生物利用基因来控制各种不同的性状表现，是一个众所皆知的事实，不过最近由两个研究团队同时发现，基因除了控制自己本身的基因活动外，还可能在群体生活中，影响其他生物的性状行为表现，也就是说，这些基因事实上影响了生态系统 (ecosystem)的演化。
发表在七月份出刊 Nature Reviews Genetics期刊的一份论文，科学家讨论了生态系统里显性 (phenotype)遗传特征的遗传性，在这份研究中，科学家以棉白杨(cottonwood tree) 树为例子，据了解这种树木多出现在西方国家的水岸边，不一样品种的棉白杨树，会产生不同量称为单宁酸 (tannins)的物质，用来加速本身棉白杨树叶的分解作用，同时滋润土壤，并且提供棉白杨树种子足够的养分，因此科学家认为这个过程，不仅仅影响棉白杨树物种的繁衍，也影响了土壤里的微生物生态，因而改变其他生物，像是棉白杨树附近植物以及微生物演化的可能。
在这篇回顾性的文章中，由 Tom Whitham博士主导的研究计划，仔细的分析了负责生合成单宁酸(tannins) 分子的基因活动，与环境中其他生物的关系，首度的证实代代相传的基因活动，确实有可能逐渐的影响生活周遭的物种，而也通过这种相互影响，缓慢沟通的环境，成就生态系统的逐渐演化。
英文原文：
Landmark Research Shows Genetic Link To Community Makeup And Ecosystem Evolution
It's common knowledge that genes control traits such as eye and hair color. But a large group of scientists from two continents has found that the genes of one organism not only control the characteristics of that individual but also dictate the behavior of thousands of other organisms in a community.
They say these genes, in fact, influence the evolution of an entire ecosystem.
"We're pushing a whole new field of research," said lead investigator Tom Whitham, Regents Professor of biological sciences at Northern Arizona University.
It's a field that has not been explored before. After all, the idea of looking at the genes of thousands of species in even a simple community is daunting at best.
"What we've done is zero in on a foundation species, because not all species are as equally important ecologically," Whitham said. The foundation, or key, species in this case is the cottonwood tree, which is the first tree to have all its genes sequenced, or mapped.
Among the genes under study are those that control the level of tannins in cottonwoods, which are dominant trees in riparian habitats in the West. Different individuals, or genotypes, of cottonwoods have different levels of tannins.
These genetically controlled tannin levels drive the structure--or phenotype--of a riparian forest, according to Whitham. Tannins affect the decomposition rate of cottonwood leaves, which in turn affects the fertility of soils, which affects the microbes in the soil, which affect the insects that live in the soil or eat the leaves, which affect the birds that feed on the insects, and so on.
In the July issue of Nature Reviews Genetics and the May issue of Evolution, Whitham and fellow researchers discuss how this phenotype is heritable on an ecosystem level. That is, the progeny of a tree are likely to support the same communities of organisms and ecosystem processes that their parents supported.
It's a premise with far-reaching implications. Consider, for example, conservation efforts to preserve biodiversity in the face of habitat destruction, climate change and other impacts on the environment. Planting trees that are genetically diverse will result in increased diversity of other species in the dependent community. The greater the tree diversity, the greater the chance of associated species surviving environmental degradation.
"It's not enough to save rare and endangered species. We need to save genetic diversity in the foundation species," said Jennifer Schweitzer, a co-author of the Nature Reviews Genetics paper and postdoctoral researcher at NAU. "Having high genetic diversity in these foundation species is insurance against changes in the future."
The research also has ramifications when it comes to genetically modified organisms and their effects on the landscapes in which they are introduced. For example, grasses that are genetically altered to prevent weed growth could pass that resistance along to exotic plants, which then might take over a community and change the evolution of that ecosystem.
More than 50 researchers from the United States, Canada and Australia are studying this genetic driver of community structure and ecosystem evolution. The work is funded by a $5 million Frontiers in Integrative Biological Research grant from the National Science Foundation. The project includes scientists from a multitude of disciplines because, as Whitham says, "No one person has all the skills to do this."
"This is an exciting project with global impact, drawing on the expertise of geneticists, ecologists, molecular biologists, biogeographers and others," said Chris Greer, program director at the National Science Foundation. "The results are expected to not only shed light on how complex biological communities function but to inform efforts to address the impact of human activities, such as landscape fragmentation, on stressed ecosystems across the planet."
The researchers are the first to study the genetic framework of communities and ecosystems in the wild. They have planted several experimental "common gardens" of cottonwoods in Arizona and Utah. The trees are propagated at NAU's research greenhouse. Through DNA fingerprinting, the scientists know the precise genetic makeup of each tree.
In one experiment, Whitham's group worked with the Bureau of Reclamation to plant about 10,000 trees at the Cibola National Wildlife Refuge along the lower Colorado River, about 20 miles south of Blythe, Calif., to examine how genetic diversity at the stand level influences communities and ecosystem processes.
"The Bureau of Reclamation gets restoration out of this project, and we get this incredible experiment," said Whitham.
All of the experiments, so far, have exceeded the researchers' expectations. "Initially we thought that the [genetic influences] would be more localized--that the influences would be less genetic and more environmental as we moved beyond the local common garden setting to all of the western U.S." In the end, however, Whitham said, "Plant genes are far more important than we ever expected them to be."
Now the researchers want to know if their findings hold true in different environments around the world. "To understand how important something is, you have to test in multiple locations," Whitham said.
A parallel study in Australia that examines the eucalyptus tree as the foundation species is yielding the same results as the studies on cottonwoods. And Whitham has just returned from South Africa and Borneo in Southeast Asia, where he is planting the seeds for further study.
