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A century ago, our understanding of behavior was dominated by naturalists. Today, we can assess and manipulate nervous systems at genetic, molecular and physiological levels. Despite our tremendous focus on understanding the brain, we still know remarkably little about how even simple brains generate complex behaviors. By studying natural behavior and the processing of natural stimuli across animals, we can unite these modern scientific techniques with natural observations to truly understand how brains make decisions in our complex world.
Our research employs a comparative approach to understand how insect brains parse the complex natural chemical environment to generate decisions. By all accounts, insects are masters of our animal kingdom. In fact, estimates suggest there are 100 times more species of insects than any other animal taxa1. The insect “microbrain” is also capable of incredibly complex decisions using a tractable nervous system. Finally, insects are known for their exquisite olfactory capabilities and use chemicals to locate mates, food, egg-laying sites, and to avoid danger, among others.
Our current research focuses on two major questions: By what mechanisms can nervous systems evolve to generate novel decisions? And second, how do nervous systems adapt to make the same decisions in diverse environments? For the first question, we examine the chemosensory basis for sympatric speciation events in Rhagoletis flies. For the second, we study how similar transcontinental species of hoverflies pollinate in subartic Swedish meadows, the Himalayan mountains, and even South Indian rainforests. We endeavor that our comparisons will allow us to generate overarching principles for decision making constrained by fundamental concepts, rather than specific physiologies.
1. Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G. B. & Worm, B. How many species are there on earth and in the ocean? Plos Biol 9, e1001127 (2011).
Avian malaria parasites (Plasmodium spp.) are prevalent worldwide, but information about their impact on birds, especially during primary infections is insufficient. In the first part of the talk I will overview the results of our recent experimental studies showing parasites development strategies and importance of the parasites to some bird
species; such data is underestimated in field studies. In the second part of the talk I will show the importance of the knowledge of classical biology and will illustrate how such information can be used together with new technologies. First, developing new methods to generate large amounts of purified DNA and working with single cells of pathogenic organisms, which can be separated using laser micro-dissection system. Both methods were developed using avian haemosporidian parasites and could be applied for molecular analysis of various microorganisms.
The third episode examines the spiders and others that produce silk. Attenborough visits New Zealand's Waitomo Caves, which are inhabited by fungus gnats whose illuminated larvae sit atop glistening, beaded filaments to lure their prey. The ability to spin silk developed early in the invertebrates' history, being first used as an adhesive. The female lacewing still applies it in this way, to suspend its eggs from plant stems. Spiders first employed it as a sensitive trip line to detect movement, and Attenborough illustrates this by encouraging a trapdoor spider. The speed with which it appears causes the presenter to jump in surprise. The webs spun by orb-weavers are complex and can comprise up to 60 metres of silk and 3,000 separate attachments. A time-lapse sequence reveals their intricate construction. The largest are made by Nephila and can be several metres across. The venomous redback spins three-dimensionally, and fixes vertical lines that suspend its unlucky meals in mid-air. Meanwhile, the bolas spider swings a length of silk with a sticky blob on the end, with which to snare passing moths. Argiope exemplifies the dangers of mating that are faced by some male spiders: unless they are careful, they can be consumed by the females. The courtship of the wolf spider, though less risky, is one of the more elaborate. Its nesting habits are discussed, along with the eventual birth of its young, which cling to their mother's back.
It is increasingly important from both a theoretical and a practical viewpoint to understand the patterns of biodiversity and ecosystem functioning in agricultural areas, especially in
areas that were cleared from rich tropical rainforest. The Western Ghats of India are one of the richest biodiversity hotspots in the world, yet only 6% of the Ghats remain under original vegetation. Much of the Ghats are planted with coffee – often grown under heavy shade provided by native trees – and tea, which is grown under scant shade provided by exotic trees. Bat species distributions are poorly known from the Western Ghats; no data exists on the response of bats to tea plantations anywhere in the world; and there is little data on how Old World bats respond to coffee plantations.
