Plasticity and Heritability of Temperature Responses in the Cereal Aphid Guild Across Two Continental Gradients Observatoire des Sciences de l’Univers de Rennes (OSUR) Rennes Mercredi 4 décembre, 14h00

Soutenance de thèse de Ruining Li (ECOBIO)

The defense will take place on Wednesday, December 4, 2024, at 14:00.

Location: OSUR Conference Room, Beaulieu Campus, Rennes (Building 14b – Ground Floor, 263 Av. Général Leclerc).

Both the presentation and slides will be in English.

The list of the jury members:

Manuel MASSOT (Rap.) Researcher CNRS, Sorbonne Université, France

Emmanuel DESOUHANT (Rap.) Professor, Université de Lyon, France

Louise VAN OUDENHOVE (Exam.) Researcher INRAE, Institut Sofia Agrobiotech PACA, France

Cécile SULMON (Exam.) Professor, Université de Rennes, Rennes, France

Joan VAN BAAREN (Dir.) Professor, Université de Rennes, Rennes, France
Gang MA (Co-encadrante) Researcher, CAAS, Beijing, China

And also invite:

Chun-Sen Ma (Co-Dir.), Professor, Hebei University, Hebei, China

Cécile Le Lann (Co-encadrante), Associate Professor, Université de Rennes, Rennes, France

You can also join us by zoom with the link. [https://univ-rennes1-fr.zoom.us/j/62764225197](https://univ-rennes1-fr.zoom.us/j/62764225197)

Please find below the abstract of my thesis:

The guild of cereal aphids are pests that are widely distributed around the world and adopt different strategies in response to climate. In this thesis, we examine the thermal responses of the three species of the guild along a longitudinal gradient from west to east in Europe, characterized by an increase in seasonal and diurnal thermal variability. We measured the basal thermal tolerance (CTmax, CTmin, CCRT) of three species in spring and autumn, and acclimatised individuals to relevant temperature regimes to estimate their thermal plasticity and the heritability of their basal thermal tolerance. The results show that the maximum critical temperature (CTmax) increases steadily with extremes of heat along the European gradient. In addition, co-gradient and counter-gradient relationships were observed for the minimum critical temperature (CTmin) and the thermal range (CTmax – CTmin), while marked seasonality and harsh winters (in Eastern Europe) led to a convergence of thermal resistance traits between species. With regard to the link between thermal plasticity and heritability, the results show that the species Sitobion avenae exhibits greater plasticity to heat and cold in regions with greater fluctuations in daily temperature. In contrast, the plasticity of Rhopalosiphum padi did not vary along the gradient, but this species had a higher heritability for heat and cold tolerance.

The link between basal heat tolerance and seasonality makes it possible to test classic hypotheses, such as climate variability and climatic extremes. New perspectives are also emerging, notably on how biotic and abiotic factors influence thermal tolerance. External selection pressures may be more important than internal constraints, leading to a homogenisation of traits linked to heat tolerance in populations collected in eastern Europe. The heat plasticity of S. avenae is linked to local diurnal fluctuations in both Europe and China, despite the fitness costs that could explain its decline in abundance. The results of this thesis provide a better understanding of the responses of species to climate change and enable us to predict population dynamics in future scenarios.

Dates et horaires de début et de fin (année – mois – jour et heure) :
Début : 2024-12-04T14:00:00.000+01:00
Fin : 2024-12-04T17:00:00.000+01:00

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Observatoire des Sciences de l’Univers de Rennes (OSUR) Campus de Beaulieu, Bâtiment 14B, Salle de conférence Jeanne d’Arc – Longs Champs – Beaulieu Rennes 35703 Ille-et-Vilaine