Kin discrimination in cooperatively breeding long–tailed tits

Abstract

Long-tailed tits Aegithalos caudatus are cooperative breeders in which helpers exhibit a kin preference in their cooperative behaviour. We investigated the mechanism through which this preference is achieved by ¢rst conducting an experiment for testing whether breeders could recognize the calls of their relatives while controlling for spatial e¡ects. We found that there were signi¢cant di¡erences in the responses of breeders to the vocalizations of kin and non-kin, suggesting that vocal cues may be used for kin recognition. We conducted a second experiment in order to investigate whether recognition is achieved on the basis of relatedness per se or through association. Nestlings were cross-fostered between unrelated broods in order to create broods composed of true and foster siblings. In subsequent years, survivors from experimental broods did not discriminate between true and fostered siblings when making helping decisions, indicating that recognition is learned and not genetically determined. We discuss the e¡ectiveness of learning through association as an indirect cue to kinship.

Kinship affects investment by helpers in a cooperatively breeding bird

“…Finally, the degree of kin discrimination in caring will depend on the mechanism of recognition used in any particular system (Komdeur & Hatchwell 1999;Komdeur et al 2008). In long-tailed tits, individuals recognize their relatives using vocal cues learned early in life (Hatchwell et al 2001a;Sharp et al 2005) allowing helpers to preferentially assist close kin in the absence of spatial cues to kinship (Russell & Hatchwell 2001). But, this raises two questions: why do some helpers help non-kin?…”

“…Helpers increase the recruitment rate of nestlings , thereby gaining substantial indirect fitness benefits . It is also known that long-tailed tits use learned vocal cues in the absence of spatial cues to kinship to recognize their relatives (Hatchwell et al 2001a;Sharp et al 2005). However, it is not known whether the provisioning effort of helpers varies in relation to kinship.…”

“…Instead, long-tailed tits use recognition cues learned during development (i.e. socially acquired cues-the equivalent of pedigree information) to discriminate kin from nonkin (Hatchwell et al 2001a;Sharp et al 2005).…”

Altruism and infidelity among warblers

“…Our findings show that, in the presence of a high frequency of female infidelity, an associative learning mechanism has evolved to focus on the mother at the nest -the only sex to which the subordinates are reliably related. David [3][4][5] . Here we show that in the cooperatively breeding Seychelles warbler (Acrocephalus sechellensis), female subordinates help to raise new nestlings by providing them with food only when the offspring are being raised by parents who also fed the subordinates themselves when they were young 3 .…”

Development of individually distinct recognition cues

“…Not only must the evolutionary costs and benefits of parent-offspring recognition ''failures'' be addressed (reviewed in Beecher, 1991;Holmes, 1990;Komdeur & Hatchwell, 1999), but one must also consider the mechanisms underlying such apparent lack of recognition, in particular the nature and development of cues to identity. For example, there has been much theoretical and empirical interest in why cuckolded male birds invest in unrelated young, yet few studies investigate whether young birds even produce kin labels in any modality or whether males can discriminate among these labels (Beecher, 1988;Bouwman, Lessells, & Komdeur, 2005;Kempenaers & Sheldon, 1996; see also Hatchwell, Ross, Fowlie, & McGowan, 2001). Such a recognition mechanism is required before preferential investment in one's own young can evolve.…”