South Africa lies at the meeting point of two ocean systems and experiences significant clines in environmental parameters such as temperature and productivity, which in turn affect the composition and species diversity along its coastline. As such, several biogeographic regions are recognised, which differ in faunal and floral composition. My talk examines the genetic, and more recently, genomic advances that try to unravel the processes that have shaped the patterns of species diversity, particularly in South Africa, with particular emphasis on the past fifteen years. My talk provides an overview of the natural history of South Africa, its marine biogeography and the challenges, constraints and successes of our lab in sequencing species at different spatio-temporal scales and contributing towards highlighting South Africa not only as a region of exception natural interest, but also scientific excellence.

Agricultural intensification is regarded as a potential solution to the rising demand for food while limiting further loss of habitat. However, agricultural lands can be rich in biodiversity and changes to way those lands are managed have the potential to drive substantial biodiversity loss. We therefore have an imperative to understand how species use landscape elements in farmlands to help develop strategies that can minimize losses in the face of intensification. In this seminar I will present case studies showing how spatial and temporal variation in the farming matrix influences reptile and frog communities and individual species. Which taxon is most at risk? How are they influenced by crop harvesting? How is their capacity to orient towards habitat altered by changes in agricultural practices? What is the risk of predation across landscape elements? Answers to these questions provide new insight into the complex responses of wildlife to changes in farming landscapes, but also provide some guidance for conservation planning as we move forwards towards peak-human.

Agricultural intensification is regarded as a potential solution to the rising demand for food while limiting further loss of habitat. However, agricultural lands can be rich in biodiversity and changes to way those lands are managed have the potential to drive substantial biodiversity loss. We therefore have an imperative to understand how species use landscape elements in farmlands to help develop strategies that can minimize losses in the face of intensification. In this seminar I will present case studies showing how spatial and temporal variation in the farming matrix influences reptile and frog communities and individual species. Which taxon is most at risk? How are they influenced by crop harvesting? How is their capacity to orient towards habitat altered by changes in agricultural practices? What is the risk of predation across landscape elements? Answers to these questions provide new insight into the complex responses of wildlife to changes in farming landscapes, but also provide some guidance for conservation planning as we move forwards towards peak-human.

Anand Malligavad is the head Projects and CSR of Sansera Foundation. He spearheaded the CSR initiative by his company to restore Kyalasanahalli lake in Anekal Taluk outside Bangalore. When the company
started this initiative in early 2017, there was hardly any water in the lake, and the lake suffered from encroachment and dumping of construction materials. We will first screen a short movie that describes
how Anand and his team worked with the villages around the lake to reclaim land from encroachment, desilt the lake and increase its water holding capacity by 27 times. With heavy monsoons last year, the lake
is now fully restored. Partnering with the NGO SayTrees, 6000 saplings were planted by volunteers on World Environment Day last year, including a large Miyawaki forest where local species of trees are
planted in high density. The lake environment is now attracting many species of birds, fish and insects and may serve as an interesting venue for ecological research. Anand will describe how the success of
this project has inspired other companies to take up restoration of other lakes in Anekal taluk-- the goal being to rejuvenate all the interconnected lakes in that area. He will briefly talk about other CSR
projects of his company in that area, including working with 22 government schools to improve the quality of education, and involve children in planting Miyawaki forests in their school compounds. Anand will
also provide pointers on approaching companies for CSR funding for environmentally or socially relevant projects.

Connectivity is considered to be essential in enhancing biodiversity conservation efforts and for benefiting adjacent areas. In the marine environment, connectivity among populations arises from dispersal during the larval stage for most sedentary species and particularly among sessile benthic invertebrates. Offspring released into the water column are transported and dispersed almost passively by water flow due to limited larval motility as compared to the horizontal flow speed. As a consequence, the spatio-temporal variability of hydrodynamics primarily shapes larval transport, which is the integration of larval dispersal over the pelagic larval duration of a species. Ocean modelling works well for hindcasting realistic coastal circulation, and can provide a comprehensive description of flow variability at high spatial and temporal resolutions, which improves the description of larval transport. In this talk, I will examine how larval transport estimates derived from bio-physical modelling can be useful to marine biodiversity conservation through the design of Marine Protected Areas (MPAs), by taking examples from the Mediterranean Sea. Species persistence in both isolated MPAs and in a network of MPAs will be discussed.

