Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
—Map of Poecilia mexicana system in southern Mexico near the Sierra Madre de Chiapas mountain range. The water flows north toward the Gulf of Mexico. Yellow triangles represent populations from sulfidic environments, whereas blue triangles represent populations from nonsulfidic environments.
