Resistance to 16 diverse species of herbivorous insects within a population of goldenrod, Solidago altissima: genetic variation and heritability

Abstract

Genetic variation in resistance to 16 species of herbivorous insects was studied in 18 clones of Solidago altissima growing in an old field near Ithaca, New York, USA. Resistance to each insect, defined as the abundance of a species attacking a particular host genotype relative to other genotypes, was measured in both the natural stand and in two experimental gardens. The heritability of resistance was estimated by parent-offspring regression and sibcorrelation. The primary result was that clones differed in resistance to 15 of 16 insect species. The resistance of genotypes to these insect species remained relatively constant over the four years of the study. However, for only 10 of these resistances were the heritability estimates significantly different from zero. Thus the common assumption of plant-insect studies - that phenotypic variation in insect abundance is closely correlated with underlying genetic variation - is only conditionally true. There is heritable variation in resistance to many insects, but not all. The insects for which we observed heritable variation in plant resistance represent five different orders and several functional groups, including leaf chewers, phloem and xylem feeders, and gall formers. There was no apparent pattern between the degree of heritability of plant resistance and the destructiveness, feeding method, breadth of host range, or taxonomic group of the insects. The lack of marked heritable variation in resistance to some insects may be the result of (a) reduced variation caused by strong selection during prolonged or repeated insect outbreaks, and (b) genotype-environment interactions that obscure differences among genotypes.

Variation in Lupinus arboreus alkaloid profiles and relationships with multiple herbivores

“…Previous studies have found no relation between tannins and galls (Espirito-Santo and Fernandes, 1998), but a positive relationship between phenolglucoside concentration and gall abundance in willow hybrids (Soetens et al, 1991). Maddox and Root (1987) found consistent heritable resistance for multiple species of stem galling insects but not other herbivore guilds, although traits associated with resistance were not identified. Although stem and bud gallers can have clear impacts on plant fitness (Quiring and McKinnon, 1999), the relationship between leaf gallers and plant fitness is not as clear.…”

“…However, studies examining the heritability of defensive compounds typically use controlled environments to minimize environmental variation (e.g. Agren and Schemske, 1993;van Dam and Vrieling, 1994), or use clones (e.g., Maddox and Root, 1987), preventing the estimation of non-additive genetic effects (but see Nuñ ez-Farfán and Dirzo, 1994;Orians et al, 1996;Roche and Fritz, 1997, for studies that estimate narrow-sense heritability in the field). Few studies have simultaneously examined how environmental variation, population-level genetic differences, and maternal and paternal effects contribute to variation in defensive compounds.…”

Genetic variation and constraints on the evolution of defense against spittlebug (Philaenus spumarius) herbivory in Mimulus guttatus

“…A number of earlier studies have contributed toward our understanding of genetic variation and constraints in herbivore defense by using clonal (Marquis, 1990;Wise, 2007) or half-sib (Maddox and Root, 1987;Fornoni et al, 2003) experimental designs (reviewed in Berenbaum and Zangerl, 1992;Kennedy and Barbour, 1992). These approaches, however, cannot partition genetic variation from most nonadditive sources, such as epistatic or dominance variation, or non-nuclear parental effects (Lynch and Walsh, 1998).…”

Variable Impact of Diverse Insect Herbivores on Dimorphic Datura wrightii

“…Consequently, frequencies of genes conferring resistance to herbivores should increase in response to herbivory. Yet, genetic variation for resistance traits is commonly found in plant populations (e.g., Berenbaum et al 1986, Maddox and Root 1987, Simms and Rausher 1987, Fritz and Price 1988, Marquis 1990, Karban 1992, Å gren and Schemske 1994, Mauricio 1998, Elle and Hare 2000. The existence of such variation has stimulated substantial interest in questions concerning the evolution of plant resistance to herbivores.…”