Sex differences in flea infections among rodent hosts: is there a male bias?

Recognizing patterns of parasite distribution among wildlife hosts is of major importance due to growing risk of transmission of zoonotic diseases to humans. Thus, sex-dependent parasite distribution in higher vertebrates is extensively studied, and males are often found more parasit- ized than females. Male-biased parasitism may be the result of weaker immunocompetence of male hosts owing to the im- munosuppressive effect of androgens. Moreover, larger hosts (males) may demonstrate higher parasite infestation levels than smaller individuals (females), as they constitute a better nutritional resource for parasites and provide them with a greater variety of niches. In the present work, we investigated sex-dependent patterns of flea distribution among three com- mon rodent species (Apodemus agrarius, Apodemus flavicollis, and Myodes glareolus). We hypothesized that males have a higher flea infestation than females. We confirm male-biased parasitism in A. agrarius and M. glareolus, but not in A. flavicollis. Additionally, flea infestation increased with body mass in A. agrarius, but not in A. flavicollis and M. glareolus. The detected differences in parasite distribution among sexes are probably the result of immunosuppressive effects of androgens and spatial behavior of males.The research was supported by the Science and Technology Foundation (Portuguese Ministry of Science, Technology and Higher Education), grant no. SFRH/BD/ 31602/2006 and the budget of the Department of Systematic Zoology (Faculty of Biology AMU, Poznań )Parasitology Researc

Masting plants: Why combine abstinence and lust in reproduction?

La majoria de plantes perennes produeixen llavors cada any, però n’hi ha algunes que mostren un comportament reproductiu estrany: les seves poblacions produeixen extraordinàries collites de manera erràtica i sincrònica, però passen alguns anys pràcticament sense reproduir-se. Són les espècies anyívoles i el motiu d’aquest comportament sexual, com es produeix, i les conseqüències que té per a les xarxes tròfiques ha intrigat els ecòlegs. En aquest treball presentem un resum del coneixement actual sobre les causes evolutives i ecològiques que promourien aquest comportament. Les dues hipòtesis més versemblants de la seva evolució serien els avantatges de controlar les poblacions de depredadors de llavors i afavorir que algunes escapin (saciat dels depredadors) i/o una millor eficàcia en la pol·linització de plantes pol·linitzades pel vent (eficiència en la pol·linització). La variabilitat entre anys en la mida de les collites seria el resultat de la possibilitat que les plantes puguin dedicar més o menys recursos a la reproducció a partir de les condicions ambientals (p. ex. meteorològiques, de mobilització de nutrients) mentre que la sincronia entre individus, fins i tot a grans escales espacials, seria el resultat de l’anomenat Efecte Moran, és a dir, la resposta a una condició ambiental amb àmplia sincronia espacial com és la meteorologia i els seus efectes en la floració o la maduració dels fruits. Finalment, es presenta el coneixement més recent sobre les causes que determinen que una espècie com l’alzina (Quercus ilex), tan important i abundant al nostre país, sigui anyívola i les seves conseqüències.Most perennial plants produce seeds every year, but some species show a bizarre reproductive behaviour: they produce bumper crops randomly and synchronously in some years, while in other years they produce virtually no seeds. These are known as masting species and the benefits of this behaviour, how it occurs, and the consequences for trophic networks have long intrigued ecologists. Here we present a summary of current knowledge about the evolutionary and ecological causes that promote masting. The two most likely hypotheses for its evolution are the advantages of controlling seed predator populations and encouraging some seeds to escape (predator satiation) and/or better efficiency in the pollination of wind-pollinated plants (pollination efficiency). The variability between years in the size of crops results from the fact that plants devote more or fewer resources to reproduction depending on the environmental conditions (e.g. meteorological conditions and nutrient mobilization). In addition, the synchrony between individuals, even at large spatial scales, is the result of the so-called Moran Effect: i.e. the response to an environmental condition with a broad spatial synchronization such as meteorology and its effects on the flowering or maturation of the fruits. Finally, we present the most recent knowledge on the reasons why the holm oak (Quercus ilex), so important and abundant in Catalonia, exhibits masting behaviour, and its consequences

It is raining mice and voles: which weather conditions influence the activity of Apodemus flavicollis and Myodes glareolus?

