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Riikka Suomisen artikkeli käsittelee reproduktion murrosta naisten lisääntymiseen liittyvien toiveiden ja pyrkimysten kautta 1900-luvun alun Suomessa. Reproduktion murros viittaa 1900-luvun alkupuoliskolla tapahtuneeseen väestölliseen muuntumiseen, jolloin lasten saamiseen liittyvä ajattelu ja toimintamallit muuttuivat ja kokonaishedelmällisyys pieneni pysyvästi. Suominen tuo tutkimuksessaan esille, millaisia lastensaantiin liittyviä toiveita ja -pyrkimyksiä naisilla oli 1900-luvun alun Suomessa. Hän lähestyy kysymystä kolmesta näkökulmasta: millaisia pyrkimyksiä naisilla oli saada lapsia, säännöstellä syntyvyyttä ja keskeyttää raskaus?

Living in high latitudes and altitudes sets specific requirements on species’ ability to forecast seasonal changes and to respond to them in an appropriate way. Adaptation into diverse environmental conditions can also lead to ecological speciation through habitat isolation or by inducing changes in traits that influence assortative mating. In this review, we explain how the unique time-measuring systems of Drosophila virilis group species have enabled the species to occupy high latitudes and how the traits involved in species reproduction and survival exhibit strong linkage with latitudinally varying photoperiodic and climatic conditions. We also describe variation in reproductive barriers between the populations of two species with overlapping distributions and show how local adaptation and the reinforcement of prezygotic barriers have created partial reproductive isolation between conspecific populations. Finally, we consider the role of species-specific chromosomal inversions and the X chromosome in the development of reproductive barriers between diverging lineages. peerReviewed

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Extremely female-biased sex ratios of parasitoid wasps in multiple-foundress groups challenges evolutionary theory which predicts diminishing bias as foundress numbers increase. Recent theory based on foundress cooperation has achieved qualitative rather than quantitative success in explaining bias among parasitoids in the genus Sclerodermus. Here, we develop an explanation, expanding the theory of local mate competition, based on the observation that male production seems dominated by some foundresses within groups. Two sex ratio effects arise from such reproductive dominance: an immediate effect via suppression of male production, and a long-term evolutionary response to reproductive skew. We analyze the outcome of these effects at the individual and group level, the latter being more readily observable. Three model scenarios are analyzed: (1) random killing of developing sons in a group by all foundresses, without reproductive skew, (2) the development of reproductive dominance by some foundresses after sex allocation decisions by all foundresses have been implemented, and (3) reproductive dominance within foundress groups before sex allocation decisions are implemented. The 3 scenarios have subtly different implications for sex ratio evolution, with Models 2 and 3 being novel additions to theory, showing how reproductive dominance can alter the outcome of sex ratio evolution. All models match observations in their outcomes better than other recently proposed theory, but Models 2 and 3 are closest to observations in their underlying assumptions. Further, Model 2 shows that differential offspring mortality after parental investment can influence the primary sex ratio even when random with respect to parental and offspring characters, but targeted at entire clutches. The novel models are solved for both diploid and haplodiploid genetic systems, and confirmed with simulations. Overall, these models provide a feasible explanation for the extremely female-biased sex ratios produced by multi-foundress groups and expand the scope of local mate competition theory to consider reproductive dominance. peerReviewed

We investigate competition between separate periodical cicada populations each possessing different life‐cycle lengths. We build an individual‐based model to simulate the cicada life cycle and allow random migrations to occur between patches inhabited by the different populations. We show that if hybridization between different cycle lengths produces offspring that have an intermediate life‐cycle length, then predation acts disproportionately to select against the hybrid offspring. This happens because they emerge in low densities without the safety‐in‐numbers provided by either parent population. Thus, prime‐numbered life cycles that can better avoid hybridization are favored. However, we find that this advantage of prime‐numbered cycles occurs only if there is some mechanism that can occasionally synchronize emergence between local populations in sufficiently many patches., We investigate competition between separate periodical cicada populations each possessing different life‐cycle lengths. We show that prime‐numbered life cycles are selected for when hybridization produces offspring with an intermediate life‐cycle length compared to their parents.

To understand how variation in warning displays evolves and is maintained, we need to understand not only how perceivers of these traits select color and toxicity but also the sources of the genetic and phenotypic variation exposed to selection by them. We studied these aspects in the wood tiger moth Arctia plantaginis, which has two locally co-occurring male color morphs in Europe: yellow and white. When threatened, both morphs produce defensive secretions from their abdomen and from thoracic glands. Abdominal fluid has shown to be more important against invertebrate predators than avian predators, and the defensive secretion of the yellow morph is more effective against ants. Here, we focused on the morph-linked reproductive costs of secretion of the abdominal fluid and quantified the proportion of phenotypic and genetic variation in it. We hypothesized that, if yellow males pay higher reproductive costs for their more effective aposematic display, the subsequent higher mating success of white males could offer one explanation for the maintenance of the polymorphism. We first found that the heritable variation in the quantity of abdominal secretion was very low (h2 = 0.006) and the quantity of defensive secretion was not dependent on the male morph. Second, deploying the abdominal defensive secretion decreased the reproductive output of both color morphs equally. This suggests that potential costs of pigment production and chemical defense against invertebrates are not linked in A. plantaginis. Furthermore, our results indicate that environmentally induced variation in chemical defense can alter an individual’s fitness significantly., How much does it cost to defend against predators? A lot if you are a male wood tiger moth as deploying their defensive secretion decreases their reproductive success. When threatened, these aposematic moths produce defensive secretions from their abdomen, which are targeted specifically against invertebrate predators. However, this invertebrate-specific defense does not come without costs: deploying the defensive secretion only once decreases the reproductive success of males.

Female sperm storage is ubiquitous in the animal kingdom and it has been shown to be linked to several evolutionary processes, from postcopulatory sexual selection to dispersal. Here we report, for the first time, long-term sperm storage in females of the tardigrade Macrobiotus polonicus. Females, isolated after a short contact with a male, were able to use the stored sperm for up to 5 weeks (mean of 2 weeks), which translates to a considerable proportion of female post-mating longevity under controlled laboratory conditions (60% on average). Our study provides the first insights into the duration of sperm storage, an underexplored feature of the reproductive biology of tardigrades. Additionally, we discuss important considerations for reproductive studies on these non-model animals. peerReviewed

During the last few decades, a plethora of sequencing studies provided insight into fungal community composition under various environmental conditions. Still, the mechanisms of species assembly and fungal spread in soil remain largely unknown. While mycelial growth patterns are studied extensively, the abundant formation of asexual spores is often overlooked, though representing a substantial part of the fungal life cycle relevant for survival and dispersal. Here, we explore asexual sporulation (spore abundance, size and shape) in 32 co-occurring soil fungal isolates under varying resource conditions, to answer the question whether resource limitation triggers or inhibits fungal investment into reproduction. We further hypothesized that trade-offs exist in fungal investment towards growth, spore production and size. The results revealed overall increased fungal investment into spore production under resource limitations; however, effect sizes and response types varied strongly among fungal isolates. Such isolate-specific effects were apparent in all measured traits, resulting in unique trait spaces of individual isolates. This comprehensive dataset also elucidated variability in sporulation strategies and trade-offs with fungal growth and reproduction under resource scarcity, as only predicted by theoretical models before. The observed isolate-specific strategies likely underpin mechanisms of co-existence in this diverse group of saprobic soil fungi. peerReviewed

