Subjects: Biology >> Botany submitted time 2023-08-24 Cooperative journals: 《广西植物》
Abstract： Castle peak is a mountain that resembles the appearance of a castle and protrudes above its surroundings. The phenotypes of Quercus phillyreoides (Fagaceae) populations located on castle peak in the Wushan Scenic Spot of southern Fujian, China, are variegated. It differs significantly from the original form in the presence of persistent yellow-brown stellate hairs on the leaves abaxial surface. To explain this phenomenon, the distribution of Q. phillyreoides populations at the summit of castle peak was investigated, where variant, original, and intermediate forms, as well as typical original populations at the foot of castle peak, another allopatric area, were studied. Differences in micromorphological traits were counted using ANOVA based on leaf epidermal anatomy. Ecological factors were linked with a view to discovering the causes of variation and possible pathways of evolution. The results were as follows: (1) The variant form forms an evergreen broad-leaved scrub community with it as the dominant species on the west side of the summit, and the small patch of scrub on the east side is dominated by the original form, with a few intermediate form individuals within the latter. (2) The density of single trichome base (STB) and compound trichome base (CTB) in the leaf adaxial epidermis of various populations is very low or even <1 mm-2, and the macroscopic expression is glabrous. The mean values of STB density of original, intermediate, and variant forms are increasing in the leaf abaxial epidermis. The mean density of CTB or typical stellate trichome (Tst) on the leaf abaxial epidermis varied from 0.481-1.122 mm-2 to 57.2 mm-2 in the variant form population compared with the original form populations, which macroscopically shows the formation of dense hairs. The stomatal length-width ratio increases from original (1.187-1.205) to variant (1.258) form. (3) ANOVA results show that variant form leaf abaxial epidermal STB, CTB density and stomatal length-width ratio are significantly increased (larger) than the original form (P≤0.01), but stomatal density and size do not show regularity and variability among populations (P>0.05). Poor soil, water and heat conditions at the summit of the Wushan castle peak. Combining the background with the obtained results, the variation in the variant Q. phillyreoides leaf abaxial trichomes and stomatal aspect ratio are resistant to drought or temperature extremes. Since pollen flow has not been interrupted, the adaptive evolution of Q. phillyreoides due to specific habitats should be the main reason for this variation compared to geographical isolation. The microscopic traits absence significant differences (P > 0.05) between the original form population on the top of castle peak and the rest original form populations, which confirms the variation has been fixed by long-term selection and the short-term environmental influences have had a limited role in shaping the variant traits. This case provides direct evidence that subtropical exceptional granitic landforms promote population differentiation and species formation.
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