Innate Host Habitat Preference in the Parasitoid Diachasmimorpha longicaudata: Functional Significance and Modifications through Learning

Parasitoids searching for polyphagous herbivores can find their hosts in a variety of habitats. Under this scenario, chemical cues from the host habitat (not related to the host) represent poor indicators of host location. Hence, it is unlikely that naïve females show a strong response to host habitat cues, which would become important only if the parasitoids learn to associate such cues to the host presence. This concept does not consider that habitats can vary in profitability or host nutritional quality, which according to the optimal foraging theory and the preference-performance hypothesis (respectively) could shape the way in which parasitoids make use of chemical cues from the host habitat. We assessed innate preference in the fruit fly parasitoid Diachasmimorpha longicaudata among chemical cues from four host habitats (apple, fig, orange and peach) using a Y-tube olfactometer. Contrary to what was predicted, we found a hierarchic pattern of preference. The parasitism rate realized on these fruit species and the weight of the host correlates positively, to some extent, with the preference pattern, whereas preference did not correlate with survival and fecundity of the progeny. As expected for a parasitoid foraging for generalist hosts, habitat preference changed markedly depending on their previous experience and the abundance of hosts. These findings suggest that the pattern of preference for host habitats is attributable to differences in encounter rate and host quality. Host habitat preference seems to be, however, quite plastic and easily modified according to the information obtained during foraging.     

Differential expression and accumulation of 14-3-3 paralogs in 3T3-L1 preadipocytes and differentiated cells

The 14-3-3 protein family interacts with more than 2000 different proteins in mammals, as a result of its specific phospho-serine/phospho-threonine binding activity. Seven paralogs are strictly conserved in mammalian species. Here, we show that during adipogenic differentiation of 3T3-L1 preadipocytes, the level of each 14-3-3 protein paralog is regulated independently. For instance 14-3-3β, γ, and η protein levels are increased compared to untreated cells. In contrast, 14-3-3ε protein levels decreased after differentiation while others remained constant. In silico analysis of the promoter region of each gene showed differences that explain the results obtained at mRNA and protein levels.     

On the evolution and diversification of an Andean clade of reptiles: combining morphology and DNA sequences of the palluma group (Liolaemidae: Phymaturus)

Phymaturus comprises 44 species mainly distributed along the south‐west of South America on both sides of the Andes. In this study we present a phylogenetic analysis of Phymaturus of the palluma group, one of its two large clades, including almost all described species. This analysis duplicates the number of in‐group taxa compared with previous contributions. We performed a total‐evidence analysis, combining molecular and morphological characters: sequencing fragments of cytochome b (cytb), 12S, and ND4, for all terminals; describing 45 new morphological characters; and incorporating all DNA sequences available from GenBank. Separate analyses of morphology and DNA partitions are presented and discussed in detail. Seven subclades are recognized here. We named three new subclades and redefined another, found to be paraphyletic. In order to recognize lineages within the traditional Phymaturus palluma group we proposed to treat it as a natural group, containing within it the ranks of clade, subclade, and lineages, respectively. The palluma group is composed by the vociferator and the bibronii clades. The vociferator clade, composed of Chilean and Argentinean species, would be the most basal in the group. Within the bibronii clade, the roigorum subclade includes the Phymaturus verdugo lineage, whereas the mallimaccii subclade would consist of 13 terminal taxa, for which three Chilean species have been added. In this study, morphological apomorphies are identified for all clades and the evolution of ‘male head melanism’ is discussed. © 2015 The Linnean Society of London     

Short-term partitioning of Cd recently taken up between sunflowers organs (<Emphasis Type="Italic">Helianthus annuus</Emphasis>) at flowering and grain filling stages: effect of plant transpiration and allometry

Aims

This work concentrated on understanding the allocation of Cd recently taken up between the organs of sunflower at early and middle reproductive growth stages. The roles of transpiration and allometry were investigated.

Methods

Sunflowers were grown hydroponically in greenhouse, being exposed to low concentrations of Cd (pCd²⁺ = 11.03). At flower bud and grain filling stages, plants were exposed for three days to ¹¹¹Cd and at the same time, subjected or not to fans to increase the transpiration. The partitioning of ¹¹¹Cd between plant organs measured by high resolution ICP-MS was then modelled.

Results

Although the use of fans increased the plant water uptake and transpiration by about 20%, there were no significant effects on the partitioning of recent Cd. Most of the recent Cd was recovered in roots (60%) and only 2.8% were found in seeds (0.8% for the husk and 2.0% for the almonds). The sequestration of recent Cd in a plant organ was successfully explained by its biomass and except for leaves, by the biomass of other organs acting as competitive sinks.

Conclusions

This work proposes a modelling approach for the partitioning of the labelled Cd between plant organs in sunflower.

     

Environmental preferences of brachiopods and bivalves across major climatic changes during the Late Palaeozoic ice age (Pennsylvanian,western Argentina)

During the late Palaeozoic ice age (LPIA), ice‐proximal marine regional communities record contrasting responses to climate change compared to ice‐distal communities. However, there is still much to be understood in distal regions in order to fully understand the palaeobiological consequences of the LPIA. Here, were analyse brachiopod and bivalve environmental preferences along the bathymetric gradient during a major glacial event and the subsequent non‐glacial interval in western Argentina. Median environmental breadths did not change with the reassembly of communities during the non‐glacial interval. Moreover, bivalves and brachiopod immigrants show similar environmental breadths although they tend to have immigrated from different palaeogeographical regions. These patterns reinforce the idea that the worldwide marine fauna was probably culled of stenotopic taxa during the LPIA. On the other hand, analysis of the preferred depths of survivors and immigrants sheds light on the substantial modification of the bathymetric diversity gradient. Among different possible explanations, the immigration of taxa with affinities for deep environments is the only one supported. In addition, results underscore the observation that the higher turnover in the offshore environment was probably driven by immigration rather than extinction. Finally, stability in environmental preferences at a regional scale is not mirrored by stability in survivors’ individual preferences, because survivors’ preferred depth is not correlated during the glacial and non‐glacial intervals. Moreover, the amount of change in survivors preferred depth is not related to their environmental breadth, nor to their occupancy. These patterns suggest: (1) instability in realized niches; and (2) individual responses of survivor genera.