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Diversity within species may be as important as among them

June 2, 2010
Courtesy of Nature
and World Science staff

For the health and re­sil­ience of a nat­u­ral en­vi­ron­ment, it may be as im­por­tant for each spe­cies to have ge­net­ic di­vers­ity with­in it­self as it is to have many dif­fer­ent spe­cies, a study re­ports.

Past stud­ies have tended to fo­cus on di­vers­ity of spe­cies as a key fac­tor in the health of an ec­o­sys­tem, the web of rela­t­ion­ships be­tween an en­vi­ron­ment and all the or­gan­isms in­hab­it­ing it.

A brown bear eats a spawn­ing sock­eye salm­on at Brooks Falls, Alas­ka, part of Bris­tol Bay. (Cred­it: Mi­chael Web­ster)

Not un­like di­vers­ity in a set of fi­nan­cial hold­ings, di­vers­ity of spe­cies in an ec­o­sys­tem helps to pro­tect it from threats. A di­verse ec­o­sys­tem of­fers re­dun­dan­cies, for ex­am­ple, in the form of two or more spe­cies that fill a si­m­i­lar ec­o­log­i­cal role so that one can take over if an­oth­er is lost.

The new stu­dy, fo­cusing on with­in-spe­cies ge­net­ic di­vers­ity, is pub­lished in the June 3 is­sue of the re­search jour­nal Na­ture.

In it, Dan­iel Schindler of the Uni­vers­ity of Wash­ing­ton and col­leagues stud­ied the ef­fects of di­vers­ity in popula­t­ion and life his­to­ries in an ex­ploited fish popula­t­ion, the sock­eye salm­on in Bris­tol Bay, Alas­ka, over 50 years. 

In­di­vid­ual, dis­crete breed­ing groups of sock­eye salm­on were sig­nif­i­cantly more var­i­a­ble in popula­t­ion than was the Bris­tol Bay sock­eye salm­on stock as a whole, the au­thors found. This in­di­cates that with­in-spe­cies vari­abil­ity was key to keep­ing sta­ble popula­t­ion lev­els as well as sta­ble catch lev­els, they added. 

“Our re­sults dem­on­strate the crit­i­cal im­por­tance of main­tain­ing popula­t­ion di­vers­ity for sta­bi­liz­ing ec­o­sys­tem ser­vic­es and se­cur­ing the economies and liveli­hoods that de­pend on them,” the au­thors wrote. It’s known that the rates at which in­di­vid­ual popula­t­ions are lost are at least 1,000 times high­er than those of spe­cies ex­tinc­tion, they added.

Sock­eye salm­on sup­port the most val­u­a­ble fish­er­ies in the Un­ited States, and nat­u­ral re­source man­age­ment de­ci­sions need to take in­to ac­count both ec­o­log­i­cal and eco­nom­ic fac­tors. The find­ings could be ap­plied to oth­er spe­cies and could pro­vide a new stand­ard for man­ag­ing risk to ex­ploited spe­cies threat­ened by cli­mate change, Schindler and col­leagues said.

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For the health and resilience of a natural environment, it may be as important for each species to have genetic diversity within itself as it is to have many different species, a study reports. Past studies have tended to focus on diversity of species as a key factor in the health of an ecosystem, the web of relationships between an environment and all the organisms inhabiting it. Not unlike diversity in a portfolio of financial assets, diversity of species in an ecosystem helps to protect it from threats. A diverse ecosystem offers redundancies, for example, in the form of two or more species that fill a similar ecological role so that one can take over if another is lost. The new study, focusing on within-species genetic diversity, is published in the June 3 issue fo the research journal Nature. In it, Daniel Schindler of the University of Washington and colleagues studied the effects of diversity in population and life histories in an exploited fish population, the sockeye salmon in Bristol Bay, Alaska, over 50 years. Individual, discrete breeding groups of sockeye salmon were significantly more variable in population than was the Bristol Bay sockeye salmon stock as a whole, the authors found. This indicates that within-species variability was key to keeping stable population levels as well as stable catch levels, they added. “Our results demonstrate the critical importance of maintaining population diversity for stabilizing ecosystem services and securing the economies and livelihoods that depend on them,” the authors wrote. Sockeye salmon support the most valuable fisheries in the United States, and natural resource management decisions need to take into account both ecological and economic factors. It’s known that the rates at which individual populations are lost are at least 1,000 times higher than those of species extinction, said Schindler and colleagues. The findings could be applied to other species and could provide a new standard for managing risk to exploited species threatened by climate change, they added.