Search results for "sää"
showing 10 items of 512 documents
Vanhemmuustyylien, vanhemmuuden stressin ja lasten ongelmakäyttäytymisen väliset yhteydet
2010
Juveniilihormonin vaikutus munantuotantoon ja seksuaaliseen antagonismiin koloradonkuoriaisilla
2012
Hormonitoiminta on yksi eliöiden säätelyjärjestelmistä. Hyönteisillä keskeisessä osassa hormonisäätelyä ovat juveniilihormonit (JH). Niiden määrä yksilöiden elimistössä säätelee monia asioita yksilöiden kehityksestä lisääntymistoimintoihin. Juuri tehokas lisääntyminen onkin eliöiden tärkeimpiä tehtäviä. Hormonitoiminta pitää yllä evoluution myötä eri lajeille ja lajiryhmille kehittyneitä erilaisia lisääntymisstrategioita: jotkin lisääntyvät harvakseltaan mutta huolehtivat poikasistaan, toiset tuottavat paljon jälkeläisiä, jotka ne jättävät selviämään yksin. Sukupuolten välillä on kuitenkin eroja optimaalisessa lisääntymisstrategiassa. Naaraat joutuvat kuluttamaan jälkeläisten tuottamiseen k…
Linnansalmen Haloset : sukutilan omaistajanvaihdokset perheyhteisön taitekohtina
2022
Halosen taiteilijasuvun talonpoikainen suurperhe on tuttu Suomen taidehistoriasta. Sukutila ja talollisen asema eivät kuitenkaan olleet heille itsestään selvä vuosisatainen jatkumo. Myös suurperhe oli enemmän ajoittainen välivaihe tilanomistajuudessa kuin pysyvä sukurakkauden ilmentymä. Tässä artikkelissa tarkastellaan Halosen sukutilan omistajanvaihdoksia perheyhteisön taitekohtina. peerReviewed
Positive Teacher Affect and Maternal Support Facilitate Adjustment After the Transition to First Grade
2016
This longitudinal study, conducted among a sample of Finnish primary-school children, examined the proposition that a single high-quality relationship (either with a teacher or a parent) can buffer against adjustment problems. Teachers rated the externalizing problems and prosocial behaviors of 378 children in Grade 1 and again in Grade 2. Relationship measures gathered in Grade 1 included teacher reports of positive affect for the child and mother reports of support for the child. The results supported our proposition by showing that for child adjustment after the transition to primary school it was critical to have at least one high-quality relationship either with a teacher or a parent. …
Scientific Reports
2020
.-- Halimubieke, Naerhulan et al.
Evolution of male and female choice in polyandrous systems
2017
We study the evolution of male and female mating strategies and mate choice for female fecundity and male fertilization ability in a system where both sexes can mate with multiple partners, and where there is variation in individual quality (i.e. in the availability of resources individuals can allocate to matings, mate choice and production of gametes). We find that when the cost of mating differs between sexes, the sex with higher cost of mating is reluctant to accept matings and is often also choosy, while the other sex accepts all matings. With equal mating costs, the evolution of mating strategies depends on the strength of female sperm limitation, so that when sperm limitation is stro…
Sexual selection, phenotypic plasticity and female reproductive output
2019
In a rapidly changing environment, does sexual selection on males elevate a population's reproductive output? If so, does phenotypic plasticity enhance or diminish any such effect? We outline two routes by which sexual selection can influence the reproductive output of a population: a genetic correlation between male sexual competitiveness and female lifetime reproductive success; and direct effects of males on females' breeding success. We then discuss how phenotypic plasticity of sexually selected male traits and/or female responses (e.g. plasticity in mate choice), as the environment changes, might influence how sexual selection affects a population's reproductive output. Two key points…
Coevolution of parental investment and sexually selected traits drives sex-role divergence
2016
Sex-role evolution theory attempts to explain the origin and direction of male–female differences. A fundamental question is why anisogamy, the difference in gamete size that defines the sexes, has repeatedly led to large differences in subsequent parental care. Here we construct models to confirm predictions that individuals benefit less from caring when they face stronger sexual selection and/or lower certainty of parentage. However, we overturn the widely cited claim that a negative feedback between the operational sex ratio and the opportunity cost of care selects for egalitarian sex roles. We further argue that our model does not predict any effect of the adult sex ratio (ASR) that is …
Diapause affects cuticular hydrocarbon composition and mating behavior of both sexes inDrosophila montana
2018
Environmental cues, mainly photoperiod and temperature, are known to control female adult reproductive diapause in several insect species. Diapause enhances female survival during adverse conditions and postpones progeny production to the favorable season. Male diapause (a reversible inability to inseminate receptive females) has been studied much less than female diapause. However, if the males maximized their chances to fertilize females while minimizing their energy expenditure, they would be expected to be in diapause at the same time as females. We investigated Drosophila montana male mating behavior under short‐day conditions that induce diapause in females and found the males to be r…
Sex roles and the evolution of parental care specialization
2019
Males and females are defined by the relative size of their gametes (anisogamy), but secondary sexual dimorphism in fertilization, parental investment and mating competition is widespread and often remarkably stable over evolutionary timescales. Recent theory has clarified the causal connections between anisogamy and the most prevalent differences between the sexes, but deviations from these patterns remain poorly understood. Here, we study how sex differences in parental investment and mating competition coevolve with parental care specialization. Parental investment often consists of two or more distinct activities (e.g. provisioning and defence) and parents may care more efficiently by s…