Parental care is one of the most variable social behaviors and it is an excellent model system to understand cooperation between unrelated individuals. Three major hypotheses have been proposed to explain the extent of parental cooperation: sexual selection, social environment, and environmental harshness. Using the most comprehensive dataset on parental care that includes 659 bird species from 113 families covering both uniparental and biparental taxa, we show that the degree of parental cooperation is associated with both sexual selection and social environment. Consistent with recent theoretical models parental cooperation decreases with the intensity of sexual selection and with skewed adult sex ratios. These effects are additive and robust to the influence of life-history variables. However, parental cooperation is unrelated to environmental factors (measured at the scale of whole species ranges) as indicated by a lack of consistent relationship with ambient temperature, rainfall or their fluctuations within and between years. These results highlight the significance of social effects for parental cooperation and suggest that several parental strategies may coexist in a given set of ambient environment.

Summary1. Herbarium collections contain long-term data for a wide range of taxa and provide unique opportunities to evaluate the importance of life-history components in driving species-specific responses to climate change. In this paper, we analyse the relationships between change in flowering dates and life-history traits within a phylogenetic framework. The study is based on an extensive data set of herbarium specimens of orchids collected in Hungary between 1837 and 2009, supplemented by recent field observations . 2. Of the 39 taxa investigated, 31 (79%) showed apparent advancement in mean flowering time. Among these, advancement was statistically significant in nine taxa. The rest (eight taxa) showed non-significant delays in flowering. Averaging across all taxa, flowering time advanced by 3 days (3.8% of flowering period) during the last 50 years compared with the period before 1960. In taxa showing significant advancement, flowering times advanced by 7.7 days (8.6% of the flowering period). The most extreme advancement was 13.9 days. 3. Multivariate models were used to evaluate ways in which life history may affect phenological responses to climate change. Pollination mode (i.e. deceptive vs. rewarding vs. autogamous), life span (i.e. short-lived vs. long-lived), biogeographical distribution type (i.e. Mediterranean vs. nonMediterranean) and flowering time (i.e. mean date of blooming) emerged as important factors that influence changes in flowering through time. Phylogenetic relatedness did not predict phenological response. The strongest response was observed in orchids that flower relatively early in spring, exhibit an autogamous or deceptive pollination mechanism, have a long life span and possess a Mediterranean centre of distribution. 4. Synthesis. Our investigation demonstrates that the majority of Hungarian orchids have shifted their yearly mean flowering to earlier dates during the past 50 years. Certain life-history traits, but not phylogenetic relatedness, were found to be important in predicting climatic responsiveness in European terrestrial orchids.

In many basal metazoans, both somatic and reproductive functions are performed by cellular derivatives of a single multipotent stem cell population. Reproduction can drain these stem cell pools, imposing a physiological cost with subsequent negative effects on somatic maintenance functions. In the freshwater cnidarian Hydra oligactis, both asexual (budding) and sexual reproductive modes (production of resting eggs) are present, and both of these are dependent on a common pool of interstitial stem cells. Resting eggs tolerate harsh abiotic conditions which neither the parental animals, nor asexual offspring can survive (e.g., freezing). Therefore, when facing unfavourable conditions and increased mortality risk, hydra polyps are expected to show higher level of differentiation of interstitial stem cells into germ cells (i.e., sexual reproduction) than other cell types needed for self‐maintenance or asexual reproduction. Here, by comparing sexually and asexually reproducing individuals to nonreproductives, we studied the physiological costs of reproduction (size of interstitial stem cell pools, their somatic derivatives and regeneration rate, which is dependent on these cell types) in H.  oligactis polyps from a free‐living Hungarian population prior to the onset of winter. Sexual individuals were characterized by significantly smaller interstitial stem cell pools, fewer nematoblasts involved in food capture and lower regeneration ability compared to nonreproductives, but asexuals did not differ from nonreproductive animals. We also found a negative correlation between germ cell counts and stem cell numbers in males (but not in females). We suggest that the lower numbers of these cell types and lower regenerative ability in sexual individuals reflect a somatic cost of sexual reproduction. Our results also suggest that increased differentiation of stem cells into gametes might limit investment into somatic functions in hydra polyps. Exhaustion of cellular resources (stem cells) could be a major mechanism behind the extreme postreproductive senescence observed in this species. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13189/suppinfo is available for this article.

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Mammals display considerable geographical variation in life history traits. To understand how climatic factors might influence this variation, we analysed the relationship between life history traits – adult body size, litter size, number of litters per year, gestation length, neonate body mass, weaning age and age at sexual maturity – and several environmental variables quantifying the seasonality and predictability of temperature and precipitation across the distribution range of five terrestrial mammal groups. Environmental factors correlated strongly with each other; therefore, we used principal components analysis to obtain orthogonal climatic predictors that could be used in multivariate models. We found that in bats, primates and even‐toed ungulates adult body size tends to be larger in species inhabiting cold, dry, seasonal environments, whereas in carnivores and rodents a smaller body size is characteristic of warm, dry environments, suggesting that low food availability might limit adult size. Species inhabiting cold, dry, seasonal habitats have fewer, larger litters and shorter gestation periods; however, annual fecundity in these species is not higher, implying that the large litter size of mammals living at high latitudes is probably a consequence of time constraints imposed by strong seasonality. On the other hand, the number of litters per year and annual fecundity were greater in species inhabiting environments with higher seasonality in precipitation. Lastly, we found little evidence for specific effects of environmental variability. Our results highlight the complex effects of environmental factors in the evolution of life history traits in mammals. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 719–736.