Fat dormouse (Glis glis) is a rodent species completely rely on the forest crown, with specific habitat selection, reproduction behavior and hibernation, which experienced considerable intra-specific evolutionary divergence. After the only documented research on this species during 2010-2013 which introduced the Iranian population as a deeply diverged lineage from other known lineages (more than 12% intra-specific variation), I decided to proceed the complementary research on the species reproduction behavior and its relationship with the mean number of nipples. My findings indicated that the populations located in the middle parts of the Hyrcanian refugium has significantly higher mean nipple count and larger litter size, where the habitat receive more precipitation and as a result, higher production. In comparison, the populations located in the both extreme parts, especially those of eastern most parts of the forests, which face with lower precipitation and consequently lower habitat production, has mean lower nipple counts and significantly lower litter size. As well as the number of nipple counts, the mean adult weight also limits the mean litter size in these areas.
