Human actions have a big effect on the genetic variety in wild animal and plant populations. This affects how well they can adapt and change when their environments shift.

1. Habitat Destruction

• When cities grow, forests are cut down, and farmland expands, animals and plants lose their homes.
• When habitats are broken up into smaller pieces, it can lower the variety of genes. This happens because isolated groups of animals or plants often breed with each other too much, leading to inbreeding.
• Research shows that 20% of species could be in danger because of losing their homes, which affects their genetic diversity.

2. Pollution

• Harmful chemicals, metals, and plastic can damage the DNA of living things.
• For instance, studies show that some underwater animals exposed to these pollutants can have their mutation rates increase by up to 60%.
• These mutations can be good or bad. If the bad mutations take over, the population could drop in size.

3. Overexploitation

• Catching too many fish and hunting too many animals can shrink their populations, leading to a loss of different genetic traits.
• When a species is hunted or fished too much, it can lose as much as 90% of its genetic variety because the rare traits are often the first to go.
• A good illustration of this is the northern elephant seal, which has lost more than 80% of its genetic variety because of a population bottleneck.

4. Climate Change

• Changes in climate can change habits and the challenges that species face, which can shift their population behaviors.
• If a species cannot adapt fast enough, it could go extinct. The ones that do survive might experience a big change in their genetic traits.
• Some studies predict that by the year 2100, genetic variation in some species could drop by 50% due to climate changes.

5. Introduction of Invasive Species

• Non-native species can take over and push out local species, which reduces the genetic variety of the native species.
• It is believed that invasive species are behind about 42% of global extinctions of threatened species.

In conclusion, human activities create pressures that lower genetic diversity in wild populations. This limits their ability to evolve and adapt to changing environments.