Size doesn’t matter shape does: A morphological study of pitcher plant in distinct forest canopy structures

Abstract

Light exposure from the sun is the most crucial variable for producing optimal pitcher size and colour variation in Nepenthes. This study aimed to observe the effect of forest canopy structure on morphological character of Nepenthes ampullaria’s pitcher parts (longitudinal, front, and peristome) both on size and shape using Geometric morphometric (GM) approach and its prey diversity. We classified the forest canopy structure into two categories: inside the canopy and open space area (gap). We used Unmanned Aerial Vehicle (UAV) images to build Canopy Height Model (CHM). Then, ForestGapR R package used to analyse and generated the forest gaps area. The prey specimens and photograph samples comprised from 9 individuals with three lower pitchers in open space area with high light exposure as well as shaded area inside the canopy. Total of 54 images were marked by point and curve to generated a landmark analysis using GeoMorph R package. Based on GM analysis, we observed that the forest canopy structure could affect Nepenthes pitcher shape but not in pitcher size. Our field result revealed Nepenthes ampullaria likely dominated by darker colour with a red spot in the shaded area and bright green colour in the open. However, based on our study the pitcher in shaded area inside the canopy have a larger number of prey species than the open area.

Morphology and pitcher's color Nepenthes in Batu Lubang Sibolga Area, North Sumatra Province, Indonesia

“…Therefore, the more varied the places where it grows, the more varied the colors appear. The appearance of colors related to the growing location can be observed in the colors that appear on the tendrils, the pitcher's body, the pitcher's cover, and the pitcher's wings (Harapan et al 2022). This exposure aligns with the obtained field observations that the N. gracilis and N. eustachya types have different pitcher colors.…”

“…However, the pitcher inside the rock canopy tends to be darker and redwood in the body (Figure 3). Harapan et al (2022) mentioned that the light intensity strongly affected the color in Nepenthes.…”

“…Simultaneously, Culicidae, Formicidae, and Rhyparochromidae are present in Nepenthes pitchers due to their close association and their UV color trapping mechanism and color pitcher darkens the lips of the plant's pitchers while lightening its body (Tarigan et al 2021). The peristome condition strongly influences the prey trapped in the pitcher (Harapan et al 2022). The prey is attracted to the peristome by the nectarsecreting gland (Bauer et al 2012).…”

“…The wettable peristome could cause the prey to slip easily into the pitcher. Such conditions would make Nepenthes' trapping strategies more efficient and increase incoming insects (Harapan et al 2022). In the open area, we assumed that the nectar fluid would evaporate shortly and the peristome would become drier than the area shaded by canopy cover (Patel 2014).…”