Sperm quantity and quality are key features explaining intra- and interspecific variation in male reproductive success. Spermatogenesis is sensitive to ionizing radiation and laboratory studies investigating acute effects of ionizing radiation have indeed found negative effects of radiation on sperm quantity and quality. In nature, levels of natural background radiation vary dramatically, and chronic effects of low-level background radiation exposure on spermatogenesis are poorly understood. The Chernobyl region offers a unique research opportunity for investigating effects of chronic low-level ionizing radiation on reproductive properties of wild organisms. We captured male bank voles (Myodes glareolus) from 24 locations in the Chernobyl exclusion zone in 2011 and 2015 and collected information on sperm morphology and kinetics. The dataset is limited in size and there overall was a relatively weak correlation between background radiation and sperm quality. Still, some correlations are worth discussing. First, midpiece segments of spermatozoa tended to be smaller in bank vole males from areas with elevated background radiation levels. Second, we demonstrated a significant positive relationship between background radiation dose rates and the proportion of static spermatozoa among males within and among study locations after 10 as well as 60 min of incubation. Our results provide novel evidence of damaging effects of low dose ionizing radiation on sperm performance in wild rodent populations, and highlight that this topic requires further study across the natural gradients of background radiation that exist in nature. peerReviewed

Photoperiodic reproductive diapause is an essential part of female life cycle in several insect species living on high latitudes, where overwintering in reproductive stage involves high risks for survival and progeny production. The sensitive period (SP), during which photoperiodic cues can trigger the switch from direct development to diapause, can last from a few hours or days after emergence to the entire life span of females. Moreover, in some species, sexually mature females can enter post-reproductive diapause as a response to decreasing day length and/or temperature. We studied the duration of SP for diapause induction and the females’ ability to enter post-reproductive diapause at short day lengths in Drosophila montana strains from different latitudes in Europe, North America, and Japan. Our study shows that the females of this species have a life-long SP and that they retain an ability to switch between reproduction and diapause as a response to back-and-forth changes in day length for at least 3 months. D. montana strains from different latitudes showed high variation in females’ ability to enter post-reproductive diapause; females of the southern strains generally requiring longer time and/or lower temperature to enter this stage than those of the northern strains. Moreover, the proportion of females that switched to post-reproductive diapause in 3 weeks in short day conditions at 16 °C showed positive correlation with the critical day length (CDL) for diapause induction and the latitudinal and continental origin of the strains. Life-long SP increases females’ flexibility to respond to short-term changes in environmental conditions and enables reproducing females to switch to post-reproductive diapause when the days get shorter and colder toward the autumn. This ability can play a major role in species phenology and should be taken into account in theoretical and empirical studies on insect adaptation to seasonal variation. peerReviewed

Pro gradu -tutkielmani sijoittuu yhteiskunnalliseen tilanteeseen, jossa sekä lastensaanti että maailmantila ovat nousseet uudenlaisen huomion kohteeksi. Samalla kun keskustelu laskevasta syntyvyydestä sekä Suomeen kipeästi kaivatuista lapsista on käynyt kiivaana, on myös uutisointi esimerkiksi ilmastokriisistä, taloudellisista haasteista sekä maailmanpoliittisista riskeistä kiihtynyt. Tutkielmani lähtökohtana toimiikin yhteiskunnallinen ympäristö, jossa nuorten aikuisten tulisi olla valmiita perheellistymään epävarmaan maailmantilaan sekä jopa turvattomaan tulevaisuuteen. Käsittelen tutkielmassani haastattelemani 11, maailmantilasta kiinnostuneen sekä ainakin vielä itse lapsettoman yliopisto-opiskelijan näkemyksiä lastensaannista, maailmantilasta ja tulevaisuudesta sekä näiden teemojen välisistä yhteyksistä. Tutkielmani tavoitteena on selvittää, miten haastattelemani opiskelijat jäsentävät ajatuksiaan perheellistymisestä ja maailmantilasta, niiden välisistä suhteista sekä lisääntymisen etiikasta. Nojaudun tutkielmassani teoreettisesti erityisesti Katharine Dow’n lisääntymisen (ekologisen) etiikan käsitteeseen sekä aikaisempaan tutkimuskirjallisuuteen, jossa perheellistymistä käsitellään yksilöllisenä ilmiönä neoliberalistisessa yhteiskunnassa. Analyysini on toteutettu teoriaohjaavan sisällönanalyysin keinoin. Haastattelemani yliopisto-opiskelijat painivat tuttujen, perheellistymispäätöksiin vaikuttavien tekijöiden kanssa. Esimerkiksi työelämän haasteet, parisuhteen löytyminen, taloudellisen tilanteen epävarmuus sekä senhetkisestä elämäntyylistä luopuminen olivat teemoja, jotka askarruttivat haastateltaviani. Näiden aihepiirien lisäksi haastateltavieni perheellistymisnäkemyksiä yhdisti kuitenkin se, että he kokivat maailmantilan ja tulevaisuuden vaikuttavan heidän käsityksiinsä perhesuunnittelusta. Analyysini osoittaa, että yliopisto-opiskelijoiden näkemyksissä nykyinen maailmantila, epävarma tulevaisuus ja perheellistyminen herättävät moninaisia ja syviä lisääntymiseettisiä pohdintoja. Suurin osa haastateltavistani koki huolta sekä siitä, millaisia vaikutuksia heidän biologisella lisääntymisellään olisi maailmantilaan ja tulevaisuuteen että erityisesti siitä, millainen vaikutus maailmantilalla ja tulevaisuudella olisi heidän lapsiinsa. Näissä huolissa lapset näyttäytyivät sekä passiivisen uhrin että aktiivisen pelastajan rooleissa tulevaisuudessa, jota on mahdotonta ennustaa. Tutkielmani osoittaa kuitenkin myös sen, että haastateltavani halusivat mahdollisesta huolesta, pelosta, stressistä tai ahdistuksesta huolimatta uskoa parempaan tulevaisuuteen. Pessimismille ei haluttu antaa valtaa, eikä maailmantilaan – erityisesti ympäristötuhoon – liittyvien viheliäisten kysymysten edessä haluttu luovuttaa. Sen sijaan haastateltavani toivoivat, että tulevat sukupolvet pystyisivät vielä niihin muutoksiin, joihin aiemmat eivät ole kyenneet. Mahdollisimman eettiset perheellistymisen muodot, vanhemmuuden keinot ja arjen käytännöt näyttäytyivät keinoina eettisempään lastensaantiin tässä maailmantilassa. Eettisemmän sekä kestävämmän elämän tavoittelu tulisi kuitenkin pystyä toteuttamaan henkilökohtaisten resurssiensa rajoissa, lempeästi ja syyllistämättä kohtuuttomasti itseään tai muita. Tutkielmani maalaa tähän maailmantilaan perheellistymisestä monitahoisen, yksilöitä eettisesti haastavan kokonaisuuden, jota haastateltavani pyrkivät erittelemään erilaisin eettisin järkeilyin. Päätökset lastensaannista, perheellistymisen keinoista tai perhe-elämän käytännöistä eivät aineistossani näyttäytyneet yksinkertaisina tai suoraviivaisina, vaan huolellisen puntaroinnin sekä eettisen arvioinnin kohteina. Haastattelemani nuoret aikuiset jäsentävätkin lisääntymiseettisiä näkemyksiään sosiaalisten, kulttuurillisten tai taloudellisten aspektien lisäksi myös ekologisesta näkökulmasta. Yliopisto-opiskelijoiden ilmentämä lisääntymisen (ekologinen) etiikka ei tue lisääntymistä maailmaan, jonka todella uskoisi olevan tuhoon tuomittu. Haastateltavani halusivat kuitenkin uskoa, että heidän jälkeläisensä vielä pystyisivät elämään hyvää elämää tässä maailmassa, mutta tämä edellyttää erilaisilta toimijoilta tekoja ympäristön, luonnon sekä ihmisten hyvinvoinnin puolesta.

