PhD‐theses - Ethologische Gesellschaft

Research Update
DIFFERENCES IN ACTIVITY BUDGETS AND SOCIAL BEHAVIOURS OF THREE MALE ALTERNATIVE
REPRODUCTIVE TACTICS IN THE AFRICAN STRIPED MOUSE (RHABDOMYS PUMILIO)
Marta Wastavino
marta.wastavino@gmail.com
Master Thesis, supervised by PD Dr. Carsten Schradin, Institute of Evolutionary Biology and
Environmental Studies, University of Zürich
Alternative reproductive tactics (ARTs) evolved in various animal taxa, from crustaceans to
mammals. Conditional ARTs evolved when a single male is able to monopolize access to
several breeding females. In such a case, other less successful males would develop an
alternative reproductive tactic, which will allow them to get at least some reproductive
success (“best of a bad job”). Some recent studies suggested that ARTs might differ in
activity and energy budgets, such that they differ in energetic costs, which could influence
reproductive success. I investigated differences in activity budgets and social behaviours of
three ARTs in the group living African striped mouse (Rhabdomys pumilio) of the South
African Succulent Karoo: 1. territorial dominant males defending a harem of 2‐4 females
and their offspring (extended family groups), 2. roaming solitary individuals and 3. adult
natally philopatric males living in extended family groups. I collected behavioural data
through focal‐animal observations in the field, observing 10 territorial breeders, 7 roamers
and 10 philopatric males. Additionally, I performed 18 experiments in an artificial arena to
study differences in aggression between roamers and breeders. I found that I) philopatric
individuals allocate their energies in survival rather than reproduction. Males following this
tactic showed high level of sociopositive behaviours and trended to travel less but forage
more than males of the two other tactics. II) The behaviour of roaming males is a trade‐off
between survival and mating i.e., roamers intrude other male territories to seek copulations
with their females, but they actively avoid risky encounters with territory owners. III)
Territorial males use most of their resources for reproduction, showing high levels of
aggressiveness towards roamers but amicable behaviours towards individuals of their social
group. In conclusion, the study revealed significant behavioural differences between male
ARTs in striped mice, especially regarding their activity budgets and correlated energy
budgets, indicating differential investment strategies into survival and reproduction.
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