TBA

Venomous and poisonous animals are found distributed throughout the tree of life. While poisonous animals are toxic when their toxins are ingested, venomous animals use specialised apparatuses to inject their toxins in to afflicted animals. In this talk I will provide an overview of venoms and poisons found in the animal kingdom, with a specific focus on three “stories” that showcase how the theme of convergent evolution underpins the fascinating biology related to such animals. Specifically, I will talk about: (i) the convergent evolution of molecular resistance to cardiac glycoside-harbouring poisonous toads, (ii) the evolution of the fangblenny venom system and its relationship with mimicry, and (iii) the coagulopathic activity of snake venoms and how this relates to the medically important, global issue of snakebite.

Leaf beetles occur worldwide; some of them are even economically important pests of agriculture. They raise broad ecological interest because of their host plant preferences and varying modes of life. Their larvae have developed an impressive repertoire of toxins and repellents to defend themselves against predators. Upon attack, the larvae discharge small droplets from specialized glandular reservoirs on their back (e.g. Chrysomelapopuli). The reservoirs represent “bioreactors” performing all late reactions of the toxin-production, starting from plant-derived or de novo synthesized glucosides. The import of the plant-derived glucosides relies on a sophisticated transport system. Physiological studies revealed a functional network of transporters guiding the plant derived glucosides through the larval body into the defensive system. As transporters usually represent trans-membrane proteins, we developed a protocol for the isolation and identification of these proteins from membranes of the defensive system. After cell lysis and differential centrifugation proteins were separated by SDS-page followed by in-gel digestion and nanoLC-HDMSE analysis. From more than 2000 proteins of glandular tissue, bioinformatic criteria revealed several ABC-transporters and candidates from the solute carriers (SLC) that mediate facilitative diffusion of their sub­strates. Expression analysis of these candidate sequences revealed for some of them high expression in the defensive glands compared to other larval tissues. A subsequent lack-of-function screening by using RNAi revealed in particular one ABC-transporter and an SLC2-candidate being involved in the uptake of salicin from hemolymph into the secretory cell. Heterologous expression of these transporters in frog oocytes confirmed salicin as a substrate. A functional model of the transport network in the leaf beetle C. populi has be developed and will be presented.

Strauss, W. Boland, A. Burse. ABC transporter functions as a pacemaker for the sequestration of plant glucosides in leaf beetles. (2013) eLife http://dx.doi.org/ 10.7554/eLife.01096 .

The 90 My-old obligate and mutualistic fig–pollinator wasp system is exploited by parasitic non-pollinating fig wasps that are fig-species specific and oviposit into their hosts from the exterior of the fig which serves as a wasp nursery. Using Ficus racemosa as the study system, we investigated the underlying mechanisms employed by parasitic wasps to locate hidden hosts, where only cues from the exterior surface or from the interior of the fig could guide this search. We also determined the preference of different parasitic wasps for oviposition sites and hosts within the fig. We show, for the first time, that the fig wasp ovipositor is an olfactory sensor that responds to host volatiles and gaseous CO2.
This sensor could be used by the parasitic wasps to evaluate ecologically relevant cues for oviposition. Chemical footprints left by previously ovipositing wasps also influenced oviposition choice. We found that physiological factors such as ageing and egg load greatly influenced oviposition behavior. These findings reveal the different ways in which parasitic wasps exploit their hosts but also have bearing on the survival of a plant–pollinator mutualism in such a complex and multiply-parasitized system.

Space observation is acknowledged as quintessential for providing reliable monitoring strategies for vegetation at multiple scales over extensive territories with a low population and limited accessibility. Optical satellite imagery represents the major source of data and covers an ample continuum of image resolution and swath. Yet vegetation monitoring in both the dry and wet tropics has long been hampered by insufficient pixel resolution that renders the well-mastered, pixel-wise classification techniques inefficient. The increasing availability of images with high spatial resolution (HSR, pixels of 10 m or less) to very high spatial resolution (VHSR, pixels of less than 2 m) has opened up new prospects by allowing the inference of vegetation properties from image texture features (i.e., inter-pixel variability with respect to distance). In the present talk, we aim to illustrate this potential through published case studies dealing with semiarid vegetation monitoring and baseline above ground biomass assessment in moist tropical forests. In both cases, we applied variants of a method called FOTO (Fourier-based textural ordination) to obtain textural features from the images and relate them to meaningful vegetation properties, such as patterns of vegetation vs. bare ground in drylands, or crown and gap size distribution in forest canopy images. Textural ordination based on Fourier spectra provides a powerful and consistent framework for identifying prominent scales of landscape patterns and comparing scaling properties across landscapes. In the case of forest landscapes, texture features relate to crown size distribution and sometimes to inter-crown gaps and therefore are often good predictors of stand structure and biomass. We also use the radiative transfer model DART as to generate canopy images from three-dimensional forest stand mockups parametrized from pantropical field plots. Simulated canopy images allowed us testing the relevance of texture approaches to retrieve stand characteristics and to explore the complementary with FOTO of features provided by Gabor and continuous wavelet transforms.