Prey animals can assess the risks predators present in different ways. For example, direct cues produced by predators can be used, but also signals produced by prey conspecifics that have engaged in non-lethal predator-prey interactions. These non-lethal interactions can thereby affect the physiology, behavior, and survival of prey individuals, and may affect offspring performance through maternal effects. We investigated how timing of exposure to predation-related cues during early development affects offspring behavior after weaning. Females in the laboratory were exposed during pregnancy or lactation to one of three odor treatments: (1) predator odor (PO) originating from their most common predator, the least weasel, (2) odor produced by predator-exposed conspecifics, which we call conspecific alarm cue (CAC), or (3) control odor (C). We monitored postnatal pup growth, and we quantified foraging and exploratory behaviors of 4-week-old pups following exposure of their mothers to each of the three odour treatments. Exposure to odors associated with predation risk during development affected the offspring behavior, but the timing of exposure, i.e., pre- vs. postnatally, had only a weak effect. The two non-control odors led to different behavioral changes: an attraction to CAC and an avoidance of PO. Additionally, pup growth was affected by an interaction between litter size and maternal treatment, again regardless of timing. Pups from the CAC maternal treatment grew faster in larger litters; pups from the PO maternal treatment tended to grow faster in smaller litters. Thus, in rodents, offspring growth and behavior are seemingly influenced differently by the type of predation risk perceived by their mothers. peerReviewed

Maternal hormones constitute a key signalling pathway for mothers to shape offspring phenotype and fitness. Thyroid hormones (THs; triiodothyronine, T3; and thyroxine, T4) are metabolic hormones known to play crucial roles in embryonic development and survival in all vertebrates. During early developmental stages, embryos exclusively rely on exposure to maternal THs, and maternal hypothyroidism can cause severe embryonic maldevelopment. The TH molecule includes iodine, an element that cannot be synthesised by the organism. Therefore, TH production may become costly when environmental iodine availability is low. This may yield a trade-off for breeding females between allocating the hormones to self or to their eggs, potentially to the extent that it even influences the number of laid eggs. In this study, we investigated whether low dietary iodine may limit TH production and transfer to the eggs in a captive population of rock pigeons (Columba livia). We provided breeding females with an iodine-restricted (I−) diet or iodine-supplemented (I+) diet and measured the resulting circulating and yolk iodine and TH concentrations and the number of eggs laid. Our iodine-restricted diet successfully decreased both circulating and yolk iodine concentrations compared with the supplemented diet, but not circulating or yolk THs. This indicates that mothers may not be able to independently regulate hormone exposure for self and their embryos. However, egg production was clearly reduced in the I− group, with fewer females laying eggs. This result shows that restricted availability of iodine does induce a cost in terms of egg production. Whether females reduced egg production to preserve THs for themselves or to prevent embryos from exposure to low iodine and/or THs is as yet unclear., Summary: Restricted dietary iodine in captive rock pigeons reduces egg production in some females, thus inducing a trade-off between offspring quality and offspring quantity.

In fish, the lipid resources of the female form a link between the environment and progeny, contributing to the contents of the egg yolk. Variation of the environmental conditions is therefore expected to affect the egg quality via maternal pathways, reflecting the female’s response to the environmental factors before spawning. We investigated the content of lipids and thyroid hormones in the ovary and eggs of the Baltic herring during 1988–2019, when salinity of the Baltic Sea first declined and then stabilized to a lower level, and winters varied between severe and mild. The total lipid resources of spawning females decreased by 40–50% during the study, and the ovarian lipid concentration followed this trend resulting in a decrease of the lipid content of eggs. The concentration of thyroid hormones in the ovary suggested a hormonal response in females to salinity and winter temperature and was observable also in the content of thyroid hormones in the eggs. A change in the egg lipid content took place approximately around 1998 (SE ± 3 years) suggesting that in declining salinity, egg quality was associated with salinity and intrinsic factors in the female, i.e., fecundity and amount of lipids deposited into the ovary. However, during the period of stable salinity, egg quality was mainly limited by the female’s lipid resources. As also the body size of the females decreased over the years, it is suggested that small body size can be a key phenotypic trait to reduce the environmental impact on egg quality in variable environmental conditions. peerReviewed

Reproductive rate of grey seal (Halichoerus grypus) females has fluctuated during the 2000s, although reproductive disturbances, which occurred earlier, are rare at present. Here we aimed to study especially the food web factors possibly affecting the birth rate of Baltic grey seals and whether birth rate can be used as an indicator of the changes in the Baltic food web. Our results showed that the birth rate of grey seals was significantly related to herring (Clupea harengus membras) and sprat (Sprattus sprattus) quality (weight) which, in turn were influenced by sprat and cod (Gadus morhua) abundance, as well as zooplankton biomass and plankter size. This suggests strong trophic coupling over three trophic levels. We thus conclude that the birth rate of grey seals can be used as an indicator of the status of the Baltic food web. Based on this, we suggest a threshold value for good food web status for a stable, non-growing seal population. Highlights • Birth rate of grey seals was related to changes in the quality of clupeids. • The quality of clupeids reflected changes in the Baltic food web. • Birth rate can thus be used as an indicator of the status of the Baltic food web. • Different threshold values of birth rate for a growing and stable seal population should be determined.

