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Potential Oxygen Limitation of Distributions And Responses to Changing Climates In Ectotherms

Periodic Reporting for period 1 - PODARCIS (Potential Oxygen Limitation of Distributions And Responses to Changing Climates In Ectotherms)

Reporting period: 2017-06-19 to 2019-06-18

The effects of altitude-related hypoxia on the ability of organisms to colonize and adapt to these altitudes during warming have, to our knowledge, not received broad scientific interest. The work of project PODARCIS has provided empirical data to fill this gap and extend these results to broader applications.

Broad Objectives:

1. Assess the multivariate acclimation responses (i.e. plasticity) in embryos and adult lizards from low to high altitude using common garden and reciprocal transplant experiments. This will enable us to assess (i) if plastic responses are sufficient to enable colonization of high altitudes, and (ii) if changes in the degree of plasticity across the altitudinal gradient are consistent with theoretical expectations.

2. Predict the dynamics of colonization in wall lizards by integrating data on physiological plasticity, reproductive output and dispersal; and thereby generate a general framework applicable to all mountainous environments affected by climate change.

To achieve these results, this project conducted a number of transplant experiments with the lizard species Podarcis muralis. These experiments employed a range of techniques including measures of whole-organisms performance and behaviour (thermal preference trials, sprint speed, thermal maxima and minima); measures of whole-organism physiology (resting and maximal metabolic rates); blood biochemistry (haematocrit, haemoglobin concentration, reactive oxygen metabolite production); reproductive output (clutch size, relative clutch mass); and development (development time, embryonic heart rate, embryonic metabolic rate). We also included measurements of morphology on adult, embryonic, and hatching lizards. Taken together, this series of experiments provides empirical tests of the theory underlying our Hierarchical Mechanisms of Thermal Limitations hypothesis and informs our understanding of how this cosmopolitan and range-expanding species will likely respond to future warming environments in mountainous habitats.

The work conducted for Project PODARCIS represents a true collaboration between the hosting scientist (Fabien Aubret) and the fellow (Eric Gangloff). Within the study system established by Aubret, Gangloff designed and implemented this series of experiments. The hosting scientist and fellow regularly exchanged ideas through meetings, informal conversations, and electronic discussions. The project benefited greatly by combining the expertise in phenotypic plasticity and evolution from the hosting scientist and the physiological training of the fellow, resulting in the development of new theory and a set of empirical experiments to test this theory. In addition to the exchange between the hosting scientist and the fellow, the projects here were conducted in collaboration with a number of scientists from Europe and North America, including G. Antonio Cordero (Eberhard Karls Universität Tübingen, Tübingen, Germany), Rory Telemeco (California State University, Fresno, USA), Brooke Bodensteiner (Yale University, New Haven, CT, USA), Essie Rodgers (Australian National University, Canberra, Australia), and Andréaz Dupoué (Curtin University, Western Australia, Australia). Additionally, we mentored two graduate-level interns: Mahaut Sorlin (research engineer; July-November 2017) and Laura Kouyoumdjian (Master’s II Intern; February-September 2018) and provided support for their next career steps. Mahaut is currently a PhD student at the University of New Orleans, USA and Laura is applying for PhD programs in Europe and Australia.

Thanks to the research and career progress made during this fellowship, Eric Gangloff will begin a permanent, tenure-track position at Ohio Wesleyan University beginning August 2019. Furthermore, Gangloff and Aubret will continue collaborations in this system, with funding pending from European INTERREG POCTEFA (Programme Opérationnel de Coopération transfrontalière Espagne-France-Andorre) program to continue experiments in 2020 and 2021.
The work of Project PODARCIS has resulted in 3 peer-reviewed publications, 4 publications in preparation, 5 conference presentations, 2 invited seminars, and multiple outreach sessions.

All publications and other outputs acknowledge the funding received from the Marie Sklodowska-Curie programme under Horizon 2020 and are freely available through the Hyper Articles en Ligne (HAL) archive maintained by the Centre pour la communication scientifique directe (France). Future publications will also comply with these obligations.

Our preliminary findings indicate that the lizard Podarcis muralis will likely be a colonizer of higher-elevation habitats. While transplanted adult lizards do not fare well at extreme high elevations, our results suggest that a combination of local adaptation and developmental plasticity in response to early-life exposure to hypoxia will facilitate the gradual upward range expansion of this species. We continue to work to disseminate this information through publications in preparation and future conference presentations.
Project PODARCIS has advanced the field of ecophysiology, especially as it pertains to quantifying the impacts of climate change, through both the collection of novel experimental data and through the development of a new theoretical framework, the Hierarchical Mechanisms of Thermal Limits hypothesis. Such work is critical to predicting the effects of future climates on wild animals and toward developing management practices and interventions to preserve endangered species. PODARCIS has also contributed to conveying a peculiar message about climate change related issues, somehow more specific and applied than widely available others, to the general public visiting the Pic du midi and its staff.