The association among herbivory tolerance, ploidy level, and herbivory pressure in cardamine pratensis

Abstract

We tested whether differences in ploidy level and previous exposure to herbivory can affect plant tolerance to herbivory. We conducted a common garden experiment with 12 populations of two ploidy levels of the perennial herb Cardamine pratensis (five populations of tetraploid ssp. pratensis and seven populations of octoploid ssp. paludosa). Earlier studies have shown that attack rates by the main herbivore, the orange tip butterfly Anthocharis cardamines, are lower in populations of octoploids than in populations of tetraploids, and vary among populations. In the common garden experiment, a combination of natural and artificial damage significantly reduced seed and flower production. We measured tolerance based on four plant-performance metrics: survival, growth, seed production and clonal reproduction. For three of these measurements, tolerance of damage did not differ between ploidy levels. For clonal reproduction, the octoploids had a higher tolerance than the tetraploids, although they experience lower herbivore attack rates in natural populations. Populations from sites with high levels of herbivory had higher tolerance, measured by seed production, than populations with low levels of herbivory. We did not detect any significant costs of tolerance. We conclude that high intensity of herbivory has selected for high tolerance measured by seed production in C. pratensis.

Among-Population Variation in Tolerance to Larval Herbivory by Anthocharis cardamines in the Polyploid Herb Cardamine pratensis

“…Tolerance to damage was not correlated with plant resistance against oviposition estimated under controlled conditions. However, populations with higher attack intensities by A. cardamines in the field were more tolerant to larval herbivory under controlled conditions than populations experiencing low attack intensity [13]. We also confirmed that tolerance was not related to any costs in the absence of herbivory [13].…”

“…Both ploidy types are used for oviposition by the butterfly Anthocharis cardamines , but tetraploid populations are often more attacked than octoploid populations [27]. A previous study with this study system [13] showed that average tolerance levels of populations were positively correlated with attack intensity in the field. The main question addressed in this study is how among-population variation in tolerance is related to variation in both resistance and attack rates among natural populations.…”

“…Based on these results, we conclude that the relationship between attack intensity and tolerance in our system is not mediated by resistance, but likely the effect of an increased selection for tolerance in populations exposed to higher intensities of damage in the field. Other studies investigating tolerance levels among populations with different levels of herbivory intensity have found an association between herbivory intensity and tolerance in some cases [12], [13] but not in other [14]–[16]. Few studies have assessed tolerance and resistance under controlled conditions and correlated these results to the attack intensity in natural populations.…”

Spatiotemporal variation in deer browse and tolerance in a woodland herb

“…As a consequence, we may expect populations at lower latitudes to have evolved greater defenses or increased tolerance to being eaten. Other work has found variation in tolerance among populations in a limited area (Bergelson and Crawley 1992, Juenger et al 2000, Banta et al 2010, Boalt et al 2010. Other work has found variation in tolerance among populations in a limited area (Bergelson and Crawley 1992, Juenger et al 2000, Banta et al 2010, Boalt et al 2010.…”

Root sprouting in Knautia arvensis (Dipsacaceae): effects of polyploidy, soil origin and nutrient availability

“…It also did not confirm the usually observed tendency towards better vegetative growth linked to clonality in polyploids, which in some cases contrasts with better generative reproduction in diploids (Č erná and Müenzbergová 2013;Henery et al 2010;Hroudová and Zákravský 1993). As pointed out by Boalt et al (2010), when examining tolerance to damage in populations of different ploidy, it is important to take into account other possibly linked factors such as phenology. As shifts in phenology promote sympatric speciation (Schluter 2001), phenological differences in different ploidy levels are to be expected.…”