Abstract Detail

Ecology

Gowda, Vinita [1], Shrotri, Saket [2].

When math can trick a moth: Density-driven maintenance of floral color polymorphism in a nocturnal moth-pollinated ginger - Curcuma caulina (Zingiberaceae).

Floral polymorphism is the presence of two or more discrete morphs of the same species, often within the same population. While it is a trait common in plants, it is particularly very common among herbaceous annuals. In a population that shows presence of floral polymorphism, some of the interesting questions one can ask to address the evolution of polymorphism are: Do the polymorphic forms show difference in their reproductive behavior and fitness? How are these polymorphic forms being maintained? Are there annual variations in the floral forms?
Here we present a case study from an endemic ginger Curcuma caulina (Zingiberaceae), a rhizomatous, nocturnal herb, endemic to northern Western Ghats, India. Based on the colour of lateral bracts we first identified three types of morphs in a population of C. caulina from the Kaas plateau, Satara. These morphs are: Green-White (GW), Green-Red (GR), and Red-White (RW). Within a population, we used morphometric and floral traits to identify density differences between the different morphs and we observed that the three morphs were present in unequal frequencies (p=0.03). The nocturnal flowers of C. caulina were observed to be pollinated by hawkmoths. Given the observed density differences, especially among sympatric morphs, we first tested if this represented a case of pollinator-mediated floral morph selection. Our nectar measurements show that the three morphs offered differential nectar rewards (p=0.03), where both the quality and the quantity of sugar differed among the morphs. Further, our manipulated experiments identified that night pollinating moths show a unique preference for the morphs with higher nectar sugar and they were able to distinguish floral colour morphs at night and revisited the same morphs repeatedly. The presence of repeat visit by moths to the rare high-quality flowers suggests that there is an active preference for higher sugar quality. Further, we show that all morphs have comparable reproductive success suggesting that different morphs may act as competitors to each other and may be in a pollinator-sharing equilibrium. The rare morph succeeds by offering sugar-rich nectar while the common nectar-poor morph succeeds by maintaining a higher encounter probability, Thus, a complex product of an ecological factor such as pollinator preference with density-dependent population dynamics explains the maintenance of floral color polymorphism in a populations of C. caulina.

1 - IISER Bhopal, Room 223, AB3, Dept. Of Biological Sciences,, IISER- Bhopal, Bhopal Bypass Road, Bhauri,, Bhopal, MP, 462066, India
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

Keywords:
floral evolution
polymorphism
pollination
pollinator-mediated selecton
hawkmoth pollination
pollination ecology.

Presentation Type: Oral Paper
Session: ECO7, Ecology: Reproductive Biology
Location: /
Date: Thursday, July 22nd, 2021
Time: 4:45 PM(EDT)
Number: ECO7008
Abstract ID:1029
Candidate for Awards:None