The human lung is a complex and highly specialized organ with over 40 differentiated cell types. Optimal lung function is determined prenatally and an in utero adverse event may interfere with the delicate lung development process and lead to variable degrees of pulmonary hypoplasia.
Fetal lung underdevelopment is a major concern for obstetricians and pediatricians since pulmonary hypoplasia (PH) may lead to severe respiratory distress immediately after birth and even to neonatal death or potential long-term morbidity. During a five year period, the author had the opportunity to conduct in experienced teams several studies on different fetal malformations that dealt with multiple aspects in the wide spectrum of PH: gastroschisis (GAS), giant omphalocele (GO), low obstructive uropathies (LUTO) and congenital diaphragmatic hernia (CDH). The thesis, which focuses on four papers published as first author, reviews important features of PH for a fetal medicine specialist. Three other publications as co-author are presented at the end of the manuscript as "additional contributions".
Contents
General introduction ................................................................................................1
1.A / The concepts of biodiversity and ecosystem functioning..............................1
1.B / The BEF framework ......................................................................................3
1.C / A glimpse of BEF early history.....................................................................5
1.D / The beginning of functional ecology.............................................................7
1.E / Functional ecology up to this day ................................................................10
How to estimate and analyze functional diversity: a summary of current
knowledge and practices........................................................................................15
2.A / The qualitative selection of functional trait.................................................15
2.A.1 / A definition of functional trait .............................................................15
2.A.2/ The different problems when selecting functional traits.......................17
2.A.3 / Phylogeny as proxy for functional diversity ........................................21
2.B / The quantification of functional diversity ...................................................23
2.B.1 / Abundance matters...............................................................................23
2.B.2 / The intraspecific trait variation ............................................................25
2.C / The environmental context ..........................................................................28
2.C.1 / Environmental filtering ........................................................................28
2.C.2 / What makes species coexist? ...............................................................31
2.C.3 / The role of phenotypic plasticity..........................................................35
2.C.4 / Expanding the local pattern to bigger scales........................................36
2.D / We live in a multivariate world...................................................................41
2.D.1 / Do not forget interactions ....................................................................41
2.D.2 / Interactions between traits ...................................................................43
2.D.3 / Other examples of traits' multidimensionality.....................................47
2.D.4 / Traits are not the only things to be multivariate...................................48
2.E / The statistical framework ............................................................................52
2.E.1 / Examples of different biases that one might encounter........................52
2.E.2 / The soft/hard framework ......................................................................54
2.E.3 / The framework's underlying assumptions ...........................................55
Microcosms & model organisms ...........................................................................61
3.A / About the usefulness of microcosms...........................................................61
3.B / The aim of the thesis, and the model organism Tetrahymena thermophila.64
3.C / Tetrahymena thermophila genetics and reproduction..................................68
3.D / The selection of T. thermophila’s functional traits......................................74
3.D.1 / Morphology – Easy traits.....................................................................75
3.D.2 / Movement – Intermediate traits...........................................................80
3.D.3 / Growth rate – The first hard trait .........................................................83
3.D.4 / Oxygen consumption – The second hard trait......................................86
3.D.5 / Expected relationships between traits..................................................94
Relationships between functional traits in an optimal environment..................97
4.A / Introduction .................................................................................................97
4.B / Methods.......................................................................................................98
4.B.1 / Culture conditions & experimental design ...........................................98
4.B.2 / Trait measurements............................................................................100
4.C / Results.......................................................................................................103
4.C.1 / Pairwise model for local pattern.........................................................103
4.C.2 / Multivariate analysis for global pattern..............................................106
4.C.4 / The intraspecific and intrastrain variability within functional traits in
T. thermophila................................................................................................114
4.C.5/ Trait change between mother and experimental cultures....................117
4.D / Discussion .................................................................................................120
Relationships between functional traits along an environmental gradient .....125
5.A / Introduction ...............................................................................................125
5.B / Methods.....................................................................................................131
5.B.1 / Culture conditions..............................................................................131
5.B.2 / Trait measurement..............................................................................132
5.C / Results.......................................................................................................137
5.C.1 / The impact of the environments on the traits.....................................137
5.C.2 / Pairwise model analysis.....................................................................142
5.C.3 / Multivariate analysis..........................................................................150
5.C.4 / Difference in the wave pattern along the temperature gradient..........156
5.C.5 / Traits changes between the different cultures ....................................160
5.D / Discussion .................................................................................................162
General discussion ................................................................................................167
References .............................................................................................................175