02103nas a2200157   4500008004100000022001400041245009100055210006900146260001600215490000700231520158800238100001901826700002401845700002101869856005501890       2019                        eng d  a0340-544300aClarifying and expanding the social complexity hypothesis for communicative complexity0 aClarifying and expanding the social complexity hypothesis for co  cJan-01-20190 v733 a<p>Variation in communicative complexity has been conceptually and empirically attributed to social complexity, with animals living in more complex social environments exhibiting more signals and/or more complex signals than animals living in simpler social environments. As compelling as studies highlighting a link between social and communicative variables are, this hypothesis remains challenged by operational problems, contrasting results, and several weaknesses of the associated tests. Specifically, how to best operationalize social and communicative complexity remains debated; alternative hypotheses, such as the role of a species&rsquo; ecology, morphology, or phylogenetic history, have been neglected; and the actual ways in which variation in signaling is directly affected by social factors remain largely unexplored. In this review, we address these three issues and propose an extension of the &ldquo;social complexity hypothesis for communicative complexity&rdquo; that resolves and acknowledges the above factors. We specifically argue for integrating the inherently multimodal nature of communication into a more comprehensive framework and for acknowledging the social context of derived signals and the potential of audience effects. By doing so, we believe it will be possible to generate more accurate predictions about which specific social parameters may be responsible for selection on new or more complex signals, as well as to uncover potential adaptive functions that are not necessarily apparent from studying communication in only one modality.</p>
1 aPeckre, Louise1 aKappeler, Peter, M.1 aFichtel, Claudia  uhttp://link.springer.com/10.1007/s00265-018-2605-402736nas a2200181   4500008004100000245007500041210006900116260001600185300001400201490000800215520216900223100002502392700002202417700002402439700002102463700001502484856005502499       2017                        eng d00aGrunt to go-Vocal coordination of group movements in redfronted lemurs0 aGrunt to goVocal coordination of group movements in redfronted l  cJan-12-2017  a894 - 9050 v1233 a<p>To remain cohesive as a group, individuals must coordinate their movements between resources. In many species, vocalisations are used in this context. While some species have specific movement calls, others use calls which are also employed in different contexts. The use of such multicontextual calls has rarely been studied quantitatively, especially during both the pre-departure and departure period associated with collective decisions. We thus investigated the use of close calls (&ldquo;grunts&rdquo;) for the coordination of collective movements in four groups of wild redfronted lemurs (Eulemur rufifrons) in Kirindy Forest, Western Madagascar. Group movements are started by an initiator, who moves away from the group and is joined by followers setting out in the same direction. We observed collective movements and recorded vocalisations from 18 focal individuals (54 movements recorded for followers, 21 for initiators). The grunt rate of both initiators and followers was higher in the pre-departure period than in a control context (i.e., during foraging). Initiators of collective movements grunted more often than followers in the pre-departure period as well as at individual departure. The latter difference was due to the initiators&rsquo; grunt rates increasing earlier than the followers&rsquo; and remaining at an elevated level for longer. These observations suggest that grunts serve to coordinate the departure by indicating the individual&#39;s readiness to move. The pre-departure period, in which both initiators and followers showed an elevated grunt rate, may provide the basis for a shared decision on departure time. The difference in initiator and follower call rates suggests that grunts may have a recruitment function, but playback experiments are required to test this potential function. Overall, our study describes how multicontextual close calls can function as movement calls, with changes in call rate providing a potential feedback mechanism for the timing of group movements. This study thus contributes to a more detailed understanding of the mechanisms of group coordination and collective decision-making.</p>
1 aSperber, Anna, Lucia1 aWerner, Lynne, M.1 aKappeler, Peter, M.1 aFichtel, Claudia1 aWright, J.  uhttp://doi.wiley.com/10.1111/eth.2017.123.issue-12