Ecology and GMOs

Since the dawn of human civilisation, whether it is for food, shelter or water, we have been heavily reliant on nature’s resources to sustain ourselves. However, since the industrial revolution, a spike in human population has resulted in a greater demand for energy and resources, where most of the problems are tackled using conventional technological means. This approach of separating the natural systems from humanity poses a threat to our resources, ecosystems and is energy intensive. However, recently there has been an effort in integrating engineering practices to provide for human needs with design practices that will protect and reconstruct our ecosystems. This is known as ecological engineering, which is seen as the way of future as it is the design of building sustainable systems by taking ecological principles into account and integrating it with the human society [1]. This allows us to tackle several environmental issues, such as, preventing destruction of wetlands, accounting for global warming, ocean acidification, protecting clean lakes and reservoirs and several other broad categories such as bioengineering and sustainable agroecology [2]. In this blog, I will focus specifically on genetically modified organisms and how that has an impact on our ecosystems, and what steps we can incorporate to ensure that the design is consistent with the ecological principles.

What are genetically modified organisms?

In order to sustain a growing population, we have been looking at new methods of farming that utilise technology, giving rise to genetically modified organisms (GMOs). GMOs are the result of bioengineering where the DNA extracted from a species is combined with the genes of an unrelated plant or animal [3]. Genetically modified crops have several benefits such as:

  • Disease, weed and pest resistant plants resulting in decreased usage of pesticides and herbicides (see this article).
  • Higher yield of crops produced, allowing the farmers to utilise their agricultural lands more efficiently. To learn about how GM crops have transformed farming in rural America, see this article) and if you’re curious about the scientific perspective on how GM crops could reduce droughts and mitigate issues such as chronic hunger, click here.
  • Foods those are more beneficial to humans due to better nutritional value, flavour and texture.
  • Food with longer shelf life that can make transportation easier.

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Fig 1: Genetically modified corn

Effects of GMOs on Biodiversity

There are several long term effects of growing genetically modified crops that can adversely affect our ecosystem and natural processes. In order to assess the health of an ecosystem, we can use several parameters such as genetic diversity and habitat [4]. Diversity in gene sequences is favourable, as such diverse systems are more ecologically resilient and are able to persist or evolve under disturbances [1]. However, if a system is low in genetic diversity it will be difficult for the system to sustain under changing environments, as all the individuals will react in the same way and may perish.

GMOs promote large scale monocultures and contain similar DNA, leaving little genetic variation between the individuals of a species which can make them more prone to climate change, diseases and pests [5, 6]. For example, GM crops such as cotton and corn contain DNA that is combined with a strain of common bacteria known as Bacillus thuringiensis (Bt) in order to make the plants pest resistant. However, pests will successfully evolve and thrive in such homogenous environments, potentially wiping out the crop as no individual plant would be able to fill the void contributing to the ecological resilience of the system [12]. Similar outcomes can result due to other disturbances such as climate change, where no individual crop would be able to withstand a change in environment due to the nature of GMO’s genetic homogeneity. Let us assess the two major problems persisting with GMOs.

Problem 1: Cross-pollination and Hybridisation

Strictly speaking, a new gene into the environment means that it should increase the biodiversity of the ecosystem. The reproductively compatible wild crops and GMOs can cross pollinate and produce a hybrid version. However, due to the engineered gene, these plants have a fitness advantage and act as unfavourable competitors in survival and reproduction with their wild counterparts and thus, reducing the genetic diversity of the wild species [5, 11]. In fact, The Food and Agricultural Organisation of the United Nations found that about 75% of the plant genetic diversity has been lost since 1900 [7].

GM crops may potentially affect the fitness of other species, population extinctions, population explosions, and changes in community structure and function inside and outside agroecosystems – Food and Agricultural Organisation of the United Nations

Solution 1: Know your environment

The simplest solution to prevent wild and native plant population extinction is to confine GMOs to agricultural lands and prevent them from growing in a natural system. However, the challenges faced in confining GMOs are that the genes inherently weave into the ecosystem by several means such as wind pollination. One fine example of unintended cross pollination of GMO and wild species is seen in Bent grass – commonly used on golf courses. Studies have shown that the herbicide resistant gene was present in wild grass up to 9 miles from its origin within one year of the grass being planted [8, 9], while typically most hybridization occurs within one mile of where the GMOs are present [8]. However, in this case, the grass was more readily transportable because it is wind-pollinated, perennial and has several close wild relatives to outcross with [10].

Applying the second design principle of ecological engineering, this problem can be approached by being equipped with sufficient information about the environment in which the crop is being grown and keeping it small scale and site specific so that spatial variability is precluded. In this context the ecological solution would be to recognise crops, such as corn, soybeans and cotton that are not perennials and do not have wild relatives growing in close proximity, hence mitigating the possibility of GMOs uncontrollably interacting in non-agricultural ecosystems, which can eliminate endangered species.

