Age‐specific responses to spring temperature in a migratory songbird: older females attempt more broods in warmer springs

Increasing global temperature has led to an interest in plasticity in the timing of annual events; however, little is known about the demographic consequences of changing phenology. Annual reproductive success varies significantly among individuals within a population, and some of that variation has to do with the number of broods attempted by reproducing adults. In birds, female age and the timing of reproduction are often predictors of multiple breeding. We hypothesize that double brooding rates may be affected by spring temperature and that the response may vary with female age. We used a long‐term reproductive data set for a migratory songbird, the prothonotary warbler (Protonotaria citrea) to assess which factors influence (a) an individual female's probability of double brooding and (b) the annual variation in population‐level double brooding rates. We found that older and earlier nesting birds are more likely to double brood, and that there is no evidence for senescence with regard to this trait such that the oldest females were most likely to double brood. Previous experience with double brooding (i.e., whether the female double brooded in the previous year) significantly increased the probability of doing so again. When assessing annual variation in the double brooding rate, we found an interaction between spring temperature and the proportion of older females in the population. Specifically, older females are more likely to double brood in years with warmer springs, but this relationship was not seen for younger females. Previous studies have shown that warmer temperatures lead to earlier and narrower peaks in resources and we hypothesize that these peaks are more available to older and earlier arriving females, enabling them to successfully raise more than one brood in a season. Understanding how different age classes respond to changing environmental conditions will be imperative to managing declining species.     

Seedling morphology of three sympatric savanna species of Byrsonima: First evidence of cryptogeal germination in Malpighiaceae and an overlooked seedling type in eudicots

Byrsonima crassifolia (L.) Kunth, B. coccolobifolia Kunth and B. verbascifolia (L.) DC. (Malpighicaceae) are sympatric species with high ecological importance in the Roraima savannas of northern Brazil. The three species can be distinguished by seedling characters. The phanerocotylar, epigeal, foliaceous seedling of B. crassifolia is similar to other forest species in the genus. On the other hand, both B. coccolobifolia and B. verbascifolia have phanerocotylar, hypogeal, foliaceous seedlings, representing a newly defined seedling group among eudicot seedling types. Byrsonima verbascifolia has a reduced epicotyl and short subsequent internodes, whereas the long cotyledonary petioles are diagnostic for B. coccolobifolia. Both B. coccolobifolia and B. verbascifolia have cryptogeal germination, which involves characters that presumably protect the plumule from the recurrent fires they are subjected in savannas (e.g., plumule burying, cotyledonary node below the soil surface, and fusion of cotyledonary petioles). This is the first report of cryptogeal germination in the Malpighiaceae as well as in Neotropical eudicots.     

A descriptive and analytical study of four neotropical drosophilid communities

Drosophilid communities living in four different physiographical regions of the state of Rio Grande do Sul (27°/34°S; 49.7°/57.5°W), Brazil, were analysed. Ignoring cosmopolitan species, this is about the southern limit of the majority of typically neotropical Drosophila species distribution. Numerical fluctuations of the most frequent species populations from each place were investigated in relation to climatic data and trophic-resource availability. Of the four locations studied, Turvo is remarkable for being an enormous ecological reserve covered with subtropical perennially rainy forest, and for having stable weather conditions. Guaiba, on the other hand, is a more climatically unstable place, with unpredictable and more scarce resources. In Turvo, the community structure is shaped by the dominance of Drosophila willistoni and a low species diversity throughout the year. Low average niche-breadth and niche-overlap indices have also been found at feeding and breeding site levels. Guaíba showed the highest species-diversity levels and was better exploited by D. simulans, a cosmopolitan species with a well-known colonizing capacity. High niche breadth and overlap indices were characteristic for most species at this place. Results are discussed in the light of the communities' species composition and of environmental factors.