Biology subjects

Quader, S.

Publications and source records attributed to Quader, S..

7 recordsLinked to original sources

bioRxiv2025

What's next for Indian Ornithology? 101 key research questions

India has a rich history of ornithology, and bird research in this field has expanded considerably in recent decades, spurred by a growing number of birdwatchers and ornithologists. Despite this progress, critical gaps remain. This paper highlights key areas where further research is needed and identifies pressing questions that will shape Indian ornithology in the coming years. Drawing from diverse inputs, we present a curated list of 101 research questions spanning across the various disciplines in ornithology - Natural History, Physiology and Disease Ecology, Behaviour, Population and Community Ecology, Habitat Ecology, Macroecology and Biogeography, Population Genetics and Evolution, Applied/Economic Ornithology and Conservation. The list was compiled through a multi-stage process, starting with a public open call for questions, followed by review and curation by a smaller panel of subject specialists. Each question was independently scored by a panel of experts based on three criteria: generality, novelty, and relevance. To account for variation in scoring styles, scores were normalised using Z-scores. The top 101 research questions were then selected based on these standardised scores. Each question is accompanied by an annotation that describes the significance of the question, and highlights opportunities to address it. While our list of research questions highlights significant research priorities, it is not intended to be exhaustive. Rather, it reflects the perspectives of those involved in its curation, who deemed these questions particularly relevant and impactful towards advancing Indian ornithology. We expect these questions to spark new project ideas among students, researchers, and citizen scientists, while guiding funders, managers, and policymakers toward priority research areas.

ecology↗

bioRxiv2024

State of India's Birds 2023: A framework to leverage semi-structured citizen science for bird conservation

Birds and their habitats are threatened with extinction around the world. Regional assessments of the State of Birds are a vital means to prioritize data-driven conservation action by informing national and global policy. Such evaluations have traditionally relied on data derived from extensive, long-term, systematic surveys that require significant resources, limiting their feasibility to a few regions in the world. In the absence of such structured long-term datasets, semi-structured datasets have recently emerged as a promising alternative in other regions around the world. Semi-structured data are generated and uploaded by birdwatchers to citizen science platforms like eBird. Such data contain inherent biases because birdwatchers are not required to adhere to a fixed protocol. An evaluation of the status of birds from semi-structured data is therefore a difficult task that requires careful curation of data and the use of robust statistical methods to reduce errors and biases. In this paper, we present a methodology that was developed for this purpose, and was applied to produce the comprehensive State of Indias Birds (SoIB) 2023 report. SoIB 2023 assessed the status of 942 bird species in India by evaluating each species based on three metrics: 1) long-term change: change in abundance between the year 2022 and the year-interval pre-2000; 2) current annual trend: mean annual change in abundance from 2015 to 2022; and 3) distribution range size. We found evidence that 204 species have declined in the long term, and 142 species are currently declining. We present and discuss important insights about Indias birds that can guide research and conservation action in the region. We hope that the detailed methodology described here can act as a blueprint to produce State of Birds assessments from semi-structured citizen science datasets and springboard conservation action in many other regions where structured data is lacking but strong communities of birders exist. Open Research StatementThe primary data are already publicly available on eBird (Sullivan et al. 2014), and other data are already published in a GitHub repository (stateofindiasbirds 2024).

ecology↗

bioRxiv2022

Long-term bird abundance in a threatened grassland ecosystem: an assessment using daily bird lists

Open Natural Ecosystems (ONEs), such as tropical grasslands, are among the most threatened habitats on Earth today. The long-term monitoring of ONEs is an important research domain that is essential for understanding anthropogenic impacts and facilitating conservation action. Using a simple day-listing method over a 13-year period, we studied species trends in a central Indian grassland-agriculture mosaic experiencing several land-use changes. Our results indicate that some grassland species (such as the Great Indian Bustard Ardeotis nigriceps) show steep declines during the study period, while other generalist species (such as the Indian Peafowl Pavo cristatus) show an increasing trend. Daily listing also reveals distinct seasonal patterns, and we discuss the Great Indian Bustard and Western Marsh Harrier Circus aeruginosus as examples. Our study highlights the utility of consistent checklist surveys to monitor population trends of bird communities within a changing landscape.

