7 Times Humans Changed Animal Evolution

Summary

This SciShow episode explores the phenomenon of 'evolutionary rescue,' where species rapidly adapt to survive environmental pressures caused by human activities. Examples include cliff swallows evolving shorter wings to avoid cars, fish maturing earlier to dodge commercial fishing, and the London Underground mosquito adapting to a new habitat. The episode also discusses the limitations of rapid evolution, emphasizing human responsibility in preserving biodiversity.

Takeaways

• 🧬 Evolution is often considered a slow process, but some species can adapt rapidly to environmental changes, a phenomenon known as 'evolutionary rescue'.
• 🕊️ Cliff swallows have adapted to living near roads by evolving shorter wings, which provide better maneuverability to avoid cars, showing a change within just a few decades.
• 🌡️ Shorter wings in cliff swallows may also help them cope with climate change by allowing them to catch fewer insects during cold snaps more effectively.
• 🐟 Commercial fishing has led to rapid evolution in fish species like salmon, cod, and herring, with many becoming smaller and reaching sexual maturity at a younger age to avoid being caught.
• 🚇 The London Underground has inadvertently created a unique habitat for a subspecies of mosquitoes that have evolved to prefer mammalian blood and do not hibernate, becoming genetically distinct from their above-ground counterparts.
• 🐍 Turtle-headed sea snakes may be evolving to cope with chemical pollutants through industrial melanism, getting darker to bind and shed ingested heavy metals.
• 🌊 The North Pacific Garbage Patch contains less plastic than expected, possibly due to the rapid evolution of microbes that can digest plastic, although this is still speculative and requires further research.
• 🦋 Edith's Checkerspot Butterflies adapted to a new host plant but faced extinction when environmental conditions changed, showing that rapid evolution is not always advantageous.
• 🐘 Tuskless elephants have become more common in areas heavily affected by poaching, as the lack of tusks provides a biological advantage against ivory hunters.
• 🔄 Rapid evolution can occur in a few generations, especially in species that breed quickly, but it is not a guaranteed solution for all species facing environmental pressures.
• 🌱 While evolutionary adaptations can be impressive, they should not be seen as a substitute for human responsibility in addressing the problems we have caused to the environment and its species.

Q & A

What is the phenomenon known as 'evolutionary rescue'?

Evolutionary rescue refers to the high-speed adaptation that some species can undergo in response to rapidly changing environmental conditions, allowing them to cope with severe population stress.

Why have cliff swallows started building nests on bridge supports instead of cliffs?

Cliff swallows have adapted to building nests on bridge supports due to the availability of such structures, which provide a similar nesting environment to cliffs but are often closer to human settlements.

How have cliff swallows adapted to the threat of cars?

Cliff swallows have evolved shorter wings, which provide them with greater maneuverability, enabling them to quickly take off vertically and evade oncoming cars.

What evolutionary advantage do shorter wings offer to cliff swallows in terms of survival?

Shorter wings allow cliff swallows to be more maneuverable, which is advantageous for evading vehicles and possibly for catching insects during cold snaps, thus helping them survive in changing environments.

How have commercial fishing operations influenced the evolution of fish species like Salmon, Cod, and Herring?

Commercial fishing operations have led to the evolution of these fish species to be smaller overall and reach sexual maturity at a younger age, as larger fish are more likely to be caught, thus favoring the survival and reproduction of smaller individuals.

What is the evolutionary significance of the London Underground mosquitoes' shift in blood meal preference?

The London Underground mosquitoes have evolved to prefer the blood of mammals over birds, likely due to the higher availability of rats compared to pigeons in the underground environment, representing a significant adaptation to their new habitat.

Why have the London Underground mosquitoes evolved not to hibernate and not require a blood meal to lay eggs?

The constant temperature and availability of food in the underground environment may have reduced the need for hibernation and the dependency on blood meals for egg-laying, allowing for year-round reproduction.

How do turtle-headed sea snakes adapt to chemical pollutants in their environment?

Turtle-headed sea snakes are evolving darker coloration due to increased melanin, which binds heavy metals and allows the snakes to store and later shed these pollutants through their skin, reducing their toxic effects.

What is the mystery surrounding the North Pacific Garbage Patch and the missing plastic?

Despite the large amount of plastic that should be present in the North Pacific Garbage Patch, scientists are finding only a fraction of the expected amount, suggesting that other factors, such as the evolution of plastic-eating microbes, may be at play.

How did the introduction of English Plantain impact the Edith's Checkerspot Butterflies?

The introduction of English Plantain led the butterflies to adapt and prefer this new host plant over their natural habitat plant. However, when cattle moved away and the fields became shaded by grasses, the butterflies were unable to switch back and their population went extinct.

What is the impact of poaching on the evolution of African elephants?

Poaching has led to an increase in the prevalence of tuskless elephants, as they are less likely to be targeted by poachers. This trait has become more common in some areas, demonstrating rapid evolutionary change in response to human activity.

Why is rapid evolution not a guaranteed solution for all endangered species?

Rapid evolution is not a guaranteed solution because it depends on the species' ability to adapt quickly over generations, which varies widely. Some species may not be able to adapt fast enough, and evolutionary changes can sometimes have negative consequences, as seen with the Edith's Checkerspot Butterflies.