diff --git a/guide/age-of-four/src/components/toc/TableOfContents.tsx b/guide/age-of-four/src/components/toc/TableOfContents.tsx
index 0e5f65af..12f460bb 100644
--- a/guide/age-of-four/src/components/toc/TableOfContents.tsx
+++ b/guide/age-of-four/src/components/toc/TableOfContents.tsx
@@ -102,7 +102,11 @@ const NAV: NavGroup[] = [
       { to: '/climate/weather',     icon: '⛈',  label: 'Weather' },
       { to: '/climate/terrain',     icon: '🌿', label: 'Terrain Evolution' },
       { to: '/climate/survival',    icon: '🛡', label: 'Survival' },
-      { to: '/climate/ecosystem',   icon: '🦌', label: 'Ecosystem' },
+      { to: '/climate/ecosystem',          icon: '🦌', label: 'Ecosystem',      end: true },
+      { to: '/climate/ecosystem/biomes',   icon: '🌳', label: 'Biome Browser' },
+      { to: '/climate/ecosystem/species',  icon: '🐾', label: 'Species Browser' },
+      { to: '/climate/ecosystem/food-web', icon: '🕸', label: 'Food Web' },
+      { to: '/climate/ecosystem/populations', icon: '📈', label: 'Populations' },
       { to: '/climate/simulation',  icon: '🎬', label: 'Simulation' },
     ],
   },