Browsing by Subject "maternal effects"

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  • Palonen, Aura (Helsingin yliopisto, 2020)
    Early life conditions have long-term effects on the fitness and survival of individuals. Foetal development is an especially crucial period and even small changes may have large impacts on the development of individuals. Mammal foetuses may be exposed to additional testosterone either from their male littermates or their mother. This additional prenatal androgen exposure leads to masculinization of female features and behavior. In males the effects of additional prenatal androgen exposure are less drastic due to their own testosterone production. The anogenital distance, defined as the distance between the anus and genitalia, has been used to determine the sex of young mammals since males have longer anogenital distances than females. An elongated anogenital distance is an indicator of additional prenatal androgen exposure in females, and in some species also in males. It correlates with for example increased aggressiveness in both females and males. In females a longer anogenital distance has also been connected to delayed puberty and decreased fertility. I studied the effects of additional prenatal androgen exposure on weight and important life-history traits in banded mongooses (Mungos mungo) with data from a long-term study. Banded mongooses are small co-operatively breeding mammals living in family groups of 10-30 individuals across sub-Saharan Africa. Breeding is extremely synchronized within groups and in most cases all pregnant females give birth on the same day. The resulting communal litter is cared for by most adults in the group regardless of relatedness. Adults escort the pups until three months of age, providing the pup with food, grooming and protection. This early life care has long-term fitness benefits for the pups. Pregnant females may change the phenotype of their offspring via maternal effects. When the competition faced by breeding females is more intense, they compensate by investing more resources to their foetuses, making them bigger. Using the anogenital distance as a proxy for additional prenatal androgen exposure, I measured its effects on weight at early life and maturity, the amount of care received as pups and whether the individual reproduced in its lifetime or not. I hypothesized that a longer anogenital distance may be an indicator of increased competitiveness in the banded mongoose. It could lead to a cumulative advantage since more aggressive individuals may be able to access more food and care, which leads to higher maturity weight and lifetime reproductive success. I also measured the effects of resource abundance and intensity of competition during gestation on the anogenital distance of the pups. I hypothesized that mothers may prepare their offspring for future competitive environment by exposing them to androgens during gestation. In males a longer anogenital distance predicted higher weight both at early life and maturity. Higher weight at the beginning of the escorting increased the amount of care received, which in turn increased weight at maturity. A longer anogenital distance therefore has both direct and indirect fitness benefits in male banded mongooses. In females, a longer anogenital distance predicted lighter weight at maturity, suggesting that it may have negative effects on female growth and development. This study offers evidence that additional prenatal androgen exposure has long-term fitness consequences on banded mongooses and that these consequences are sex specific. Future research should focus on confirming the connection between additional prenatal androgen exposure and longer anogenital distance in this species, as well as assessing the effects of prenatal androgen exposure on survival, puberty and growth of especially female individuals.
