Many species of tephritid flies (Diptera: Tephritidae) perform a wing waving display ('supination') to deter attacks from jumping spiders. This display, along with the dark bands on the wings, has been thought to deter spiders through a form of mimicry termed 'predator mimicry'. In a series of studies with jumping spiders and the Mexican fruit fly, I explored this interaction from a visual ecology perspective. Using an custom built eye-tracker that traces the movement of the retina in the principal eyes, I played videos of displaying flies and monitored the response. I describe the patterns of retinal movement of jumping spiders in three treatments: during fly display, fly walking and a still fly. We show that the deterrent effect is achieved by exploiting the sensory biases of the predator.

The pervasive effects of climate change on the biosphere are increasingly evident with many well-documented impacts on species ranges and phenological events. As ectotherms, the phenologies of plants and insects are highly sensitive to changes in temperature. The vast majority of studies of climate change effects on terrestrial organisms have focused on the responses of individual organisms to changes in temperature and precipitation patterns. Far fewer studies have examined the effects of climate change on biotic interactions, yet studies are vital for our understanding of how climate change has (and will continue to) alter communities and ecosystems. This talk explores how changing temperatures differentially alter the phenologies of members of a simple trophic community (cowparsnip, its insect herbivore – parsnip webworm, and its parasitoid wasp – Copidosoma sosares) across an elevational gradient, resulting in phenological matches in warmer years and mismatches in colder years. In cooler years, cowparsnips at higher elevations largely escape herbivory; in warmer years, cowparsnip populations at higher elevations experience reduced fitness due to substantially increased levels of herbivory.

The evolution and biogeography of various taxa in Peninsular India are of particular interest as this region, a Gondawanan fragment, is critical to our understanding of historical biogeography in the Oriental realm. Over the past decade, molecular tools have enabled testing of alternative historical scenarios of faunal exchange and consequent biogeographic patterns. The snakes of Peninsular India, despite their spectacular diversity, remain poorly known with regard to their biogeographic affinities. While most Indian snakes are considered to be Malayan relicts, this hypothesis remains unexplored. Hence, we explored historical patterns of dispersal and diversification within Peninsular India using two distantly related snakes with broad differences in ecology and biology; an arboreal, non-venomous genus, Ahaetulla (vine snakes), belonging to the family Colubridae, and the genus Trimeresurus (pit vipers) a group of terrestrial and arboreal, venomous snakes belonging to the family Viperidae.

First, using an extensive taxon sampling of snakes from Peninsular India and adjoining Northeast India, we delimited species using a coalescent method and a multi-criteria approach including genes, geography and morphology. The results reveal the presence of several new lineages of snakes, including morphologically cryptic lineages, in both genera. Second, using mitochondrial and nuclear DNA, we reconstructed the phylogenies of the delimited lineages. In vine snakes, we discovered a deeply divergent lineage (Proahaetulla gen. nov.) from the southern Western Ghats, that is sister to all remaining members of Ahaetulla. In Trimeresures, we recovered multiple clades, one of which is predominantly peninsular Indian with a few Southeast Asian lineages. Third, we tested for clade congruence in patterns of diversification and dispersal using ancestral range reconstruction of geographical ranges. In contrast to earlier hypotheses, Peninsular India emerged as a centre of snake diversification and Western Ghats as a major centre of in-situ radiation for both clades. Patterns of dispersal show signatures of congruence and contrast between the clades, with the Western Ghats acting as a major source for colonisation of ancestral lineages into the arid regions in Peninsular India and adjoining Sri Lanka as well as Southeast Asian regions.

Organizers: Dr. Maria Thaker (CES) and Dr. Meena Balgobal (Colorado State University)

Open to registered participants only.

