Biology subjects

Gowda, V.

Publications and source records attributed to Gowda, V..

8 recordsLinked to original sources

bioRxiv2026

Revealing taxonomic signals in plant volatiles with phytochemistry, machine learning and trait mapping

Plant volatiles have long been used as taxonomic characters, especially in chemotaxonomy. Exploring the utility of chemotaxonomy has been widely regarded critical for drug discovery, despite the knowledge that phytochemicals are often evolutionarily labile. Despite this, the use of chemotaxonomy has been restricted primarily due to the complex interpretations behind translating chemical characters into phylogenetically operational characters. In this paper, we propose a method that integrates phytochemistry, machine learning, and trait mapping to examine whether plant volatiles retain signals for classification across broad taxonomic ranks and which components of the volatile metabolites carry these signals. Leveraging a global dataset comprising 2,139 volatiles across 429 plant species, we trained classifiers on presence-absence data and molecular fingerprints that can predict species to their taxonomic ranks. Incorporating structural features improves performance, suggesting that plant volatiles may encode lineage-specific chemical signatures. Rather than single diagnostic markers, combinations of volatiles informed taxonomic predictions, indicating biosynthetic constraints within volatile clusters. Fingerprint-derived clusters showed a lineage-dependent pattern when mapped onto phylogeny. The proposed method provides an integrated approach to revisit chemotaxonomy and trait evolution to understand the chemical diversity across lineages. This approach can also support comparative chemical prediction, especially for understudied closely related plant groups.

plant biology↗

bioRxiv2026

Morph bias in inflorescences and individual plants reduces opportunities for geitonogamy in a monomorphic enantiostylous species

O_LIEvolution of enantiostyly, a stylar polymorphism characterised by left- or right-handed flowers, is predicted to counter selfing through disassortative pollen movement. However, in monomorphic enantiostyly, both morphs are present on the same individual, and geitonogamy has been proposed to depend on the morph ratio of an individual. C_LIO_LIUsing the monomorphic enantiostylous Didymocarpus podocarpus (Gesneriaceae), endemic to the Eastern Himalayas, we hypothesised that geitonogamous events would be reduced when plants have a biased morph ratio, due to disassortative pollen movement. We first established the natural morph ratios and reproductive compatibilities of the morphs, and next examined the role of morph ratios in pollen movement by recording pollinator visitation patterns using visual observations and quantum dots. C_LIO_LIOur results show that most inflorescences and plants exhibit a stochastic skew in their morph ratios, while populations maintain an isoplethic ratio. Pollen transfer and pollination success were higher between morphs than within morphs, and inter-morph pollinator switches within a plant significantly decreased with an increase in morph bias. C_LIO_LIWe show that within a plant, biased morph ratios combined with disassortative pollen movement can limit the occurrence of geitonogamous events, thus providing a mechanism to improve pollination success while also retaining reproductive assurance. C_LI

ecology↗

bioRxiv2025

Are ant-plant mutualisms stronger at lower latitudes? A case study using the castor plant in the Indian subcontinent

The Biotic Interactions Hypothesis (BIH) predicts that species interactions will intensify from the poles to the tropics. We studied the ant-plant defensive interaction mediated by extrafloral nectaries (EFNs) in the castor bean plant, Ricinus communis, across a [~]21{degrees} latitudinal gradient in its naturalized range in India. Among our study sites, we found that the ant-EFN mutualism in castor bean gets stronger from sub-tropical to tropical latitudes. Investment in mutualism by plants and visitation by ants increased from higher to lower latitudes. Further, latitude significantly explained ant community composition. However, contrary to the predictions of the BIH, standing herbivory increased with latitude, perhaps because plants invest less in biotic defence at higher latitudes. To our knowledge, our study is the first to test for the patterns predicted by the BIH for an ant-plant interaction in the Paleotropics. Results from our study can also help inform sustainable pest control practices for R. communis since India is the worlds largest producer of castor oil.

ecology↗

bioRxiv2024

Mass flowering and flowering asynchrony characterise a seasonal herbaceous community in the Western Ghats

