and
Lake Prespa are the two largest lakes in North Macedonia. Within North Macedonia, there are multiple areas that are likely high in endemism. Lake Ohrid is an extensively studied area, and its diversity is reflected in a high number of endemic species. Lake Prespa lies quite close to Lake Ohrid, and the two lakes are connected
hydrologically. While Lake Prespa has fewer species than Lake Ohrid and while the two lakes share similar species compositions, Lake Prespa has its own endemic species and species more closely related to more western water bodies than to Lake Ohrid. Within Lake Ohrid alone there are over 100 insects, 75 flatworms (35 endemic to the lake and nearby waterbodies), 72 gastropods (56 endemic), 52 ostracods (33 endemic), 49
rotifers, 43 Acari, 36 oligochaetes (17 endemic), 36 copepods (six endemic), 31
Cladocera (one endemic), 30 endemic
ciliates, 24 leeches (12 endemic), 24 nematodes (three endemic), 14
amoebas, 13 bivalves (two endemic), 10–11 Amphipoda (9 endemic), four isopods (3 endemic), four sponges, and two decapods. The
Ancylus genus species in this lake are monophyletic, likely
evolving within the lake itself. The same situation is true for leeches from the genus
Dina. Lake Prespa is less well studied, but is known to have at over 100 insects, 90 crustaceans, 60 rotifers, 50 flatworms, 36 molluscs (27 of which are snails), 35 annelids, and three sponges. Seven of these snails are endemic, as is the mollusc
Pisidium maasseni.
Radix snail species in both Ohrid and Lake Prespas are related, and there are endemic species within springs near the
Monastery of Saint Naum that are unrelated to the species found in the lakes. Lake Dojran has 17 rotifers. It is expected that mountainous areas will also contain a number of endemic species. North Macedonia contains many areas of ice age
refugia, which retain significant plant diversity. Plant endemism and sub-endemism is high around mountainous areas. Mammal diversity is highest in the mountainous west of the country. Caves in the west, especially within the drainage basins of the
Radika, Galichica, Jakupica, and Poreche rivers, are thought to have rates of invertebrate endemism of around 90%. 57 species of
stygofauna are known, including 14 pseudoscorpions, 12 beetles, and 10 isopods. ==Human influence==