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The building-up of social relationships:
behavioural types, social networks and
cooperative breeding in a cichlid
Roger Schu
¨rch1,2, Susan Rothenberger1and Dik Heg1,*
1
Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern,
Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland
2
Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus,
OH 43210, USA
Consistent individual differences in behavioural types may not only cause variation in life-history
decisions, but may also affect the choice of social partners and sociality in general. Here, we
tested whether and how behavioural type influences the establishment of social ties using the coop-
eratively breeding cichlid, Neolamprologus pulcher. In a habitat saturation experiment with
individuals pre-tested for behavioural type, we first analysed whether behavioural type affected
the likelihood of settlement (i.e. social status), group sizes, and the types of dominant and subordi-
nate individuals accepted as group members. Corrected for effects of body size and sex, the
behavioural type did not affect settlement. However, bold dominant males only accepted smaller
females, and grouped with bold subordinates, while shy dominant males accepted larger females
than themselves, and grouped with shy subordinates. Second, we analysed the relationships between
behavioural type and the aggressiveness or affiliation social network. Behavioural type significantly
affected the number and quality of connections within the two networks. We show that behavioural
types affect group composition, social networks and status achieved, in interaction with body size.
Thus, the interactions within groups may depend not only on age, size and sex, but also on the
behavioural type of the individuals involved.
Keywords: cooperation; social network; body size; status; Cichlidae
1. INTRODUCTION
It has been recognized that individual ‘states’ (sensu
McNamara & Houston 1996), like dominance status,
sex and body size, may influence the likelihood of
acquiring and maintaining dominant positions in the
future (e.g. van de Pol et al. 2007). However, individ-
uals of the same species may not only differ in their
states, but they may also consistently differ in the
expression of their behavioural traits across context
and/or time, resulting in behavioural types (alterna-
tively known as temperament, coping styles or animal
personalities; e.g. Koolhaas et al. 1999;Sih et al.
2004;Re
´ale et al. 2007). Typically, individuals differ
consistently in the so-called bold – shy continuum
(reviewed in Sih et al. 2004), where shy individuals
are both non-aggressive and hardly explore novel
environments, and where bold individuals are both
aggressive and explorative. The consistency or repeat-
ability of behavioural traits averages at 0.37 (Bell et al.
2009). We refer to these individual differences in the
expression of behavioural traits as ‘behavioural types’
(sensu Sih et al. 2004).
Behavioural types might affect social connections
with the neighbourhood and eventually may affect
future social positions similar to states (e.g. site-related
dominance, Heg et al. 2000; also McDonald 2007;
Ryder et al. 2008;Krause et al. 2010). Recently,
social network theory has provided a comprehensive
and detailed tool to describe social connections
and how they may affect settlement decisions by
individuals (McDonald 2007) or group stability (e.g.
Flack et al. 2006) and thus might potentially affect
access to reproductive opportunities (e.g. van Oers
et al. 2008).
Whether behavioural types may affect social con-
nections and settlement has been little explored (but
see Fraser et al. 2001;Pike et al. 2008;Harcourt
et al. 2009;We b s t e r et al. 2009; reviewed also in
Cote et al. 2010), and even fewer studies have
explored effects in a cooperatively breeding species
(but see Raihani et al. 2008;Schu
¨rch & Heg 2010a).
This is unfortunate, because in cooperative breeders
one can expect strong effects of the behavioural types
on life-history decisions (Wolf et al. 2007), which is
likely to coevolve with how they behave in a social
context (Schu
¨rch & Heg 2010b). For instance, shy,
non-explorative and non-aggressive subordinates may
benefit from a high likelihood to survive to old age
and inherit the breeding position, because they do
not engage in risky exploration behaviour (to locate
vacancies). They may also avoid eviction from the
*Author for correspondence (dik.heg@iee.unibe.ch).
Electronic supplementary material is available at http://dx.doi.org/
10.1098/rstb.2010.0177 or via http://rstb.royalsocietypublishing.org.
One contribution of 16 to a Theme Issue ‘Evolutionary and
ecological approaches to the study of personality’.
Phil. Trans. R. Soc. B (2010) 365, 4089–4098
doi:10.1098/rstb.2010.0177
4089 This journal is q2010 The Royal Society
