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"In the post industrial age, human activities have become increasingly influential on nature, reshaping the very foundations of our planet's ecosystems."
Describe two abiotic selection pressures caused by human activity and their potential impact on organisms in the ecosystem. (4 marks)
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Answers could include two of the following.
Climate warming:
→ One major abiotic pressure is the increase in global temperatures due to climate change. This increase has affected both the atmosphere and the oceans.
→ Ocean warming has led to heat-tolerant coral species in the Great Barrier Reef having a survival advantage over less tolerant species.
Pollution (plastics):
→ Another significant selection pressure is from plastic waste, particularly in rivers and oceans.
→ Sea turtles frequently mistake plastic bags for jellyfish, leading to blockages in their digestive systems and sometimes fatal outcomes.
Light pollution:
→ Light pollution is another abiotic selection pressure created by humans.
→ In urban areas, light pollution has been shown to affect the breeding behaviour of birds, favouring those that can adapt to nesting and foraging under artificial light conditions.
Answers could include two of the following.
Climate warming:
→ One major abiotic pressure is the increase in global temperatures due to climate change. This increase has affected both the atmosphere and the oceans.
→ Ocean warming has led to heat-tolerant coral species in the Great Barrier Reef having a survival advantage over less tolerant species.
Pollution (plastics):
→ Another significant selection pressure is from plastic waste, particularly in rivers and oceans.
→ Sea turtles frequently mistake plastic bags for jellyfish, leading to blockages in their digestive systems and sometimes fatal outcomes.
Light pollution:
→ Light pollution is another abiotic selection pressure created by humans.
→ In urban areas, light pollution has been shown to affect the breeding behaviour of birds, favouring those that can adapt to nesting and foraging under artificial light conditions.
Describe, providing an example, an abiotic factor that could act as a selection pressure in
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a. Desert ecosystem:
→ An abiotic factor acting as a selection pressure is extremely low rainfall/moisture.
→ For example, the thorny devil lizard has evolved a unique skin structure that allows it to collect and channel water to its mouth from any part of its body, enabling it to survive in extremely arid conditions.
b. Aquatic ecosystem:
→ In an aquatic ecosystem, water temperature can act as a significant abiotic selection pressure.
→ The Great Barrier Reef, for example, experiences coral bleaching events when water temperatures rise. These events stress the coral and if prolonged, can potentially kill the coral.
a. Desert ecosystem:
→ An abiotic factor acting as a selection pressure is extremely low rainfall/moisture.
→ For example, the thorny devil lizard has evolved a unique skin structure that allows it to collect and channel water to its mouth from any part of its body, enabling it to survive in extremely arid conditions.
b. Aquatic ecosystem:
→ In an aquatic ecosystem, water temperature can act as a significant abiotic selection pressure.
→ The Great Barrier Reef, for example, experiences coral bleaching events when water temperatures rise. These events stress the coral and if prolonged, can potentially kill the coral.
Describe two biotic factors that could act as selection pressures in a grassland ecosystem.
For each factor, briefly explain how it might influence the organisms living in that environment. (4 marks)
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Predation:
→ Predation by herbivores like grazing animals could favour plants with defensive structures or compounds.
→ eg. the Acacia tree, common in Australian grasslands, has developed long, sharp thorns as a defensive structure against herbivores.
Competition:
→ Competition for resources such as light or nutrients might select for faster-growing or taller plant species.
→ Gum trees can grow to impressive heights which gives them an advantage in capturing sunlight.
Parasites:
→ Parasites causing fungal infections, could drive the evolution of resistance mechanisms in both plants and animals.
→ Ticks are a parasite that can attach to the skin of animals like kangaroos and cattle, feeding on their blood and transmitting diseases. Animals with tick resistance will have a survival advantage.
Answers could include two of the following.
Predation:
→ Predation by herbivores like grazing animals could favour plants with defensive structures or compounds.
→ eg. the Acacia tree, common in Australian grasslands, has developed long, sharp thorns as a defensive structure against herbivores.
Competition:
→ Competition for resources such as light or nutrients might select for faster-growing or taller plant species.
→ Gum trees can grow to impressive heights which gives them an advantage in capturing sunlight.
Parasites:
→ Parasites causing fungal infections, could drive the evolution of resistance mechanisms in both plants and animals.
→ Ticks are a parasite that can attach to the skin of animals like kangaroos and cattle, feeding on their blood and transmitting diseases. Animals with tick resistance will have a survival advantage.
In a coral reef ecosystem, which of the following scenarios represents a biotic selection pressure rather than an abiotic one?
\(B\)
→ An outbreak of coral-eating crown-of-thorns starfish is a biotic selection pressure because it involves the direct interaction between living organisms (the starfish and the coral).
→ The other options are abiotic factors related to physical or chemical changes in the environment.
\(\Rightarrow B\)