The interaction between metabolic rate, habitat choice, and resource use
in a polymorphic freshwater species
Abstract
1. Resource polymorphism is common across taxa and can result in
alternate ecotypes with specific morphologies, feeding modes, and
behaviours that increase performance in a specific habitat. This can
result in high intraspecific variation in the expression of specific
traits and the extent to which these traits are correlated within a
single population. Although metabolic rate influences resource
aquisition and the overall pace of life of individuals it is not clear
how metabolic rate interact with the larger suite of traits to
ultimately determine individual fitness. 2. We examined the relationship
between metabolic rates and the major differences (habitat use,
morphology, and resource use) between littoral and pelagic ecotypes of
European perch (Perca fluviatilis) from a single lake in Central Sweden.
3. Standard metabolic rate (SMR) was significantly higher in pelagic
perch but did not correlate with resource use or morphology. Maximum
metabolic rate (MMR) was not correlated with any of our explanatory
variables or with SMR. Aerobic scope (AS) showed the same pattern as
SMR, differing across habitats, but contrary to expectations, was lower
in pelagic perch. 4. This study helps to establish a framework for
future experiments further exploring the drivers of intraspecific
differences in metabolism. In addition, since metabolic rates scale with
temperature and determine predator energy requirements, our observed
differences in SMR across habitats will help determine ecotype-specific
vulnerabilities to climate change and differences in top-down predation
pressure across habitats.