Map of the world

Theory at the service of conservation


About

Tanjona

I am a Malagasy ecologist on a mission to protect our unique biodiversity. Since I am more skilled in Mathematics than identifying plants or animals, I primarily develop mathematical and statistical models to better understand patterns and processes of biodiversity loss.

I obtained a MSc in applied mathematics with Arthur Randrianarivony at the University of Antananarivo. I did a PhD with Ilkka Hanksi and Otso Ovaskainen at the University of Helsinki. I completed a first postdoc with Emma Goldberg at the University of Minnesota, and a second postdoc with Anthony Ives and Monica G. Turner at the University of Wisconsin-Madison (ACES). I am currently an adjunct professor at the department of Life Science and department of Mathematics at the University of Fianarantsoa. I am also a Honorary Fellow at the University of Wisconsin-Madison.


Research

I work at the interface of theoretical ecology and conservation biology. I assess the role of environmental variability, spatial processes, and species interactions to understand stability and resilience of ecosystems. I am not tied to a specific system and my work spans various continents: Asia, Europe, Northern America, and Madagascar, and involves topics such as phylogeography, paleoecology, and contemporary ecology. My work ranges from pure theoretical work to big data analyses. Still, my research are generally motivated by conservation related questions in Madagascar.
habitat destruction in Madagascar

Habitat destructions and landscape heterogeneity

There are two traditions for studying space in ecology: spatial ecology and landscape ecology. I use and combine the strength of both disciplines for applications in conservation biology to:

  • Quantify the loss of habitat quality, quantity, and fragmentation in Madagascar
  • Assess how much landscape details are needed to understand community dynamic in a fragmented landscapes
  • Elaborate on how species-area relationship (SAR) and its derivatives can be used to estimate biodiversity loss
  • thermal performance curve

    Species' niche

    Niche is a central ecological concept that characterizes how a species responds to the environment and thus for its conservation. My work aims to

  • Reconstruct species performance as a function of body size, temperature, and resource availability based on metabolic theory
  • Understand the efficiency of various plant regeneration strategies with respect to distrubance regime with a focus on stand-replacing fire
  • Infer fundamental and realized niche in changing environments both using theoretical and empirical work
  • extinction threshold as a function of niche breadth

    Stochastic processes

    Stochasticity (random variation) may change the fundamental ways in which systems functioned, rather than simply adding "noise" that made the patterns harder to see. Although stochasticity is present in all ecological systems, its role is underappreciated. With a focus on environmental stochasticity and more abstact concept, I

  • Assess the relative role of deterministic and stochastic processes for community assembly, stability, and resilience
  • Diversify the type of stochastic processes used in models (e.g., using processes with memory)
  • Explore ways to include environmental stochasticity in models (e.g., beyond additive noise)
  • phylogenetic pattern

    Miscellaneous

    I am broadly interested in method developments. I am developing phylogenetic comparative methods and a statistical approach to optimize fungal spores counting. I have been analyzing large spatiotemporal data: crop yield in the USA, evolution of malaria in Madagascar, and influence of political instability on the economy of Madagascar. If it hasn't be obvious yet, I am always excited to venture into new projects.


    Publications and in prep.

