Menu Content/Inhalt
Home
Sujet de thèse en écophysiologie

Conflits entre balance hydrique et thermique pendant la reproduction: une base de la vulnérabilité climatique chez un reptile vivipare?

Ecole Doctorale 227, Muséum National d'Histoire Naturel-Sorbonne Universités - 2018
 
Adder by Olivier Lourdais
 
 
Last Updated ( dimanche, 01 avril 2018 )
Read more...
 
ANR Aquatherm on the right track
A project funded by Agence Nationale de la Recherche in France to support a group of four CNRS and University laboratories working on ecological impacts of climate change in wild populations of terrestrial ectotherms.
 
Check our latest news at our Wix Website
Read more...
 
Should i stay or should i go?
Water restriction should initiate a range of behaviors related to a flight response. However, there is little evidence that changes in water availability across development influence offspring behavior in wild animals. Experiments with lizards demonstrate that maternal water restriction increased the anxiety of their juveniles, whereas their exploration was higher in dry environments. Thus, water availability may be a critical determinant of space use behavior and dispersal syndromes.
 
Read more at BES website
 
Les télomères biomarqueurs de l'extinction
 Les signaux d’alerte précoce des extinctions catastrophiques sont devenus récemment un paramètre crucial à déterminer afin d’anticiper les trajectoires des populations. L’utilisation des réponses fonctionnelles des espèces aux changements environnementaux pour préciser ces signaux d’alerte demeure encore largement inexploitée. Nous proposons dans cette étude que la longueur des télomères, séquences d’ADN non codantes et protectrices des chromosomes, représente un outil moléculaire prometteur pour alerter sur le déclin précoce de la population. En effet, la réduction de taille des télomères est fréquemment associée aux processus de vieillissement et peut être accélérée par une exposition chronique à des facteurs de stress environnementaux. Afin de tester cette proposition, nous avons mesuré les télomères de lézards vivipares (Zootoca vivipara) du même âge moyen dans 10 populations naturelles le long d’un gradient de risque d’extinction lié aux changements climatiques. De manière remarquable, nous avons trouvé des télomères extrêmement courts dans les populations en voie d’extinction par rapport aux populations non menacées. Les résultats de cette étude identifient donc les télomères comme un biomarqueur extrêmement prometteur et un mécanisme probable du risque d’extinction des populations en milieu naturel.
 

Photograph of a lizard in the field by A. Dupoué

Photographie sur le terrain d'A. Dupoué

Voir l'article dans Scientific Reports
 
Last Updated ( dimanche, 01 avril 2018 )
 
Parent-offspring conflict and water

When water is running out, mothers optimise their reproductive effort at the expanse of offspring survival

The relationships between a parent and its offspring are conflictual in almost all organisms. In nature, parent-offspring conflicts can occur whenever resources become depleted. Conflicts are usually examined when parents bred their offspring, but gestation also represents a battleground for conflicts between mothers and their embryos. Though mother-offspring conflicts have typically been investigated for energy, we recently demonstrated that it may also occur whenever water availability becomes limited. In this new study, we examined the occurrence of an allocation trade-off for water between pregnant female lizards and their offspring, and consequences of water restriction during gestation on their growth, survival and reproduction. Using robust experimental methods, we restricted the access to water in half of the pregnant females during two weeks, a significant proportion of the gestation time. Changes in physiology (hydration state and stress hormones) during water restriction were examined and compared with those of non reproductive lizards, and future performances were scored in outdoor enclosures. All lizards were dehydrated and potentially chronically stressed in response to water restriction. In pregnant females, the intensity of dehydration increased with the number of offspring, but water restriction had no impact on current reproductive performances. Thus, the female water balance was traded in favour of immediate reproduction success in this lizard species. Water restriction resulted in higher future reproductive effort the second year for females but a lower survival rate for their offspring. Thus, water restriction triggered unforeseen intergenerational conflicts between future offspring survival and future maternal reproductive effort. Such conflicts may be critical for our understanding of major transitions in reproductive strategies.

Common lizard in a field enclosure by A. Dupoué

Photograph by A. Dupoué

Read more in our Functional Ecology paper

Last Updated ( dimanche, 01 avril 2018 )