A Maya hamlet (Hypoplectrus maya) from Belize | Photo: Lisa Carne, © Fragments of Hope 2018, http://fragmentsofhope.org

03/08/2020 | ZMT working group Fish Ecology and Evolution has done extensive research on the Maya hamlet, a reef fish that is endemic to only a small region of the Mesoamerican Barrier Reef System (MBRS) in Belize. The fish live within a 50km segment of the MBRS and have become increasingly threatened as their habitat suffers from the ill effects of coastal developments, sedimentation, mangrove deforestation and climate change.

Based on the research by Dr. Oscar Puebla and his team, the International Union for Conservation of Nature (IUCN) has now changed the status of the Maya hamlet from Vulnerable (VU) to Endangered (EN). The change followed exchanges between the scientists and the IUCN after the publication of the study.  

The Maya hamlet (Hypoplectrus maya) fulfils an important role in the coral reefs system of the MBRS as a mesopredator that is associated with the iconic and also declining staghorn coral. The researchers could show that the Maya hamlet is indeed a distinct evolutionary lineage by analysing its genome and comparing it to other species from the same genus. Furthermore, they could attribute a unique demographic history of continuous decrease in effective population size since the Maya hamlet diverged from congeners just ~3,000 generations ago.

Benjamin Moran, the first author of the publication and now a PhD candidate at Stanford University, says: “The restricted distribution of the Maya hamlet, its decline in both count and effective population sizes, and the degradation of its habitat place it at risk of extinction.”

Oscar Puebla, an expert in population genetics, thinks that this particular case of so-called microendemism may be driven by the combination of the narrow ecological niche and the restrictive oceanographic conditions which can be found in the southern MBRS, a region which shows an unusually high number of marine microendemics.

Referring to the rapid decline of the Maya hamlet, he adds. “We conclude that the evolution of marine microendemism can be a fast and dynamic process, with extinction possibly occurring before speciation is complete.”