Rodents constitute a crucial part of food chains in many ecosystems; thus, changes in their activity might influence many other species in the community. Moreover, daily variations in activity appear to be an important adaptation, helping rodents to cope with fluctuating intensity of predation pressure and food availability. We investigated how the nightly activity of the yellow-necked mouse (Apodemus flavicollis) and the bank vole (Myodes glareolus) changes with weather conditions. Increased cloud cover enhanced activity of mice, but this effect tended to be weaker during the full moon. In turn, the activity of bank voles was positively influenced by moon phase regardless of cloud cover. Temperature had a negative effect on the activity of both species. Rainfall positively influenced A. flavicollis capture numbers, but tended to decrease the activity of M. glareolus. Therefore, while the activity of both mice and voles was under a strong influence of weather variables, their responses to weather were largely species specific.Polish Ministry of Science and Higher Education Grant NN304391537, Adam Mickiewicz Foundatio

The effects of local climate on the correlation between weather and seed production differ in two species with contrasting masting habit

Altres ajuts: MB was supported by the Polish National Science Centre grant Sonatina No. 2017/24/C/NZ8/00151. JSz was supported by the Foundation for Polish Science (FNP) scholarship "Start". MFM is a postdoctoral fellow of the Research Foundation - Flanders (FWO)Many plant species present inter-annual cycles of seed production (mast seeding), with synchronized high seed production across populations in some years. Weather is believed to be centrally involved in triggering masting. The links between meteorological conditions and seeding are well-recognized for some species, but in others consistent correlates have not been found. We used a spatially extensive data set of fruit production to test the hypothesis that the influence of weather on seed production is conditioned by local climate and that this influence varies between species with different life history traits. We used two model species. European beech (Fagus sylvatica) that is a flowering masting species, i.e. seed production is determined by variable flower production, and sessile oak (Quercus petrea) that is a fruit-maturation masting species, i.e. seed production is determined by variable ripening of more constant flower production. We predicted that climate should strongly modulate the relationship between meteorological cue and fruit production in Q. petrea, while the relationship should be uniform in F. sylvatica. The influence of meteorological cue on reproduction in fruiting masting species should be strongly conditioned by local climate because the strength of environmental constraint that modulates the success of flower-to-fruit transition is likely to vary with local climatic conditions. In accordance, the meteorological cuing was consistent in F. sylvatica. In contrast, in Q. petraea the relationship between spring temperature and seed production varied among sites and was stronger in populations at colder sites. The clear difference in meteorological conditioning of seed production between the two studied species suggests the responses of masting plants to weather can be potentially systematized according to their masting habit: i.e. fruiting or flowering

Declining fruit production before death in a widely distributed tree species, Sorbus aucuparia L.

International audienceAbstractKey messageTrees are commonly thought to increase their seed production before death. We tested this terminal investment hypothesis using long-term data on rowan trees (Sorbus aucuparia) and found no support. Rather, seed production declined significantly before death, which points to the potential detrimental effects of reproductive senescence on regeneration in stands of old trees.ContextAging poses a fundamental challenge for long-lived organisms. As mortality changes with with age due to actuarial senescence, reproductive senescence may also lead to declines in fertility. However, life history theory predicts that reproductive investment should increase before mortality to maximize lifetime reproductive success, a phenomenon termed terminal investment.AimsTo date, it is unclear whether long-lived, indeterminantly growing trees experience reproductive senescence or display terminal investment.MethodsWe investigated fruit production of rowan (Sorbus aucuparia L.), widely distributed trees that live up to 150 years, as they approached death.ResultsIn our study population in Poland’s Carpathian Mountains, 79 trees that died produced up to 20% fewer fruits in the years before their demise compared to 199 surviving trees of the same population.ConclusionThe pattern of reproductive investment in S. aucuparia is suggestive of age-independent reproductive senescence rather than terminal investment. These findings highlight that the understanding of the generality of life history strategies across diverse taxa of perennial plants is still in its infancy

Is forest fecundity resistant to drought? Results from an 18-yr rainfall-reduction experiment

