Eviction and troop reconstruction in a single matriline of ring-tailed lemurs (Lemur catta): What happened when "grandmother" died?

Abstract

Eviction of subordinate females is well known in female-dominated ring-tailed lemur society. In almost all cases, evictions result from a dominant matriline targeting aggression towards subordinate matrilines. Here, we report an eviction in a large, single matrilineal troop after the death of the troop's "Grandmother." Although the troop contained 3 18 individuals and 8 females over several years, no evictions occurred while the Grandmother was alive. After her death, a newly dominant female and her younger sisters evicted their nieces whose higher-ranking mother had already died. The younger relatives of the evicted females did not follow their mother and sisters but stayed in the natal troop. We suggest (1) the presence of certain females like Grandmother may function as a deterrent to eviction among descendants; (2) if eviction occurs within a single matriline, aggressors evict the most distant kin; (3) a newly dominant female may form a subgroup with her younger and subordinate sisters rather than older and higher-ranking ones to circumvent intragroup competition; and (4) the juveniles of evicted female kin do not always follow the nomadic evictees but may choose the safer strategy of remaining within their natal troop.