Line 12 2 1/2 inch muffin cups with paper baking cups. Set muffin cups aside.
In a medium mixing bowl, stir together flour, whole wheat flour, sugar, baking powder, baking soda, and salt. Make a well in center of dry mixture.
In another medium mixing bowl combine the egg, sour cream, and oil or applesauce. Add it all at once to the dry mixture. Stir just until moistened. Fold in pecans.
Spoon about half of the batter into the prepared muffin cups, filling each 1/3 full. Top each with 1 teaspoon of the peach preserves. Then top with remaining batter, filling 2/3 full. Bake in a 400 F oven for 18 - 20 minutes or until golden. Cool in muffin cups on a wire rack for 5 minutes Then remove muffins from muffin pan. Serve warm.