Recruitment is a primary determinant of the long-term dynamics of plant populations in changing environments. However, little information is known about the effects of anthropogenic environmental changes on reproductive ecology of trees. We evaluated the impact of experimentally induced 18 yr of drought on reproduction of three contrasting forest trees: Quercus ilex , Phillyrea latifolia and Arbutus unedo. Rainfall reduction did not decrease tree fecundity. Drought, however, affected the allocation of resources in Q. ilex and A. unedo but not the more drought tolerant P. latifolia. Larger crop production by Q. ilex and A. unedo was associated with a stronger decrease in growth in the rainfall-reduction plots compared with the control plots, suggesting that these species were able to maintain their fecundity by shifting their allocation of resources away from growth

Climate change and plant reproduction: trends and drivers of mast seeding change

Climate change is reshaping global vegetation through its impacts on plant mortality, but recruitment creates the next generation of plants and will determine the structure and composition of future communities. Recruitment depends on mean seed production, but also on the interannual variability and among-plant synchrony in seed production, the phenomenon known as mast seeding. Thus, predicting the long-term response of global vegetation dynamics to climate change requires understanding the response of masting to changing climate. Recently, data and methods have become available allowing the first assessments of long-term changes in masting. Reviewing the literature, we evaluate evidence for a fingerprint of climate change on mast seeding and discuss the drivers and impacts of these changes. We divide our discussion into the main characteristics of mast seeding: interannual variation, synchrony, temporal autocorrelation, and mast frequency. Data indicate that masting patterns, are changing, but the direction of that change varies, likely reflecting the diversity of proximate factors underlying masting across taxa. Experiments to understand the proximate mechanisms underlying masting, in combination with the analysis of long-term datasets, will enable us to understand this observed variability in the response of masting. This will allow us to predict future shifts in masting patterns, and consequently ecosystem impacts of climate change via its impacts on masting.</p

Fine-scale spatial heterogeneity of invertebrates within cryoconite holes

Cryoconite holes (water-filled reservoirs) are considered ecologically simple ecosystems but represent biological hotspots of biodiversity on glaciers. In order to check for fine-scale spatial distribution of metazoans on the bottom of the holes, in this study, we analysed three groups of grazing invertebrates as a model: tardigrades, rotifers, and mites. We addressed differences within cryoconite holes comparing the distribution of invertebrates within and between separate holes and between glaciers at a worldwide scale. We divided each cryoconite hole into three sampling zones (established in relation to water flow on a glacier) and collected nine subsamples within cryoconite holes on glaciers in the Arctic (Longyearbreen), Norway (Blåisen), the Alps (Forni) and maritime Antarctic (Ecology Glacier). Generally, we found no consistent difference in sampling zones within cryoconite holes, which suggests homogeneity on the hole floors. However, we did find strong differences and high heterogeneity between subsamples, even within the same zone. Invertebrate densities ranged between 52 and 426 individuals per ml in subsamples collected from the same hole. We found from zero to four trdigrade species in the cryoconite hole on Longyearbreen. Our results show that benthic animals in cryoconite holes in various climatic zones have heterogeneous spatial distribution, even if no preference could be highlighted for upstream versus downstream areas with respect to water flow. The distribution of invertebrates may result from ecosystem disturbance by flushing water and animals’ active movement. Cryoconite holes, usually considered to be simple ecosystems, seem to be complex habitats where hidden spatial heterogeneity may affect abundance and diversity of organisms

Evolution of masting in plants is linked to investment in low tissue mortality

AbstractMasting, a variable and synchronized variation in reproductive effort is a prevalent strategy among perennial plants, but the factors leading to interspecific differences in masting remain unclear. Here, we investigate interannual patterns of reproductive investment in 517 species of terrestrial perennial plants, including herbs, graminoids, shrubs, and trees. We place these patterns in the context of the plants’ phylogeny, habitat, form and function. Our findings reveal that masting is widespread across the plant phylogeny. Nonetheless, reversion from masting to regular seed production is also common. While interannual variation in seed production is highest in temperate and boreal zones, our analysis controlling for environment and phylogeny indicates that masting is more frequent in species that invest in tissue longevity. Our modeling exposes masting-trait relationships that would otherwise remain hidden and provides large-scale evidence that the costs of delayed reproduction play a significant role in the evolution of variable reproduction in plants.</jats:p

