Ecology

Opportunities at Prof Saskya Van Nouhuys lab.

Field Assistant Position: I am looking for a field assistant to work in my lab at the Centre for Ecological Sciences at IISc in Bangalore. We study ecological interactions between species, and the consequences of these interactions at the population and community levels, mostly using insects and plants. See http://ces.iisc.ac.in/new/?q=user/435 for more details about our research.

Zeroing In with Prof. Renee M Borges

Podcast from the Borges Lab (courtesy Zeroing In. The Science Podcast)

Part I:

"Around 200 years back, Darwin set out on his historic voyage around the world, observing and cataloguing the immense diversity the world had to offer, he laid down the foundation for a theory that shook the foundation of biology, the theory of evolution out of which was born the field of evolutionary ecology which tries to unravel the countless puzzles of life nature has to offer.

Topic: 
Through the looking glass: Phoresy as seen in the light of mutualism
Speaker: 
Satyajeet Gupta, IISc
Date & Time: 
4 Feb 2021 - 3:00pm
Event Type: 
Thesis Defense
Venue: 
Microsoft Teams link below abstract
Coffee/Tea: 
None
Abstract:

Phoresy is the dispersal of small organisms on larger ones to move out of an unfavourable habitat. Although these interactions are transient, they can form tight links with mutualistic interactions if the phoretic organisms are dependent on both mutualistic partners, one serving as a vehicle with the other providing a substratum for development. These linked tripartite interactions may further lead to increase in host specificity in phoretic organisms. Therefore, to understand the effects of phoretic interactions on the entire mutualistic system and factors that can help the phoretic organisms to gain host-specificity, I investigated the phoretic nematode community associated with the fig–fig wasp brood-site pollination mutualism. I chose Ficus racemosa, a wide-spread and a common tropical keystone fig species, which shows a mutualistic relationship with a unique pollinating fig wasp species and harbours a host-specific phoretic nematode community. Ficus racemosa has an Indo-Australian distribution and is known to be associated with several nematode species throughout its range. A few nematode species have also been reported from India, but they lacked comprehensive detail on their morphology and also molecular characterization, thus making it difficult to carry out further species-specific studies. Therefore, we firstly characterised the phoretic nematode community associated with the Ficus racemosa system in south India, using both morphological and molecular approaches and found a mixture of plant-parasitic, animal-parasitic and possibly omnivorous taxa. We found that the nematode community consisted of three new nematode species out of which one species showed phenotypic plasticity. The phylogenetic analysis based upon near-full-length small subunit (SSU) and D2–D3 expansion segments of large subunit (LSU) rRNA genes showed that the species have close affinities with sister nematode species reported from Ficus racemosa from other geographical locations outside India. To determine the effects of phoretic nematodes on the entire mutualism, we performed various bioassays and determined the fitness effects of phoretic organisms on both mutualistic partners, i.e., figs and pollinator fig wasps. We found that not only did the nematodes negatively affect the survival, flight ability, offspring number and predation risk faced by their fig wasp vehicles, but they also negatively impacted fruit seed number and size in a density-dependent manner. Furthermore, wasps arriving at their destinations carried lower phoretic nematode load compared to dispersing wasps suggesting that there is selection on hitchhiker numbers within a vehicle during the dispersal process. Using choice experiments with single nematodes and employing conspecific as well as heterospecific co-travellers, we showed that these phoretic organisms were able to distinguish between vehicles with different hitchhiker density and physiological states. Plant-parasitic nematodes preferred vehicles devoid of conspecifics and likely hitchhiked in pairs, while animal-parasitic nematodes preferred vehicles with conspecifics within a certain density range. Both types of nematodes were insensitive to the presence of heterospecific co-travellers. The nematodes used volatiles and carbon dioxide for this intra-specific vehicular discrimination. We also characterized the volatiles emitted by the pollinator wasps and identified the possible set of compounds that might elicit an attraction response in the nematodes towards their vehicles. Overall, we show that phoretic nematodes have a density-dependent negative effect on the mutualism between figs and their pollinating fig wasps and that they use parameters such as vehicle physiology and existing traveller load within the vehicle to select a vehicle for their dispersal.

https://teams.microsoft.com/l/channel/19%3abb4ece80bcaf4251a935efa618fc8...

The scent of life: Phoretic nematodes use wasp volatiles and carbon dioxide to choose functional vehicles for dispersal.

Scent of Life

"Ever thought, "what is the scent of life?" and "can nematodes differentiate between different physiological states of their host?". To get answers and insights on the vehicle-passenger relationship do read this paper.

 https://link.springer.com/article/10.1007/s10886-021-01242-5#citeas

 

CES invites applications for Inclusive Ecology Workshop, Feb 2021 (Deadline 5th Feb)

Inclusive Ecology is an online workshop organised by the Centre for Ecological Sciences, Indian Institute of Science, Bengaluru. 

The workshop will introduce participants to broad concepts and approaches in the fields of Ecology, Evolution, Behaviour, Conservation and Quantitative Thinking via workshops. We will also conduct workshops on building professional skills, careers in ecology, and life as a PhD. student.

Too many, too few, or empty: the number of passengers determines whether nematodes will hitchhiker on a vehicle

JAEBlog

Ever thought, if tiny organisms can count and how do they do it? Find the answer in this paper. Also, find cool insights on the vehicle-passenger relationship.

 https://animalecologyinfocus.com/2021/01/08/too-many-too-few-or-empty-the-number-of-passengers-determines-whether-nematodes-will-hitchhike-on-a-vehicle/

Foraging in nature

foraging

Butterflies respond to complex ecological conditions while foraging in the wild. The spatial scale of resource distribution and also adult nectar and larval resources influences butterfly foraging decisions. At large-spatial scales butterflies spent more time feeding in resource-poor areas as compared to resource-rich areas but at small spatial scales butterflies spent more time foraging in resource-rich patches. Our findings indicate that animals are capable of evaluating multiple resources at multiple spatial scales.

Announcement of Vacancy for the Position of JRF for herpetofaunal research in the LTEO programme

Candidates with the following additional qualifications/skills will be preferred:

• Experience in field work with herpetofauna

• Quantitative skills including statistics and study design.

• Data analysis skills including working knowledge of R and GIS.

Remuneration: Salary will be commensurate with qualifications and work experience in accordance with GOI and IISc scales.

How to apply:

CES welcomes a new faculty member: Umesh Srinivasan

Umesh Srinivasan

It gives us great pleasure to welcome Dr. (Dr.) Umesh Srinivasan to CES. Umesh joins as Assistant Professor after completing a postdoc at Princeton University, prior to which he completed his PhD at NCBS. The doctor in parenthesis refers to an MBBS he did before he became obsessed with ecology and conservation!

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