Keywords: above ground biomass, canopy grain, FOTO method, patterned semiarid vegetation, tropical moist and wet forest, continuous wavelet transform

If you are interested in a Ph.D. program at CES, don’t wait till next year, apply now! The Centre for Ecological Sciences, Indian Institute of Science is now accepting applications for mid-term admissions.

Online applications will be open from 1 Oct 2017 to 31 Oct 2017.

Short-listed candidates will be called for an interview on 20-21 November 2017, and the semester will begin for accepted students on 1 Jan 2018.

Eligibility criteria and application forms can be found here http://ces.iisc.ac.in/new/?q=ces-phd-program and http://iisc.ac.in/admissions/.

If you are interested in a Ph.D. program at CES, don’t wait till next year, apply now! The Centre for Ecological Sciences, Indian Institute of Science is now accepting applications for mid-term admissions.

Online applications will be open from 1 Oct 2017 to 31 Oct 2017.

Short-listed candidates will be called for an interview on 20-21 November 2017, and the semester will begin for accepted students on 1 Jan 2018.

Eligibility criteria and application forms can be found here http://ces.iisc.ac.in/new/?q=ces-phd-program and http://iisc.ac.in/admissions/.

TBA

Dear All,

As all of us know that it is time to handover ESS command to new set of people for the upcoming academic year, we had sent out a broadcasting asking interested people to volunteer. Unfirtunately, we didn't receive even a single nomination. This situation has compelled us to think about the viability of ESS in current scenario. Department chairperson has decided to meet students and discuss further action plan for the role and existence of ESS. We request all the students ( PhDs, Post docs, Project assistants) to join this meeting and help in formulating future direction for ESS.

In group-living animals, sociality maybe impacted by both ancestral relationships, and current socioecological factors. Assessing their relative/dynamic effects on the evolution of diverse social systems has been a major challenge for researchers. I present aspects of my research that focus on examining the impact of phylogenetic relatedness, group-size and resource-competition, and most recently human impact, on nonhuman primate social structure and/or zoonotic infection risk. In this regard, macaques (genus: Macaca) are an ideal genus, with their similar social organizations and well-established phylogenies, but diverse (despotic-to-tolerant) social styles, geographic ranges, and degrees of overlap with human landscapes. First, I use a comparative approach to reveal that the structure of
dominance relationships across macaques show strong phylogenetic signals, i.e. members of the Sulawesi lineage show more shallow hierarchies and less transitivity/certainty in their dominance networks than those of the Arctoides and/or Fascicularis lineages. In contrast, grooming network structure seems more labile to the influence of group-size, with larger groups showing more modular, less dense network connections than smaller groups. Second, I describe contrasting evidence that sociodemographic factors impact within-species differences in macaque sociality. Among free-ranging rhesus macaques, larger group-size and/or intense resource-competition appear to generate greater degrees of despotism, i.e. more asymmetry in dominance and lower rates of post-conflict
affiliation. However, among wild Tibetan macaques, larger group-size/severe rangerestriction appeared to lower degrees of despotism, i.e. shallow dominance hierarchies and greater reciprocity in grooming on account of a decreased demand for rank-related benefits such as support in conflicts. Thus some aspects of social behavior maybe linked to ancestry, whereas others are labile to socioecological and/or supply-and-demand biological markets conditions. My current research is implementing the conceptual framework of coupled-natural-and-human-systems to assess the impact of anthropogenic
factors on variation in macaque social networks and susceptibility to zoonotic bacterial pathogens. Further, work on captive rhesus macaques is revealing that increased social network connections may either socially buffer individuals from microbial infection risk, or enhance such risk owing to contact-mediated sharing/transmission of microbes. This may depend on pathogen-specific modes of transmission and/or overall social context. This naturally sets the stage for future investigations of the socioecological bases of zoonotic infection/ transmission through networks of free-living primate populations. I
end by conceptualization group social structure as social reaction-norms, i.e. where groups may respond similarly to variation in extrinsic factors, but may have inherently different ranges of responses to the same conditions.