeze proteins in Antarctic notothenioid fish and Arctic cod By Eduardo Villatoro

Evolution:

Evolution To understand this, we must review Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life

Types of evolution:

Types of evolution Divergent Convergent

Divergent evolution:

Divergent evolution The accumulation of differences between groups which can lead to the formation of new species This results from diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection Homologous structures

Homologous structures:

Homologous structures Forelimbs in mammals

Convergent evolution:

Convergent evolution The evolution of similar features in independent evolutionary lineages Analogous structures

Analogous structures :

Analogous structures Bats and Birds: wings

Convergent evolution:

Convergent evolution Not solely based on morphological structures Can be expressions of proteins that have similar functions Ex. evolution of antifreeze proteins in Antarctic notothenioid fish and Arctic cod

Different origins:

Different origins Christina Cheng Antarctic notothenioid fish and Arctic cod did not develop antifreeze proteins through a common ancestor

Species:

Species Arctic cod: Boreogadus saida Antarctic notothenioid: Dissostichus mawsoni

Antifreeze:

Antifreeze AFGP: antifreeze glycoprotein In mammals, glycoproteins are an important part of the immune system and used for white bloods cell recognition In these polar fish, glycoproteins acts as antifreeze, attaching and dissolving the ice crystals found in the fishes blood. Allowing the fish to survive in a -1.9 C habitat

Cont. :

Cont. The AFGP in both fish is nearly identical, suggesting common ancestry Further analysis reveals the contrary Antarctic notothenioid AFGP originate from a pancreatic trypsinogen, different from the Artic cod. This signifies that trypsinogen is not responsible for AFGP production in Artic cod.

Cont.:

Cont. Through DEAE-cellulose ion exchange the AFGP genes of both fish were purified and then the RNA was sequenced and analyzed data revealed Arctic cod AFGP gene is unrelated to notothenioid AFGP gene or trypsinogen gene, and very likely arose from a different genomic locus.

Climatic evidence:

Climatic evidence Paleoclimatic data of the polar regions also agrees with the molecular evidence of convergent evolution Evolution of AFGPs in both groups of fishes are recent and separate events. AFGP bearing Antarctic notothenioid, existed about 7-15 mya, which is in line with the cooling of the Antarctic Ocean to freezing temperatures about 10-14 mya (mid-Miocene) the freezing of the North Polar oceans occurred at about 2.5 mya (late-Pliocene) indicating that AFGP evolution in Artic cods was much more recent

Thank you for for listening.:

Thank you for for listening.