Contrasting herbivory patterns and leaf fluctuating asymmetry inHeliocarpus pallidusbetween different habitat types within a Mexican tropical dry forest

Abstract

Abstract:Leaf fluctuating asymmetry (FA) is considered an important indicator of environmentally induced stress in plants, but the relationship between herbivory and FA levels is not clear. In this study we compared leaf size and shape, leaf area consumed by herbivorous insects, and FA levels between individuals of Heliocarpus pallidus (Tiliaceae) from two adjacent and contrasting habitat types (deciduous and riparian) in the Chamela–Cuixmala tropical dry-forest biosphere reserve. Ten individuals of H. pallidus were collected in each habitat type. Leaf shape was assessed using geometric morphometric techniques. Results indicated statistically significant differences in leaf shape between individuals from the two habitat types. In individuals from the riparian habitat leaf area (mean = 42.3 ± 1.2 cm2), herbivory levels (mean = 25.5% ± 1.8%) and FA levels (mean = 0.38 ± 0.04 cm) were significantly higher than in individuals from the deciduous habitat (17.2 ± 3.5 cm2; 9.6% ± 1.0% and 0.18 ± 0.04 cm, respectively). Within habitats, significant correlations were found between total leaf area and percentage leaf area removed by insects (R2 = 0.92 in riparian habitats, R2 = 0.9 in deciduous habitats), and between percentage leaf area removed and FA (R2 = 0.70 in riparian habitats, R2 = 0.79 in deciduous habitats). As has been suggested for other plant species, it is possible that the more favourable conditions in the riparian habitat enhance leaf growth, resulting in higher FA. Also, individuals in this habitat might be characterized by lower chemical defence and/or higher nutritional quality, which would explain the higher herbivory levels.

Fluctuating asymmetry of and herbivory on Poincianella pyramidalis (Tul.) L.P. Queiroz (Fabaceae) in pasture and secondary tropical dry forest

“…Most such studies have shown that plant asymmetry is greater in disturbed areas. However, studies involving the eff ects of habitat type on FA in semi-arid environments are scarce and relatively recent (Cuevas-Reyes et al 2011;Costa et al 2012) and there have as yet been no studies involving the plant life of the Brazilian caatinga (shrublands). In caatinga environments, stressors such as long periods of drought aff ect the vegetation as a whole and can thus increase FA.…”

Fluctuating asymmetry and herbivory in two ontogenetical stages ofChamaecrista semaphorain restored and natural environments

“…While some studies show positive relationships (Møller 1995(Møller , 1996 2003; Stiling 2011, 2005), others show no relationship (Ban˜uelos et al 2004;Dı´az et al 2004;Telhado et al 2010). Differences in plant chemistry, plant age, environmental conditions, and enemy free-space have been suggested as possible causes for these differences (Lempa et al 2000;Cornelissen et al 2003;Ban˜uelos et al 2004;Cornelissen and Stiling 2005;Cuevas-Reyes et al 2011a, 2011b. Our results suggest that in both habitat conditions, symmetry of leaves did not change with the level of herbivory.…”

“…Therefore, FA reflects developmental instability during ontogenetic stages as a result of environmental disturbances and hence has been considered a reliable indicator of environmentally induced stress in different taxa (Wauters et al 1996;Anciles and Marini 2000;Leamy and Klingenberg 2005;Hagen et al 2008;Cornelissen and Stiling 2011). In plants, some studies indicated higher levels of FA in disturbed habitats, pollution, urbanization, climate changes, parasitism, and herbivore pressure (Chistyakova and Kryazheva 2001;Stiling 2005, 2011;Cuevas-Reyes et al 2011a, 2011b; but see Telhado et al 2010). Plants respond to herbivore damage in different ways (Cuevas-Reyes et al 2004), one is altering the developmental instability of leaves during ontogenetic stages (Dı´az et al 2004).…”

“…In some studies, leaf FA is positively related with the levels of herbivory suggesting that leaf FA serves as an indicator of plant stress as result of herbivore attack (e.g. Lempa et al 2000;Cuevas-Reyes et al 2011a), while in other studies no relationship has been found (Ban˜uelos et al 2004;Dı´az et al 2004;Telhado et al 2010). Differences in environmental conditions, enemy-free space, plant chemistry, and plant age have been suggested as possible causes for these differences (Ban˜uelos et al 2004;Cornelissen and Stiling 2005;Cornelissen et al 2003;Lempa et al 2000).…”

Leaf phenotypic variation and developmental instability in relation to different light regimes

“…All these studies found that leaves presented fluctuating asymmetry, and in fact, in a recent study, Santos et al (2013) found true patterns of fluctuating asymmetry in B. brevipes. Fluctuating asymmetry has long been considered as a phenotypic indicator of developmental instability and a biomarker of plant stress (Kozlov et al 2001), and it is related to several biotic (e.g., herbivory, competition, parasitism) and abiotic factors (e.g., pollution, climate, nutrients) (Rettig et al 1997;Cuevas-Reyes et al 2011;Beasley et al 2013;Uhl 2014;Ivanov et al 2015;Alves-Silva & Del-Claro 2016). For instance, B. brevipes with high parasitism by galls have increased fluctuating asymmetry (Santos et al 2013).…”