Rapid climate change, pollution, landscape alteration and expanding urbanisation all caused by human activities over the years have impacted even the most resilient species in the Earth's ecosystems, finds a study.
Researchers at Stanford University have discovered that modern small mammal communities from the Anthropocene are less diverse and are differently structured then even a few centuries ago, during the Holocene (around 500 years ago), showing the extent of the impacts of human activities on our ecosystems.
Anthropocene is an unofficial unit of geological time and is defined as the most recent period in Earth's history (from the 1950s to present) when human activity started to have a significant impact on the planet's ecosystems and climate.
This impact is increasingly modifying natural ecosystems and threatening biodiversity, for example by quickly expanding urbanisation, the team wrote in the paper published in Frontiers in Ecology and Evolution.
To understand the impacts of land modification, the team focussed on small mammals, such as rats and shrews, which are foundational to terrestrial ecosystems.
Due to their population abundance, small individual geographic ranges, and habitat specificity, small mammals respond quickly to changes in land use, habitat, and climate, making them good indicators of ecosystem health.
They also have a low extinction rate due to their high fertility, abundance, and growth rate. They have therefore remained taxonomically stable over thousands of years.
The team examined thousands of small mammal bones and teeth from modern (Anthropocene) raptor pellets and three (Holocene) archaeological sites along the gradient, representing different levels of human modification today,
The results showed "small mammal diversity decreased with increasing human modification today, said Dr Viteri, of Stanford University.
Species richness and evenness decreased across the modern sites based on the level of human modification.
"Second, the overall make-up of today's small mammal communities is fundamentally distinct from past communities, even 500 years ago."
This shows that human activities have impacted even the most resilient species in the Earth's ecosystems.
However, the results also demonstrate that even a relatively small, protected space can at least partially protect native faunal communities," Viteri said.
Conservation scientists have long debated over how large protected areas must be in order to buffer species loss in an increasingly human-modified world. Many studies have shown that larger reserves do a better job of conserving biodiversity.
Yet this study shows the importance of smaller protected areas in urban environments, where large spaces for conservation are lacking.
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