@article {152123, title = {Polychaete worm density correlates with aggregate shorebird density, prey intake rate and foraging success at an intertidal mudflat in Bangladesh}, journal = {ARDEA}, volume = {112}, year = {2024}, month = {02/2024}, abstract = {

Migratory shorebirds have suffered considerable declines because their migratory habits make them susceptible to threats in many different parts of the world. Successful conservation initiatives therefore require an understanding of their ecology not just at their breeding sites, but also at wintering and staging sites. Previous studies have shown that relationships between shorebirds and their wintering habitats are complex and context specific, underlining the importance of continued investigation of their ecology in new contexts. In this study, we investigated the relationship between prey density and shorebird abundance at stretches of mudflat spread across two islands in coastal Bangladesh. To explore whether prey density influenced shorebirds{\textquoteright} ability to find and ingest prey, we also examined relationships with intake rates and foraging success. We found that the density and richness of shorebird communities increased with increasing polychaete worm density across small stretches of mudflat within each island. We also found evidence that prey intake rates and foraging success increased with available food, implying that food as a resource may be limiting in this landscape. Shorebirds may be required to spend more energy foraging in suboptimal habitats, explaining (in part) why densities are higher in habitats with more available prey. Our study suggests that prey density is an important correlate of shorebird density in this important South Asian wintering ground. Our results may have management implications, but this requires further study.

}, doi = {10.5253/arde.2023.a10}, author = {Sultana, Irin and Khandakar, Naim and Das, Delip K. and Quader, Suhel and Viswanathan, Ashwin} } @article {107010, title = {Fine-tuned spatiotemporal dynamics of sporophylls in movement-assisted dichogamy: A study on Clerodendrum infortunatum}, journal = {PLANT SPECIES BIOLOGY }, year = {2022}, month = {02/2022}, abstract = {

Hermaphroditism is cost-effective because a common investment in reward and attractive structures yields benefits through both male and female reproductive success. However, the advantage is accompanied by an increased risk of self-pollen deposition, which is generally disadvantageous. Hermaphroditic plants reduce self-pollen deposition by separating sporophylls (a term applied to the stamens and carpels) either spatially (herkogamy) or temporally (dichogamy). In movement-assisted dichogamy, both sporophylls show coordinated motion in opposite directions. However, the effectiveness of this movement in reducing self-pollen deposition may be compromised at the point when the sporophylls cross each other and are close enough to interfere, resulting in a transition phase problem. The solution to this problem lies in the details of the spatiotemporal dynamics of the sporophylls in relation to their reproductive maturity. We studied these details across the floral lifetime of a protandrous shrub, Clerodendrum infortunatum (Lamiaceae), in rainforest fragments of the Western Ghats, India. We took photos of flowers at regular time intervals and measured sporophyll angles from the images. We also carried out a field experiment to determine stigma receptivity. We found that the stigma lobes remained narrowly opened at transition, and the stigma surfaces remained non-receptive. Our findings suggest that the effectiveness of dichogamy is maximized through two properties of the transition phase: physical resistance to self-pollen deposition by narrow stigma lobe opening and chemical non-receptivity of the stigma during this phase. This study emphasizes the importance of accessory adaptations in movement-assisted dichogamy to tackle the transition phase problem.

}, doi = {10.1111/1442-1984.12367}, author = {Mukhopadhyay, Amritendu and Quader, Suhel} } @article {123116, title = {Pollination inaccuracy: estimating male fitness in the movement-assisted dichogamous species Clerodendrum infortunatum}, journal = {Evolutionary Ecology}, year = {2022}, month = {12/2022}, abstract = {

