Behavioral constraints on local adaptation and counter-gradient variation: Implications for climate change

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Resource allocation to growth, reproduction, and maintenance varies across species' latitudinal ranges.
• Local adaptation and counter-gradient variation hypotheses explain this variation.
• Burying beetles (Nicrophorus orbicollis) exhibit latitudinal variation in reproduction and brood size.

Purpose of the Study:

• Test local adaptation and counter-gradient variation hypotheses in N. orbicollis reproductive traits.
• Investigate the effect of environmental temperature on phenotypic expression.
• Determine if reproductive traits covary or if local adaptation limits adaptive responses in other traits.

Main Methods:

• Common garden experiment with N. orbicollis from three latitudinal populations.
• Measured effects of environmental temperature on reproductive trait expression.
• Compared phenotypic variation across populations and environmental conditions.

Main Results:

• Beetles initiated breeding less at extreme temperatures, especially those outside their native range, supporting local adaptation.
• Brood size was larger at temperatures matching the beetles' local environment.
• Lower latitude populations produced more offspring at lower temperatures, consistent with counter-gradient variation.
• No evidence of adaptive variation in other adult or offspring performance traits was found.

Conclusions:

• N. orbicollis uses temperature as a cue to initiate reproduction, avoiding costly attempts.
• Local adaptation to narrow temperature ranges for breeding may constrain adaptation in other reproductive traits.
• Temperature acts as a significant constraint shaping reproductive behavior in this species.