生物利用基因來控制各種不同的性狀表現(xiàn),，是一個(gè)眾所皆知的事實(shí)，不過最近由兩個(gè)研究團(tuán)隊(duì)同時(shí)發(fā)現(xiàn),，基因除了控制自己本身的基因活動(dòng)外,，還可能在群體生活中，影響其他生物的性狀行為表現(xiàn),，也就是說,，這些基因事實(shí)上影響了生態(tài)系統(tǒng) (ecosystem)的演化。
發(fā)表在七月份出刊 Nature Reviews Genetics期刊的一份論文,，科學(xué)家討論了生態(tài)系統(tǒng)里顯性 (phenotype)遺傳特征的遺傳性,，在這份研究中，科學(xué)家以棉白楊(cottonwood tree) 樹為例子,，據(jù)了解這種樹木多出現(xiàn)在西方國家的水岸邊,，不一樣品種的棉白楊樹，會(huì)產(chǎn)生不同量稱為單寧酸 (tannins)的物質(zhì),，用來加速本身棉白楊樹葉的分解作用,，同時(shí)滋潤土壤，并且提供棉白楊樹種子足夠的養(yǎng)分,，因此科學(xué)家認(rèn)為這個(gè)過程,，不僅僅影響棉白楊樹物種的繁衍，也影響了土壤里的微生物生態(tài),，因而改變其他生物,，像是棉白楊樹附近植物以及微生物演化的可能。
在這篇回顧性的文章中,，由 Tom Whitham博士主導(dǎo)的研究計(jì)劃,，仔細(xì)的分析了負(fù)責(zé)生合成單寧酸(tannins) 分子的基因活動(dòng)，與環(huán)境中其他生物的關(guān)系,，首度的證實(shí)代代相傳的基因活動(dòng),，確實(shí)有可能逐漸的影響生活周遭的物種，而也通過這種相互影響,，緩慢溝通的環(huán)境,，成就生態(tài)系統(tǒng)的逐漸演化。
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.