In hermaphroditic dichogamous species, sporophylls are separated in time. However, the separation of sporophylls can lead to pollination inaccuracy, especially in movement-assisted dichogamy, where sporophylls alter their position over time. Is pollination inaccuracy minimised by the second sporophyll taking the exact position of the first? We address this question in Clerodendrum infortunatum, a movement-assisted dichogamous species. We made predictions from optimality arguments, and tested these by measuring sporophyll angles over time, by experimentally manipulating flowers, and by estimating correlates of the resultant fitness, taking into account pollen export, pollination inaccuracy and the resultant total pollen delivered. Contrary to expectation, anthers do not have a fixed position in the male phase, and pollination inaccuracy is high. Further, when the number of pollen grains on anthers is highest, anthers are paradoxically not positioned at the pollen export peak. Also, pollen export and pollen deposition peaks do not align. Despite this seeming maladaptiveness, the starting position of the anthers is, in fact, very close to the theoretical optimum, which results in the highest overall male fitness, measured as the total pollen delivered over the entire male phase. Instead of a simple positional exchange of sporophylls, stamens display a more complicated dynamic strategy that appears close to optimal even though naive measures of pollination inaccuracy are high.

}, doi = {10.1007/s10682-022-10221-5}, author = {Mukhopadhyay, A and Quader, Suhel} } @article {90237, title = {Securing biodiversity, securing our future: A national mission on biodiversity and human well-being for India}, journal = {BIOLOGICAL CONSERVATION}, volume = {253}, year = {2021}, month = {01/2021}, abstract = {

Highly populated tropical countries face tremendous pressures in reconciling the needs for improved economic security and the protection of declining biodiversity. India is no exception and its biodiversity is under severe pressure due to complex interactions among land use change, other human economic activities, and climate change. Preservation and restoration of biodiversity is perhaps the cheapest and least risky way to mitigate the impacts of threats such as climate change, diminishing food and nutritional security, declining economy, absence of affordable healthcare, rising zoonotic diseases and lack of capacity to address these issues. Here we describe a framework for biodiversity conservation - the National Mission on Biodiversity and Human Well-Being (NMBHWB) for India - which integrates biodiversity, ecosystem services, climate change, agriculture, health, bio-economy and capacity building in the realm of biodiversity science. We provide an overview of the seven Programs of the Mission which make it interdisciplinary, integrative, and comprehensive in its approach. The Mission explicitly links research with policy-making and implementation for effective management of biodiversity with sustainable development. With its emphasis on convergence and synergies among various goals, themes and project sites, the Mission will further develop new models for stakeholder consultations and co-production of knowledge. We posit that the NMBHWB will enable India to realize the United Nations Sustainable Development Goals and Targets while advancing India{\textquoteright}s commitments to the Paris Agreement on climate change and other international environmental conventions and treaties.

}, doi = {10.1016/j.biocon.2020.108867}, author = {Bawa, Kamaljit S and Sengupta, Asmita and Chavan, Vishwas and Chellam, Ravi and Ganesan, R. and Krishnaswamy, Jagdish and Mathur, Vinod B. and Nawn, Nandan and Olsson, Shannon B and Pandit, Nitin and Quader, Suhel and Rajagopal, Prabhakar and Ramakrishnan, Uma and Ravikanth, G. and Sankaran, Mahesh and Shankar, Darshan and Seidler, Reinmar and Shaanker, R. Uma and Vanak, Abi Tamim} } @article {82442, title = {Antipredatory Responses of Mosquito Pupae to Non-Lethal Predation Threat-Behavioral Plasticity Across Life-History Stages.}, journal = {Environ Entomol}, year = {2020}, month = {2020 Sep 04}, abstract = {

Antipredatory behavioral responses tend to be energetically expensive, and prey species thus need to resolve trade-offs between these behaviors and other activities such as foraging and mating. While these trade-offs have been well-studied across taxa, less is known about how costs and benefits vary in different life-history contexts, and associated consequences. To address this question, we compared responses of the yellow fever mosquito (Aedes aegypti [Diptera: Culicidae]) to predation threat from guppy (Poecilia reticulata [Cyprinodontiformes: Poeciliidae]) across two life-history stages-larvae (data from previous study) and pupae (from this study). Pupae are motile but do not feed and are comparable to larvae in terms of behavior. To understand how physiological costs affect the threat sensitivity of pupae, we used sex (with size as a covariate) as a proxy for stored energy reserves, and quantified movement and space use patterns of male (small-sized) and female (large-sized) pupae when exposed to predation threat. We found that pupae did not alter movement when exposed to predator cues but instead altered spatial use by spending more time at the bottom of the water column. We found no effect of pupa sex (or size) on the behavioral responses we measured. We conclude that pupa behavior, both antipredatory and otherwise, is primarily targeted at minimizing energy expenditure, as compared with larval behavior, which appears to balance energy expenditure between the opposing pressures of foraging and of avoiding predation. We suggest that antipredatory defenses in metamorphosing prey are modulated by varying energetic trade-offs associated with different life-history stages.