    Published

    • McCary, M.A., J. Phillips, T. Ramiadantsoa, L.A. Nell, A.R. McCormick, J.C. Botsch. Transient top-down and bottom-up effects of resources pulsed to multiple trophic levels. In press. in Ecology.
    • Kucharick, C.J., T. Ramiadantsoa, J. Zhang, A.R. Ives. Spatiotemporal trends in crop yields, yield variability, and yield gaps across the USA. Crop Science, 60(4), 2085-2101
    • Ramiadantsoa, T. , M.A. Stegner, J.W. Williams, and A.R. Ives. 2019. The potential role of intrinsic processes in generating abrupt and quasi-synchronous tree declines during the Holocene. Ecology, 100(2): e02579
    • Ramiadantsoa, T. , I. Hanski, and O. Ovaskainen. 2018. Responses of Generalist and Specialist Species to Fragmented Landscapes. Theoretical Population Biology. 124:31-40.
    • Ratajczak, Z., S.R. Carpenter, A.R. Ives, C.J. Kucharik, T. Ramiadantsoa, M. A. Stegner, J. W. Williams, J. Zhang, and M.G. Turner. 2018. Abrupt Change in Ecological Systems: Inference and Diagnosis. Trends in Ecology & Evolution, Volume 33, Issue 7.
    • Ihantamalala, F. A., F.M.J. Rakotoarimanana, T. Ramiadantsoa, J.M. Rakotondramanga, G. Pennober, F. Rakotomanana, S. Cauchemez, C.J.E. Metcalf, V. Herbreteau, and A. Wesolowski. 2018. Spatial and temporal dynamics of malaria in Madagascar. Malaria Journal 17, no. 1: 58.
    • Ramiadantsoa, T., J. Sirén, and I. Hanski. 2017. Phylogenetic comparative method for geographical radiation. Annales Zoologica Fennica Vol. 54. No. 1–4 (special issue in honor of Ilkka Hanski).
    • Ramiadantsoa, T., O. Ovaskainen, J. Rybicki, and I. Hanski. 2015. Large-scale habitat corridors for biodiversity conservation: A forest corridor in Madagascar. PloS ONE 10: e0132126.

    Submitted and in prep.

    Ramiadantsoa, T., Z. Ratajczak, M.G. Turner. A Goldilocks model for the response of fire-prone forests to changing fire regime: a case study of Yellowstone Nation Park. Submitted to Ecology.

    Rice, B., …, T. Ramiadantsoa, … C.J.E. Metcalf. High variation expected in the pace and burden of SARS-CoV-2 outbreaks across sub-Saharan Africa. Soumis à Nature

    Ramiadantsoa, T., E.M. Temba, H. Rakouth, H.J. Rakotoniriana. Evidence of biodiversity loss in Madagascar? A multi-taxa review.

    Ramiadantsoa, T., Solofondranohatra, C.L.,. Reconstructing Malagasy grassland during the Holocene. In prep. for Malagasy Nature.

    Ramiadantsoa, T. and A.R. Ives. Consequences of the structure of environmental variability on population and community stability. In prep. for Ecology Letters.

    Ramiadantsoa, T. and E.E. Goldberg. Exploring the role of body size in shaping thermal performance of insects.

    Perrotti, A.G., M. Traschel, T. Ramiadantsoa, ..., J.W. Williams. Optimal counting methods for coprophilous fungal spore analysis.

    Ramiadantsoa, T. , C.J.E. Metcalf. Selection of extreme life-history traits under hypervariable environments: a theoretical perspective.

    Ramiadantsoa, T., C. Fritsch. Extinction threshold and transient dynamics of orphaned plants.

    Rakotoarivelo, O., Ramiadantsoa, T., Economic impacts of political instability in Madagascar.


    Teaching and outreach

    I spent a bit of my time showing how mathematics can be applied to ecology and conservation, and giving a glimpse of the life of a research to high school students in Madagascar. I also co-founded (with Cara Brook) and teach workshops (E2M2)to improve quantitative skills in Madagascar. Benjamin Rice and I are supporting (financially and academically) master's students in the STEM field until completion of the thesis. I am also creating a new peer review scientific journal called "zava-boary" (nature in Malagasy) to provide masters students an opportunity to publish their work free of charge.

    My other activites include fostering cultural exchanges between Madagascar and other countries. I am a member of two societies: the Finnish-based (Suomi-Madagascar Seura) and the Malagasy-based (Madagascar-Finland). On top of cultural exchanges, we organize fund raising to help underprivileged students in Madagascar. Additionally, I have been organizing Malagasy language course for linguists students at the University of Helsinki.


    Contact & CV

    My CV
    Email: ramiadantsoa-AT-wisc.edu
    Twitter: @TRamiadantsoa