We analyzed the variability in vendace population parameters in the context of a life table. Parameters related to growth, fecundity and survival were estimated for post-recruitment (age > 1 growing season) life stages of Lake Southern Konnevesi vendace in both very high and low population abundance regimes. Pre-recruitment survival producing population stability was then determined. We found a very strong compensatory density dependence in growth, fecundity and survival: during low abundance, a lifetime reproductive output of a female was almost 20 times that of the abundant regime. To maintain the low abundance regime, pre-recruitment survival must counterbalance it by decreasing to a very low level. Potential drivers of high variability in pre-recruit survival and potential for depensation, Allee effect, are discussed, as well as the implications of the results on fisheries management and risk of extinction due to anthropogenic stressors such as global warming or extensive predator stocking. peerReviewed

The evolution and diversification of animal reproductive modes have been pivotal questions in behavioural ecology. Amphibians present the highest diversity of reproductive modes among vertebrates, involving various behavioural, physiological and morphological traits. One such feature is the amplexus, which is the clasp or embrace of males on females during reproduction and is found almost universally in anurans. Hypotheses about the origin of amplexus are limited and have not been tested thoroughly, nor have they taken into account evolutionary relationships in most comparative studies. However, these considerations are crucial to an understanding of the evolution of reproductive modes. Here, using an evolutionary framework, we reconstruct the ancestral state of amplexus in 685 anuran species. We investigate whether the type of amplexus has a strong phylogenetic signal and test whether sexual size dimorphism could have influenced amplexus type or male performance while clasping females. Overall, we found evidence of ≥34 evolutionary transitions in amplexus type across anurans. We found that amplexus type exhibits a high phylogenetic signal and that amplexus type does not evolve in association with sexual size dimorphism. We discuss the implications of our findings for the diversity of amplexus types across anurans. peerReviewed

Predation involves more than just predators consuming prey. Indirect effects, such as fear responses caused by predator presence, can have consequences for prey life history. Laboratory experiments have shown that some rodents can recognize fear in conspecifics via alarm pheromones. Individuals exposed to alarm pheromones can exhibit behavioural alterations that are similar to those displayed by predator-exposed individuals. Yet the ecological and evolutionary significance of alarm pheromones in wild mammals remains unclear. We investigated how alarm pheromones affect the behaviour and fitness of wild bank voles (Myodes glareolus) in outdoor enclosures. Specifically, we compared the effects of exposure of voles living in a natural environment to a second-hand fear cue, bedding material used by predator-exposed voles. Control animals were exposed to bedding used by voles with no predator experience. We found a ca. 50% increase in litter size in the group exposed to the predator cue. Furthermore, female voles were attracted to and males were repelled by trap-associated bedding that had been used by predator-exposed voles. Movement and foraging were not significantly affected by the treatment. Our results suggest that predation risk can exert population-level effects through alarm pheromones on prey individuals that did not encounter a direct predator cue.

The work has been supported by the Academyof Finland to A.H. (project 267244) and Natural Environment Research Council (NERC) funding (NE/J020818/1 to M.G.R.; NE/L501852/1 to R.A.W.W.). The incidence of reproductive diapause is a critical aspect of life history in overwintering insects from temperate regions. Much has been learned about the timing, physiology and genetics of diapause in a range of insects, but how the multiple changes involved in this and other photoperiodically regulated traits are inter-related is not well understood. We performed quasinatural selection on reproduction under short photoperiods in a northern fly species, Drosophila montana, to trace the effects of photoperiodic selection on traits regulated by the photoperiodic timer and/or by a circadian clock system. Selection changed several traits associated with reproductive diapause, including the critical day length for diapause (CDL), the frequency of diapausing females under photoperiods that deviate from daily 24 h cycles and cold tolerance, towards the phenotypes typical of lower latitudes. However, selection had no effect on the period of free-running locomotor activity rhythm regulated by the circadian clock in fly brain. At a genomic level, selection induced extensive divergence from the control line in 16 gene clusters involved in signal transduction, membrane properties, immunologlobulins and development. These changes resembled those detected between latitudinally divergent D. montana populations in the wild and involved SNP divergence associated with several genes linked with diapause induction. Overall, our study shows that photoperiodic selection for reproduction under short photoperiods affects diapause-associated traits without disrupting the central clock network generating circadian rhythms in fly locomotor activity. Publisher PDF

Ecology of the glacial relict macrocrustacean Gammaracanthus lacustris, a rare inhabitant of deep Fennoscandian lakes, is poorly understood. We studied the life cycle and trophic position of this cold‐stenothermic amphipod in Lake Paasivesi, eastern Finland. The study is based on intensive sampling and analyses of fatty acid composition as well as stable carbon (δ13C) and nitrogen (δ15N) isotope ratios. Both day and night, the G. lacustris population occurred at depths below 25 m at temperatures 40 mm and live up to 4 years. The oldest and the largest individuals and females seemed to favour the deepest zones. In October, almost 100% of females with length at least 25 mm (i.e. females presumably at least 1‐year‐old) had an embryo sack with 20–200 eggs or embryos—the larger the female, the more young it had. The developing eggs of G. lacustris had a very high fatty acid content, indicating that the females invest heavily on provisioning their young. Furthermore, the fatty acid composition differed among life stages, and in particular the eggs had a higher proportion of eicosapentaenoic acid than juveniles or adults. The stable δ13C and δ15N isotope ratios and fatty acid biomarkers of the food web, together with visual observations, indicate that G. lacustris is a carnivore that feeds mainly on zooplankton and other relict macrocrustaceans. Due to its high content of essential polyunsaturated fatty acids, G. lacustris is a valuable prey for fish and other predators in the food web. However, as a glacial relict with strict habitat requirements the species is vulnerable to global warming and local environmental changes. These facts should be considered in the management of lakes and their catchments. peerReviewed

The availability of iron (Fe) varies considerably among diet items, as well as ecosystems. Availability of Fe has also changed due to anthropogenic environmental changes in oceanic as well as inland ecosystems. We know little about its role in the nutrition of ecologically important consumers, particularly in inland ecosystems. Physiological studies in several taxa indicate marked effects of dietary Fe on oogenesis. We predicted that differential Fe supply to algae will impact algal Fe concentration with consequences on the life history of the freshwater grazer, Daphnia magna. We found that algal Fe concentration increased with Fe supply, but did not affect algal growth, indicating that the majority of experimental Fe additions were likely adsorbed to, or stored in algal cells. Regardless, data indicate that algal Fe impacted the reproductive traits (age and size at maturity) but not juvenile growth rate of Daphnia. A subsequent experiment revealed that Fe concentration in eggs was significantly higher than the rest of Daphnia. These results indicate that the concentration of Fe in or on algal cells may vary considerably among ecosystems overlying distinct geological formations differing in Fe, possibly with important implications for zooplankton life histories. Understanding the mechanisms underlying this response is unlikely to be accomplished by a strict focus on Fe because we found correlated shifts in the algal ionome, with concomitant ionome-wide adjustments in Daphnia. Information on ionome-wide responses may be useful in better understanding the responses of biota to changes in the supply of any one element. peerReviewed

Striking variation in melanin coloration within natural populations is likely due to the different fitness outcomes of alternative phenotypes in varying environmental conditions. There are two types of melanin: eumelanins yield blackish hues, whereas pheomelanins yield reddish hues. The production of eumelanins requires low levels of glutathione (GSH), which is the most important intracellular antioxidant, whereas the production of pheomelanins requires high levels of GSH. We investigated the oxidative status of male pied flycatchers (Ficedula hypoleuca) with different degrees of melanin coloration under different temperatures during the nestling period. Moreover, we assessed the oxidative status of offspring in relation to their biological or foster father's melanin coloration and ambient temperature. To separate offspring genotype effects and paternal effects in different temperatures, we used a partial cross-foster design. The temperature differently affected the oxidative status of differently colored male pied flycatchers and their foster offspring. When the weather was relatively cold, black males had higher glutathione S-transferase levels compared with brown males, indicating enhanced stress in black males. Foster offspring of black males had a lower ratio between reduced and oxidized GSH followed by higher total amount of GSH than foster offspring of brown males. Thus, foster offspring of black males seem to suffer from oxidative stress under relatively cold weather compared with those of brown males, and vice versa under relatively warm weather. Although differently colored males experienced changes in their oxidative status under different temperatures, the link between paternal melanin coloration and offspring oxidative stress appears to be environmentally induced. peerReviewed

