Experimental evolution of local adaptation under unidimensional and multidimensional selection.

Area of Science:

• Evolutionary Biology
• Ecology
• Speciation

Background:

• Local adaptation drives biological diversity and ecological speciation.
• Divergent selection in structured populations promotes adaptation to local environments.
• Real-world environments often present multidimensional selection pressures.

Purpose of the Study:

• To investigate how the dimensionality of divergent selection impacts local adaptation.
• To experimentally test evolutionary theory predictions on multidimensional selection.
• To differentiate the effects of selection dimensionality from selection strength.

Main Methods:

• Experimentally evolved 32 pairs of monogonont rotifer populations.
• Applied either unidimensional (one stressor pair) or multidimensional (three stressor pairs) divergent selection.
• Maintained equal total selection strength across treatments and assayed fitness in home/away environments.

Main Results:

• Multidimensional selection initially increased then decreased local adaptation.
• Unidimensional selection showed a slower but sustained increase in local adaptation.
• Observed results contradicted existing 'weak multifarious' and 'stronger selection' hypotheses.

Conclusions:

• Adaptation to multidimensional divergent selection may favor generalist genotypes.
• Multidimensional selection might result in transient, rather than stable, local adaptation.
• Experimental evolution provides insights into the complexities of local adaptation under varied selection regimes.