Question:
What types of variation accounts for nearly 90% of the genetic variation found within a tree species growing in natural stands? ______________
What types of variation accounts for nearly 90% of the genetic variation found within a tree species growing in natural stands? ______________
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In cross-pollinated forest trees, most of the "genetic action" happens right inside the stand through individual tree-to-tree differences.
Updated On: Aug 20, 2026
- Provenance & Site
- Site and Stand
- Stand and Tree to Tree
- Tree to tree and Provenance
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Question:
Genetic variation in tree species occurs at different hierarchical levels. The question asks which specific levels of variation represent the bulk of the total genetic diversity.
Step 2: Detailed Explanation:
• Levels of Variation: Variation can be found between provenances (geographic locations), between stands within a region, and between individual trees within a stand.
• Within-Population Diversity: Studies in forest genetics (especially in widely distributed, cross-pollinated species) consistently show that the majority of genetic diversity is found "within" populations rather than "between" geographic regions.
• The 90% Rule: For many forest trees, about 80-90% of the total genetic variation is accounted for by differences between individual trees in the same stand and differences between local stands. Only 10-20% is usually due to differences between distant provenances.
• Implication: This means that selecting the best individuals from a local, high-quality stand often provides a greater opportunity for genetic gain than searching for a better provenance thousands of miles away.
Step 3: Final Answer:
The majority of genetic variation is found at the stand and tree-to-tree level.
Genetic variation in tree species occurs at different hierarchical levels. The question asks which specific levels of variation represent the bulk of the total genetic diversity.
Step 2: Detailed Explanation:
• Levels of Variation: Variation can be found between provenances (geographic locations), between stands within a region, and between individual trees within a stand.
• Within-Population Diversity: Studies in forest genetics (especially in widely distributed, cross-pollinated species) consistently show that the majority of genetic diversity is found "within" populations rather than "between" geographic regions.
• The 90% Rule: For many forest trees, about 80-90% of the total genetic variation is accounted for by differences between individual trees in the same stand and differences between local stands. Only 10-20% is usually due to differences between distant provenances.
• Implication: This means that selecting the best individuals from a local, high-quality stand often provides a greater opportunity for genetic gain than searching for a better provenance thousands of miles away.
Step 3: Final Answer:
The majority of genetic variation is found at the stand and tree-to-tree level.
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