1. Global climate change imposes a serious threat to natural populations of many species. Estimates of the effects of climate change‐mediated environmental stresses are, however, often based only on their direct effects on organisms, and neglect the potential transgenerational (e.g. maternal) effects. 2. We tested whether high temperature (i.e. an experimental heatwave), which is known to reduce the performance of adult Lymnaea stagnalis snails, affects the produced offspring (eggs and hatchlings) through maternal effects, and how strong these effects are compared with the effects of direct exposure of offspring to high temperature. We examined the effect of maternal thermal environment (15°C versus 25°C) on per offspring investment (egg size), and the role of both maternal and offspring thermal environments (15°C versus 25°C) on hatching success and developmental time of eggs, offspring survival after hatching, and hatchling size at the age of 5 weeks. 3. Exposure of mothers to high temperature reduced the size of oviposited eggs, increased their hatching success, and also made the onset of hatching earlier. However, high maternal temperature reduced the survival and the final size of hatched juveniles. Direct exposure of offspring to high temperature reduced their survival (both eggs and hatchlings) but increased the developmental rate and growth of those individuals that survived. Interestingly, the magnitude of maternal effects on hatching success of eggs and hatchling survival were similar to the direct effects of high temperature. 4. Our results indicate that heatwaves can affect natural populations through transgenerational maternal effects and that the magnitude of those effects can be equally strong to the direct effects of temperature, although this depends on the trait considered. These findings highlight the importance of considering the transgenerational effects of climate warming when estimating its effects in the wild., Freshwater Biology, 64 (12), ISSN:0046-5070, ISSN:1365-2427

Global climate change affects natural populations of many species by increasing the average temperature and the frequency of extreme weather events (e.g. summer heat waves). The ability of organisms to cope with these environmental changes can, however, depend on their genetic properties. For instance, genetic load owing to inbreeding could alter organisms’ responses to climate change-mediated environmental changes but such effects are often overlooked. We investigated the effects of an experimental heat wave (25°C versus 15°C) on life history (reproduction, size) and constitutive immune defence traits (phenoloxidase-like and antibacterial activity of haemolymph) in relation to inbreeding by manipulating the mating type (outcrossing, self-fertilization) in two populations of a hermaphroditic freshwater snail, Lymnaea stagnalis. High temperature increased reproduction and size of snails but impaired their immune function. In one of the two study populations, inbreeding reduced reproductive output of snails indicating inbreeding depression. Furthermore, this effect did not depend on the temperature snails were exposed to. Our results suggest that L. stagnalis snails can be negatively affected by inbreeding but it may not alter their responses to heat waves. ISSN:1932-6203

