Geographical variation in allometry in the guppy (Poecilia reticulata)

Area of Science:

• Evolutionary biology
• Ecology
• Ichthyology

Background:

• Static allometry, the relationship between character and body size, is not well understood.
• Ecological factors like predation may influence allometry.

Purpose of the Study:

• To investigate the effect of predation pressure on static allometry in guppy caudal fin length.
• To compare allometry in guppy populations across different geographical areas with varying predation levels.

Main Methods:

• Compared caudal fin length to body length allometry in adult male guppies (Poecilia reticulata).
• Analyzed populations from different geographical areas with differing predation pressures.
• Assessed allometric slopes and elevations.

Main Results:

• Predation pressure did not alter allometric slopes or elevations.
• Guppy populations from the Northern Range, Trinidad, exhibited lower allometric intercepts than those from Caroni and Oropouche drainages.
• Allometric elevation was found to be more variable than the allometric slope.

Conclusions:

• Specific selection pressures, potentially from the prawn Macrobrachium crenulatum, may drive changes in relative caudal fin size.
• Environmental factors beyond predation could also influence these allometric variations.
• Allometric elevation appears more susceptible to environmental influences than allometric slope.