Evaluate the effects of biotechnology on the genetic diversity of agricultural and natural populations, and the impact on biodiversity

What this dot point is asking

NESA wants you to evaluate, not just describe, the effect of biotechnology on biodiversity. Cover both agricultural and natural populations, give specific named examples for each side of the argument, and end with a justified judgement.

The answer

Biodiversity has three levels: genetic diversity within species, species diversity within ecosystems, and ecosystem diversity within the biosphere. Biotechnology affects all three.

Negative effects on agricultural biodiversity

Monoculture and varietal narrowing. Industrial agriculture promotes a small number of high-yielding transgenic or hybrid varieties. The result is genetic uniformity across large areas:

• Bt cotton accounts for more than 90 percent of cotton in India and the United States.
• Most commercial Cavendish bananas are genetic clones, leaving the crop highly vulnerable to Tropical Race 4 of Panama disease.
• Holstein dairy cattle worldwide trace much of their genetics to fewer than 100 elite sires.

Loss of landraces. Patented seed and standardised varieties displace farmer-saved seed and traditional landraces, eroding the genetic base from which future crops will be bred. The Mexican maize landrace decline is a documented case.

Cloning narrows livestock pools. Reproductive cloning of high-value bulls and racehorses concentrates allele frequencies still further.

Negative effects on natural biodiversity

Gene flow to wild relatives. Transgenes can introgress from crops into wild populations via cross-pollination, especially in canola, sunflower and rice. The escaped genes can either swamp local adaptation or, if they confer fitness, create "superweeds."

Non-target organisms. Bt toxin is generally specific to Lepidoptera, but some studies show effects on non-target butterflies (Monarch caterpillars on milkweed exposed to Bt corn pollen). Recent meta-analyses suggest the net effect on non-target arthropods is small or positive due to reduced spraying.

Resistance evolution. Glyphosate-tolerant crops have selected for glyphosate-resistant weeds (Palmer amaranth, horseweed). Bollworm resistance to Bt has emerged in India and the United States. Resistance management requires refuges, crop rotation and rotation of modes of action.

Positive effects: conservation biotechnology

Whole genome sequencing. Sequences of endangered species identify the level of inbreeding, regions of low diversity and disease alleles. Used in the Tasmanian devil insurance population to manage devil facial tumour disease and in the kakapo recovery programme.

Assisted reproduction. Artificial insemination, in vitro fertilisation, embryo transfer and somatic cell nuclear transfer maintain populations of critically endangered species. The northern white rhino is being preserved through oocyte collection and IVF.

Gene and seed banks. The Svalbard Global Seed Vault stores more than one million plant accessions. The Frozen Zoo at San Diego cryopreserves cell lines from over 10,000 animals. The Australian PlantBank holds seeds and tissue cultures of native flora.

De-extinction and genetic rescue. CRISPR allows the introduction of lost alleles into living relatives. The Colossal Mammoth Project aims to edit Asian elephant cells with mammoth alleles. The thylacine project in Australia (Colossal and University of Melbourne) aims to use dunnart cells. Genetic rescue has been used in Florida panthers and black-footed ferrets.

Reduced land conversion (land sparing). Higher per-hectare yields from biotechnology can reduce pressure to clear new habitat, indirectly protecting biodiversity. The strength of this effect is debated.

Summary table

Evaluation

Biotechnology's effect on biodiversity is split:

• Agricultural genetic diversity is on a clear downward trend driven by varietal consolidation and patented seed. This is the dominant negative impact.
• Natural genetic diversity receives mixed effects. Gene flow and resistance evolution are real concerns; conservation applications partially offset these.

The most defensible judgement is that biotechnology accelerates the loss of agricultural genetic diversity while providing important conservation tools that did not previously exist. The net outcome depends heavily on policy choices: seed-saving rights, refuge requirements, biobank funding and gene-flow regulation.

Worked example

You are asked to evaluate the impact of Bt cotton on biodiversity in India.

Positive. Pesticide use dropped by roughly half between 2002 and 2014; on-farm arthropod diversity (bees, ladybirds, ground beetles) rose. Yields nearly doubled, reducing pressure to clear forest for new cotton.

Negative. Local cotton varieties were abandoned in favour of Bollgard hybrids. Bollworm resistance has emerged. Patent dependence on Monsanto (now Bayer) seed concentrates control. Farmer debt has been associated with the high seed cost in some regions.

Judgement. Bt cotton has a mixed effect: positive on landscape arthropod diversity through reduced spraying, negative on cotton genetic diversity through varietal consolidation. The technology is broadly successful but requires resistance management and seed-system regulation to sustain the gains.

Common traps

Saying biotechnology is "always bad" for biodiversity. It includes conservation tools (sequencing, biobanks, assisted reproduction) that are unambiguously positive.

Saying biotechnology is "always good." Monoculture and gene flow are real, well-documented negative effects.

Confusing genetic diversity with species diversity. Genetic diversity refers to allele variation within a species; species diversity refers to the number of species in an ecosystem.

Ignoring the policy dimension. The net effect on biodiversity depends heavily on regulation (refuge requirements, gene-flow rules, seed-saving rights), not on the technology alone.

In one sentence

Biotechnology reduces agricultural genetic diversity through monoculture, patented seed and cloning, and threatens natural genetic diversity through gene flow and resistance evolution, but also supports conservation through whole genome sequencing, cryopreservation, assisted reproduction and emerging de-extinction, so the net impact depends on which application is considered and on the surrounding policy framework.