Evolutionary ecology of parental care: sexual selection, fitness and alternative personalities
Lead Research Organisation:
University of Sheffield
Department Name: Animal and Plant Sciences
Abstract
Traditional theories of sexual selection are often based on the assumption that there are substantial genetic (or 'indirect') benefits to be accrued from choosing among potential mates. There is growing empirical evidence, however, that this assumption may not always be valid and that in some systems non-genetic (or 'direct') benefits of mate choice may be more important than previously realised. The overall aim of this study is to conduct the most comprehensive empirical test of direct models of sexual selection in a wild population, using parental care in birds as our model system. Parental care in birds is a good framework for this type of test because birds provide many of the classic examples in sexual selection and parental care provides a scenario where direct benefits may be substantial. For this project we will use an already established, island population of house sparrows, Passer domesticus, which is ideally suited to our needs because we can monitor both lifetime reproduction and survival for all individuals, thereby allowing us to estimate fitness components with unusual precision. For this population we also have a long-term cross-fostered breeding pedigree, which will allow us to estimate the relative roles of a wide range of genetic and non-genetic factors. In addition, we will also test for links between the amount of parental care that a male provides and other aspects of his reproductive behaviour. We are particularly interested, for instance, in whether there is a trade-off between the amount of effort a male expends on parental care and his ability to seek additional sexual partners. Finally, based on the empirical data that we gather, we will build a theoretical model that seeks to explain why different individuals display such different strategies when it comes to the provision of parental care, and explores whether this variation reflects differences in overall 'personality' among individuals.
Organisations
Publications
CLEASBY I
(2010)
The influence of sex and body size on nestling survival and recruitment in the house sparrow JUVENILE SURVIVAL IN THE HOUSE SPARROW
in Biological Journal of the Linnean Society
Cleasby IR
(2011)
Food supplements increase adult tarsus length, but not growth rate, in an island population of house sparrows (Passer domesticus).
in BMC research notes
Dawson DA
(2010)
New methods to identify conserved microsatellite loci and develop primer sets of high cross-species utility - as demonstrated for birds.
in Molecular ecology resources
Dawson DA
(2013)
High-utility conserved avian microsatellite markers enable parentage and population studies across a wide range of species.
in BMC genomics
Dawson DA
(2012)
Microsatellite resources for Passeridae species: a predicted microsatellite map of the house sparrow Passer domesticus.
in Molecular ecology resources
Garratt M
(2017)
Life-span Extension With Reduced Somatotrophic Signaling: Moderation of Aging Effect by Signal Type, Sex, and Experimental Cohort.
in The journals of gerontology. Series A, Biological sciences and medical sciences
Girndt A
(2019)
Male age and its association with reproductive traits in captive and wild house sparrows
in Journal of Evolutionary Biology
Hsu YH
(2015)
Are extra-pair males different from cuckolded males? A case study and a meta-analytic examination.
in Molecular ecology
| Description | Evolutionary ecology of parental care: sexual selection, fitness and alternative personalities All the original objectives proved highly productive and many of the results are still in the process of being published. Summaries of some of the highlights, most of which have already been published. No evidence for adverse effects on fitness of fitting passive integrated transponders (PITs) in wild house sparrows Passer domesticus (Schroeder et al. 2011) We used passive integrated transponders (PITs) to measure nest visits. PITs are increasingly used to study behaviour in birds. We used the delifing method to test for any adverse fitness effects of PITs by comparing individuals that did and did not have PITs fitted. Our results provide a solid basis for the assumption that such PITs are safe to use in small passerines, with no deleterious effects. Social and genetic benefits of parental investment suggest sex differences in selection pressures (Schroeder et al 2013) Provisioning behaviour in altricial birds is often used to measure parental investment and is assumed to have fitness consequences to the parents providing it. We disentangled the long-term fitness consequences, in terms of recruits, of provisioning behaviour from those of other parental investments and individual quality through a cross-fostering design. Provisioning conferred social fitness benefits in terms of recruits to both parents. Females that fed young more produced more genetic recruits, even though foster parents reared the offspring. Males, but not females, that fed their young more had lower survival. Different selection pressures are therefore acting on each sex. The study confirmed that it is appropriate to use provisioning behaviour as a measure of parental investment, since we showed that this behaviour was costly to parents and that the genetic fitness benefits exceeded the costs. Sex specific social genetic effects lead to an increase in the total heritable variation in parental-care behaviour (Schroeder et al 2013 and in prep). The social environment, namely conspecifics, can influence the expression of phenotypes. The genetic part of this indirect effect represents a social genetic effect (SGE). SGEs are a vital component of heritable variation, yet most empirical studies have ignored them. We showed that sex-specific SGEs increased the total heritable variation from 3% to 14% in female parental care and from 2% to 5% in male parental care. Our data suggest that the female trait could evolve through indirect selection by her mating partner, which most theoretical models have ignored. Our results showed that the assumption that repeatability is the upper limit of heritability should be used cautiously when applied to socially interactive traits, and highlight the importance of accounting for social effects. Passerine birds breeding under chronic noise experience reduced fitness (Schroeder et al 2012) We used our long-term data on house sparrows to test for the effects of noise from large electricity generators within our Lundy study population. We showed that exposure to noise led to fewer young of lower body mass, and fewer recruits. Our results suggest a previously undescribed mechanism to explain how environmental noise can reduce fitness in passerine birds: by acoustically masking parent-offspring communication. More importantly, using a cross-fostering set-up, our results demonstrated that birds breeding in a noisy environment experienced significant fitness costs. Chronic noise is omnipresent around human habitation and probably produces similar fitness consequences in a wide range of urban bird species. Transgenerational negative effects of older parents on offspring fitness in a natural population (Schroeder et al in prep) A non-genetic, transgenerational effect of parental age on offspring fitness - the Lansing effect - has been described in many taxa in the laboratory and is a potentially important influence on population dynamics, population age structure, and the evolution of ageing and lifespan. Yet, such an effect of parental age has never been demonstrated in a wild population. We discovered sex-specific negative effects of parental and grandparental ages on offspring lifetime reproductive fitness in our pedigreed population. Birds born to older fathers, and daughters born to older mothers and older grandmothers, had reduced lifetime fitness. In a long-term cross-fostering experiment we showed that this Lansing-type effect was transgenerational and matrilineally inherited, and over two generations. Our study illuminated the hidden consequences of late-life reproduction. |
| Exploitation Route | The main users are other academics, but our findings will in time be of use to several sectors. House sparrows are declining and now red-listed, so the baseline information that we collect will ultimately help organisations such as National Trust (owners of Lundy Island), RSPB, Natural England and BTO (to which we submit data) understand the reasons for the decline. Our discoveries about the effect of ageing on the reproductive output of offspring are likely to be of interest to bodies concerned with animal husbandry, especially agriculture, zoos and conservation breeding programmes. The same results may ultimately influence human health research. The work provided the basis of a newly funded project with a strongly developed Pathways to Impact plan. In the new study we are following up the negative, epigenetic effect of age on the reproductive success of offspring and grand-offspring. The impact plan involves communicating these results to the animal husbandry community, in particular zoos involved in conservation captive breeding programmes, and engaging with them in analyses to test if there is a previously unexpected conflict between minimising inbreeding and keeping reproductive animals beyond naturally occurring reproductive ages. |
| Sectors | Environment |
| Description | They led to the impact plan in the new, current grant. |
| Sector | Environment |
| Description | SURE Scheme student grant |
| Amount | £1,080 (GBP) |
| Organisation | University of Sheffield |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 06/2012 |
| End | 07/2012 |