Rare species perform unique roles, even in diverse ecosystems

May 28, 2013

A new study, published 28 May in the open access journal PLOS Biology, has revealed the potential importance of rare species in the functioning of highly diverse ecosystems. Using data from three very different ecosystems—coral reefs, tropical forests and alpine meadows—a team of researchers led by David Mouillot at the University of Montpellier 2, France, has shown that it is primarily the rare species, rather than the more common ones, that have distinct traits involved in unique ecological functions. As biodiversity declines, these unique features are therefore particularly vulnerable to extinction because rare species are likely to disappear first.

"These unique features are irreplaceable, as they could be important for the functioning of ecosystems if there is major ," explained Dr Mouillot.

Biodiverse environments are characterized by a large number of . These rare species contribute to the taxonomic richness of the area, but their functional importance in ecosystems is largely unknown. Represented by few individuals or distributed over narrow geographic areas, rare species are generally considered to have little influence on the functioning of an ecosystem compared with more common species. Indeed, it is often assumed that they fulfill the same ecological roles as those of common species but have less impact because of their low abundance; a phenomenon known as 'functional redundancy'. This redundancy suggests that rare species merely serve as an "insurance" policy for the ecosystem, in the event of an ecological loss.

To test this, the team of researchers analyzed the extent to which rarer species in the three different ecosystems performed the same ecological functions as the most common ones. They examined biological and biogeographical information from 846 , 2979 and 662 and found that most of the unique and vulnerable functions, carried out via a combination of traits, were associated with rare species.

Examples of such species supporting vulnerable functions include the giant moray (Gymnothorax javanicus), a predatory fish that hunts at night in the labyrinths of ; the pyramidal saxifrage (Saxifraga cotyledon), an alpine plant that is an important resource for pollinators; and Pouteria maxima, a huge tree in the rainforest of Guyana, which is particularly resilient to fire and drought. Not only are they rare but they have few functional equivalents among the more common species in their respective ecosystems.

"Our results suggest that the loss of these species could heavily impact upon the functioning of their ecosystems," said Dr Mouillot. "This calls into question many current conservation strategies."

The work emphasizes the importance of the conservation of rare species, even in diverse ecosystems. Rare species are more vulnerable and serve irreplaceable functions, explained Dr Mouillot: the preservation of biodiversity as a whole—not just the most common species, but all those who perform vulnerable functions—appears to be crucial for the resilience of ecosystems.

"Rare species are not just an ecological insurance," he said. "They perform additional ecological functions that could be important during rapid transitions experienced by ecosystems. The vulnerability of these functions, in particular biodiversity loss caused by climate change, highlights the underestimated role of rare species in the functioning and resilience of ecosystems. Our results call for new experiments to explicitly test the influence of species rarity and the uniqueness of combinations of traits on ecological processes." This line of research will also inform the lively debate about the relationship between biodiversity and ecosystem functioning.

Explore further: Revealing hidden fungal species using DNA: The importance of recognizing cryptic diversity

More information: Mouillot D, Bellwood DR, Baraloto C, Chave J, Galzin R, et al. (2013) Rare Species Support Vulnerable Functions in High-Diversity Ecosystems. PLoS Biol 11(5): e1001569. doi:10.1371/journal.pbio.1001569

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

Plants with dormant seeds give rise to more species

5 hours ago

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Scientists tether lionfish to Cayman reefs

15 hours ago

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Plants with dormant seeds give rise to more species

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Treating depression in Parkinson's patients

A group of scientists from the University of Kentucky College of Medicine and the Sanders-Brown Center on Aging has found interesting new information in a study on depression and neuropsychological function in Parkinson's ...