Out Of The Quagmire Of Plant Defense Hypotheses

Abstract

Several hypotheses, mainly Optimal Defense (OD), Carbon: Nutrient Balance (CNB), Growth Rate (GR), and Growth-Differentiation Balance (GDB), have individually served as frameworks for investigating the patterns of plant defense against herbivores, in particular the pattern of constitutive defense. The predictions and tests of these hypotheses have been problematic for a variety of reasons and have led to considerable confusion about the state of the "theory of plant defense." The primary contribution of the OD hypothesis is that it has served as the main framework for investigation of genotypic expression of plant defense, with the emphasis on allocation cost of defense. The primary contribution of the CNB hypothesis is that it has served as the main framework for investigation of how resources affect phenotypic expression of plant defense, often with studies concerned about allocation cost of defense. The primary contribution of the GR hypothesis is that it explains how intrinsic growth rate of plants shaped evolutionarily by resource availability affects defensive patterns. The primary contribution of the expanded GDB hypothesis is that it recognizes the constant physiological tradeoff between growth and differentiation at the cellular and tissue levels relative to the selective pressures of resource availability, including explicitly taking into account plant tolerance of damage by enemies. A clearer understanding of these hypotheses and what we have learned from investigations that use them can facilitate development of well-designed experiments that address the gaps in our knowledge of plant defense.

Influence of plant resistance traits in selectiveness and species strength in a tropical plant‐herbivore network

“…However, in the particular case of tropical systems, where herbivorous insects are highly specialized to their host plants ( Novotny et al, 2002 ;Novotny and Basset, 2005 ;Ødegaard et al, 2005 ;Weiblen et al, 2006 ;Forister et al, 2012Forister et al, , 2015, it is likely that species strength is independent from the host plants biomass or abundance. In this case, plant resistance traits play an important role infl uencing herbivore preferences ( Coley and Barone, 1996 ;Stamp, 2003 ;Agrawal, 2005 ;Poelman et al, 2008 ) and thus their species strength, or their relative importance as food for herbivores. Host species with foliar qualities palatable to their consumers (e.g., low defense and high water or nitrogen content) can host a greater variety of herbivores and thus will have greater species strength Once completed, the plant specimens will be incorporated into the herbarium XAL and entomological specimens in the collection of INECOL.…”

Phenolic content and growth of wetland macrophytes: Is the allocation to secondary compounds driven by nutrient availability?

“…shading level, nitrogen availability, atmospheric CO 2 ). For a detailed review, see Stamp (2003), but briefly:…”

Resource allocation in Copaifera langsdorffii (Fabaceae): how a supra-annual fruiting affects plant traits and herbivory?

“…Plants have limited resources to invest in reproduction, growth and defense against herbivorous insects or pathogens (Bazzaz, Chiariello, Coley, & Pitelka, 1987;Herms & Mattson, 1992;Stamp, 2003). Usually, the demand of resources for those three processes cannot be simultaneously met, resulting in a trade-off in the resource allocation among different physiological routes (Herms & Mattson, 1992;Obeso, 2002;Weiner, Campbell, Pino, & Echarte, 2009).…”

“…Usually, the demand of resources for those three processes cannot be simultaneously met, resulting in a trade-off in the resource allocation among different physiological routes (Herms & Mattson, 1992;Obeso, 2002;Weiner, Campbell, Pino, & Echarte, 2009). The differential investment in resources produces changes in plant traits (e.g., architecture, growth and concentration of defense compounds), which may extend their effects to higher trophic levels (Bazzaz et al, 1987;Obeso, 2002;Stamp, 2003;Buckley & Avila-Sakar, 2013). Trade-offs in resource allocation are especially important in plants with supra-annual fruiting, since the investment in fruit production is high and limited into short periods (Janzen, 1971;Kelly, 1994;Newstrom, Frankie, & Baker, 1994).…”

“…Alternatively, when the availability of nutrients (N) is restricted (e.g. during a mass fruiting event), the excess of C normally is displaced to the synthesis of carbon-based compounds (Bryant et al, 1983;Herms & Mattson, 1992;Stamp, 2003). Among the carbon-based chemical defenses, tannins are among the most efficient ones against chewing herbivores (Coley, 1986).…”