Experimental increase in fecundity causes upregulation of fecundity and body maintenance genes in the fat body of ant queens

In most organisms, fecundity and longevity are negatively associated and the molecular regulation of these two life-history traits is highly interconnected. In addition, nutrient intake often has opposing effects on lifespan and reproduction. In contrast to solitary insects, the main reproductive individual of social hymenopterans, the queen, is also the most long-lived. During development, queen larvae are well-nourished, but we are only beginning to understand the impact of nutrition on the queens' adult life and the molecular regulation and connectivity of fecundity and longevity. Here, we used two experimental manipulations to alter queen fecundity in the ant Temnothorax rugatulus and investigated associated changes in fat body gene expression. Egg removal triggered a fecundity increase, leading to expression changes in genes with functions in fecundity such as oogenesis and body maintenance. Dietary restriction lowered the egg production of queens and altered the expression of genes linked to autophagy, Toll signalling, cellular homeostasis and immunity. Our study reveals that an experimental increase in fecundity causes the co-activation of reproduction and body maintenance mechanisms, shedding light on the molecular regulation of the link between longevity and fecundity in social insects.

Social Disruption: Sublethal pesticides in pollen lead to Apis mellifera queen events and brood loss

Eusocial Apis mellifera colonies depend on queen longevity and brood viability to survive, as the queen is the sole reproductive individual and the maturing brood replenishes the shorter lived worker bees. Production of many crops rely on both pesticides and bee pollination to improve crop quantity and quality. We looked at the resiliency of queens and their brood after one month of sublethal exposure to field relevant doses of pesticides that mimic exposure during commercial pollination contracts. We exposed full size colonies to pollen contaminated with field-relevant doses of the fungicides (chlorothalonil and propicanizole), insecticides (chlorypyrifos and fenpropathrin) or both, noting a significant reduction in pollen consumption in colonies exposed to fungicides compared to control. While we found no difference in the total amount of pollen collected per colony, a higher proportion of pollen to non-pollen foragers was detected in all pesticide exposed colonies. After ceasing treatments we measured brood development, discovering a significant increase in brood loss and/or cannibalism across all pesticide exposed groups. Sublethal pesticide exposure in general was linked to reduced production of replacement workers and a change in protein acquisition (pollen vs. non-pollen foraging). Fungicide exposure also resulted in increased loss of the reproductive queen.

Linking plant spatial aggregation with reproductive traits and near-source seed dispersal: ecological adaptation to heavy grazing

Aims Ecological strategies related to the adaptation of plants to environmental stress have long been studied by ecologists, but few studies have systematically revealed the ecological process of plant adaptation to herbivores as a whole. Methods In this study, Stipa breviflora, the dominant species in the desert steppe of Inner Mongolia, was used to analyse its reproductive individual characteristics and seed traits as well as the soil seed bank and spatial patterns under heavy-grazing and no-grazing treatments. Important Findings The results showed that the number of reproductive branches positively affected the number of vegetative branches. The analysis of the soil seed bank showed that the density of S. breviflora seeds beneath reproductive S. breviflora individuals was significantly higher than that in bare land. The seed density was also significantly negatively correlated with the seed characteristics and the soil seed bank in bare land. The spatial distribution of S. breviflora was aggregated under heavy grazing. Our results suggest that under heavy grazing, reproductive activity plays a key role in resource allocation. Stipa breviflora evolved the ecological strategy of nearby diffusion by regulating the morphological characteristics of the seeds, which promotes a positive spatial correlation between the juvenile and adult populations at a small scale, thus leading to the formation of ‘safe islands’.

Fitness costs of parasites explain multiple life history tradeoffs in a wild mammal

SummaryReproduction in wild animals can divert limited resources away from immune defence, resulting in increased parasite burdens. A longstanding prediction of life history theory states that these parasites can harm the reproductive individual, reducing its subsequent fitness and producing reproduction-fitness tradeoffs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent fitness in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation for downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life history tradeoffs, supporting the role of parasites as an important mediating factor in wild mammal populations.