Wings in insects come in many forms. I will show how coloration and wings in insect wings are shaped by different and conflicting selection pressures. I will do this by presenting results and conclusions from several studies. 1) By estimating damselfly wing reflectance, and use receptor noise models we have explored the visual discriminability of wing coloration in a three level system: bird, damselfly and fly. Results show that males are more discriminable. 2) I will also show how bird predation selects for wing shape and wing coloration in a damselfly system. 3) By using a phylogenetic approach we have shown that wing shape and wing coloration are associated. Our results show interesting differences in wing shape among species that probably are shaped by sexual selection. 4) Finally, I will present results from a study exploring how range size and migration affects wing shape in North American dragonflies.

Phylogeography is an important tool when studying how genetic variation is distributed in space within and among species. In a conservation genetic context, phylogeographic information can be used to identify Evolutionary Significant Units and Management Units. Such are important when identifying unique evolutionary lineages among species and when preserving local adaptations.

In this talk I will present my research on the phylogeography of two closely related cold adapted grouse species: the willow grouse (Lagopus lagopus) and the rock ptarmigan (L. muta). I will show that local rock ptarmigan populations are highly differentiated and while such structure also can be revealed among willow grouse populations the phylogeographic signal is often less clear. This is what is expected from microhabitat use and the extent of habitat distribution of each species. Nevertheless, local adaptation to climate can be seen in peripheral some populations on the British isles where whole genome data suggest differentiation among a number of candidate genes but also regions of the genome with low variation.

This thesis is spurred by the overarching question “why is a plant where it is in space and time?”, asked in the context of a tropical dry forest plant community in southern India, based on long-term research conducted in a large (0.5 km2) permanent sampling plot. We attempted to deconstruct the structure and dynamics of the plant community by first establishing the spatial structure of soils, topography and lithology in the plot. We then assessed how this spatial structure, together with temporal variation in precipitation, affected abundances of the eight most dominant species in the plot. Finally, we broke up abundance variation into the components of recruitment, mortality and stem radial growth and assessed how these respond to variation in environmental factors (precipitation, temperature, soils, topography and fire) and biotic neighborhoods.

Local-scale lithological variation was an important first-order control over soil variability at the hillslope scale in this tropical dry forest, by both direct influence on nutrient stocks and indirect influence via control of local relief. Species separated into two broad groups in niche space – one consisting of three canopy species and the other of a canopy species and four understory species – along axes that corresponded mainly to variation in soil P, Al and a topographic index of wetness. Our results suggest that this tropical dry forest community consists of several tree species with broadly overlapping niches, and where significant niche differences do exist, they are parsimoniously viewed as autecological differences between species that exist independently of interspecific interactions. Temporal environmental factors (time since last fire, precipitation, and minimum and maximum temperatures) appear to be the strongest drivers of dynamics in this community, followed by conspecific and heterospecific neighborhoods, followed by spatial environmental factors (soils and topography). It is hoped these results will provide information relevant to understanding, managing, and predicting the future of this ecosystem and contribute towards the development of general theories of plant community ecology

Hi! My name is Sandhya and I am an alumnus of CES. I passed out in 2013, and I transitioned into a career in popular science.
In this talk, I will wander through my career trajectory from academia to science writing, a detour into entrepreneurship and onto my current role as Programme Manager for
Mongabay-India. It all may look neat when summed up in one line, but I will share the questions and doubts that were an integral part of this journey. It will not be all
about me though -- I will entertain questions throughout and try to put across larger themes that everyone can take home and adapt to their individual journeys.

