Behavioural and physiological plasticity are key drivers of ecological patterns, such as
dispersal, predator–prey interactions and reproduction, thereby affecting the distribution of species and influencing ecosystem functioning. Species with apparently very similar ecological requirements can exhibit opposite ability to cope with anthropic disturbances: some decline drastically while others manage to quickly expand their population, and even invade new ecosytems. Distinctive phenotypic or life-history traits( 1) are regularly investigated to explain the ecological success or decline of species. Surprisingly, cognitive ability is rarely considered in conservation context (2). Learning capacities and behavioural flexibility allowing to cope with novel conditions are potentially key traits when conditions are changing rapidly. Behavioural flexibility is correlated with increased growth rate, greater foraging and reproductive success, and better ability to detect and evade predators (3,4). It is both strongly repeatable and variable between individuals within the same population (5). By contrast, native population in rather stable environment, with low selection pressure for plasticity, may be unable to adjust their behaviour to rapidly changing environment, which in turn increase their susceptibility to
invasive alien species.

We propose to explore the importance of behavioural plasticity in a context of conservation in two freshwater benthic fish species with overlapping ecological niche. The invasive fish species, the round goby Neogobius melanostomus is a rapidly invasive alien fish species. It is originated from the Ponto-caspian region, was introduced by boat water ballasts 20 years ago in the region of the Great Lakes in North America, where this species is now ubiquitous and has dramatic consequences on the native fauna (6). More recently, populations are settled in Western Europe rivers, notably in France: the invasion front is currently located in Saone river, in Bourgogne Franche-Comté (7). The invasion front is expected to reach the river Rhône and the major alpine lakes (Lake Geneva, Lake Annecy, Lake Bourget) in the next few years. The Rhône Apron Zingel asper is endemic to the River Durance and River Doubs. The IUCN rates this species as being « critically endangered », and it is the under the close monitoring of national action plans for its urgent conservation (Plan national d’actions en faveur de l’Apron du Rhône 2020-2030). Due to their similar benthic life and almost perfectly matching ecological niche, this species is at high risk to be outcompeted by the invasive Goby which has been observed in rivers connected to the basin of the Apron.
These biological models provide unique opportunity to compare behavioural,
ecological and physiological performances of two benthic species with close ecological
requirement, the invasive goby strongly threatening the conservation of the endangered
Apron. This research project will involve field work in North-East of France for population
sampling and in natura behavioural experiment. The aim of the project is to assess the
behavioural and physiological plasticity that could partly explain their local ecological success.
To this end, different individuals will be sampled along the invasion gradient (Goby), or from one of its native populations in Doubs River (Apron). We will compare their performance using a wide range of integrative tools including behavioural phenotyping, measures of acoustic communication between individuals using hydrophone (8) and in vivo ecophysiology performances (swim ability, oxygen consumption, fecundity, aging, life span). We also intend to assess the competitive ability of both species in terms of foraging and territoriality. These measures will be correlated with behavioural flexibility tests based on the ability to cope with novel situations (response to novelty, such as anthropic noise) or to learn novel foraging opportunity. We propose to develop automated set-up combining visual and acoustic stimulus with food rewards (9) based on Raspberry PI units. This project has important applied implications in term of conservation. We would like to assess and anticipate the ability to the Apron to cope with the imminent encounters with the Round goby. We aim at gaining knowledge that will enhance the management and conservation of our freshwater ecosystems.

Supervision.
This PhD thesis will be co-supervised by a behavioural ecologist specialized in the evolution of mating tactics (F.-X. Dechaume-Moncharmont, Lehna, Lyon), an ecologist with special interest in foraging strategy and acoustic communication in fish species (Vincent Médoc, ENES – CNRL, Saint-Etienne), and an ecophysiologist (Loic Teulier, Lehna, Lyon) specialized in bioenergetic efficiency in fish species. This work will also be performed in collaboration with the OFB (Office Français de la Biodiversité) which monitors the invasion of the Round Goby, and the PNA Apron for the urgent protection of this species.

Applicants.
Applicants should have a Master (MSc) and a strong background in at least one of the following areas: animal behaviour, ecology, ecophysiology, or conservation biology. Solid knowledge in statistics would be appreciated.

References :
(1) Chuang, A. et al. Glob Change Biol 22, 494–512 (2016).
(2) Szabo, B. et al. Front. Ecol. Evol. 8, 187 (2020).
(3) Cauchoix, M. et al. Front. Ecol. Evol. 8, 106 (2020)
(4) Berger-Tal, O. et al. in Conservation Behavior (eds. Berger-Tal, O. et al.) 95–120 (Cambridge University Press, 2016).
(5) Cauchoix, M. et al. Phil. Trans. R. Soc. B 373, 20170281 (2018).
(6) Kornis, M. S. et al. Journal of Fish Biology 80, 235–285 (2012)
(7) Manné, S. et al. Knowl. Managt. Aquatic Ecosyst. 02 (2013).
(8) Zeyl, J. N. et al. Journal of Experimental Biology 216, 1075–1084 (2013).
(9) Griebling, H. J. et al. Animal Behaviour 170,
43–50 (2020)

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