Variation in vertebral number and its morphological implication in Galaxias platei

Area of Science:

• Ichthyology
• Zoology
• Ecology

Background:

• Galaxias platei exhibits wide geographic variation across its distribution.
• Understanding vertebral number variation is crucial for assessing population fitness.

Purpose of the Study:

• To investigate the variation in vertebral number across the distribution of Galaxias platei.
• To determine the environmental factors influencing vertebral number variation.
• To explore the morphological and functional implications of vertebral number changes.

Main Methods:

• Examined vertebral counts from 22 distinct localities spanning 40° to 55° S.
• Analyzed geographic and environmental data, including latitude, altitude, and mean winter air temperature.
• Assessed morphological changes in vertebral regions and discussed hydrodynamic consequences.

Main Results:

• Mean vertebral number (NMW) increases significantly towards higher latitudes, confirming Jordan's rule.
• Mean winter air temperature showed a strong negative correlation with NMW, indicating its explanatory power.
• Vertebral number increase is primarily located in the pre-pelvic and caudal regions.

Conclusions:

• Galaxias platei adheres to Jordan's rule, with vertebral counts influenced by environmental factors like temperature.
• Morphological shifts in vertebral number have implications for hydrodynamics, swimming performance, and fitness.
• Geographic variation in vertebral number highlights adaptive strategies in Galaxias platei.