Flowering synchrony within a community may be facilitated by climatic factors and by ecological interactions that promote shared pollination services. In contrast, flowering asynchrony is promoted when there is inter-species competition for pollinators. In this multiyear study, we analyse the flowering phenology of a seasonal, herbaceous community (Kaas plateau) in Western Ghats, India to identify environmental constraints that may influence flowering synchrony. We addressed the questions: (a) Is flowering seasonality correlated with climatic factors? (b) Is there evidence for flowering synchrony within the community? (c) Do plant-pollinator interactions shift with flowering phenology? In Kaas, we recorded flowering phenology of 76 herbaceous species and found that climatic factors influenced their flowering phenology. We also identified the community to be composed of a few mass flowering (MF) species ([~]30%) and several non-mass flowering (nMF) species ([~]70%). Using two novel synchrony indices, temporal overlap (SItemp) and synchrony in abundance (SIabd), we also identified higher asynchronous flowering within the community than expected. Notably, species sharing the same floral colour, showed marked absence of synchrony, thus suggesting that competition and not pollinator-mediated facilitation drives flowering asynchrony within Kaas. Finally, pollination networks were observed to shift with flowering abundances within the community. Our findings reveal that even seasonal landscapes like the laterite plateaus, despite their short flowering season that last only 4-5 months, exhibit an overall asynchronous flowering phenology. And, the synchronous flowering for which the Kaas plateau is famous, was noted to be mostly due to a few mass flowering species that alter across years.

ecology↗

bioRxiv2024

Revisiting Aristotle's observation on bees: High floral constancy is common among bees but it is shaped by the locally abundant flowering species

Floral constancy is the tendency of a pollinator to sequentially visit flowers of the same species despite the availability of other rewarding plants. In a phytodiverse community, resource assurance may lead to pollinators displaying floral constancy to the most abundant plant species. We tested this by investigating if pollinators are floral constant on the abundant or the non-abundant plants within a seasonally flowering tropical community. We quantified floral constancy in three social (Apis spp.) and two solitary (non-Apis) Indian native bees using three approaches, that is by manually tracking the bees, analysing their pollen load, and examining pollen sacs of returning bees at their hive. We next examined in Apis cerana indica if constancy in individual bees translated to hive-level constancy. We found that in our community with distinct co-flowering patches, bees were constant to the most abundant species within a localised patch, and not to the most abundant species in the landscape. While the pollen loads from both the social and solitary bees suggested that they show high floral constancy (> 70% uni-dominant pollen), their values differed significantly (p < 0.0001). Finally, approximately 90% of individuals within a hive showed floral constancy (monolectic), but collectively, a hive displayed polylectic foraging. Our findings highlight that the foraging patterns of native pollinators has been understudied and is a critical first step towards connecting reproductive assurances to plant-pollinator dependencies in large landscapes.

animal behavior and cognition↗

bioRxiv2024

Pollinator visitation pattern and differential reproductive compatibilities maintain bract colour polymorphism in a nocturnal ginger from Western Ghats, India

Background and aimsFloral color polymorphism is common in angiosperms, yet in perennial, clonal plants, proximate trait differences and reproductive differences among sympatric morphs remain poorly understood. This is primarily because perennial individuals can carry signatures of past selection regimes. We studied bract color polymorphism in a nocturnal ginger Curcuma caulina to ask: (i) Do nectar rewards, reproductive compatibility and pollinator visitation differ among color morphs? (ii) Does morph abundance correlate with fitness via ecological (pollinator-mediated) or physiological (compatibility) pathways? (iii) Do these traits predict realized reproductive success? MethodsWe measured 22 floral/vegetative traits (n=30 per morph), nectar rewards (106 flowers), pollinator visitation rates (648 hours), and physiological compatibility (471 hand-pollinations treatments) and natural fruit and seed set ([≥]50 per morph) across three dominant morphs. Path analysis tested direct and indirect effects of morph abundance, nectar traits, pollinator visitation, and compatibility on reproductive fitness. Key resultsMorphs did not differ in their morphological traits but showed differential nectar and reproductive compatibility traits. The rare red-white morph produced the highest nectar energy, received the most visits, had a leaky self-compatibility, and yet showed lowest seed count per fruit, while the most common green-red morph was self-incompatible, showed higher cross-compatibility and had highest seeds per fruit. The second common green-white morph showed intermediate abundance and also showed leaky self-compatibility. Path analysis indicated that morph abundance had both direct and indirect effects on reproductive fitness, mediated by nectar, pollinator visitation and compatibility. ConclusionsReproductive success of the polymorphic C. caulina is a result of multi-trait interactions including pollinator interaction. That is, nectar traits and mating-system differences shape reproductive fitness of the morphs. We also highlight that in polymorphic perennial plants contemporary selection regimes may be acting alongside genotypic vestiges (historical genotypes present in extant population), thus complicating any frequency-dependent selection regime.

