Bees and wasps are central-place foragers which return to their nest after extended
foraging or hunting trips. When they leave the nest for the first time, they perform
structurally elaborate learning flights to memorise the visual features of the
surrounding environment for guidance on their return. They are also known to perform
learning flights at newly discovered feeding sites. We study these learning flights
in experiments with the buff-tailed bumblebee, Bombus terrestris L., to understand
what and how insects learn. Because B. terrestris nests in the ground and will
collect nectar from ground vegetation, it is possible to compare the learning
flights acquiring information about the nest and a feeding site in circumstances in
which the visual surroundings of each site are very similar. Differences between
nest and feeder departure flights and learning may be related to the greater need of
bees to remember the precise position of their nest hole than the location of
conspicuous flowers.

Taste and smell have a similar function: detecting chemicals from the external world. Despite this
common functionality, the two systems are designed very differently both at the level of the sensory
receptors and in the way information is mapped into the brain. While olfaction is tuned towards
detecting volatile chemicals from air, the taste system is specialized for detecting non-volatile
molecules through contact. Usually the two systems have been studied separately, under the
assumption that both systems are tuned to detect divergent and non-overlapping ensemble of
molecules. We show through electrophysiology that taste sensilla on the proboscis of Drosophila
detect airborne molecules associated with food like acetic acid, acetone and isoamyl propionate,
as well as compounds known to be aversive to the olfactory system like 1-octen-3-ol (associated
with pathogenic microbes). Behavioral tests like Y-maze assay, 4-arm olfactometer assay and
proboscis extension response show that flies deprived of their olfactory organs are capable of
showing response to acetic acid vapors. However mutant flies lacking taste sensilla (and with
olfactory organs ablated) do not respond to such vapors. This shows that the taste system has the
ability to detect some volatile compounds at close range, raising questions about whether there is
a clear separation between the olfactory and gustatory sensory space, at least in insects.

Climate change could influence many aspects of an organism’s energy budget.
For animals that rely on torpor (short-term hypothermia) to save energy
overnight, increasing night time temperatures could be problematic since
they would limit the degree to which metabolic rate could be lowered. Most
studies on the use of torpor explore how it is affected by decreased
environmental temperatures, and have associated its use with decreased
ambient temperature. Climate change presents a challenge where organisms
face increased, rather than decreased, ambient temperatures. Because torpid
organisms reduce their body temperature and metabolic rates as ambient
temperatures get colder, warming temperatures could reduce the efficiency,
and potentially the use of hypothermia. Here, we first defined new ways of
comparing torpor use across species. We then compared measurements of
torpor in hummingbirds across different natural temperature regimes to
evaluate the possible effects of rising temperatures on energy management.
We found that hummingbirds save an average of 82% of their energy per
hour they used torpor. We also found that temperate birds used torpor
more often at a colder than at a warmer site, supporting our hypothesis
that warming could reduce torpor use. In contrast, tropical hummingbirds at
a slightly warmer site used torpor more often than hummingbirds at a
slightly colder site, suggesting that climate change could affect tropical
and temperate birds differently.

Man-made environmental change is the predominant threat to global biodiversity. Amphibians seem to be particularly sensitive to these changes. In the first part of the talk the author examines, based on examples from the Afrotropics, how anthropogenic activities, such as selective logging, forest fragmentation, agriculture, and hunting, influence amphibian communities (i.e. species and functional diversity) in different forest types and savanna. The second part of the talk focuses on the potential adaptability of particular amphibian species to environmental change, thereby illustrating how limited our knowledge, even concerning European species, still is.