The Domesticated Gene

Enough of the “selfish gene,” already. It was a clever mental game, once, to imagine that genes are the ultimate units of evolution. That organisms are no more than a gene’s way of making more genes. The concept fundamentally confuses levels in biology. It implies that genes can have intent and moral perspective. The anthropomorphism is grossly misleading. Even Richard Dawkins, who originally launched the concept, now seems to acknowledge as much. When the notion was introduced, sociobiology was also new, promoting an evolutionary and genetic view of behavior. It was all too easy to consider all behavior, like genes, as “selfish.” Explanations of cooperation, “altruism,” and social reproductive behavior were reduced to genes through the concepts of inclusive fitness and kin selection. The supremacy of the individual seemed to epitomize Darwinism. These perspectives thus gradually became entrenched, and now appear as fact in virtually every textbook: another sacred bovine? Recently, however, E. O. Wilson, the prominent founder and advocate of sociobiology, has renounced kin selection in explaining societies with a single reproductive individual. The idea was that genetic relatedness could explain why some individuals did not themselves reproduce but instead helped others, their kin, reproduce similar genes. Three decades of research have shown that many cooperative breeding societies (such as termites) do not exhibit the required genetic structure of haplodiploidy. Moreover, many species that do (including sawflies and horntails) are not social. The documented cases and the explanation do not align. Rather, the societies in question—from ants and honeybees to beetles, shrimp, and naked mole rats—all seem to have nests with restricted access, guarded by just a few individuals. The social cooperation seems just an “ordinary” adaptation to certain conditions. The striking reproductive structure, Wilson now contends, is an evolutionary consequence—not a cause—of the social organization. Wilson’s dramatic turnabout illustrates a wider shift in perspective. For decades William Hamilton’s notion of kin selection largely eclipsed Robert Trivers’s concept of reciprocity as an explanation for cooperation. While the former is commonly presented in educational contexts, the latter has been nearly always absent.

Flora of inland Atlantic riparian forests in southwestern Brazil

The flora of the Atlantic Rainforest of Mato Grosso do Sul, southwestern Brazil, has not been inventoried in spite of being the westernmost inland region of this domain. We present an inventory of the riparian flora of inland Atlantic Forest in Mato Grosso do Sul. We describe the species distribution along three habitats with contrasting flood conditions: non-flooded, seasonally flooded, and swampy forests. The inventory consisted of sampling every reproductive individual, during 12 months on 1.12 ha of plots inside a 24 ha study area. We recorded 1967 individuals of 253 species and 72 families. The most representative families in number of species were Asteraceae (27), Fabaceae (19), Myrtaceae (17), Cyperaceae (12), Rubiaceae, Solanaceae and Orchidaceae (10 each). The most abundant reproductive species were Guarea macrophylla (169 individuals), Miconia chamissois (85) and Conyza bonariensis (80). Eleven species of six families were recorded for the first time in Mato Grosso do Sul, two of them endemic to the Atlantic Forest - Passiflora jilekii and Capanema micromera. We found 119 species exclusively in non-flooded habitat, 19 in seasonally flooded habitat, and 31 in swampy forest. Guarea macrophylla was the most frequent species in swampy forest, and Gochnatia polymorpha in non-flooded. The riparian forest flora at the study site resembles the Atlantic Forest and includes wide distribution riparian species; the variation of flood conditions among habitats favors its richness. Our records add new occurrences for Mato Grosso do Sul and new distribution ranges for some plant species, what arises concern upon the local biodiversity conservation.

Reproductive mechanisms in a Nasutitermes species (Isoptera: Termitidae)

The number of reproductive individuals present in colonies of Nasutitermes sp. was analysed, and its possible reproductive strategy discussed. Twenty-four nests were collected and opened, and a single queen and king were found in 17 of them. In the other 7 nests, no queen or king were neither found, nor any other reproductive individual. All quee ns were weighed, and the number of eggs laid by them was counted. No relationship between the volume of the nests and the weight of their respective queens was found, but the number of eggs laid by the queens during an hour was positively correlated to their weight .