A population growth rate is the sum of all individuals’ reproduction and survival, which in turn depend on many external and internal factors, e.g. weather and individual reproductive history. In plants, for example, previous reproduction can deplete an individual’s resources, resulting in trade-offs between demographic functions. To understand these demographic processes, it is necessary to follow populations for many years. Such long-term studies are especially crucial for endangered species, as they can reveal the causes of population declines and provide information that is directly applicable for the management. In my thesis, I applied this approach to the study of rare orchids. Specifically, I analyzed long-term orchid monitoring data from two countries, Finland and Estonia, to assess the external and internal factors that affect the performance of these long-lived plants, which reproduce both sexually (via seeds) and vegetatively (via new ramets). My research reveals that plant performance depends on both the demographic history and the environment of a plant. For example, although Finnish and Estonian populations of the lady’s slipper orchid, Cypripedium calceolus, differed in direction and statistical significance of their responses to environmental factors, the two most-influential weather variables in both cases were spring snow depth and the temperature of the previous summer. However, the influence of weather on both flowering and vegetative growth was dwarfed by the effect of plants’ own demographic histories: there was a trade-off between current and future reproduction which created asynchronous two-year cycles in reproduction and growth. Furthermore, in all three studied orchid species — the lady’s slipper orchid (C. calceolus), the fairy’s slipper orchid (Calypso bulbosa), and the dark-red helleborine (Epipactis atrorubens) — the probability of dormancy (a state in which the plant spends a year or more underground) and the demographic costs this state incurred with respect to size or future reproduction depended on a plant’s size and whether it flowered prior to dormancy. In other words, dormancy had both absolute and relative costs in large, but not in small, individuals. Finally, I show here that environmental alteration via selective tree removal can be used as a management method to increase orchid reproduction via both seeds and ramets. Tiivistelmä Populaation kasvunopeus riippuu siitä, kuinka monta yksilöä populaatioon syntyy ja kuinka monta yksilöä kuolee. Yksilöiden lisääntyvyyteen ja elossa säilyvyyteen puolestaan vaikuttavat monet ulkoiset ja sisäiset tekijät, kuten sää ja yksilön oma lisääntymishistoria. Kasvilla on rajallinen määrä resursseja, joten sen pitää tehdä kompromisseja eri elintoimintojen, esimerkiksi kasvun ja lisääntymisen, välillä. Klonaaliset kasvit voivat myös lisääntyä usealla tavalla: joko suvullisesti siemenistä tai kasvullisesti tuottamalla uusia versoja. Demografisten prosessien tutkimisessa pitkäaikaiset seuranta-aineistot ovat välttämättömiä. Pitkäaikaisseurannat voivat myös paljastaa uhanalaisen lajin populaation taantumisen syyt ja näistä seurannoista saatua tietoa voidaan soveltaa harvinaisten lajien, esimerkiksi kämmeköiden, suojelutoimien suunnittelussa. Tässä väitöskirjassa analysoin aineistoa kämmeköiden pitkäaikaisseurannoista Suomesta ja Virosta. Tavoitteenani oli arvioida ulkoisten ja sisäisten tekijöiden merkitystä pitkäikäisten kasvien menestykselle. Tulokset osoittavat, että kasvin menestys riippuu sekä yksilön omasta demografisesta historiasta että sen ympäristöstä. Eri säätekijöiden vaikutus tikankontin (Cypripedium calceolus) kasvuun ja kukkimiseen vaihteli Suomen ja Viron välillä, mutta lumen syvyys ja edellisen kasvukauden lämpötila nousivat merkittävimmiksi tekijöiksi molemmissa maissa. Tikankontin kasvu ja kukinta riippuivat kuitenkin säätä enemmän kasvin omasta demografisesta historiasta. Runsas lisääntyminen edeltävällä kasvukaudella vähensi lisääntymistä tulevalla kasvukaudella, mikä johti kaksivuotiseen jaksottaisuuteen tikankontin lisääntymisessä ja kasvussa. Tutkiessani dormanssia (lepotila, jossa kasvi ei tuota maanpäällistä versoa) kolmella kämmekkälajilla, tikankontilla, neidonkengällä (Calypso bulbosa) ja tummaneidonvaipalla (Epipactis atrorubens), havaitsin lisäksi, että todennäköisyys siirtyä dormanssiin riippui kasvin koosta. Myöskin tämän lepotilan aiheuttamat kustannukset olivat riippuvaisia kasvin aikaisemmasta tilasta. Isoilla kasveilla dormanssilla oli sekä suoria kustannuksia että kustannuksia suhteessa versomiseen. Pienillä kasveilla näitä kustannuksia ei ollut. Osoitan väitöskirjassani myös, että maltillisella puunpoistolla voidaan lisätä tikankonttipopulaatioiden siementuottoa ja versotiheyttä.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting 5–15% of women of reproductive age. The syndrome is characterized by menstrual irregularities, hyperandrogenism and polycystic ovaries. Infertility is a major problem in PCOS and it can be explained partially by chronic anovulatory cycles. Excess body weight and insulin resistance are common among women with PCOS, exposing them to the most common pregnancy complication, gestational diabetes mellitus (GDM) and, later in life, to a higher risk of developing glucose metabolism disorders eventually leading to outbreak of type 2 diabetes mellitus (T2DM). However, the respective roles of the syndrome per se, excess body weight and hyperandrogenism regarding the aforementioned complications are still to be clarified. The objectives were first to determine the risks of PCOS, infertility problems and decreased fertility at age 26 in women with a history of menstrual irregularity or elevated androgen levels in adolescence (at age 16). We also aimed to clarify whether PCOS per se is associated with decreased fertility and increased incidence of miscarriage, GDM, prediabetes and T2DM. Lastly, we focused on the respective roles of excess body weight and hyperandrogenism as regards the development of GDM and impaired glucose metabolism. The study populations were derived from the prospective Northern Finland Birth Cohorts 1966 and 1986, comprising all expected births in 1966 (n = 5889 females) and 1986 (n = 4567) in the two northernmost provinces of Finland. The data was complemented with fertility rates and diagnoses of GDM and T2DM from registers held by the National Institute for Health and Welfare and The Social Insurance Institution of Finland. Menstrual irregularity or elevated androgen levels in adolescence were associated at age 26 with increased risks of PCOS and infertility problems, but not with decreased fertility rates. At the end of their reproductive life women with symptoms of PCOS were not more often childless, had had a similar incidence of miscarriages but had a smaller family size compared with healthy women, and obesity further decreased family size in this group. Excess body weight and elevated androgen levels, but not PCOS per se, were independent risk factors of GDM. The increased risk of T2DM in PCOS was mainly due to excess body weight, although both factors had a synergistic effect on the development of T2DM. Tiivistelmä Monirakkulainen munasarjaoireyhtymä (PCOS) on yleinen naisilla esiintyvä hormonaalinen häiriö, josta kärsii 5–15% lisääntymisikäisistä naisista. Kuukautiskierron häiriöt, mieshormoniylimäärä ja monirakkulaiset munasarjat ovat ominaisia oireyhtymälle. Lapsettomuus on keskeinen ongelma oireyhtymässä, mikä johtuu osittain kroonisesta ovulaatioiden epäsäännöllisyydestä tai niiden puuttumisesta. Ylipainoa ja insuliiniresistenssiä esiintyy usein oireyhtymää sairastavilla naisilla ja ne altistavat raskausajan diabeteksen puhkeamiselle. Myöhemmällä iällä PCOS-naisilla on suurentunut riski sairastua sokeriaineenvaihdunnan häiriöihin, jotka lisäävät riskiä tyypin 2 diabeteksen (T2DM) puhkeamiselle. PCOS:n, ylipainon ja mieshormoniylimäärän itsenäiset roolit edellä mainittujen häiriöiden kehittymisessä ovat kuitenkin edelleen epäselviä. Ensimmäisenä tavoitteena oli selvittää PCOS:n, lapsettomuusongelmien ja alentuneen hedelmällisyyden riskiä 26-vuotiaana naisilla, joilla todettiin kuukautiskierron häiriö tai kohonneet mieshormonipitoisuudet nuoruusiällä (16-vuotiaana). Toiseksi selvitimme, liittyykö PCOS itsessään alentuneeseen hedelmällisyyteen sekä kohonneeseen keskenmenojen, raskausdiabeteksen, diabeteksen esiasteiden ja T2DM esiintyvyyteen. Lisäksi selvitimme ylipainon ja mieshormoniylimäärän itsenäisiä rooleja raskausdiabeteksen ja muiden sokeriaineenvaihdunnan häiriöiden kehittymisessä. Tutkimusaineistoina olivat Pohjois-Suomen syntymäkohortit 1966 (n = 5889 naista) ja 1986 (n = 4567 naista), joihin sisältyivät kaikki elävänä syntyneet lapset vuosina 1966 ja 1986 kahdesta Suomen pohjoisimmasta läänistä. Tutkimusaineistoja täydennettiin hedelmällisyyslukujen ja GDM- sekä T2DM-diagnoosien osalta Terveyden ja hyvinvoinnin laitoksen ja Kansaneläkelaitoksen ylläpitämistä rekistereistä. Nuoruusiän kuukautiskierron häiriöt ja mieshormoniylimäärä olivat yhteydessä suurentuneeseen riskiin kehittää PCOS ja kärsiä lapsettomuusongelmista, mutta näiden yhteyttä alentuneisiin hedelmällisyyslukuihin 26-vuotiaana ei todettu. PCOS-oireiset naiset eivät kärsineet lapsettomuudesta lisääntymisiän aikana verrokkinaisia enemmän ja keskenmenojen esiintyvyys ei eronnut oireisten ja terveiden naisten välillä. Oireisilla naisilla oli kuitenkin pienempi perhekoko kuin verrokeilla, ja lihavuus entisestään pienensi perhekokoa oireisilla naisilla. Ylipaino ja mieshormoniylimäärä olivat itsenäisiä riskitekijöitä raskausdiabeteksen kehittymiselle. PCOS ei ollut riskitekijä raskausdiabeteksen kehittymiselle. Kohonnut T2DM-riski PCOS:ssa johtui lähinnä ylipainosta, vaikkakin molemmat tekijät olivat itsenäisiä riskitekijöitä T2DM:n kehittymiselle.

The timing of sex in facultatively sexual organisms is critical to fitness, due to the differing demographic consequences of sexual versus asexual reproduction. In addition to the costs of sex itself, an association of sex with the production of dormant life stages also influences the optimal use of sex, especially in environments where resting eggs are essential to survive unfavourable conditions. Here we document population dynamics and the occurrence of sexual reproduction in natural populations of Daphnia magna across their growing season. The frequency of sexually reproducing females and males increased with population density and with decreasing asexual clutch sizes. The frequency of sexually reproducing females additionally increased as population growth rates decreased. Consistent with population dynamic models showing that the opportunity cost of sexual reproduction (foregoing contribution to current population growth) diminishes as populations approach carrying capacity, we found that investment in sexual reproduction was highest when asexual population growth was low or negative. Our results support the idea that the timing of sex is linked with periods when the relative cost of sex is reduced due to low potential asexual growth at high population densities. Thus, a combination of ecological and demographic factors affect the optimal timing of sexual reproduction, allowing D. magna to balance the necessity of sex against its costs.

