PHYLOGENETIC STUDIES OF COADAPTATION: PREFERRED TEMPERATURES VERSUS OPTIMAL PERFORMANCE TEMPERATURES OF LIZARDS.

Area of Science:

• Physiological Ecology
• Evolutionary Biology
• Herpetology

Background:

• A core principle in physiological ecology is the tight coadaptation of behavior and physiological performance.
• Understanding thermal preferences and performance dependencies is crucial for predicting species' responses to environmental changes.

Purpose of the Study:

• To test the principle of coadaptation using Australian skinks (Lygosominae).
• To investigate evolutionary patterns in thermal preferences (T_p) and the thermal dependence of sprinting.
• To examine the relationship between thermal preferences and critical thermal maxima (CTMax) and optimal sprinting temperatures (T_o).

Main Methods:

• Comparative study of Australian skink genera.
• Analysis of evolutionary patterns in thermal preferences and thermal dependence of sprinting.
• Application of nonphylogenetic and phylogenetic (minimum-evolution) approaches.

Main Results:

• Thermal preferences (T_p) varied significantly among genera (24°–35°C), while CTMax (38°–45°C) and T_o (32°–35°C) showed less variation.
• Diurnal genera exhibited high T_p, T_o, and CTMax; nocturnal genera showed low T_p but moderate to high T_o and CTMax.
• Phylogenetic analyses indicated tight coadaptation primarily in genera with high T_p, with partial coadaptation evolving in others.

Conclusions:

• Evolutionary pressures can lead to the evolution of low thermal preferences, even at the cost of reduced performance, indicating partial coadaptation.
• Instances of 'antagonistic coadaptation' were observed, where thermal preferences and sprinting performance evolved in opposing directions.
• Factors driving partial and antagonistic coadaptation in skinks warrant further investigation.