Model Human Activity Biodiversity Effects - Biology

Non-target capture; increases mortality of many species. Accidental capture kills species that aren't being targeted.

Removes some trees; typically less severe than clear-cutting. Maintains canopy cover and some habitat structure.

Habitat link between patches; reduces isolation and boosts gene flow. Connects isolated patches to allow movement and breeding.

Inbreeding and genetic drift reduce genetic diversity. Small isolated populations lose genetic variation through breeding patterns.

Low density reduces survival or reproduction; extinction risk increases. Very small populations struggle to find mates and reproduce.

A single identifiable discharge location (for example, a pipe). Single source makes pollution easier to identify and control.

Diffuse runoff from many locations (for example, farms and streets). Scattered sources make pollution harder to track and regulate.

Warmer water from discharge; dissolved oxygen decreases. Warm water holds less dissolved oxygen than cool water.

Reduces non-target insects and alters food webs; diversity declines. Pesticides kill beneficial insects that support food webs.

Species restricted to one area; limited range increases extinction risk. Cannot escape to other areas when local habitat is destroyed.

Species richness and evenness generally increase over time. Restoration removes human stressors and allows natural recovery.

Atmospheric heat trapping; added $CO_2$ drives warming and range shifts. Enhanced greenhouse effect accelerates climate change impacts.

Declines in sensitive species such as mayflies and some fish. Acid-sensitive species disappear first as pH decreases.

Reduces non-target insects and alters food webs; diversity declines. Pesticides kill beneficial insects that support food webs.

Diffuse runoff from many locations (for example, farms and streets). Scattered sources make pollution harder to track and regulate.

A single identifiable discharge location (for example, a pipe). Single source makes pollution easier to identify and control.

Low density reduces survival or reproduction; extinction risk increases. Very small populations struggle to find mates and reproduce.

Reduced fitness from mating among relatives and harmful recessives. Related individuals share more harmful recessive alleles.

Random allele frequency change; stronger when population size is small. Random sampling effects are proportionally larger in small populations.

Inbreeding and genetic drift reduce genetic diversity. Small isolated populations lose genetic variation through breeding patterns.

Habitat link between patches; reduces isolation and boosts gene flow. Connects isolated patches to allow movement and breeding.

Fragmentation, edge effects, and higher mortality; diversity declines. Roads create barriers and increase wildlife-vehicle collisions.

Removes some trees; typically less severe than clear-cutting. Maintains canopy cover and some habitat structure.

Land degradation to arid conditions; reduces productivity and diversity. Lower rainfall and plant growth support fewer species.

Forest removal; rapid declines in habitat specialists and richness. Forest-adapted species lose habitat and cannot survive elsewhere.

Non-target capture; increases mortality of many species. Accidental capture kills species that aren't being targeted.

Contaminants cause toxicity and habitat degradation; diversity declines. Toxins directly kill organisms and degrade water quality.

Harvesting faster than replacement; reduces populations and diversity. Taking more than natural reproduction can replenish.

Non-native species that spreads and harms native communities. Outcompetes natives and lacks natural predators or diseases.