}, issn = {1938-2936}, doi = {10.1093/ee/nvaa101}, author = {Chandrasegaran, Karthikeyan and Sriramamurthy, Rasikapriyaa and Singh, Avehi and Ravichandran, Pooja and Quader, Suhel} } @article {83636, title = {Opinion: Envisioning a biodiversity science for sustaining human well-being.}, journal = {Proc Natl Acad Sci U S A}, year = {2020}, month = {2020 Sep 30}, issn = {1091-6490}, doi = {10.1073/pnas.2018436117}, author = {Bawa, Kamaljit S and Nawn, Nandan and Chellam, Ravi and Krishnaswamy, Jagdish and Mathur, Vinod and Olsson, Shannon B and Pandit, Nitin and Rajagopal, Prabhakar and Sankaran, Mahesh and Shaanker, R Uma and Shankar, Darshan and Ramakrishnan, Uma and Vanak, Abi Tamim and Quader, Suhel} } @article {54878, title = {Size{\textendash}logging interactions and population dynamics in tropical understorey birds}, journal = {Current Science}, volume = {116}, year = {2019}, month = {03/2019}, pages = {795-801}, abstract = {

Demographic vital rates (e.g., fecundity and survival) determine population size and viability. However, how anthropogenic habitat change differentially influences these dynamic population processes for species with different traits remains unknown. Crucially, this limits a mechanistic understanding of species- and commu-nity-level patterns in response to intensity of habitat change, and therefore, impedes robust prediction of future species responses. We investigated how size (across 26 forest birds, spanning almost an order of magnitude in body mass) and habitat modification (logging intensity, from intact forest to a 2.5-fold re-duction in tree density) might interact to influence survival, reproduction and dispersal. Data were col-lected over five sessions under the robust design in a capture-mark-recapture framework and analysed using reverse time capture{\textendash}recapture models. We found that smaller species were more fecund with in-creased logging intensity, and dispersed from more heavily logged to more intact forest. With increasing size, species reproduced better in progressively more intact forest, and dispersed from intact forest into more logged forest. These results indicate important trait-linked differences in the relative significance of various demographic processes in influencing species responses to varying intensities of habitat change. Separating the mechanistic processes underlying observed patterns is crucial to understanding and predicting anthropogenic impacts on biodiversity.

}, url = {https://www.currentscience.ac.in/php/toc.php?vol=116\&issue=05}, author = {Srinivasan, U and Quader, Suhel} } @article {45928, title = {Ants on Clerodendrum infortunatum: Disentangling Effects of Larceny and Herbivory.}, journal = {Environ Entomol}, volume = {47}, year = {2018}, month = {2018 Oct 03}, pages = {1143-1151}, abstract = {

Nectar larcenists extract nectar from flowers without pollinating them. A reasonable expectation is that any form of nectar larceny should have a detrimental effect on the plant{\textquoteright}s reproductive success. However, studies reveal an entire range of effects, from highly negative to highly positive. This variation in effect may be partly explained by additional, unmeasured, effects of nectar larcenists on plants. In a study system where two ant species Tapinoma melanocephalum (Fabr.) (Hymenoptera: Formicidae) and Trichomyrmex destructor (Jerd.) (Hymenoptera: Formicidae) act as nectar larcenists, we examined the effect of larceny on the female reproductive success of Clerodendrum infortunatum Gaertn. (Lamiales: Lamiaceae) in rain forest fragments of the Western Ghats, India. This was done through a combination of field observations and a series of field experiments looking at the effects of excluding ants from inflorescences. We found that T. destructor reduces fruit set considerably. Rather than this being a consequence of nectar larceny, however, our experiments show that the negative effect arises instead from the herbivorous behavior of the ant. At a population level, both ant species prefer edges over interiors of forest patches, spatially concentrating the interaction zone to forest edges. Simultaneously considering multiple ecological interactions and disentangling their relative contributions might explain the large variation across species in the observed effect of larceny. The overall population effect of nectar larceny and herbivory is likely to depend on the spatial structuring of plants and ants.