  • Acevedo, Nathalie; Scala, Giovanni; Merid, Simon Kebede; Frumento, Paolo; Bruhn, Sören; Andersson, Anna; Ogris, Christoph; Bottai, Matteo; Pershagen, Göran; Koppelman, Gerard H.; Melen, Erik; Sonnhammer, Erik; Alm, Johan; Söderhäll, Cilla; Kere, Juha; Greco, Dario; Scheynius, Annika (2021)
    DNA methylation changes may predispose becoming IgE-sensitized to allergens. We analyzed whether DNA methylation in peripheral blood mononuclear cells (PBMC) is associated with IgE sensitization at 5 years of age (5Y). DNA methylation was measured in 288 PBMC samples from 74 mother/child pairs from the birth cohort ALADDIN (Assessment of Lifestyle and Allergic Disease During INfancy) using the HumanMethylation450BeadChip (Illumina). PBMCs were obtained from the mothers during pregnancy and from their children in cord blood, at 2 years and 5Y. DNA methylation levels at each time point were compared between children with and without IgE sensitization to allergens at 5Y. For replication, CpG sites associated with IgE sensitization in ALADDIN were evaluated in whole blood DNA of 256 children, 4 years old, from the BAMSE (Swedish abbreviation for Children, Allergy, Milieu, Stockholm, Epidemiology) cohort. We found 34 differentially methylated regions (DMRs) associated with IgE sensitization to airborne allergens and 38 DMRs associated with sensitization to food allergens in children at 5Y (Sidak p
  • Hockerstedt, Layla; Susi, Hanna; Laine, Anna-Liisa (2021)
    1. Maternal effects of pathogen infection on progeny development and disease resistance may be adaptive and have important consequences for population dynamics. However, these effects are often context-dependent and examples of adaptive transgenerational responses from perennials are scarce, although they may be a particularly important mechanism generating variation in the offspring of long-lived species. 2. Here, we studied the effect of maternal infection of Plantago lanceolata by Podosphaera plantaginis, a fungal parasite, on the growth, flower production and resistance of the progeny of six maternal genotypes in nutrient-rich and nutrient-poor environments. For this purpose, we combined a common garden study with automated phenotyping measurements of early life stages, and an inoculation experiment. 3. Our results show that the effects of infection on the mother plants transcend to impact their progeny. Although maternal infection decreased total leaf and flower production of the progeny by the end of the growing season, it accelerated early growth and enhanced resistance to the pathogen P. plantaginis. 4. We also discovered that the effects of maternal infection affected progeny development and resistance through a three way-interaction between maternal genotype, maternal infection status and nutrient availability. 5. Synthesis. Our results emphasize the importance of maternal effects mediated through genotypic and environmental factors in long-living perennials and suggest that maternal infection can create a layer of phenotypic diversity in resistance. These results may have important implications for both epidemiological and evolutionary dynamics of host-parasite interactions in the wild.
  • Tringali, Angela; Bowman, Reed; Husby, Arild (2015)
    Sexually dimorphic plumage coloration is widespread in birds and is generally thought to be a result of sexual selection for more ornamented males. Although many studies find an association between coloration and fitness related traits, few of these simultaneously examine selection and inheritance. Theory predicts that sex-linked genetic variation can facilitate the evolution of dimorphism, and some empirical work supports this, but we still know very little about the extent of sex linkage of sexually dimorphic traits. We used a longitudinal study on juvenile Florida scrub-jays (Aphelocoma coerulescens) to estimate strength of selection and autosomal and Z-linked heritability of mean brightness, UV chroma, and hue. Although plumage coloration signals dominance in juveniles, there was no indication that plumage coloration was related to whether or not an individual bred or its lifetime reproductive success. While mean brightness and UV chroma are moderately heritable, hue is not. There was no evidence for sex-linked inheritance of any trait with most of the variation explained by maternal effects. The genetic correlation between the sexes was high and not significantly different from unity. These results indicate that evolution of sexual dimorphism in this species is constrained by low sex-linked heritability and high intersexual genetic correlation.
  • Pietarinen, Jaakko; Maki-Tanila, Asko (2020)
    Maternally affected traits, such as juvenile growth and survival, provide resilience in mammal species, in particular for reindeer living in extreme northern habitat. The genetic variation in such traits is caused by direct and maternal genetic effects (DGE and MGE, respectively). We used Willham's variance-component approach and extended a family index with the focal individual and its full- and half-sibs to an approximated BLUP (pseudo-BLUP) by including the parents' estimated breeding values. Most of the deviations of the predicted responses from the simulated ones were 4.1% for DGE and 5.3% for MGE. The benefits of index and BLUP selection are high in the case of negative correlation, large full-sib family and in particular, when maternal half-sibs are available. Higher economic value for MGE than for DGE is needed, since with equal heritabilities and economic weights for the effects the maternal response is 40 to 70% of the direct one. With negative correlation, records on collateral relatives beyond sibs are possibly needed. They would support also the prediction of MGE in uniparous reindeer lacking full-sib information.