Recording-2025-02-20T19:56:12.337Z

Chapter 56: Conservation Biology and Global Change

Overview

• This is the last chapter of the AP curriculum, covering conservation biology and the concept of global change, primarily focusing on climate change.

• The chapter discusses how human activities contribute to species extinctions and the effects of climate change on biodiversity.

Extinction

• Extinction is a natural process, necessary for ecological evolution.

• Normal Extinction Rate: Known as the background extinction rate, but the current rate is 100 to 1,000 times faster due to human activities.

• Anthropogenic Activities: Refers to human-induced changes affecting extinction rates.

Biodiversity

• Defined at three levels:

  • Genetic Diversity: Variability within species that enables populations to survive environmental changes and natural selection.

  • Species Diversity: Number of different species within an ecosystem, more than just species count but includes ecological roles.

  • Ecosystem Diversity: Variety of ecosystems within a landscape. Diversity across ecosystems increases resilience and productivity.

• Current Species Count: Approximately 2 million species are documented, but estimates suggest there may be between 5 to 100 million species on Earth.

• Many species may go extinct before being discovered.

Types of Extinction

• Global Extinction: A species is lost entirely from all ecosystems worldwide.

• Local Extinction: A species is extinct in a particular area but exists elsewhere (e.g., fish species affected by hurricanes in specific regions).

Habitat Loss

• Major driver of extinction, with around 73% of recent extinctions linked to habitat loss, primarily from agriculture and urban development.

• Fragmentation: Disruption of ecosystems into smaller patches, severely impacts ecosystem function even if some habitat remains intact.

• Wildlife Corridors: Solutions such as land bridges and artificial pathways help connect fragmented habitats to support biodiversity.

Invasive Species

• Defined as species introduced outside their native range, can be harmful by disrupting local ecosystems and outcompeting native species.

• Example: Spotted Lanternfly (Asian origin, detrimental to local trees).

• Invasive plants like Kudzu introduced for erosion control, have overrun native vegetation leading to significant ecological changes.

• Impact on Extinction: Invasive species can lead to competition, resource depletion, and ultimately, extinction of native species.

Overharvesting (Overexploitation)

• Involves removing more individuals from a population than it can sustain, leading to population decline.

• High-risk for species with small populations or long gestation periods (e.g., elephants hunted for ivory).

• Example: Bluefin tuna population has decreased by 80% in the last 45 years due to sushi demands, fetching high prices in markets.

Global Change and Climate Change

• Climate change alters ecosystems and can affect biodiversity through various mechanisms including habitat shifts and changing resource availability.

• Acid Precipitation: Result of atmospheric pollution, affecting regions far from the source of the pollutants.

Critical Habitat

• Refers to the essential components of an ecosystem that a species needs for survival and reproduction, varies by species.

• Example: Red-cockaded woodpecker requires mature pine trees and low underbrush for nesting and feeding.

• Importance of protecting critical habitats to ensure species survival.

Biodiversity Hotspots

• Areas rich in endemic species are vital for conservation efforts; protecting them is crucial as these species are not found anywhere else.

• Current Protection: 7% of the world's land is protected, but there is a need for targeted conservation of biodiversity hotspots.

• Conclusion: Protecting areas with high biodiversity and critical habitats is key to maintaining ecological balance and preventing species extinction.