Temperature affects the early allometric growth pattern of Coreius guichenoti

Research Hypothesis
This study tested the hypothesis that water temperature critically regulates early growth trajectories and allometric development (disproportionate growth of body parts) in Coreius guichenoti larvae. Specifically:

Optimal growth occurs within a narrow thermal range.

Temperature drives energy allocation trade-offs between survival organs (head/eyes) and locomotory structures (trunk/tail).

Dam-induced thermal shifts in the Yangtze River disrupt natural development, threatening wild populations.

Data Description
Source: Laboratory experiment exposing larvae to 5 temperatures (17.5°C, 20°C, 22.5°C, 25°C, 27.5°C) for 30 days post-hatching.
Measurements:
7 morphological traits tracked: Total Length (TL), Standard Length (SL), Head Length (HL), Eye Diameter (ED), Trunk Length (TRL), Body Height (BH), Tail Length (TAL).
Sampling: 20 larvae per temperature group on Days 5, 10, 15, 20, 25, 30.
Data Structure:

Key Notes:

Temperature codes: d (17.5°C), e (20°C), f (22.5°C), g (25°C), h (27.5°C).

Key Findings
1. Growth Performance
Low temps (17.5–22.5°C):

Declining growth rates (e.g., 0.31 → 0.20 mm/day at 17.5°C).

Small asymptotic sizes (TL=19.22–28.48 mm).

High temps (25–27.5°C):

Peak growth at 25°C (0.92 mm/day post-inflection).

Largest size at 25°C (TL= 87.83 mm).

Stable growth at 27.5°C (0.94 mm/day) but higher deformity risk.

Optimal Range: 22.5–25°C (high growth + delayed inflection points).

2. Allometric Growth Shifts
Trait Low Temp (17.5–20°C) High Temp (≥25°C)
Head (HL/ED) Persistent positive allometry (*b* >1) Shift from isometric → negative allometry
Trunk (TRL) Early negative → late positive allometry Early negative → late positive allometry
Body Height (BH) Sustained positive allometry Positive → negative allometry post-inflection
Tail (TAL) Negative/isometric growth Positive → isometric growth
Example: At 17.5°C, head growth outpaced the body (survival focus); at 25°C, tail growth accelerated (locomotion focus).

3. Inflection Point Dynamics
Head trait (HL/ED) inflection delayed at higher temperatures.

Growth strategy transition: "Survival-first" (low temp) → "Growth-first" (high temp).

How to Use This Data
Model Growth Dynamics:

Fit Gompertz models to TL/SL vs. age data (all R² > 0.94).

Calculate allometric exponents: Trait = a × SL^b.

Detect Inflection Points:

Apply piecewise regression (e.g., R’s segmented package) to identify growth-phase shifts.

Compare Thermal Strategies:

Contrast trait development across temperatures (e.g., TAL at 20°C vs. 25°C).