Mammoths, Large-Bodied Mammals' Declining Population Changed Ecosystems

Researchers found that the extinction of mammoths, mastodons and other large-bodied animals more than 13,000 years ago in the Americas changed the structure of their ecosystems altogether. This study is one of the first to examine the structure of mammal communities after the massive extinction during the Pleistocene period, according to a of team researchers from the University of New Mexico.

"We found significant differences between extinct mammals and modern ones," Felisa Smith, lead author of the study, said in a news release. "Extinct mammals were twice as likely to form strong species pairs than modern ones."

The researchers were fixed on understanding how surviving animals responded and recuperated after the massive extinction. To determine these factors, the researchers examined fossil samples from an ideal site, Hall's Cave, in the Edward's Plateau in Texas. This enabled them to find out what happened to the mammals' communities after the extinction of about 70 species of large-bodied mammals that weighed much more than 600 kilograms.

The researchers were able to compare the structure and composition of mammal communities over time. This allowed them to make connections and diversities between the species.  The researchers were not interested in the extinction itself, though.

"We don't care who or what caused the extinction" Seth Newsome, co-author of the study and a biology professor, said.  "But rather in what this event can tell us about how ecosystems respond to the loss of large-bodied animals."

The researchers found that the mammal community underwent significant changes, where grazers were replaced by frugivores/granivores (fruit and grain eaters) 15,000 years ago. Today, the bison is the only large-bodied grazer that remains in the world. Apart from mass extinction, the structure of the mammal community was also impacted by climate and vegetation changes.

The findings of this study enabled the researchers to understand the role of large-bodied animals within ecosystems. This also allows researchers to develop potential conservation planning for present species that are relatives of extinct species.

The study also revealed that modern ecosystems may be less adaptable to present and future environmental changes, according to the researchers.

"Our results strongly suggest that modern mammal communities are less cohesive than they were in the past," said Newsome.

The work was published in the journal Ecography.

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