Marco López Luna
M.Sc. Student- Universidad Juárez Autónoma de Tabasco
Location: Urban and Suburban Lakes in Tabasco State, Mexico
Research: Urban Heat Island: Effect of Incubation Temperatures on the Sex Ratio of Wild Hatchling Morelet´s Crocodiles (Crocodylus moreletii) in Southeastern México
Species/Topic: Morelet's Crocodiles (Crocodylus moreletii)
Abstract: Crocodiles, as like many other reptiles, lack sex-specific chromosomes. Instead, they exhibit temperature-dependent sex determination (TSD), meaning the egg incubation temperature determines the sex of the developing embryo. During egg incubation of Morelet´s crocodiles (Crocodylus moreletii), relative cool temperatures produce females and warm temperatures produce males. Recently, a highly biased sex ratio was observed in the wild population of C. moreletii in an urban lake in southeast Mexico (Laguna de las Ilusiones, Villahermosa, Tabasco), where for every 17 males observed there was only a single female recorded (López-Luna, unpublished data). It is our hypothesis that this biased sex ratio is due in part to higher temperatures inside the city, associated with urban development and industrial activities. This effect, referred to as 'Urban Heat Island' (UHI), may alter population growth as well as the long-term stability this population of endangered C. moreletii by producing an exaggerated number of males and limited number of females.