To answer the question, we examine four species of the fish genus Bathygobius, two species of which are found on the Atlantic coast and two on the Pacific. The differences allopatric species had presumably arisen due to separation of the original common gene pool by the closure of the Isthmus of Panama. By using artificial hybridization experiments and laboratory breeding tests we were able to show that the species on the same side of the Isthmus are completely reproductively separated by pre-mating behavioral isolating mechanisms. The allopatric (transisthmian) species, although now morphologically different, have still not, after 3 million years, evolved complete reproductive isolation, and hybridization in aquaria occurs regularly when presented with no choice of mates or with unbalanced sex ratios of allopatric species.

I’m currently exploring the possibility of establishing a graduate-level university at STRI that would train students from around the world and allow them to spend their full graduate careers doing research in the tropics. Hundreds of students have completed Ph.D. research at STRI but they are generally required to return to their home institutions for at least a year to complete their doctoral degrees. Establishing a graduate-level university based in the tropics would, in a significant way, help address the global imbalance between the world’s best universities, 94 percent of which are in the temperate zone, and Earth’s biodiversity, 80 percent of which is found in the tropics.