Bats play important roles in ecosystem functioning. They occupy many different trophic niches, so are likely to show a wide range of responses to habitat degradation and conversion. We
looked at changes in bat species composition from reserve forests to forest fragments, and again from coffee plantations to tea plantations. We assessed the functional diversity of bats retained in various habitats within the modified landscape - using a multiple trait space based approach to functional diversity for the first time in bats - by quantifying a range of traits from
diet to wingspan that affect a species’ ecological role. We also assessed the degree of trait filtering occurring in heavily modified plantation types. Further spatial analyses revealed how bats are using the mosaic landscape under study, and help assess the degree to which further habitat modification could impact different bat species.
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The Northwest Atlantic has become a notorious example of fishing down
marine food webs. It is also an uncontrolled experiment testing the
performances of marine populations under extremes of abundance. In this
talk I draw upon field experiments and long-term monitoring of two of the
region’s iconic commercial species - sea urchins and lobsters - to
illustrate how an altered food web is testing species performance under
demographic extremes. On one hand, depleted sea urchin populations have
failed to recover likely because they need large spawning aggregations to
reproduce, and the dense kelp beds that have resurged in the absence of
these grazers further inhibit larval recruitment. In contrast, the collapse
of top predatory fish, such as cod, has allowed lobsters to increase to
historic highs, such that crowding is evident from changes in habitat use,
shelter competition and heightened intra-specific predation. As conservation
measures are implemented in the region, fishery scientists
must seize upon these opportunities to understand population dynamics at
the poorly studied extremes of abundance.
The ocean is the largest living space in the world and covers at present 70.8% of the surface of the Earth. But we should really think of the ocean in terms of volume – around 1,370 million km3. Biodiversity cannot be likened to a simple list of species that inhabit a particular ecosystem. It is considerably more than a catalog or inventory, and in fact includes the entire set of relationships between living beings among themselves and with their environment. The physical consequences of osmotic flux (water and electrolytes) in the marine environment led living organisms to different strategies. The recognized species diversity in the ocean does not exceed 13% of all living species currently described – less than 250 000. This is very little, and may be explained for two reasons.
The first is that our knowledge, especially for deep zones and for microorganisms, various bacteria and protists is still only very partial, so we significantly underestimate oceanic diversity. New techniques, such as coupling between flow cytometry and molecular probes, are allowing us to discover extraordinary biological diversity. At present, widespread sequencing of the ocean water mass, "random genome sequencing" provides data that seems to be mostly unknown. The very recent Tara Oceans expedition's circumnavigation of the world's ocean provides us with valuable information on the abundance and variety of viruses, bacteria and mainly protists. For all prokaryotes and very small eukaryotes, molecular approaches (sequencing of 16S or 18S ribosomal RNA among others) bring surprising new information every day.
Discerning spatial patterns of biodiversity and understanding their proximate and ultimate causes is central to biogeography and one of the key concepts in macroecology. Two of the best-documented spatial patterns of biodiversity are the latitudinal and elevational gradients in species richness. After more than a century of research on species richness along both gradients, we know that both ecological and evolutionary factors may drive the distribution of species along these gradients. While the influence of these factors on overall richness has been studied, their effect on the distribution of species as mediated by species-specific traits has received far less attention.
Different groups with varying life histories, traits and adaptations are likely to behave differently in response to their environment. For my study, I will examine the distribution patterns of different functional types of plants along elevational gradients. I will further examine how these patterns contribute to the plant species richness along the gradient. Species traits have also been shown to influence the geographic range size of a species. However, our understanding of how plant traits influence species elevational range size is still very poor. Hence, I will examine how plant traits interact with an environmental gradient to influence species range sizes. Such studies involving species range limits are important in the context of rapid climate change.
Theory posits that growth rate, fecundity and survival decrease towards range margins due to change in environmental conditions. But how these changes in environmental conditions towards the edges affect functional traits of species and how both factors together impose limitations on elevational range expansion is not well known.
Overall, my study will focus on both the patterns as well as the processes of distribution and diversity along elevational gradients.