ecology↗

bioRxiv2020

Using Citizen Science to build baseline data on tropical tree phenology

Large-scale and long-term understanding of the phenology of widespread tree species is lacking in the tropics, and particularly in the Indian subcontinent. In the absence of baseline information, the impacts of climate on tree phenology, and thus on trophic interactions downstream of tree phenology, are also poorly understood. Citizen scientists can help bridge this gap by contributing simple, technology-based information over large spatial scales and over the long term. In this study, we describe an India-wide citizen science initiative called SeasonWatch, with preliminary insights into contributor behaviour and species phenology. Over a period of 8 years, between 2011 and 2019, cumulative contributor numbers have increased every year, although consistent contribution remains constant and low. The phenological patterns in the 4 most-observed species (Jackfruit Artocarpus heterophyllus Lam., Mango Mangifera indica L., Tamarind Tamarindus indica L., and Indian Laburnum Cassia fistula L.) are described, with discernible seasonal peaks in flowering and fruiting. Seasonal peaks are influenced by tree phenology reported in the south Indian state of Kerala, which has the maximum number of contributors and most number of observations per contributor, comprising 89% of all observations. We look in detail at the flowering phenology of one particular species, Cassia fistula, which appears to show aberrant phenology, reflecting a potential shift away from historical baselines. Latitudinal patterns in the phenology of widespread species such as Mangifera indica are also discernible from 4 seasonal bioblitz events organised during 2018-19, with trees in lower latitudes exhibiting flowering and fruiting phenology earlier than the higher latitudes. We conclude that there are signs of shifts in phenological patterns, as in the case of C. fistula, and extend a call for action to sustain long-term interest and participation by contributors to develop a baseline for common tropical tree species that can be used to understand long-term consequences of climate change on tropical tree phenology.

ecology↗

bioRxiv2020

Optimal inaccuracy: estimating male fitness in the movement-assisted dichogamous species Clerodendrum infortunatum

In hermaphroditic species, sexual interference can drive the evolution of dichogamy, where sporophylls (reproductive parts) 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? Are the sporophylls optimally positioned and stable in their respective active phases? We address these questions in Clerodendrum infortunatum, a protandrous, 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 pollen load is highest, anthers are paradoxically not positioned at the pollen export peak. Also, pollen export and pollination accuracy peaks do not align. This seeming maladaptiveness of anther positioning nevertheless results in 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 which appears close to optimal even though naive measures of pollination inaccuracy are high. Such a strategy of maximising overall male fitness, integrating over the dynamics of stamen trajectory, could well be a general characteristic of protandrous movement-assisted dichogamy.

evolutionary biology↗

bioRxiv2020

Fine-tuned spatiotemporal dynamics of sporophylls in movement-assisted dichogamy: a study on Clerodendrum infortunatum

Over 70% of flowering plants are hermaphroditic, with male and female parts in the same flower. 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 disadvantageous for both self-compatible and self-incompatible species. Hermaphroditic plants reduce self-pollen deposition by separating sporophylls (male and female reproductive parts) either spatially (herkogamy) or temporally (dichogamy). In movement-assisted dichogamy, both sporophylls are involved in a coordinated motion, where they move in opposite directions. However, the effectiveness of this adaptation 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. The findings suggest that the effectiveness of dichogamy is maximised 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 emphasises the importance of accessory adaptations in movement-assisted dichogamy to tackle the transition phase problem, which is inherent in this particular form of dichogamy.

plant biology↗

bioRxiv2019

Factors affecting the survival of tree seedlings following shifting cultivation in the Eastern Himalaya

O_LIThe seedling stage is considered an important bottleneck determining forest community composition during succession. Seedling growth and survival are known to be affected by factors such as light availability, herbivory and competition with existing vegetation. A shifting cultivation landscape with a cycle of clearing and regeneration provides an experimental setup to understand secondary succession.\nC_LIO_LIWe introduced tree seedlings of three species with differing life history strategies in an uncut forest and in sites formed 2, 6, 12, 25, 50 and 100 years following shifting cultivation in a subtropical landscape in the Eastern Himalaya. Seedlings of a pioneer species Saurauia nepalensis, a mid-successional species Terminalia myriocarpa and a mature forest species Castanopsis indica were introduced in plots with a control and three treatments: shading (light manipulated), clearing of vegetation (reduced competition), and exclosures (mammal herbivory excluded) and monitored for 18, 22 and 23 months, respectively.\nC_LIO_LISaurauia survived relatively well in all sites, Terminalia seedlings survived relatively well in the 12 and 25 year sites, and Castanopsis seedlings survived well in the 100 year site and the uncut forest. In the early successional site, survival of Saurauia was higher within exclosures indicating negative effects of herbivory. In the same site, clearing vegetation improved the survival of Terminalia, implying competition with existing vegetation. Castanopsis had the highest survival in uncut forest and survival was almost nil in the early successional site.\nC_LIO_LISynthesis: Seedling survival in a successional landscape depended on species-as well as site-specific factors. The existing vegetation in an early successional site had a negative effect on the survival of the mid-successional species, while herbivory had a negative effect on the pioneer species. Survival of the mature forest species in the early successional site was negligible but was high in old successional and uncut forest sites, indicating that mature forest species can colonize sites and survive only after certain physical and biotic aspects of the environment have been met. Our experiments were useful to examine factors that affect survival of tree species with differing life history strategies in a shifting cultivation landscape.\nC_LI

ecology↗