Chew on This: Plant Defense Strategies and Spiral-Horned Antelope Diet Composition in Gorongosa National Park, Mozambique

Abstract

In order to avoid being eaten by herbivores, plants develop a wide variety of defense mechanisms. These include physical structures, such as spines, and chemical compounds, such as tannins, that cause harm to the plant’s predators and may deter them from feeding. Plants must navigate their allocation of resources between investing in growth and developing their plant material and investing in various defense mechanisms. Moreover, not every herbivore species is successfully deterred by every plant defense mechanism – some have higher preference for consuming certain types of defense mechanisms than others. This study seeks to examine the trade-offs that plants in Gorongosa National Park, Mozambique experience in resource investment using chemical defense, physical defense, and nutritional quality metrics. Additionally, this study aims to uncover how these plant traits (chemical, physical, nutritional) are represented in the diets of three species of spiral-horned antelope (bushbuck, nyala, and kudu) and whether the diet characteristics can be predicted based on the antelopes’ body weight. While there does not appear to be a trade-off in plants’ investment in these traits based on statistical analysis, the traits do have significant relationships with herbivore body weight. Larger herbivores are consuming fewer physical defenses, and their diets are more digestible. Chemical defenses, however, exhibit a concave relationship with body weight, with herbivores of intermediate size consuming the highest concentration of chemical defenses. Understanding these plant-herbivore interactions is crucial for conservation as new ecological baselines are forming in Gorongosa.