}, issn = {1938-2936}, doi = {10.1093/ee/nvy090}, author = {Mukhopadhyay, Amritendu and Quader, Suhel} } @article {29733, title = {Context-dependent interactive effects of non-lethal predation on larvae impact adult longevity and body composition.}, journal = {PLoS One}, volume = {13}, year = {2018}, month = {2018}, pages = {e0192104}, abstract = {

Predation impacts development, behavior and morphology of prey species thereby shaping their abundances, distribution and community structure. Non-lethal threat of predation, specifically, can have a strong influence on prey lifehistory characteristics. While investigations often focus on the impact of predation threat on prey in isolation, tests of its interactive effects with food availability and resource competition on prey survival and fitness can improve understanding of costs, benefits and trade-offs of anti-predator strategies. This study, involving Aedes aegypti mosquitoes as a model organism, investigates both simple and interactive effects of predation threat during the larval stage on survival, size at and time to maturity, stored teneral reserves of glycogen, protein and lipid in adults, and adult longevity. Our results show that development times of mosquito larvae were increased (by 14.84\% in males and by 97.63\% in females), and size of eclosing adults decreased (by 62.30\% in males and by 58.33\% in females) when exposed to lowered nutrition and elevated intraspecific competition, but that predation had no detectable effect on these simple traits. Teneral reserves of glycogen, protein and lipid and adult longevity were positively correlated with adult body size. Non-lethal predation threat had significant interactive effects with nutrition and larval competition on teneral reserves in males and adult longevity in males and females. The sexes responded differently to conditions encountered as larvae, with the larval environment affecting development and adult characteristics more acutely for females than for males. The outcome of this study shows how threat of predation on juveniles can have long-lasting effects on adults that are likely to impact mosquito population dynamics and that may impact disease transmission.

}, issn = {1932-6203}, doi = {10.1371/journal.pone.0192104}, author = {Chandrasegaran, Karthikeyan and Kandregula, Samyuktha Rao and Quader, Suhel and Juliano, Steven A} } @article {45441, title = {Responses of interspecific associations in mixed-species bird flocks to selective logging}, journal = {Journal of Applied Ecology}, volume = {55}, year = {2018}, month = {07/2018}, pages = {1637-1646}, abstract = {

  1. Non-trophic interactions (or, inter-species associations) play a prominent role in determining community structure and function. Mixed-species bird flocks are networks of non-trophic associations that confer foraging and anti-predator benefits to participant species. Yet, the responses of these interspecific associations to anthropogenic environmental changes are poorly understood.

  2. Selective logging is pervasive in the tropics, and can affect associations in mixed-species bird flocks by altering resource availability and/or predation risk, or through the altered abundances of species participating in mixed flocks. Across a gradient of logging intensity, we examined how the number and strength of associations in two different mixed-species flock types responded to logging intensity, while simultaneously controlling statistically for changes in the abundances of species in response to logging.

  3. Across the logging gradient, we used network analyses to: (1) quantify the proportion of potentially realizable associations, and (2) measure the strengths of these realized associations. For both these analyses, we used null models to investigate whether changes in the network properties of mixed flocks were simply abundance-driven, or congruent with expectations of how flock properties might be modified by selective logging.

  4. In understorey flocks, after controlling statistically for changing abundances of participant species, the proportion of realized associations decreased with increasing logging intensity, whereas mean association strength did not show any relation with logging intensity. In midstorey flocks, both the proportion and mean strength of realized associations increased with increasing logging intensity.

  5. Synthesis and applications. By statistically separating abundance and behaviour-mediated effects, we show that interspecific associations in mixed-species bird flocks respond to potential resource and/or predation changes from logging, but that their functional roles persist in logged forest. We show that logged forests can conserve not only community richness, but also function. Thus, these logged forests must be prevented from ongoing conversion into non-forest habitats such as agriculture and plantation.

}, doi = {10.1111/1365-2664.13097}, author = {Borah, B and Quader, Suhel and Srinivasan, U} }