IB Environmental systems and societies Topic 3.1F Human Activities and Selective Forces Revision Notes (HL)

IB Environmental systems and societies Topic 3.1F Human Activities and Selective Forces Revision Notes (HL) | RevisionDojo

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Human Activities as Selective Forces

Human activities are now a major driver of selection pressures on other species.
These pressures can cause evolutionary change over very short time spans.

Definition

Selective pressure

Selective pressure refers to any environmental factor (natural or human-made) that influences which traits are favorable for survival and reproduction in a population.

Note

Human-induced pressures drive evolutionary change, sometimes in unexpected directions.

Climate Change as an Evolutionary Pressure

Burning fossil fuels alters temperature and rainfall, forcing species to adapt.
Some are evolving heat tolerance or shifting their breeding cycles.
Because the change is so rapid, many species cannot adapt in time, so extinction risk rises.

Example

Polar bears are showing smaller body sizes and altered hunting as sea ice declines.

Hunting, Poaching, and Selection for Smaller Traits

Human hunting changes which traits are common in a population.
Overharvesting the largest individuals selects for smaller or tuskless forms.

Case study

In Gorongosa, Mozambique, heavy ivory poaching during the civil war favoured elephants born without tusks.
The share of tuskless females rose from about 2% to nearly 50%.

Habitat Modification and Fragmentation

Urbanisation, agriculture, and deforestation fragment habitats and isolate populations.
Fragmented populations face genetic drift, reduced gene flow, and new pressures, which can drive allopatric speciation.

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Note

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Tip

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IB Environmental systems and societies 3.1F Human Activities and Selective Forces Notes

Human Activities as Selective Forces

Climate Change as an Evolutionary Pressure

Hunting, Poaching, and Selection for Smaller Traits

Habitat Modification and Fragmentation

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Human Activities as Selective Forces

Climate Change as an Evolutionary Pressure

Hunting, Poaching, and Selection for Smaller Traits

Habitat Modification and Fragmentation

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 3.1F Human Activities and Selective Forces Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Human Activities as Selective Forces

Climate Change as an Evolutionary Pressure

Hunting, Poaching, and Selection for Smaller Traits

Habitat Modification and Fragmentation

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Human Activities as Selective Forces

Climate Change as an Evolutionary Pressure

Hunting, Poaching, and Selection for Smaller Traits

Habitat Modification and Fragmentation

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account