Restrictive mating by females on black grouse leks

Lebigre

2017

J Ornithol

There is widespread interest in the relationship between individual genetic diversity and fitness-related traits (heterozygosity-fitness correlations; HFCs). Most studies have found weak continuous increases of fitness with increasing heterozygosity, while negative HFCs have rarely been reported. Negative HFCs are expected in cases of outbreeding depression, but outbreeding is rare in natural populations. Negative HFCs may also arise through viability selection acting on low heterozygosity individuals at an early stage producing a skew in the heterozygosity distribution. We tested this idea using survival and clutch parameters (egg mass, egg volume, chick mass, clutch size) in female Black Grouse Lyrurus tetrix and carried out simulations to determine how survival selection may impact the HFCs measured using clutch parameters. We show that survival is positively related to both individual heterozygosity and female body mass. There was a positive effect of body mass on all clutch parameters, but the selective mortality of females with both low heterozygosity and low body mass led to overrepresentation of high heterozygosity-low body mass females and hence a negative relationship between egg volume and heterozygosity. Using simulated data, we show that survival selection acting on both low body mass and low heterozygosity leads to a skew in the quality of breeding females, resulting in negative HFCs with egg volume. Our results indicate that survival selection can strongly influence the strength and direction of any HFCs that occur later in life and that only an integration of all aspects of individual reproductive investment and reproductive success can enable us to fully understand how heterozygosity can shape individual fitness.Keywords Inbreeding Á Outbreeding Á Neutral loci Á Selective mortality Á Genetic diversity Zusammenfassung Selektion auf Ü berlebensfähigkeit führt bei weiblichen Birkhühnern Lyrurus tetrix zu negativen HFC-Werten

Section: Study Sites and Capture Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Viability selection creates negative heterozygosity–fitness correlations in female Black Grouse Lyrurus tetrix

Lebigre

2017

J Ornithol

“…940017) and a Kingfisher magnetic particle processor. All of the individuals were then genotyped at 11 autosomal microsatellite loci (see Lebigre, Alatalo, Siitari, & Parri, 2007 for details). Standardized multilocus heterozygosity ( sMLH ) was calculated based on the 11 autosomal loci (see Soulsbury & Lebigre, 2018) using inbreedR (Stoffel et al., 2016) within R version 3.2.1 (R Core Team 2014).…”

Section: Methodsmentioning

confidence: 99%

Age‐ and quality‐dependent DNA methylation correlate with melanin‐based coloration in a wild bird

Lipponen

Wood

et al. 2018

Ecology and Evolution

Secondary sexual trait expression can be influenced by fixed individual factors (such as genetic quality) as well as by dynamic factors (such as age and environmentally induced gene expression) that may be associated with variation in condition or quality. In particular, melanin‐based traits are known to relate to condition and there is a well‐characterized genetic pathway underpinning their expression. However, the mechanisms linking variable trait expression to genetic quality remain unclear. One plausible mechanism is that genetic quality could influence trait expression via differential methylation and differential gene expression. We therefore conducted a pilot study examining DNA methylation at a candidate gene (agouti‐related neuropeptide: AgRP) in the black grouse Lyrurus tetrix. We specifically tested whether CpG methylation covaries with age and multilocus heterozygosity (a proxy of genetic quality) and from there whether the expression of a melanin‐based ornament (ultraviolet‐blue chroma) correlates with DNA methylation. Consistent with expectations, we found clear evidence for age‐ and heterozygosity‐specific patterns of DNA methylation, with two CpG sites showing the greatest DNA methylation in highly heterozygous males at their peak age of reproduction. Furthermore, DNA methylation at three CpG sites was significantly positively correlated with ultraviolet‐blue chroma. Ours is the first study to our knowledge to document age‐ and quality‐dependent variation in DNA methylation and to show that dynamic sexual trait expression across the lifespan of an organism is associated with patterns of DNA methylation. Although we cannot demonstrate causality, our work provides empirical support for a mechanism that could potentially link key individual factors to variation in sexual trait expression in a wild vertebrate.

“…A small blood sample was taken from the birds' brachial vein from which DNA 164 was extracted and all individuals were genotyped at 11 microsatellite loci (detailed 165 description in Lebigre et al 2007). We measured individuals' pairwise relatedness using 166…”

Section: Remain In Their Natal Area (Caizergues and Ellison 2002; Warmentioning

confidence: 99%

“…10 days at the end of April-early May when 172 nearly all copulations take place (Lebigre et al 2007 …”

Section: Lek Observations 171mentioning

confidence: 99%

No behavioural response to kin competition in a lekking species

Lebigre

Timmermans

2016

Behav Ecol Sociobiol

28The processes of kin selection and competition may occur simultaneously if limited individual 29 dispersal i.e. population viscosity, is the only cause of the interactions between kin. 30 Therefore, the net indirect benefits of a specific behaviour may largely depend on the 31 existence of mechanisms dampening the fitness costs of competing with kin. In lekking 32 species, males may increase the mating success of their close relatives (and hence gain 33 indirect fitness benefits) because female prefer large leks. At the same time, kin selection 34 may also lead to the evolution of mechanisms that dampen the costs of kin competition. As 35 this mechanism has largely been ignored to date, we used detailed behavioural and genetic 36 data collected in the black grouse Lyrurus tetrix to test whether males mitigate the costs of 37 kin competition through the modulation of their fighting behaviours according to kinship and 38 the avoidance of close relatives when establishing a lek territory. We found that neighbouring 39 males' fighting behaviour was unrelated to kinship and males did not avoid settling down with 40 close relatives on leks. As males' current and future mating success are strongly related to 41 their behaviour on the lek (including fighting behaviour and territory position), the costs of kin 42 competition may be negligible relative to the direct benefits of successful male-male 43 contests. As we previously showed that the indirect fitness benefits of group membership 44 were very limited in this black grouse population, these behavioural data support the idea 45 that direct fitness benefits gained by successful male-male encounters likely outbalance any 46 indirect fitness benefits. 47 49Keywords: dominance, indirect fitness benefits, kin selection, kin competition, territoriality, 50 sexual selection, sociality 51 52 3 Significance statement 53Kin selection might be involved in the formation of groups because the fitness benefits of 54 increasing group size can be accrued when groups hold close relatives. However, the fitness 55 costs of competing with kin could counter-balance these indirect fitness benefits unless 56 mechanisms enabling individuals to limit kin competition. Using data collected in the black 57 grouse (Lyrurus tetrix) we show that males do not modulate their fight frequency and 58 intensity according to their kinship and do not avoid establishing territories with closely 59 related neighbours. As we previously showed that the indirect fitness benefits of group 60 display were very small and as this study shows that males do not show any sign of kin 61 competition avoidance, the indirect effects associated with male group display are likely to be 62 very small in this system. 63 4 Introduction 64