Developmental plasticity does not improve performance during a species interaction: Implications for species...

Area of Science:

• Ecology
• Evolutionary Biology
• Physiology

Background:

• Species interactions and environmental context influence species distribution.
• Phenotypic plasticity can alter species' environmental tolerances and interactions.
• The guppy (Poecilia reticulata) is restricted to freshwater in Trinidad despite brackish water tolerance.

Purpose of the Study:

• To investigate how salinity influences the competitive interaction between Poecilia reticulata and Poecilia picta.
• To determine the role of acute and developmental salinity responses on fish competition.
• To understand the factors limiting the freshwater range of Poecilia reticulata.

Main Methods:

• Compared salinity tolerances of P. reticulata and P. picta without competition.
• Reared P. reticulata in freshwater and brackish water to assess developmental plasticity.
• Tested competitive interactions between P. reticulata and P. picta under different salinity conditions.

Main Results:

• P. reticulata exhibited lower salinity tolerance than P. picta.
• The outcome of P. reticulata and P. picta competition was context-dependent on salinity.
• Development in brackish water did not enhance P. reticulata's competitive performance in brackish conditions.

Conclusions:

• P. reticulata's freshwater range is limited by reduced salinity tolerance and competitive disadvantage in brackish water.
• Non-adaptive plasticity can restrict species range expansion, contrary to adaptive plasticity's role in colonization.
• Environmental context critically shapes species interactions and distribution limits.