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Cousseau L, Van de Loock D, Apfelbeck B, Githiru M, Matthysen E, Lens L. Kin do not always help: testing multiple hypotheses on nest feeding in a cooperatively breeding bird. Behav Ecol 2022. [DOI: 10.1093/beheco/arac073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
In cooperatively breeding species, group members may derive multiple benefits from helping to raise other individuals’ offspring, yet not all individuals do so. In this study, we tested predictions from the “kin selection”, “pay-to-stay”, “group augmentation” and “skills” hypotheses, to explain why group members feed nestlings of breeding placid greenbuls (Phyllastrephus placidus). In our study population, about 70% of the breeding pairs were accompanied by subordinates, and in 60% of these cases at least one subordinate helped in provisioning nestlings. In total, 80% of the subordinates were related to one or both breeders. In accordance with the “kin selection” hypothesis, and contrary to the “pay-to-stay” hypothesis, all the helpers were first-order kin of the breeding female (although relatedness to the breeding male did not explain variation in helping) and the presence of helpers was associated with increased survival of the breeding pair. However, the propensity to help varied among group members, as 46% of group members related to the breeding female did not feed nestlings. Younger helpers fed offspring more often than older ones, supporting the “skills” and “group augmentation” hypotheses. However, support for the “group augmentation” hypothesis was mixed since subordinate sex and group size did not explain additional variation in helping propensity and effort. We argue that in addition to indirect and direct benefits, also the costs of helping as well as other types of helping aside from provisioning must be considered to better understand variation in helping behavior.
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Affiliation(s)
- Laurence Cousseau
- Terrestrial Ecology Unit, Ghent University , K. L. Ledeganckstraat, Ghent , Belgium
| | - Dries Van de Loock
- Terrestrial Ecology Unit, Ghent University , K. L. Ledeganckstraat, Ghent , Belgium
- Evolutionary Ecology Group, University of Antwerp, Campus Drie Eiken, Universiteitsplein , Wilrijk , Belgium
- Department of Zoology, National Museums of Kenya , Nairobi , Kenya
| | - Beate Apfelbeck
- Department of Zoology, National Museums of Kenya , Nairobi , Kenya
- Evolutionary Zoology Group, Biosciences, University of Salzburg , Hellbrunnerstr., Salzburg , Austria
| | - Mwangi Githiru
- Department of Zoology, National Museums of Kenya , Nairobi , Kenya
- Wildlife Works , Voi , Kenya
| | - Erik Matthysen
- Evolutionary Ecology Group, University of Antwerp, Campus Drie Eiken, Universiteitsplein , Wilrijk , Belgium
| | - Luc Lens
- Terrestrial Ecology Unit, Ghent University , K. L. Ledeganckstraat, Ghent , Belgium
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Suh YH, Bowman R, Fitzpatrick JW. Staging to join non-kin groups in a classical cooperative breeder, the Florida scrub-jay. J Anim Ecol 2022; 91:970-982. [PMID: 35085401 DOI: 10.1111/1365-2656.13669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 01/12/2022] [Indexed: 11/30/2022]
Abstract
1. Why unrelated members form groups in animal societies remains a pertinent topic in evolutionary biology because benefits for group members often are not obvious. We studied subordinates that disperse to join unrelated social groups in the Florida scrub-jay Aphelocoma coerulescens, a cooperative breeding species mainly composed of kin-based groups. 2. We evaluated potential adaptive benefits of dispersing to become an unrelated helper (staging) versus remaining home and dispersing only to pair and breed (direct dispersal) to understand why non-kin-based groups form. 3. Using 35 years of demographic data, we quantified life history aspects of staging individuals and tested associations between social and ecological factors on the natal and staging territories. We compared fitness outcomes between dispersal strategies by analyzing survival, breeding recruitment, and direct reproductive output. We tested for sexual asymmetry potentially driven by differences in territory acquisition patterns and female-biased dispersal for this species. 4. Of birds that reached one-year-old, 28% staged at a non-natal territory before breeding or disappearing. Staging dispersers departed at younger ages and moved greater distances than direct dispersers. When looking at proximate factors on the natal territory associated with staging, males left groups with many same-sex helpers, while females often left when their father disappeared. For both sexes, staging individuals more likely came from high-quality territories and joined groups with fewer same-sex helpers than in their natal group. While staging and direct dispersers did not differ in survival or likelihood of becoming a breeder, staging males became breeders later and had lower lifetime reproductive success than direct dispersers. 5. In Florida scrub-jays, staging appears to be an alternative strategy for female helpers, but a best-of-a-bad-situation for males. This sexual asymmetry is consistent with males having more options than females to achieve higher reproductive success by breeding near home. Tradeoffs in cost-benefits of departing the natal territory and joining unrelated groups as a helper seem to best explain alternative dispersal patterns, with optimal social queues primarily driving the benefits. This research highlights plasticity in dispersal behavior in response to social and environmental conditions and offers a new perspective in our understanding of non-kin-based social groups.
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Affiliation(s)
- Young Ha Suh
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, 14853.,Cornell Lab of Ornithology, Ithaca, 14850
| | - Reed Bowman
- Avian Ecology Program, Archbold Biological Station, Venus, 33960
| | - John W Fitzpatrick
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, 14853.,Cornell Lab of Ornithology, Ithaca, 14850
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Cousseau L, Hammers M, Van de Loock D, Apfelbeck B, Githiru M, Matthysen E, Lens L. Habitat fragmentation shapes natal dispersal and sociality in an Afrotropical cooperative breeder. Proc Biol Sci 2020; 287:20202428. [PMID: 33323076 DOI: 10.1098/rspb.2020.2428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
It remains poorly understood how effects of anthropogenic activity, such as large-scale habitat fragmentation, impact sociality in animals. In cooperatively breeding species, groups are mostly formed through delayed offspring dispersal, and habitat fragmentation can affect this process in two opposite directions. Increased habitat isolation may increase dispersal costs, promoting delayed dispersal. Alternatively, reduced patch size and quality may decrease benefits of philopatry, promoting dispersal. Here, we test both predictions in a cooperatively breeding bird (placid greenbul, Phyllastrephus placidus) from an Afrotropical cloud forest archipelago. Males born in fragmented forest dispersed about 1 year earlier than those born in continuous forest. Contrary to females, males also started to reproduce earlier and mostly settled within their natal patch. Females only rarely delayed their dispersal for more than 1 year, both in fragmented and continuous forests. Our results suggest that early male dispersal and reproduction is jointly driven by a decrease in the value of the natal territory and an increase in local breeding opportunities in fragmented forest. While plasticity in dispersal strategies of cooperative breeders in response to anthropogenic change is believed to optimize reproduction-survival trade-offs, to what extent it shapes the ability of species to respond to rapid environmental change remains to be studied.
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Affiliation(s)
- Laurence Cousseau
- Terrestrial Ecology Unit, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Martijn Hammers
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, PO Box 11103, 9700 CC Groningen, The Netherlands
| | - Dries Van de Loock
- Terrestrial Ecology Unit, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium.,Evolutionary Ecology Group, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.,Department of Zoology, National Museums of Kenya, Nairobi, Kenya
| | - Beate Apfelbeck
- Evolutionary Zoology Group, Department of Biosciences, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria.,Department of Zoology, National Museums of Kenya, Nairobi, Kenya
| | - Mwangi Githiru
- Department of Zoology, National Museums of Kenya, Nairobi, Kenya.,Wildlife Works, PO Box 310-80300, Voi, Kenya
| | - Erik Matthysen
- Evolutionary Ecology Group, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Luc Lens
- Terrestrial Ecology Unit, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium
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