ecology↗

bioRxiv2021

Floral evolution and pollinator diversification in Hedychium J.Koenig (Zingiberaceae): one of Mr. Darwin's tropical fantasies

PREMISEHedychium J.Koenig (ginger lilies: Zingiberaceae) is endemic to the Indo-Malayan Realm (IMR) and is known for its fragrant flowers. Two different pollination syndromes characterize the genus: diurnal or bird pollination and nocturnal or moth pollination systems. To date, no attempt has been undertaken to understand the evolution of floral traits in this genus. METHODSWe estimated ancestral character-states, phylogenetic signals, and character correlations for thirteen discrete and eight continuous floral traits representing 75% species diversity of Hedychium. Diversification rate estimation analyses were also employed to understand trait-dependent diversification in the genus. RESULTSInflorescence structure, cincinnus capacity, and curvature of floral tubes revealed strong phylogenetic dependence, whereas number of open flowers per inflorescence per day, color of the labellum, and exertion of the stigma characterized higher ecological effects. Diversification rate estimations suggested that the labellum width, floral tube length, and labellum color played a major role in the evolutionary diversification of Hedychium. CONCLUSIONSWe identified bract type and cincinnus capacity as synapomorphies for Hedychium, while the island-specific clade III was characterized by slender cylindrical inflorescence, coiling of floral tubes, and longer bract to calyx ratio. The circum-Himalayan clade IV is the most speciose, derived, and with most variable floral traits. Although floral color and size lacked any association with pollinator-specific traits (moth and bird pollination), pale colored flowers were most common in the early diverging clades (clade I, II-el., and II-de.), indicating their ancestral nature, when compared to brightly colored flowers.

evolutionary biology↗

bioRxiv2020

When to be a male? Role of resource-limitation and pollinators in determining gender in an andromonoecious spiderwort.

The evolution and maintenance of sexual systems in plants is often driven by resource allocation and pollinator preferences, and very little is known about their role in determining floral sex expression in plants. In annual, entomophilous plants three major constraints can be identified towards optimal reproduction: 1) nutrient resources available from the environment, 2) nutrient resources allocated towards reproduction, i.e., fruits vs. flowers, and 3) pollinator visitations.Andromonoecy is a sexual system where plants bear both staminate and hermaphrodite flowers on the same inflorescence. The optimal resource allocation hypothesis suggests that under nutrient constraints, plants will produce more male flowers since they are energetically cheaper to produce over the more expensive hermaphrodite flowers. We test this hypothesis in the andromonoecious Murdannia simplex (Commelinaceae) by quantifying male and hermaphrodite flowers in a natural population and contrasting the distribution of the two sexes in plants from two resource conditions (stream population vs. plateau population). We next carried out choice experiments to test pollinator preference towards a specific sex.We found that in M. simplex, production of hermaphrodite flowers is resource-dependent and under resource constraints fewer numbers of flowers were produced and most of them were males. We failed to observe pollinator preference towards either sex but Amegilla spp. and Apis cerana showed higher visitation towards the most abundant sex within a trial, suggesting frequency-dependent visitation. Thus, we conclude that environmentally driven resource constraints play a bigger role in driving floral sex expression in Murdannia over direct pollinator-driven constraints.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