Abstract Detail

Reproductive Processes

Albal, Asawari [1], G, Azad [2], Shrotri, Saket [2], GOWDA, VINITA [2].

What drives floral gender expression? Example from an andromonoecious spiderwort Murdannia simplex (Commelinaceae).

Resource allocation and pollinator preferences are known to have driven the evolution and maintenance of sexual systems in plants. Gender or sex in plants, therefore can be seen as a physiological, functional, and behavioral response of a plant to the resources present in its environment. Annual, entomophilous plants have three major constraints towards optimal reproduction: 1) nutrient resources obtained from the environment, 2) nutrient resources allocated towards reproduction, i.e., fruits vs. flowers, and 3) pollinator visitations. These three factors are not necessarily mutually exclusive and their role in driving gender expression in flowers in a natural environment has not been well-studied. Andromonoecy is a sexual system where the plant bears staminate and hermaphrodite flowers on the same inflorescence and occurs in ~2% of flowering plants. Studies show that it has evolved multiple times within the angiosperms and yet our understanding of the underlying evolutionary mechanisms resulting in this sexual system is limited. The optimal resource allocation hypothesis, one of the most widely accepted hypotheses on the evolution of andromonoecy, suggests that under nutrient constraints, plants will produce more male (staminate) flowers since they require lesser energy than the more expensive hermaphrodite flowers. In this study, we test this resource-allocation hypothesis in Murdannia simplex (Commelinaceae), an andromonoecious herb present on the Kaas Plateau, Maharashtra state, India. We asked the following questions- a) Is there a gender bias in the production of flowers in M. simplex and does it vary with the progression of the flowering season?  b) Do pollinators prefer male or hermaphrodite flowers? c) Is pollinator preference or resource-limitation a major driver of gender expression in M. simplex?   We measured gender distributions in a large natural population, and compared the gender distributions between two different resource conditions: resource-rich stream population vs. resource-poor plateau population. We also carried out choice experiments using a floral-density manipulated setup, to quantify pollinator preference towards any gender. We found that production of flowers is resource-dependent and resource constraints result in fewer flowers as well as production of more male flowers over hermaphrodites. We did not observe any pollinator preference towards either gender but interestingly, some pollinators like Amegilla spp. (Zonamegilla) and Apis cerana displayed frequency-dependent visitations. Thus we conclude that gender expression in Murdannia is driven by nutrient-resource constraints in its environment rather than any pollinator-driven constraints.

1 - University of Toronto Mississauga, Biology, Mississauga, ON, L5L 1C6, Canada
2 - Indian Institute Of Science Education And Research Bhopal, Department Of Biological Sciences, Tropical Ecology And Evolution (TrEE) Lab, Room 303, AB3, IISER Bhopal, Bhauri Campus, Bhopal By Pass Road, Bhopal, MP, 462066, India

pollinator preference.

Presentation Type: Oral Paper
Session: REP1, Reproductive Processes 1
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 11:45 AM
Number: REP1008
Abstract ID:575
Candidate for Awards:None

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