Biocemented earthen structures like termite mounds are one amongst many examples of animal-built structures with exogenous and/or endogenous materials that have received scrutiny from architects, structural engineers and soil scientists. However, little is known about the process of construction at different length and time scales. In this interdisciplinary study between ecologists and engineers, we explore termite mound construction at micro-, meso- and macroscales represented by aggregation of soil into bricks with the help of termite secretions, cementation and curing of bricks, and densification and compaction of mound soil over its lifetime. The above processes occur over a wide range of time spans – from a few seconds to decades. This ongoing work provides us insights into the process of mound construction by close to a million termite individuals working in tandem without an architect or masterplan and leading to stable structures that are three orders of magnitude larger than individual termites and retain structural stability for decades.

The India-Asia collision in the early Tertiary and the subsequent climatic and geographic shifts had profound effect in shaping the biotic community on both the landmasses. However, the impact of such abiotic factors on freshwater invertebrates is not well understood. Freshwater snail family Viviparidae is known to have colonized India from Southeast Asia, but knowledge on the temporal pattern of these dispersals is lacking. Understanding these patterns will help us elucidate the role of climatic fluctuations and geographic changes in shaping the biogeography of freshwater organisms across the India-Southeast Asia interface. To this end, samples of all the described species of Viviparid snails were collected across the Indian subcontinent and multiple molecular markers were sequenced. Phylogenetic analysis, molecular dating, and ancestral area reconstruction were carried out with a dataset consisting of the Indian species and major Southeast Asian Viviparid genera. Preliminary results suggest independent colonization of the Indian subcontinent by two distinct lineages of viviparid snails. Furthermore, contrary to our expectations, one of the two lineages seems to have dispersed after the late Miocene aridification intensified in Peninsular India. A clearer picture will soon emerge following further analysis. Comparative studies on the ability of the two lineages to withstand aridity might provide insight into this intriguing pattern.

Why are there only 2 sexes? Why are sperm much smaller than eggs in most sexually reproducing organisms? In this talk, I will review the literature on the evolution of anisogamy. Theories for the evolution of anisogamy can be broadly divided into three categories-- those that emphasize the conflict between the sperm and egg strategies (and regard sperm as parasites), ones that emphasize the mechanisms of contact between eggs and sperm, and ones that stress on a uniparental inheritance of cytoplasmic DNA. Tests of these theories are often carried out on data from colonial green algal species, which show a range from isogamy to anisogamy.

TBA

Evolution is essentially quantitative and can be understood best via mathematical theories. But few courses or even text books cover basics of evolution in a quantitative way. In this context, I will introduce Price equation in an intuitive way. Its simple, elegant and easy to make sense of. I argue that basic evolutionary biology courses teach principles of evolution using Price Equation, which has a prerequisite of no more than an understanding of mean, variance, slope and correlation.

For most of the animals, if not all, finding their way to a particular place is crucial for survival. To address this challenge of way-finding, different animals have evolved with different homing strategies. Social hymenopterans like honey bees, ants and wasps are of special interest – foragers of these insects show excellent homing capabilities while having simple neural resources. In this study field, honey bees and ants (desert ants, in particular) are among the most studied animals. Compared to these insects, our understanding on the homing mechanisms of social wasp is rather poor. For my thesis, I have studied homing behaviour of the tropical social wasp Ropalidia marginata, a predator in their foraging habit. To begin with, first I had to know their typical foraging range, which I found to be within about 500 m from their nest. Forager wasps possess a surprisingly well-developed familiarity with their foraging landscape, apparently more intricate than honey bees and desert ants. They acquire this spatial familiarity through flying around the landscape before starting foraging for food. Compared to honey bees and desert ants, this learning period in wasps appears to be much longer – this can be attributed to the much higher density of the tropical landscape in which they have evolved. I have also found that, if needed, they can fly to a distance of about 1.5 km for foraging and can return to their nest even if passively displaced to familiar and unfamiliar places. To return from unfamiliar places, they probably use some sort of searching mechanisms – a skill that they improve with their age. Such searching behaviour is prevalent throughout other hymenopteran insects. I conclude that capability and mechanisms of spatial orientation, navigation and homing in animals are much influenced by their evolutionary origin and the environment in which they have evolved.