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.

Identify two ways biotechnology can reduce genetic diversity in agricultural crops. [2 marks]

In a fictional rice variety, a Bt resistance allele appears in 2 percent of an insect population after 5 years of Bt rice cultivation. Predict how this frequency will change over the next 10 years if no refuge crop is planted, and explain the mechanism. [3 marks]

Evaluate the impact of biotechnology on biodiversity. (a) Describe one application that reduces biodiversity. (b) Describe one application that increases or preserves biodiversity.