ECOTYPIC DIVERGENCE IN ALPINE POLEMONIUM VISCOSUM: GENETIC STRUCTURE, QUANTITATIVE VARIATION, AND LOCAL ADAPTATION

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Science

Background:

• Polemonium viscosum exhibits a wide elevational range on Pennsylvania Mountain, Colorado.
• Alpine environments present unique selective pressures influencing plant adaptation.

Purpose of the Study:

• To investigate genetic structure and ecotypic divergence in Polemonium viscosum across an elevational gradient.
• To determine if observed phenotypic differences between high and low elevation populations are adaptive.

Main Methods:

• Allozyme analysis to assess genetic differentiation between krummholz and summit subpopulations.
• Greenhouse experiments to evaluate quantitative variation in progeny.
• Reciprocal transplant experiments to test for local adaptation.

Main Results:

• Significant genetic differentiation (Fst values of 0.015 and 0.069) was detected between krummholz and summit subpopulations, indicating restricted gene flow.
• Summit progeny exhibited higher leaf production and lower aphid resistance compared to krummholz progeny.
• Reciprocal transplant experiments confirmed adaptive differences, with progeny performing better in their native habitats.

Conclusions:

• Polemonium viscosum demonstrates ecotypic divergence driven by elevational differences.
• Genetic structure and phenotypic variation are shaped by contrasting selective pressures at different altitudes.
• Local adaptation is evident, with populations specialized for their respective high-elevation environments.