Appendix C. Site elevations, relationship between flooding and salinity, and productivity.

Site elevations, relationship between flooding and salinity, and productivity

Appendix B. Color figures showing site locations and study species.

Color figures showing site locations and study species

Appendix A. ANOVA table, multiple regression and correlation results for analyses of aboveground biomass.

ANOVA table, multiple regression and correlation results for analyses of aboveground biomass

Preference and Performance in Plant–Herbivore Interactions across Latitude–A Study in U.S. Atlantic Salt Marshes

<div><p>High-latitude plants are often more palatable to herbivores than low-latitude conspecifics. Does increased plant palatability lead to better herbivore performance? Our field and laboratory work investigated (A) whether high-latitude plants have traits indicating that they should be higher-quality foods for herbivores; (B) whether geographic differences in plant quality are more important than local adaptation of herbivores. We studied 3 plant species and 6 invertebrate herbivores in U.S. Atlantic Coast. Past studies had shown high-latitude individuals of these plants are more palatable than low-latitude conspecifics. We documented plant traits and herbivore performance (body size) in the field across latitude. We collected individuals from different latitudes for factorial (plant region x herbivore region) laboratory experiments, examining how herbivore performance was affected by plant region, herbivore region, and their interaction (i.e., local adaptation). Field surveys suggested high-latitude plants were likely of higher quality to herbivores. Leaf nitrogen content in all plant species increased toward high latitudes, consistent with lower leaf C/N and higher leaf chlorophyll content at high latitudes. Furthermore, leaf toughness decreased toward higher latitudes in 1 species. The body size of 4 herbivore species increased with latitude, consistent with high-latitude leaves being of higher quality, while 2 grasshopper species showed the opposite pattern, likely due to life-history constraints. In the laboratory, high-latitude plants supported better performance in 4 herbivore species (marginal in the 5th). The geographic region where herbivores were collected affected herbivore performance in all 6 species; however, the pattern was mixed, indicating a lack of local adaptation by herbivores to plants from their own geographic region. Our results suggest that more-palatable plants at high latitudes support better herbivore growth. Given that geographic origin of either plants or herbivores can affect herbivore performance, the nature of plant-herbivore interactions is likely to change if climate change “reshuffles” plant and herbivore populations across latitude.</p> </div

Measurements of soil and vegetation at oiled and control sites (means ± SE).

<p>Data were analyzed with ANOVA; p-values for the main effects of oil and year, and their interaction, are shown.</p

Appendix A. A table listing collection sites and geographic coordinates.

A table listing collection sites and geographic coordinates

The independent and dependent variables for the study of herbivore performance.

<p>The independent and dependent variables for the study of herbivore performance.</p

Plant and herbivore species studied.

<p>Plant common name, family, growth form, herbivore taxonomic group, feeding guild, and diet range are indicated in parentheses.</p

Summary of ANOVA results (d.f., F statistics, and p-values) for invertebrate groups.

<p>Sample sizes are as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032735#pone-0032735-t001" target="_blank">Table 1</a>. Asterisks indicate variables that were natural log transformed before analysis.</p

Densities of marine invertebrates and terrestrial arthropods at oiled and control sites in 2010 and 2011.

<p>A) <i>Littoraria</i> m⁻²; B) crab burrows m⁻²; C) total terrestrial arthropods 0.56 m⁻² (not including crustaceans); D) predators 0.56 m⁻²; E) sucking herbivores 0.56 m⁻²; F) stem-boring herbivores 0.56 m⁻²; G) parasitoids 0.56 m⁻²; and H) detritivores 0.56 m⁻². Open bars indicate control sites; filled bars indicate oiled sites. Data are means ±1 SE.</p