Complex sentence: Since the 1970s, the rates of hybridization between the pallid and shovelnose have increased and this is attributed to changes in the Mississippi and Missouri Rivers, forcing pallid sturgeons into areas where they have a greater chance of encountering shovelnose sturgeons.
Split into simpler sentences: Since the 1970s, the rate of hybridization between the pallid and shovelnose has increased. This is attributed to changes in the Mississippi and Missouri Rivers, forcing pallid sturgeons into areas where they have a greater chance of encountering shovelnose sturgeons.