Profiling insular vertebrates prone to biological invasions: What makes them vulnerable?

Abstract

Human activities continue to impact biodiversity worldwide at an accelerating rate (Ceballos et al., 2015). Among various drivers that negatively affect global biodiversity, invasive alien species (IAS) are considered to be the primary cause of extinctions (Blackburn et al., 2019). Because almost 9 of 10 extinctions associated with IAS involve insular endemic species (Bellard, Cassey, et al., 2016), insular systems are particularly impacted by this threat. Moreover, intrinsic island features such as simplified ecosystems and high endemism due to a specific eco-evolutionary history promote the high extinction proneness of insular species (Tershy et al., 2015). Combined with the ongoing IAS threat, this puts strong pressure on contemporary insular biodiversity. For example, IAS are currently associated with more than a quarter of critically endangered insular terrestrial vertebrates (Dueñas et al., 2021). Since the rate of introduction of alien species into new ecosystems is currently increasing and does not appear to be slowing down (Seebens et al., 2017), it is of primary importance to understand the vulnerability of insular ecosystems to biological invasions.Species vulnerability to threats depends on extrinsic factors such as stress intensity as well as intrinsic factors such as ecological traits (e.g., body size, type of habitat, and diet), which affect the capacity of species to adapt and thrive under changing environments (Clavel et al., 2011). The link between species traits and vulnerability to major threats has been widely documented. For instance, universal characteristics associated with a "slow-living" pace (correlated with large body size) or a small geographical range have been shown to be particularly important to explain the species extinction risk (Chichorro et al., 2019). However, the

Risk assessment for the native anurans from an alien invasive species, American bullfrogs (Lithobates catesbeianus), in South Korea

“…5 A) are at high to extreme risk from the invasion of IAB. This finding is in accordance with other alien invasive species risk assessments for the vertebrates worldwide 30 , 32 . Accordingly, authors suggested invasive species as one of the major causes of the amphibian declines and extinctions 31 .…”

“…Accordingly, authors suggested invasive species as one of the major causes of the amphibian declines and extinctions 31 . Similar to the present study, previous studies found more than 50% of insular and 23% of endangered (IUCN category) amphibian species to be threatened by the invasive species 30 , 32 . Although we evaluated a fewer number of traits and scored all equally, the method was capable to assess species-level risks from the IAB locally.…”

“…Given consideration of invasive species as one of the primary causes of worldwide species extinctions but with lack of adequate information, assessment of species-level risk from the invasive species is very important 30 , 31 . Specifically, the amphibians, which hosted more than 50% of insular populations with invasive species threatened species, require a species-level risk assessment 32 .…”

Threatened and extinct island endemic birds of the world: Distribution, threats and functional diversity

“…Our analyses build on the findings of previous studies to highlight that the main threats to island endemic bird species are agricultural expansion, introduced species and biological resource use (e.g., hunting) (Table 1; Johnson & Stattersfield, 1990; Leclerc et al, 2018; Leclerc, Villéger, et al, 2020; Russell & Kueffer, 2019; Spatz et al, 2017; see Lees et al, 2022, for a review of threats to all bird species), with climate change expected to become an increasingly prevalent threat going forward (e.g., see Leclerc, Courchamp, & Bellard, 2020, for a vulnerability assessment of island endemic mammals and future climate change). There is a large literature on the impacts of introduced species on island species, in particular the loss of many endemic seabirds and ground‐nesting birds due to predation from introduced cats and rats (Bellard et al, 2016; Marino et al, 2022; Richards et al, 2021; Spatz et al, 2017). Our analyses indicate that CR species in particular are threatened by introduced species, highlighting the urgency required to deal with this issue on many islands before it is too late.…”

Sex‐specific shifts in morphology and diet in a frog after 50 years of anthropogenic habitat fragmentation

“…Hence, it is reasonable to expect that males and females respond differently to environmental alternations (Algar & López‐Darias, 2016). It is well‐known that numerous amphibian species exhibit SSD (Pincheira‐Donoso et al, 2021), and many populations can be found on small islands (Marino et al, 2021). Yet, far fewer studies have addressed the differentiation of body size shifts between sexes on islands for amphibian populations (but see Baxter‐Gilbert et al, 2020; Li et al, 2011).…”