Sujet de thèse sur les stratégies de reproduction alternatives chez le gobie

DOCTORAL SCHOOL E2M2
E2M2 COMPETITIVE RECRUITMENT FOR DOCTORAL CONTRACTS / CAMPAIGN 2020
Subject: Alternative reproductive tactics in structured populations of invasive fish species
Scientific Research theme: Evolutionary biology, Population biology, Ecophysiology
PhD supervisor (NOM Prénom) :
DECHAUME-MONCHARMONT F.-Xavier
Research unit:
LEHNA, UMR 5023, Lyon
Co-supervisor (NOM Prénom):
MEDOC VincentResearch unit:
ENES/CRNL, UMR CNRS 5292, St-Etienne
E-mail: fx.dechaume@univ-lyon1.fr E-Mail : vincent.medoc@univ-st-etienne.fr
 

In  polygynous  or  polygynandrous  species,  strongly  biased  operational  sex-ratios  (OSR) frequently induce high male reproductive skew. Such an intense male -male competition over access to females leads to the evolution of strategies characterized by high-competitiveness1, dominance,  territoriality  and  aggressive  partner  monopolization.  Yet,  sympatric polymorphisms  in which several alternative mating tactics  co-exist as the result of  frequency dependant games2.  Population of dominant morphs  in which males actively defend territory or females can be invaded by sneaker males, which are typically smaller and less aggressive than dominant males.  This  existence of multiple optimal investments  in competitiveness is  the result of the trade-off between being able to acquire many or high-quality resources and the ability to make the best use of these resources. Sneaker males typically attain many extra-pair copulations  without  investing  in  territorial  defence,  thus  achieving  reproductive  success equivalent to the one of more dominant morphs.
During  expansion  of  their  range,  invasive  species  experience  contrasted  conditions along the invasion gradient: the evolutionary pressures are rather different  at the invasion front  and  at the range-core. For example, low densities at the edge of the range mean that males should experience lower sexual  competition. Thus, investment into reproduction may trade-off with adaptations for more rapid dispersal: recent invasion unleashes evolutionary and ecological pressures and should favour low resource allocation to reproduction3.

Biological  model  and  field  work.  We  propose  to  explore  the  evolution  of  alternative reproductive  tactics  in  a  rapidly  invasive  fish  species,  the  round  goby  Neogobius melanostomus. Round gobies, originated from the Ponto-caspian region, were 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  fauna4. More recently,  populations are now settled  in  Western Europe  rivers, notably in France: the invasion front is currently located in the rivers of Alsace-Lorraine in North-East of France5.  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.
In this species,  a polymorphism of reproductive strategies has been characterized by the presence in the same  population  of several alternative tactics of reproduction6,7: certain so-called Guarder  males invest substantially in reproduction (defence of the partner and the territory,  nest  building,  parental  care),  and  other  males  called  Sneakers  favour  a  lower investment  in  reproduction  and  seeking  to  obtain  st ealthy  copulations,  less  effective  than those of the Guarders but also less costly in time and energy.
This biological model provides unique opportunity to compare behavioural, ecological and  physiological  performances  between  populations  at  different  stages  of  the  invasive process.  This  research  project  will  involve  several  field  trips  in  North-East  of  France  for population  sampling  and  in  natura  behavioural  observations.  The  aim  of  the  project  is  to decipher the underlying constraints controlling the alternative reproductive tactics and their local ecological success. To this end, different populations will be sampled along the invasion gradient  and  compared  using  a  wide  range  of  integrative  tools  including  behavioural phenotyping,  measures  of  acoustic  communication  using  hydrophone8 and  in  vivo ecophysiology performances (swim ability, oxygen consumption,  fecundity, aging, life span).
We also intend to  compare  the competitive ability of  these  morphs  (Guarder  vs.  Sneaker)  in terms  of  foraging  or  territoriality  against  other  non-invasive  species  and  therefore  gain 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 (FXDM, Lehna, Lyon), an ecologist with special interest in foraging strategy and acoustic communication in fish species (VM, ENES – CNRL, Saint-Etienne), and an ecophysiologist (Loic Teulier,  Lehna, Lyon) specialized in  bioenergetic efficiency in fish species.
 

Applicants. Applicants should have a Master (MSc) and a strong background in at least one of the  following areas:  animal behaviour, ecology,  or ecophysiology. Solid knowledge in statistics would be appreciated.
References : 1 Dechaume-Moncharmont, F.-X. et al. Animal Behaviour 114, 249–260 (2016).
2 Baldauf, S. A. et al. Nature Communications 5, 5233 (2014). 3 Friesen, C. R. et al. Biol. Lett.
15,  20190339  (2019).  4  Kornis,  M.  S.  et  al.  Journal  of  Fish  Biology  80,  235–285  (2012).
5 Manné, S.  et al.  Knowl. Managt. Aquatic Ecosyst.  02 (2013).  6  Myles-Gonzalez, E.  et al.
Behav Ecol 26, 1083–1090 (2015). 7 McCallum, E. S. et al. Can. J. Fish. Aquat. Sci. 76, 1562–
1570 (2018). 8 Zeyl, J. N. et al. Journal of Experimental Biology 216, 1075–1084 (2013)