Comment les étapes de développement d'un organisme au cours de sa vie sont liées à l'évolution de son espèce dans le temps ?
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan.

Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes (see evolutionary developmental biology and recapitulation theory), individual organisms develop (ontogeny), while species evolve (phylogeny).

Ontogeny, embryology and developmental biology are closely related studies and those terms are sometimes used interchangeably. Aspects of ontogeny are morphogenesis, the development of form and shape of an organism; tissue growth; and cellular differentiation. The term ontogeny has also been used in cell biology to describe the development of various cell types within an organism. Ontogeny is a useful field of study in many disciplines, including developmental biology, cell biology, genetics, developmental psychology, developmental cognitive neuroscience, and developmental psychobiology. Ontogeny is used in anthropology as "the process through which each of us embodies the history of our own making".
Étapes du développement

Le développement d'un organisme se déroule par la fécondation, la clivage, la blastulation, la gastrulation, l'organogenèse et la métamorphose en adulte. Chaque espèce animale suit un parcours légèrement différent à travers ces étapes, car certaines peuvent être plus courtes ou plus longues en comparaison avec d'autres espèces, et le lieu de développement varie selon le type d'animal (par exemple, dans une coquille d'œuf dure, un utérus, une coquille d'œuf molle, sur une feuille de plante, etc.).
### Query ###
Comment les étapes de développement d'un organisme au cours de sa vie sont liées à l'évolution de son espèce dans le temps ?

### Main Text ###
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan.

Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes (see evolutionary developmental biology and recapitulation theory), individual organisms develop (ontogeny), while species evolve (phylogeny).

Ontogeny, embryology and developmental biology are closely related studies and those terms are sometimes used interchangeably. Aspects of ontogeny are morphogenesis, the development of form and shape of an organism; tissue growth; and cellular differentiation. The term ontogeny has also been used in cell biology to describe the development of various cell types within an organism. Ontogeny is a useful field of study in many disciplines, including developmental biology, cell biology, genetics, developmental psychology, developmental cognitive neuroscience, and developmental psychobiology. Ontogeny is used in anthropology as "the process through which each of us embodies the history of our own making".

### Supplementary Text ###
Étapes du développement

Le développement d'un organisme se déroule par la fécondation, la clivage, la blastulation, la gastrulation, l'organogenèse et la métamorphose en adulte. Chaque espèce animale suit un parcours légèrement différent à travers ces étapes, car certaines peuvent être plus courtes ou plus longues en comparaison avec d'autres espèces, et le lieu de développement varie selon le type d'animal (par exemple, dans une coquille d'œuf dure, un utérus, une coquille d'œuf molle, sur une feuille de plante, etc.).

### Draft ###

Query: "Comment les étapes de développement d'un organisme au cours de sa vie sont liées à l'évolution de son espèce dans le temps ?"

Translation check: "How are the developmental steps of an organism during its life linked to the evolution of its species over time?"

Key terms:
- étapes de développement = developmental stages/steps
- au cours de sa vie = during its life (individual level)
- évolution de son espèce = evolution of its species (phylogenetic level)
- dans le temps = over time (temporal dimension)

### 1. Domain Mapping

Core domains needed:
● Developmental biology (ontogeny)
● Evolutionary biology (phylogeny) 
● Evo-devo (evolutionary developmental biology)
◐ Recapitulation theory (historical, contested)

? Translation precision: "étapes de développement" could mean embryological stages or entire lifespan development. Context suggests both.

### 2. Conceptual Foundations

**Ontogeny vs Phylogeny:**
- Ontogeny = individual development (fertilization → death)
- Phylogeny = species evolutionary history (common ancestor → present)

These are **not** the same process. Critical distinction.

→ Individual organisms develop, species evolve.

**Developmental stages:**
Standard sequence: fertilization → cleavage → blastulation → gastrulation → organogenesis → metamorphosis → adulthood

### 3. Evolutionary Developmental Biology

Modern connection: Evo-devo studies how developmental mechanisms (gene regulatory networks, timing, spatial patterns) change during evolution.

Key principles:
- Gene regulatory networks constrain developmental pathways
- Heterochrony (timing changes) drives morphological evolution  
- Modular developmental architecture allows evolutionary tinkering
- Developmental genes often pleiotropic → multiple evolutionary targets

### 4. Historical Connections

**Recapitulation theory (Balfour, Haeckel):**
"Ontogeny recapitulates phylogeny" - embryos pass through adult stages of ancestors during development.

⚠ **Severely outdated** - embryonic "recapitulation" now understood as conservative developmental programs with occasional heterochronic shifts.

### 5. Mechanistic Links

Developmental constraints on evolution:
- **Architectural constraints:** Body plans limited by developmental toolkit
- **Timing constraints:** When/where genes express matters for evolution
- **Pleiotropic effects:** Developmental genes affect multiple traits
- **Evolvability landscapes:** Some developmental states more mutable than others

∴ Development shapes evolutionary possibilities through:
1. Constraint (what's buildable)
2. Bias (what's easily modifiable)  
3. Timing (when changes occur developmentally)

### 6. Synthesis

**Core relationship:** Individual development (ontogeny) can influence population-level evolutionary change (phylogeny), but they operate at different scales with different mechanisms.

Developmental biology provides the **substrate** and **constraints** for evolutionary change - it determines what morphological variations are possible and how they can be deployed during an organism's lifetime.

**Modern understanding:** Reciprocal feedback, not linear causation. Developmental innovations (novel gene regulatory patterns) can enable evolutionary transitions, while evolutionary pressures can constrain or redirect developmental programs.

**Key insight:** Evolution "tinkers" with existing developmental toolkits rather than generating de novo solutions. Developmental conservation vs evolutionary lability creates the tension that drives adaptive radiation and morphological diversification.

NB: This relationship is **context-dependent** - varies by organism, developmental stage, environmental context, and evolutionary timescale.

### Answer###
Le développement d'un organisme au cours de sa vie (son ontogenèse) et l'évolution de son espèce dans le temps (sa phylogenèse) constituent des processus distincts mais interconnectés.

L'ontogenèse désigne l'origine et le développement d'un organisme depuis la fécondation jusqu'à l'âge adulte, incluant toutes les étapes de son développement individuel : fécondation, clivage, blastulation, gastrulation, organogenèse et métamorphose éventuelle. Chaque espèce animale suit un parcours de développement légèrement différent, avec des étapes pouvant être plus courtes ou plus longues selon l'espèce.

La distinction fondamentale est qu'un individu développe (ontogenèse) tandis qu'une espèce évolue (phylogenèse). Les processus développementaux peuvent cependant influencer les processus évolutifs subséquents. Cette interaction entre développement individuel et évolution constitue l'objet d'étude de la biologie évolutive du développement.

La théorie de la récapitulation, bien que parfois évoquée dans ce contexte, ne représente plus l'explication actuelle de cette relation. Elle postulait que l'embryon repassait par les stades adultes successifs de ses ancêtres évolutifs, mais cette interprétation a été abandonnée au profit d'une compréhension plus nuancée des liens entre développement et évolution.

La relation entre ces deux niveaux biologiques reste un domaine d'étude complexe qui implique plusieurs disciplines scientifiques.