Effectiveness of predator satiation in masting oaks is negatively affected by conspecific density

La variación en la disponibilidad de las semillas da forma a las comunidades de plantas, y se ve fuertemente afectada por la depredación de las semillas. En algunas especies de plantas, la variación temporal en la producción de semillas es especialmente alta y está sincronizada en grandes áreas, lo que se denomina "siembra en mástil". Una ventaja selectiva de este fenómeno es la saciedad de los depredadores, que supone que la siembra en mástil ayuda a las plantas a escapar de la depredación de las semillas mediante la inanición de los depredadores en los años de escasez y la saciedad en los años de mástil. Sin embargo, aunque se puede predecir que la depredación de la semilla tiene un fuerte componente espacial y depende de las densidades de las plantas, apenas se ha investigado si la eficacia de la saciedad de los depredadores en las plantas de mastelero cambia según el efecto Janzen-Connell. Estudiamos, durante un período de 8 años, la producción de semillas, los patrones espacio-temporales de depredación de semillas de gorgojos y la abundancia de gorgojos adultos en una población de encinas (Quercus ilex) que consiste en árboles intercalados en parches que cubren un continuo de densidad conespecífica. Los robles aislados sacian eficazmente a los depredadores, pero esto es superado por el aumento de la densidad de plantas conespecíficas. La falta de saciedad de los depredadores en los árboles que crecen en parches densos fue causada por la redistribución de los insectos entre las plantas que probablemente los atenuó contra la escasez de alimentos en los años de escasez, y cambió el tipo de respuesta funcional del gorgojo del tipo II en los árboles aislados al tipo III en los árboles que crecían en parches densos. Este estudio proporciona la primera evaluación empírica de la noción de que el apareamiento y la saciedad del depredador deberían ser más importantes en las poblaciones que empiezan a dominar sus comunidades, y es coherente con la observación de que el apareamiento es menos frecuente y menos intenso en bosques diversos.Variation in seed availability shapes plant communities, and is strongly affected by seed predation. In some plant species, temporal variation in seed production is especially high and synchronized over large areas, which is called ‘mast seeding’. One selective advantage of this phenomenon is predator satiation which posits that masting helps plants escape seed predation through starvation of predators in lean years, and satiation in mast years. However, even though seed predation can be predicted to have a strong spatial component and depend on plant densities, whether the effectiveness of predator satiation in masting plants changes according to the Janzen-Connell effect has been barely investigated. We studied, over an 8-year period, the seed production, the spatiotemporal patters of weevil seed predation, and the abundance of adult weevils in a holm oak (Quercus ilex) population that consists of trees interspersed at patches covering a continuum of conspecific density. Isolated oaks effectively satiate predators, but this is trumped by increasing conspecific plant density. Lack of predator satiation in trees growing in dense patches was caused by re-distribution of insects among plants that likely attenuated them against food shortage in lean years, and changed the type of weevil functional response from type II in isolated trees to type III in trees growing in dense patches. This study provides the first empirical evaluation of the notion that masting and predator satiation should be more important in populations that start to dominate their communities, and is consistent with the observation that masting is less frequent and less intense in diverse forests.• National Science Foundation (Polonia). Becas Preludio 2015/17/N/ NZ8/01565, y Etiuda no. 2015/16/T/NZ8/00018, para Michał Bogdziewicz • Foundation for Polish Science Start Scholarship. Ayuda para para Michał Bogdziewicz • Gobierno de Extremadura. Programa de Atracción de Talento Investigador. Ayuda TA13032, para Raúl Bonal Andrés • Junta de Comunidades de Castilla-La Mancha/Fondo Social Europeo. Proyectos PII1C09-0256-9052 y PPII-2014-01-P • Ministerio de Economía y Competitividad de España y la Unión Europea Fondo de Desarrollo Regional. Proyecto AGL2014-54739-R (I+D+i) • Generalitat de Catalunya. Proyecto BEEMED (SGR913)peerReviewe