Problem 2: Adverse effect of GMOs on the Ecological network

The above design strategy addresses the issue of keeping GMOs separate from the wild species to ensure that natural ecosystems thrive and maintain their complexity and diversity. However, once a gene is introduced to the environment they are close to impossible to remove as they are continually reproducing and dispersing. According to studies conducted by Pimentel, pollen from Bt crops are highly detrimental to non target caterpillars and Monarch butterflies [14], which act as pollinators along with birds and bees. This interferes with the delicate balance in the ecosystem as other organisms that are closely related to the target pests are affected (for more information on the importance of butterflies in an ecosystem click here.  In addition to this, toxins produced from the Bt crops to repel pests can easily be introduced into aquatic ecosystems through water used in irrigation and have an impact on the aquatic life [15].

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Fig 2: Monarch butterfly essential in the ecological system

Solution 2: Modification and recoding of Genome

Implementing the first principle of ecological design principle to minimise the impact GMOs have on the overall ecosystem, researchers have devised methods that would ensure that ecosystems remain healthy and ecologically resilient. These are some of the approaches to prevent GMOs from hybridising with non GMOs:

  • Creating a second generation of sterile seeds or seeds that would depend on chemicals for fertility [5].
  • Modifying the genes so that only two GMO plants must be crossed to create an offspring with advantageous traits.
  • Recoding the genome of the bacteria to incorporate synthetic amino acids, which are not present in the wild, hence curtailing the chance of DNA from GMOs being shared with the naturally occurring plants.

 Though the introduced gene cannot be eradicated completely using ecological engineering principles, the changes in the ecosystem can be anticipated and known about so that contamination into non-agrarian lands can be kept to a minimum.

Incorporating GMOs into the natural habitat

In order to combine the GMOs with traditional farming, some principles can be used to not only improve the biodiversity of the ecosystem but also introduced genes with the natural habitat. The fourth ecological principle states that we need to let nature do some of the engineering to maximise the flow of energy into the system. An example of this would be incorporating crop rotation, a traditional farming method, to GMOs. Crop rotation not only acts as a pest control method, but also ensures the soil is rejuvenated and is able to sustain its nutrients. Furthermore, crop rotations increase the number of species grown on a certain piece of agricultural land, improving the biodiversity of the ecosystem in terms of the variety of species present. Other ways of integrating GMOs into the natural world is to utilise the competitive advantages of the GMOs to create forage grass and forest trees that have defences against insects, diseases and are equipped with mechanisms against drought or freezing.

Risk Assessment

In order to weigh out the risks and benefits of using GM crops, a risk assessment can be carried out to be fairly predictable as long as there are no unexpected interactions within the genome. However, as the spatial scale increases, predicting the impact of genetically modified crops and their associated risks and benefits get progressively more difficult. The diagram below is an illustration of predictability of direct and indirect effects of GM crops when they interact at a range of scales.

A comprehensive approach such as the below mentioned table needs to be used to assess the relative benefits and risks of GM crops for other ecosystems and for people.

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Fig 1: Difficulty in predicting the direct and indirect effects of GM crops and their potential impacts.

“An incremental and tiered approach to risk assessment that moves from the laboratory to greenhouse and field trials and finally to gradually increased, monitored use” – Suggested methodology by ecologists

 A list outlining the risks would allow us to reap the benefits of GMOs whilst preventing and mitigating risks. The table below is a risk analysis on all the issues that have been covered in this blog.

Type of Impact Benefit-Related Questions Risk-Related Questions
Agricultural Are there alternatives available that result in biodiversity and ecological benefits?

Does the GM crop prevent some specific harm to humans or ecosystems, e.g., does it reduce pesticide use?

Are risks minimized though good design, e.g., ensuring only two GMOs can hybridise to result in an offspring with advantageous traits?

Has the organism been studied to ensure that genetic modifications made to produce a desired trait have not also resulted in risky changes?

Ecological Does the GM crop help solve an existing environmental problem, e.g., does it produce sterile feral animals to control pests [16]? Does the modified trait have the potential to increase the fitness of the organism outside of the managed environment e.g., act as fierce competitors to the existing wild species?

Can the genome spread across the locality and hybridise with other relative species? In the locale of release, can the trait spread to other species?

Final thoughts

Though genetic engineering seems to be the way of the future, it can only successfully fit into the existing ecosystem through careful management and proper knowledge of the environment. Ecological design principles must be closely adhered to while making decisions to ensure ecological networks are interacting with each other harmoniously with the humanity.

Check out my interview with a friend who had questions to ask about GMOs.

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