Biodiversity is a multidimensional construct, but it is rarely treated as
such. Most often, we use the single metric of species richness to
quantify biodiversity loss though it is well known that functional,
phylogenetic, and other dimensions of biodiversity can be equally
important. We use structural equation modeling to explore how the loss of
diversity in multiple dimensions provides novel insights into the way
ecosystems function. We provide three examples; (1) the consequences of
herbivory on understory vegetation in a hardwood forest, (2) the
consequences of nitrogen enrichment on arctic tundra vegetation, and (3)
the consequences of biogeography on the fragility of bird communities in
the Solomon Islands. These studies support the argument that the well
documented, often adverse consequences of biodiversity loss on ecosystem
functions and services are likely to be more complex than prevailing
unidimensional studies have proven.

testgrp@ces.iisc.ernet.in

Intrasexual competition is ubiquitous in nature. In males, such competition for mates can lead to the evolution of conspicuous and costly morphological traits. However, competition through social interactions can
also occur for resources other than mates (such as food) and has been termed as social selection or social competition. Social competition in females, though not as conspicuous as that in males, may be widespread and is understudied. It can have important evolutionary consequences for individual phenotype and on the genetic and social structure of a population. Most of our understanding of traits involved in intrasexual competition comes from studies of males and less is known about social competition in females. Individuals can compete using physical fights. They are extremely costly and less common in females than in males, because of the inherent differences life histories of the two sexes. However, there are various alternatives to physical fights, an important one being
signalling and displays.
I propose to study intrasexual competition in females in a wild population of the Peninsular rock lizard* (Psammophilus dorsalis),* using a combination of observational and experimental approaches. These lizards can be easily be marked and followed over their lifetime. Preliminary work shows that females display towards other females and they vary in their display rates, using which they appear to compete among themselves for establishing and maintaining territories. Females also vary in their responses to a simulated intrusion. Thus, this study system is ideal for examining social competition in females.
This study will focus on the adaptiveness of signalling and aggression in females and examine differences between the sexes in these behavioural traits. I first plan to study territoriality (an outcome of competition) in females and compare patterns with those of males. I will also characterise physical features of territories to quantify the resources that might be under competition. I then propose to examine signalling and aggression over female lifetimes and study the factors influencing variation in these traits. I also plan to study the relationship between signalling and reproductive success in females. Finally, I propose to compare social signalling in intrasexual competition between males and females of *P. dorsalis*.

The evolution of elaborate phenotypic traits, which are widespread in the animal kingdom, is usually attributed to sexual selection. However, natural selection can impose constraints on the degree of elaboration of such traits. Therefore, animal signals reflect a balance between the two forces of natural and sexual selection. I am interested in understanding the relative strength of these forces in maintenance of a complex signal type: dynamic colour change. Males of the peninsular rock agama (*Psammophilus dorsalis*) exhibit rapid dynamic colour changes on their lateral and dorsal body regions during social interactions. The costs, benefits, and adaptive significance of this dynamic colour change is yet unknown.
The main objectives of my study are to: (1) examine the relative importance of different components of the dynamic colour signal by assessing behavioural responses of males and females to each signal component independently and together; (2) determine the information content of the multicomponent colour signal by examining whether the magnitude of colour change is associated with key measures of health and immunity, and (3) quantify the effect of ecological variables such as microhabitat, social intensity, and predation intensity on visual signalling.

An acoustic communication system consists of a sender, a receiver and a signal. In my thesis I have focused on the receiver. The model system I chose was the tree cricket species, Oecanthus henryi. In a cricket mating system, usually the male calls and the female recognizes and responds to the call. A female in a cricket mating system is thus faced with three kinds of issues: recognizing the conspecific call, localizing the call and discriminating among conspecific males based on individual differences in the calls. My thesis objectives are focused upon these three broad themes. I have examined the role of call carrier frequency in maintaining sender-receiver match thus aiding conspecific recognition. I have also explored the role of carrier frequency in discrimination among conspecific males. O. henryi is found in sympatry with a congeneric calling tree cricket species, O. indicus. I studied reproductive isolation between the two based on calls. Finally since O. henryi is found on bushes, the males and females are separated in azimuth as well as in elevation; hence I studied the mechanism of 3D sound localization in these insects.

Many terrestrial ectotherms are capable of rapid colour change, yet it is unclear how these animals accommodate the multiple functions of colour, particularly camouflage, communication and thermoregulation. I will discuss visible and near-infrared (NIR) colour change, the mechanisms that generate it, how it is used for communication, camouflage and thermoregulation, trade-offs between these functions and their evolutionary consequences.