The influences of environmental change and development on leaf shape in Vitis

Abstract

Premise: The size and shape (physiognomy) of woody, dicotyledonous angiosperm leaves are correlated with climate. These relationships are the basis for multiple paleoclimate proxies. Here we test whether Vitis exhibits phenotypic plasticity and whether physiognomy varies along the vine.

Methods: We used Digital Leaf Physiognomy (DiLP) to measure leaf characters of four Vitis species from the USDA Germplasm Repository (Geneva, New York) from the 2012-2013 and 2014-2015 leaf-growing seasons, which had different environmental conditions.

Results: Leaf shape changed allometrically through developmental stages; early stages were more linear than later stages. There were significant differences in physiognomy in the same developmental stage between the growing seasons, and species had significant differences in mean physiognomy between growing seasons. Phenotypic plasticity was defined as changes between growing seasons after controlling for developmental stage or after averaging all developmental stages. Vitis amurensis and V. riparia had the greatest phenotypic plasticity. North American species exhibited significant differences in tooth area:blade area. Intermediate developmental stages were most likely to exhibit phenotypic plasticity, and only V. amurensis exhibited phenotypic plasticity in later developmental stages.

Conclusions: Leaves have variable phenotypic plasticity along the vine. Environmental signal was strongest in intermediate developmental stages. This is significant for leaf physiognomic-paleoclimate proxies because these leaves are likely the most common in leaf litter and reflect leaves primarily included in paleoclimate reconstructions. Early season and early developmental stages have the potential to be confounding factors but are unlikely to exert significant influence because of differential preservation potential.

Keywords: climatic sensitivity; leaf ontogeny; leaf physiognomy; paleoclimate proxy; phenotypic plasticity.

Figure 1

Four species of Vitis. From the top: Vitis acerifolia, Vitis aestivalis, Vitis riparia, and Vitis amurensis. Leaves are numbered from shoot tip (1) to base (12). Petioles are aligned to show differences in leaf size and shape between species and through development. The scale bar is 5 cm.

Figure 2

A Vitis acerifolia leaf processed with the Digital Leaf Physiognomy method. The petiole is removed to measure blade area. Internal perimeter is the perimeter of the leaf with the teeth removed.

Figure 3

Leaf characters in four species of Vitis exhibited four general patterns. Both leaf‐growing seasons were combined when there were no significant statistical differences between leaf‐growing seasons for the character. (A) The developmental stages of V. acerifolia, V. aestivalis, and V. riparia followed the same trend, while V. amurensis values were offset, as demonstrated by tooth area: perimeter. (B) The developmental stages of some species had statistical differences between leaf‐growing seasons and different species clustered together based on year, as demonstrated by compactness. (C) The early developmental stages of all species were distinct, but late developmental stages were virtually indistinguishable, as demonstrated by total teeth: blade area. (D) The developmental stages showed no difference between leaf‐growing seasons and all species showed similar changes through development. Patterns of leaf characters (A) were similar for North American species but not V. amurensis, (B) were different between leaf‐growing seasons, (C) changed through development, or (D) were identical in all species.

Figure 4

Vitis acerifolia binned significant effect table for temperature and precipitation. Leaf shape variables included in the Digital Leaf Physiognomy climate equation are italicized—the larger the circle, the stronger the statistical relationship. Circle color is determined by whether the change between leaf‐growing seasons was as expected based on the correlation in Peppe et al. (2011) (blue) or the opposite of the expected change (orange).

Figure 5

Vitis aestivalis binned significant effect table for temperature and precipitation. Leaf shape variables included in the Digital Leaf Physiognomy climate equation are italicized—the larger the circle, the stronger the statistical relationship. Circle color is determined by whether the change between leaf‐growing seasons was as expected based on the correlation in Peppe et al. (2011) (blue) or the opposite of the expected change (orange).

Figure 6

Vitis riparia binned significant effect table for temperature and precipitation. Leaf shape variables included in the Digital Leaf Physiognomy climate equation are italicized—the larger the circle, the stronger the statistical relationship. Circle color is determined by whether the change between leaf‐growing seasons was as expected based on the correlation in Peppe et al. (2011) (blue) or the opposite of the expected change (orange).

Figure 7

Vitis amurensis binned significant effect table for temperature and precipitation. Leaf shape variables included in the Digital Leaf Physiognomy climate equation are italicized. The larger the circle, the stronger the statistical relationship. Circle color is determined by whether the change between leaf‐growing seasons was as expected based on the correlation in Peppe et al. (2011) (blue) or the opposite of the expected change (orange).