Emissions from metal mining activities are known to deteriorate the quality of aquatic habitats and impair the condition and reproductive potential of fish. Metal extraction by biomining methods has been considered to cause fewer emissions, but for example in Finland, the impacts of a bioheapleaching technology utilizing metal mine on the local freshwaters have been substantial. In this thesis, the impacts of the bioheapleaching mine emissions on three native fish species, brown trout (Salmo trutta) European perch (Perca fluviatilis) and whitefish (Coregonus lavaretus pallasi), were investigated. Manganese and sulphate concentrations have been elevated in the mining impacted waters, and in our laboratory experiment with whitefish early life stages, a continuous exposure to manganese sulphate increased the early life stage mortality and impaired the larval growth and yolk consumption. In addition, the tolerance of the whitefish early life stages to manganese sulphate varied among the female parents, and the tolerance also seemed to be linked to larval metallothionein messenger RNA induction. In the long-term in situ egg incubation experiment, however, no mining impact related effect on brown trout and whitefish embryonic mortality or growth was observed. Although low water pH increased the embryonic mortality of both species, the low water pH was characteristic to the waterbodies at the study region in general. With wild male perch, the liver and testes size were lower in the mining impacted study lakes, indicating lower energy resources compared to the males from the reference lakes. The perch from the mining impacted lakes also had lower sperm counts, which seemed to have been compensated by elongated sperm motility. These results suggested that the condition and reproductive potential of fish may have been compromised in the bioheapleaching mine impacted lakes.

Natural populations often experience environments that vary across space and over time, leading to spatio-temporal variation of the fitness of a genotype. If local conditions are poor, organisms can disperse in space (physical movement) or time (dormancy, diapause). Facultatively sexual organisms can switch between asexual and sexual reproduction, and thus have a third option available to deal with maladaptedness: they can engage in sexual reproduction in unfavourable conditions (an ‘abandon-ship’ response). Sexual reproduction in facultatively sexual organisms is often coupled with dispersal and/or dormancy, while bet-hedging theory at first sight predicts sex, dispersal and dormancy to covary negatively, as they represent different escape mechanisms that could substitute for each other. Here we briefly review the observed links between sex, dormancy and dispersal, and model the expected covariation patterns of dispersal, dormancy and the reproductive mode in the context of local adaptation to spatio-temporally fluctuating environments. The correlations between sex, dormancy and dispersal evolve differently within species versus across species. Various risk-spreading strategies are not completely interchangeable, as each has dynamic consequences that can feed back into the profitability of others. Our results shed light on the discrepancy between previous theoretical predictions on covarying risk-spreading traits and help explain why sex often associates with other means of escaping unfavourable situations.This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences’.

In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here, we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g., when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests ("split sex ratios"), which promotes the evolution of altruistic helping by daughters in mated queen nests. However, when helpers evolve to be efficient and increase nest production significantly, virgin reproduction is selected against. Our results suggest that adaptive virginity could have been an important stepping stone on the pathway to eusociality in haplodiploids. We further show that virginity can be an adaptive reproductive strategy also in primitively social haplodiploids if workers bias the sex ratio toward females. By remaining virgin, queens are free to produce sons, the more valuable sex in a female-biased population. Our work brings a new dimension to the studies linking reproductive strategies with social evolution.

Sperm competition may select for male reproductive traits that influence female mating or oviposition rate. These traits may induce fitness costs to the female; however, they may be costly for the males as well as any decrease in female fitness also affects male fitness. Male adaptations to sperm competition manipulate females by altering not only female behaviour or physiology, but also female morphology. In orb-weaving spiders, mating may entail mutilation of external structures of the female genitalia, which prevents genital coupling with subsequent males. Here, we present a game theoretical model showing that external female genital mutilation is favoured even under relatively high costs of mutilation, and that it is favoured by a high number of mate encounters per female and last-male sperm precedence.

Limited resources force individuals to trade-off between life-history traits. A vast diversity of life-history strategies, which optimally combine life history traits, can be found. Knowledge of the genetic basis of this phenotypic variation is key to understanding evolutionary processes. I approached life-history evolution by estimating quantitative genetic parameters for a set of life-history traits in the bank vole (Myodes glareolus). The work is based on a laboratory-kept colony subjected to two-way selection for litter size (High- (H) and Low- (L) lines). Costs of the created reproductive strategies were observed in natural conditions. Selection increased the difference in litter size between lines, even though the response was asymmetric. The difference persisted in outdoor enclosures. A life-history trade-off between offspring number and offspring size was explained by environmental correlations as associated genetic correlations were even positive. Lines did not diverge in offspring size. In the enclosures maternal body mass had greater effect on pup survival in the L-line. Litter and maternal environment explained most of the phenotypic variation in pup body mass during the nursing period, while direct genetic variation emerged later, implicating selection on early size in the bank vole. Male and female metabolic rate did not seem to share genetic background; the first lacking additive genetic variation and the latter being bound to fecundity by genetic correlation close to one. Testosterone, a principle determinant of male reproductive success in the bank vole, was contrasted with humoral immune system in the both sexes. In general, with the exception of metabolism, the estimated genetic parameters did not set absolute constraints for life-history evolution. However, dimensionality of the additive genetic co(variance) matrix constrains evolution to act along certain trait combinations. In the future, research should strive to find genetic mechanisms, which, through the endocrine system, produces phenotypic co(variation) in different life-history traits.

Lääketieteen historian klassikkotekstejä on saatettu suomen kielelle vain muutamia. Hippokraattisesta kirjoitusperinteestä tunnetuin teksti on nykyaikana Vala. Yksin valan perusteella on kuitenkin vaikea ymmärtää Hippokrateen ajan lääketiedettä, koska teoksessa käsitellään pääosin eettisiä ja hallinnollisia seikkoja. Syventävissä opinnoissani olen tutustunut antiikin lääketieteeseen ja tämän myötä toimitettuihin kreikankielisiin laitoksiin säilyneistä hippokraattisista teoksista. Asia- ja tyyliseikkojen perusteella valitsin teoksista yhden ja saatoin sen suomen kielelle. Valittu teos käsittelee yhdentoista alakappaleen verran lisääntymistä teoreettisena ongelmana. Teos sopii tyylinsä perusteella parhaiten n. 400-luvulle eaa. Alakappaleiden rakenne on löyhä, ja sen sijaan että kirjoittaja etenisi alakappaleiden myötä itsestäänselvistä asioista kohti kiistanalaisia, hän esittää useita rinnakkaisia oletuksia ja lisää oletusten yhteensopivuudella esityksensä uskottavuutta. Antiikin ajattelun tarkempi arviointi on lähtökohtaisesti vaikeaa, joten olen pyrkinyt helpottamaan tulkintatyötä selitysosiolla. Teoksen kirjaajasta ei ole luotettavaa tietoa eikä opillisia vaikuttimia pystytä täysin vakuuttavasti osoittamaan. Opinnäytetyössäni käyn läpi myös muutamien lisääntymiselle keskeisten teoreettisten ongelmien kehityskulkuja.

