Thesis Defense at CES on 20 January 2015 at 11:00 am titled "The role of nursery size and plant phenology on reproduction and relationships within a fig–fig wasp nursery pollination system" by Anusha Krishnan from CES, IISc

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Topic: 
The role of nursery size and plant phenology on reproduction and relationships within a fig–fig wasp nursery pollination system
Speaker: 
Anusha Krishnan, CES, IISc
Date & Time: 
20 Jan 2015 - 11:00am
Event Type: 
Thesis Defense
Venue: 
CES Seminar Hall, 3rd Floor, Biological Sciences Building
Coffee/Tea: 
Before the talk
Abstract:

In obligate nursery pollination mutualisms such as the fig–fig wasp system, enclosed inflorescences (syconia) function as sites of seed production, as well as brood-sites for the progeny of herbivorous pollinators, non-pollinating gallers and parasitoids of the two. Induced or natural variation in plant reproductive traits such as inflorescence or nursery size (syconium volume) and within-plant reproductive phenology (within-tree asynchrony) can affect various direct, indirect and feedback effects among the organisms in the community. Furthermore, changes in the abiotic environment could have major impacts on the biotic associations in the system either by affecting the community members directly, or through their effects on plant reproductive traits. Ficus racemosa with its fig wasp community comprised of a single pollinator, three non-pollinating parasitic gallers and three non-pollinating parasitoids was used as a model to investigate: (1) The role of mutualistic and parasitic fig wasps in affecting within-tree phenology; (2) Direct and indirect biotic associations in the system and the influence of inflorescence size (syconium volume) and within-tree phenology on them; (3) Effect of the abiotic climate on the reproduction of and the biotic associations between the organisms of the community Investigations revealed that syconium development times were subject to a tug-of-war between inhabitants and are likely a compromise between conflicting demands from developing seeds and different wasp species. Besides direct competition for resources and predator–prey interactions, the F. racemosa community also displays exploitative or apparent competition and trait-mediated indirect interactions mediated by syconium volume and within-tree asynchrony. The reciprocal effects of higher trophic level fauna on plant traits (and vice versa) within this system drive a positive feedback cycle between syconium inhabitants and within-tree reproductive asynchrony. Temperature, relative humidity and rainfall defined four seasons: winter; hot days, cold nights; summer and wet seasons. Syconium volumes, fig wasp reproduction and seed production varied between seasons. The effect of within-tree asynchrony on pollinators was variable across season and was mediated through variations in syconium volume. Within-tree asynchrony itself was positively affected by intra-tree variation in syconium contents and volume, creating a unique feedback loop which also varied across seasons.

Speaker Bio: 
Graduate Student Prof. Renee M. Borges' lab CES