What is the evidence that invasive species are a significant contributor to the decline or loss of threatened species? A Systematic Map

Abstract

Background: The Convention on Biological Diversity has reported invasive species as 2nd greatest cause of species extinction (COP10). However few efforts have been made to collate the evidence to support or contest the impact of invasive species on the decline and/or extinction of threatened species across large taxonomic or geographical scales. This Systematic Review was commissioned by the United States Department for Agriculture (USDA) Invasives Causing Extinction (ICE) programme to determine if the COP10 statement was based on scientific evidence. The evidence needs to be systematically reviewed and mapped to determine the importance and relevance of any such effects in order to develop national and international policies addressing the loss of threatened species, and to prioritise research and mitigation efforts.

The role played by invasive species in interactions with endangered and threatened species in the United States: a systematic review

“…This systematic review was carried out following the guidelines specific to conservation interventions developed for the Collaboration for Environmental Evidence (CEE) CEE 2013). The search strategy and inclusion criteria were included in a protocol published in advance in a peer-reviewed journal (Roberts et al 2013).…”

“…The following search string was used: ("invasive species" OR "invasive alien species" OR IAS OR feral OR "introduced species" OR "non-indigenous" OR alien OR "invasive plant" OR "invasive weed" OR exotic OR "non-native") AND (scientific name of all imperilled species listed separated by the Boolean operator 'OR'). Additional references were identified using Google Scholar and specialised invasive databases (see Roberts et al 2013).…”

Invasive Species Removal Promotes Habitat Restoration but Does Not Immediately Improve the Condition of a Threatened Plant Subspecies

“…Many rare plant species occupy specific, marginal niches (Rabinowitz 1981) and are thought to be stress tolerators with poor competitive ability (Grime 2001). A systematic review of interactions among invasive and rare species showed that 80% of studies reported competition (Roberts et al 2015). Over time, competition from invasive species can lead to rare species extinctions, especially if populations are small or vulnerable to multiple threats.…”

“…Though potentially widespread, interactions among rare and invasive species have been studied for only about 6% of species listed as endangered, threatened, or candidate under the U.S. Endangered Species Act (ESA 1973, as amended;Roberts et al 2015). Among those studies, many have failed to measure mechanisms of interspecific impacts or causes of population declines in species of concern (Roberts et al 2015).…”

“…Endangered Species Act (ESA 1973, as amended;Roberts et al 2015). Among those studies, many have failed to measure mechanisms of interspecific impacts or causes of population declines in species of concern (Roberts et al 2015).…”