Extreme weather events may be driving replacement of native species with exotic ones

Subject : Environment

Section: Biodiversity

Context:

Extreme weather events are affecting land, marine and freshwater ecosystems by influencing the displacement of native species with non-native ones, a recent analysis has found.

Key findings:

The increasing frequency of extreme weather events such as heatwaves, cold waves, droughts and floods due to climate change is influencing ecosystems.
Marine animals overall remained insensitive to extreme weather events, irrespective of whether they were native or non-native however, native molluscs, corals and anemones showed negative effects due to heatwaves.
Heatwaves and storms affected non-native species in terrestrial and freshwater habitats.

Impact of extreme weather events on Native and non-native species:

Native Species

Non-native species

Native animals responded adversely to heatwaves, droughts and cold spells in terrestrial ecosystems and displayed more vulnerability to extreme weather events.
They indicated declines in body conditions, life history traits, abundance, distribution and recovery in terrestrial ecosystems and community structure in freshwater ecosystems.
Native terrestrial animals were affected harder by heatwaves, cold spells and drought. Native freshwater species, on the other hand, were vulnerable to most events except cold spells.

Non-native species were less abundant in terrestrial ecosystems and their body conditions and life history traits were affected in freshwater systems.
Non-native terrestrial animals were affected only by heatwaves, while their counterparts in freshwater animals showed susceptibility to only storms.Non-native marine animals remained largely unaffected by most disturbances.

Why do non-native animals show less sensitivity to extreme weather events compared to native species belonging to the same taxonomic class?

The non-native or invasive species have higher growth rates, higher phenotypic plasticity, stronger competitive abilities, quicker recovery and proliferation and broader tolerance of disturbance compared to the native species.
- Plasticity is the capacity of an individual organism to alter its behaviour, physiology/gene expression, and/or morphology in direct response to changing environmental conditions.
Severe drought events deceased native invertebrates and fishes by increasing water salinity, facilitating the establishment of non-native salt-tolerant counterparts.