Çağan H. Şekercioğlu

oceanic midwater to freshwater occurred? " the authors write. The two environments are remarkably different and require fish to be adapted to remarkably different ecological and physiological constraints. The authors consider whether there was a gradient in productivity between freshwater and marine environments at the time of the evolution of these eels. Another possibility the authors consider is that there was a vacant niche in freshwater when multiple marine species were emerging. " Multiple lineages of marine eels in marine environments, including voracious predators such as moray eels, " may have led to a vacant niche in freshwater, they suggest. " How can we explain why this apparent evolutionary shift of the freshwater eel life history from the oceanic midwater to freshwater occurred? " The authors speculate that some ancestral forms may have come to estuaries during their larval or juvenile phases and developed an adaptive behaviour of regularly inhabiting estuaries and occasionally entering freshwater in tropical regions because of higher food availability, better survival or to escape from predators. " Once natural selection resulted in the emergence of eels that regularly used freshwater for growth, " a new life history was established, they suggest. But what is most evolutionarily remarkable is the return to the deep ocean by these species to breed. " Reproductive behaviour is typically conservative and constrained by many ecological and physical factors, " the authors say. So the migration of freshwater eels back to their offshore habitats over an evolutionary timescale represents a remarkable relic of the reproductive behaviour of these enigmatic animals that share a common ancestry with pelagic eels of the deep ocean, they write. " This surprising discovery offers a new perspective on the evolutionary origin of the freshwater eels, " and may provide novel insights into the evolutionary process of their unique migrations, they believe. Instead of playing soccer, I brought home insects, lizards, hedgehogs, and other critters. My mom, a worrywart, took me to a child psychiatrist to cure me of this nature madness: he reassured her that I was not a budding psychopath and told her to encourage my interest in nature. However, I had no role models, no natural history museum in Istanbul, and no mentors until I was in high school. I saw my first field guide at 15 and started birding immediately. I wrote my college application essay on insect collecting. The lack of natural history …