Ecosystems can exhibit multiple stable states at similar external conditions. Such systems shift from one stable state to another abruptly and discontinuously, when they cross certain threshold parameters. Some examples of such abrupt shifts include coral bleaching, woodland encroachment of grasslands and desertification in semi-arid ecosystems. These transitions in ecosystems are often associated with loss of biodiversity and economic impacts, therefore are important to predict. These systems with multiple stable states, in some cases, can be understood as systems with a free energy functional having multiple local minima. In this theoretical framework, these abrupt transitions in ecosystems are similar to the discontinuous or first order phase transitions. In this thesis, we use the tools from the theory of non-equilibrium phase transitions to understand the mechanisms that cause abrupt transitions in spatially extended ecosystems and the statistical properties of these systems which can help us predict them.

Previous studies have shown that strong local positive feedback among individuals is an important mechanism for systems to have multiple stable states. In our study, we use a lattice based model of vegetation dynamics with basic processes as birth, death and positive feedback among individuals. In its simple version, this model is in the same universality class as directed percolation which is well known to exhibit a continuous phase transition from an active state to an absorbing state. Using master equation expansion for finite sized systems, we construct stochastic differential equations for our discrete state lattice model. We analytically show that systems with finite size can have multiple stable states even in the absence of positive feedbacks. Our numerical simulations of the spatial models confirm these results. Small sized ecological systems, therefore, can undergo discontinuous transition from an active high density state to a bare state where larger ecosystems would have survived.

It is well-known that systems close to a continuous phase transition show slow recovery from the perturbations. This phenomenon is known as critical slowing down. Since ecological systems are finite in extent and rarely in steady states, signatures of critical slowing down are seen before the discontinuous transition as well. In spatial systems, critical slowing down manifests as increase in spatial correlations and spatial variance in the system. Theoretical studies have shown that these signatures can be used as early warning signals for the imminent transitions. These spatial signals have been tested in microbial systems in lab, but few studies show their validity in the field. We hypothesize that above spatial metrics increase when a transition occurs along the gradient of driver in space. We first test this “space-for-time substitution” in a lattice model where driver changes along space. This model shows a transition from one state to another across space. We show that spatial metrics like variance and correlations show an increase even before the transition along the spatial gradient of driver. We, then, test these theoretical predictions in a savanna ecosystem using remotely-sensed and the ground-truthed data. In this ecosystem, grassland and woodland states co-occur at similar rainfall values and the abrupt transition occurs along the rainfall gradient in space. We show that critical slowing down based spatial indicators show theoretically expected trends before the transition. Therefore, we argue that simple spatial metrics can be used to anticipate the abrupt shifts in large-scale ecosystems.

In addition to the early warning signals, it is important to quantitatively estimate the threshold parameter at which the system is likely to shift to another state. To estimate this threshold, we use the property of phase transitions that systems show diverging correlations at the critical point. Therefore, in finite ecosystems showing alternative stable states, we hypothesize that the spatial location at which variance and correlation in the state variable are maximum will be closest to the transition. We used a spatially-explicit model of vegetation dynamics in which the driver value shows a gradient in space. We show that the point at which spatial variance and correlation in vegetation are maximum, is indeed the critical point of the system. We then test this method of finding the critical point in real ecosystems by analysing spatial data from regions of Africa and Australia that exhibit alternative vegetation biomes.

In summary, we employ a model from non-equilibrium statistical physics to understand abrupt transitions in ecological systems. We show that stochasticity caused by finite sized systems can lead to abrupt transitions in spatial ecosystems. We suggest simple spatial metrics to quantify critical points in real ecosystems, offering a significant advance from current studies that only proposed qualitative metrics of proximity to critical points. This thesis presents an elegant example of how principles of nonequilibrium phase transitions can be applied to a complex biological system, by modelling and testing their predictions with data from ecosystems.