Biological altruism, defined as a behaviour that benefits others at an apparent cost to the focal individual, is found abundantly across different levels of biological organization. While kin selection has been useful for explaining both cooperation and conflict in specialized cooperative societies, more theoretical work has to be done to develop models for realistic ecological and life-history contexts. This thesis aims to fill this gap by providing several new insights on the role of ecology and life-history in various social systems. Firstly, I propose a model that incorporates realistic ecological mechanisms of population regulation and study how different population regulation mechanisms affect the evolution of helping behaviour. I show that nest-site limitation strongly favours evolution of helping behaviour even if the helpers are relatively inefficient. I also find that interactions between density dependent mechanisms and life-history traits affect the evolution of social behaviour. Secondly, I consider a resource allocation model for eusocial insect colonies that incorporates the dynamics of colony growth and the conflict between the queen and the workers over the sex ratio. I show that conflict over sex allocation gives rise to a suboptimal pattern of colony growth, while the queen wins the sex allocation conflict. Thirdly, I study optimal reproductive tactics in facultatively cooperative wasps. I show that co-foundress nests and costly helping can evolve even with a low average relatedness between co-foundresses, but only during the initial stages of the nesting cycle. Costly helping during the reproductive phase can only evolve if the relatedness between co-foundresses is high. In conclusion, this thesis demonstrates the importance of considering ecological and life-history aspects in the study of social interactions from early stages of helping behaviour to resolving conflicts in eusocial insect colonies.

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 strong, males are often reluctant and choosy, whereas females tend to accept available matings. Male reluctance evolves because a male's benefit per mating diminishes rapidly as he mates too often, hence losing out in the process of sperm competition as he spends much of his resources on mating costs rather than ejaculate production. When sperm limitation is weaker, females become more reluctant and males are more eager to mate. The model thus suggests that reversed sex roles are plausible outcomes of polyandry and limited sperm production. Implications for empirical studies of mate choice are discussed.

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 emerge. First, condition-dependent expression of male sexual traits makes it likely that sexual selection increases female fitness if reproductively successful males disproportionately transfer genes that are under natural selection in both sexes, such as genes for foraging efficiency. Condition-dependence is a form of phenotypic plasticity if some of the variation in net resource acquisition and assimilation is attributable to the environment rather than solely genetic in origin. Second, the optimal allocation of resources into different condition-dependent traits depends on their marginal fitness gains. As male condition improves, this can therefore increase or, though rarely highlighted, actually decrease the expression of sexually selected traits. It is therefore crucial to understand how condition determines male allocation of resources to different sexually selected traits that vary in their immediate effects on female reproductive output (e.g. ornaments versus coercive behaviour). In addition, changes in the distribution of condition among males as the environment shifts could reduce phenotypic variance in certain male traits, thereby reducing the strength of sexual selection imposed by females. Studies of adaptive evolution under rapid environmental change should consider the possibility that phenotypic plasticity of sexually selected male traits, even if it elevates male fitness, could have a negative effect on female reproductive output, thereby increasing the risk of population extinction. This article is part of the theme issue ‘The role of plasticity in phenotypic adaptation to rapid environmental change’.

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 independent of the source of ASR variation. Finally, to increase realism and unify earlier models, we allow for coevolution between parental investment and investment in sexually selected traits. Our model confirms that small initial differences in parental investment tend to increase due to positive evolutionary feedback, formally supporting long-standing, but unsubstantiated, verbal arguments., Females tend to invest more than males in caring for offspring, which has been argued to be a consequence of the small initial difference in investment in eggs versus sperm. Here, Fromhage and Jennions formalize this argument mathematically in a model of the evolution of sex roles in parental care.

Lisääntymissysteemiltään gynodieekkisissa kasvipopulaatioissa on tavallisesti sukupuoleltaan kahdenlaisia yksilöitä, puhtaasti emikukkaisia kasveja sekä kaksineuvoisia kukkia tuottavia kasveja. Nämä eri sukupuolet eroavat toisistaan geneettisten, morfologisten ja fysiologisten piirteiden suhteen. Lisääntymissysteemi vaikuttaa myös yksilöiden resurssiallokointitapaan sekä siihen miten ja missä suhteessa gynodieekkisten populaatioiden yksilöt osallistuvat geenien siirtämiseen jälkeläisilleen. Emikasvit osallistuvat jälkeläistuotantoon siemenaiheita tuottamalla ja kaksineuvoiset kasvit siemenaiheita sekä siitepölyä tuottamalla. Edellä mainitut sukupuolisidonnaisten erojen vaikutukset voivat heijastua myös yksilöiden resistenssiin. Esimerkiksi enemmän lisääntymiseen panostava sukupuoli saattaa olla alttiimpi patogeeneille, sillä on mahdollista ettei kasvi kykene allokoimaan resursseja lisääntymisen ohella samanaikaisesti resistenssin ylläpitämiseen. Mikäli gynodieekkisen populaation emikasvien ja kaksineuvoisten kasvien kyvyssä ylläpitää resistenssiä on sukupuolisidonnaisista ominaisuuksista johtuvia eroja, voi tämä edelleen vaikuttaa kuolleisuuden tai heikentyneen jälkeläistuotannon kautta kasvipopulaation geneettiseen rakenteeseen ja populaation sukupuolijakaumaan. Seuraukset voivat heijastua takaisin lajin lisääntymissysteemin evoluutioon sekä vaikuttaa kasvin ja muun ympäristön välisiin ekologisiin vuorovaikutussuhteisiin. Tässä työssä tutkittiin kasvihuonekokeen avulla sitä, vaihteleeko gynodieekin metsäkurjenpolven (Gerianium sylvaticum) patogeeniresistenssi yksilön sukupuolen mukaan eli eroaako emikasvien, välimuotojen tai kaksineuvoisten kasvien alttius kurjenpolvenhärmälle (Podosphaera fugax). Tutkimuksessa havaittiin, että välimuotojen ja kaksineuvoisten välillä oli kokoeroja, jotka eivät kuitenkaan vaikuttaneet sukupuolten härmäinfektionlaajuuteen. Kvalitatiivisessa tai kvantitatiivisessa resistenssissä ei havaittu sukupuolisidonnaisia eroja. Tutkimuksen perusteella gynodieekkiseen lisääntymissysteemiin kuuluvat sukupuolisidonnaiset erot eivät ainakaan metsäkurjenpolvella vaikuta sukupuolten infektioalttiuteen. Gynodioecious plant populations are usually composed of two kinds of gender morphs, females and hermaphrodites. Between these two genders there are genetic, morphological and physiological differences that may influence plant's resource allocation patterns and how and to what extent each morph contributes to the production of offspring. In a gynodioecious population females allocate resources to ovule production whereas hermaphrodites allocate resources to both ovule and pollen production. Since resources are limited, these differences in resource allocation patterns may influence other life cycle traits through trade-offs. In case of infection, gender morph that allocates more of its resources to reproduction, that is, to the production of certain kinds of flowers, may not be able to allocate enough resources to resistance. If females and hermaphrodites differ in their resource allocation patterns and it affects their resistance in different ways this may eventually lead to changes in population's genetic structure and its sex ratio through increased mortality or decreased production of offspring. These changes may eventually influence the evolution of plant breeding system and ecological interactions between plants and their environment. In this study greenhouse experiment was set up to study whether females, intermediates or hermaphrodites of gynodioecious Geranium sylvaticum differ in their susceptibility to fungal pathogen, Podosphaera fugax. The results showed that gender morphs have size differences that did not, however, have an effect on the extent of plant infection. Qualitative resistance did not differ significantly between genders and neither did quantitative resistance of leaves and reproductive organs. Based on the results it seems that there are no significant differencies between quantitative or qualitative resistance of different genders of Geranium sylvaticum to Podosphaera fugax.