Quick questions on Effects of biotechnology on biodiversity: HSC Biology Module 6

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

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.

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."

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.

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.

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.

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.

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.

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.

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

Devil Facial Tumour Disease has reduced wild Tasmanian devil (Sarcophilus harrisii) populations by more than 80 percent since 1996. Save the Tasmanian Devil Program uses biotechnology to maintain a genetically diverse insurance population at zoos including Sydney's Taronga. Researchers sequence individual devils' MHC genes (responsible for immune recognition) and selectively breed pairs to maximise allelic diversity, since DFTD spreads partly because wild devils have very low MHC variation.

The Wollemi pine (Wollemia nobilis), rediscovered in 1994 in Wollemi National Park west of Sydney, exists as fewer than 100 mature wild trees and shows extremely low genetic diversity (almost identical at all sequenced loci, suggesting recent clonal reproduction). Botanic gardens around the world propagate the species by cuttings, which produces genetically identical plants. While this safeguards the species against extinction by fire (catastrophic in 2019-2020), it offers no resistance variation against the introduced soil pathogen Phytophthora cinnamomi, which has already killed wild Wollemi pines.

"Evaluate" wants a justified judgement weighing strengths and limitations; "analyse" wants you to break down how each technique acts; "explain" wants cause and effect. Use the table examples (or named stimulus) you are given rather than your own.

End an "evaluate" response with a clear, supported position (for example "net negative for agricultural diversity, policy-dependent overall"). Sitting on the fence costs the top band.

Monoculture (Cavendish), gene flow (canola to wild Brassica), resistance (glyphosate-resistant weeds) on the negative; sequencing (Tasmanian devils), cryopreservation (Svalbard) on the positive. Precise examples lift a Band 4 answer to Band 6.