Invasive Species in Puerto Rico: The View From El Yunque

Jess K Zimmerman,Julissa Rojas-Sandoval,Aaron B Shiels

doi:10.3389/fevo.2021.640121

Abstract

Native flora and fauna of Puerto Rico have a long biogeographic connection to South America. Theory and empirical evidence suggest that islands, particularly those distantly isolated from the mainland, should be more susceptible to naturalizations and invasions of non-native species than continental areas. Anthropogenic disturbances can facilitate accidental and deliberate introductions of non-native species. In this study, we asked: What is the current status of introduced species within El Yunque National Forest (EYNF), the largest and most well-conserved forest area of Puerto Rico? To address this question, we reviewed the literature and surveyed local experts to identify introduced plant and animal taxa that are behaving as invaders within EYNF. We hypothesized that well-conserved forest areas within EYNF would be more resistant to invasions than disturbed areas along roads and ruderal areas with a long history of human activity. We found that there is only partial evidence that supports our hypothesis and this evidence is strongest in vascular plants, but not for the other taxonomic groups analyzed. Our combined results showed that currently the more ubiquitous invasive species in EYNF include some mammals (feral cat, rat, and mongoose) and some invertebrates (earthworms, mosquito, and Africanized honeybee). For many taxa, there is little information to thoroughly test our hypothesis, and thus more detailed surveys of the status of non-native and invasive species in EYNF are needed.

Highlights

Islands are isolated land masses that frequently exhibit simplified ecological systems containing locally adapted and endemic species, often with small population sizes, low reproductive rates, and a lack of predator defenses compared with mainland counterparts (Wilson and MacArthur, 1967; Moser et al, 2018)
About 46% (77 species from the 168 non-native species) are species previously listed as invasive in Puerto Rico (O’Connor et al, 2000; Kairo et al, 2003; Brown et al, 2006; Cohen and Ackerman, 2009; Más and Lugo-Torres, 2013; Ackerman et al, 2014; Rojas-Sandoval and Acevedo-Rodríguez, 2015; Burman et al, 2017). When considering their invasive status within the El Yunque National Forest (EYNF), we identified a total of 37 species (Table 1)
We found that many of the documented invaders in EYNF are species that were originally intentionally introduced into Puerto Rico as ornamentals (Valdés Pizzini et al, 2011; Areces-Berazain and Rojas-Sandoval, 2017) that have escaped cultivation (e.g., Calathea lutea, Hedychium coronarium, and Spathoglottis plicata)

Summary

Introduction

Islands are isolated land masses that frequently exhibit simplified ecological systems containing locally adapted and endemic species, often with small population sizes, low reproductive rates, and a lack of predator defenses compared with mainland counterparts (Wilson and MacArthur, 1967; Moser et al, 2018). These attributes make island ecosystems more susceptible than mainland ecosystems to human-related impacts, such as the introduction and establishment of non-native species. We might expect Caribbean islands to be more diverse and more resistant to the establishment of introduced species, including those that are potentially invasive (i.e., species spreading rapidly into new areas; terminology follows Blackburn et al, 2011) than more isolated islands in ocean basins

Methods

Results

Conclusion