Conservation Biology Notes

The Biodiversity Crisis

• Scientists have identified nearly 2 million species, with estimates suggesting 8.7 million may exist.
• Human activities have significantly altered the Earth, converting natural habitats for human use and impacting carbon and nitrogen cycles.
• These alterations are leading to a sixth major mass extinction, referred to as the biodiversity crisis, marking the beginning of the "Anthropocene" era.

Conservation Biology

• Conservation biology is an applied science focused on preserving species, natural habitats, and ecosystem services.
• It integrates multiple fields:
  • Ecology
  • Physiology
  • Molecular biology
  • Genetics
  • Economics
  • Evolutionary biology
• It differs from environmentalism, which is a political viewpoint.

Four Levels of Biodiversity

• Biodiversity includes:
  • Genetic diversity
  • Species diversity
  • Ecosystem diversity
  • High level Taxonomic Diversity

Genetic Diversity

• Genetic diversity includes variation within and between populations.
• Both natural and human-cultivated species are at risk of losing genetic diversity.
• Natural populations in preserves and zoo animals are particularly vulnerable, with zoo animals potentially evolving traits unsuitable for the wild.

Newfoundland Pony

• Changes in agriculture practices jeopardize genetic diversity in human-cultivated species.
• Low genetic diversity in crops increases the risk of disease and limits future development of new strains.
• Centuries of domestic animal breeding are at risk due to obsolescence.
• Loss of varieties in crops over time is significant. For example, sweet corn varieties decreased from 288 in 1903 to 17 in 1983.

Species Diversity

• Species diversity is the variety of species in an ecosystem or the entire biosphere.
• The U.S. Endangered Species Act defines:
  • Endangered species: "in danger of becoming extinct throughout all or a significant portion of its range"
  • Threatened species: likely to become endangered in the foreseeable future
• Conservation biologists are concerned about species loss due to alarming extinction rates.
• Globally, significant percentages of birds, mammals, and amphibians are threatened with extinction.
• Extinction can occur locally or globally.

Examples of Endangered Species

• Philippine eagle
• Yangtze River Dolphin (possibly extinct)
• Rusty patched bumblebee
• Javan rhinoceros
• Prairie fringed orchid

Impact of Local Extinction

• Local extinction can negatively affect other species in the ecosystem.
• Example: Flying foxes (bats) are vital for pollination and seed dispersal in the Pacific Islands.

Ecosystem Diversity

• Ecosystem diversity is the variety of ecosystems in the biosphere.
• Human activities are reducing ecosystem diversity.
• Over 50% of wetlands in the contiguous United States have been drained and converted.

Higher Level Taxonomic Diversity

• Loss of species representing major branches of the tree of life leads to a loss of higher level taxonomic diversity.
• This would mean the disappearance of entire families, orders, or classes of organisms.
• Example: Tuatara are the last remaining members of Rhyncocephalia, a group that existed before the dinosaurs.

Justifications for Biodiversity Conservation

• Self Interest
• Theistic/Philosophical/Aesthetic/Ethical

Self-Interest Justifications

• Intact ecosystems provide:
  • Food
  • Recreation
  • Materials
  • Scientific Value
  • Water supply
  • Climate regulation
  • Other Ecosystem services

Scientific Value

• Species related to agricultural crops can provide important genetic traits.
• Example: Virus-resistant rice was bred by crossing commercial rice with a wild variety.
• 25% of prescriptions in the U.S. contain substances originally from plants.
  • Rosy periwinkle: contains alkaloids that inhibit cancer growth.
  • Pacific yew tree: contains a terpenoid used in breast cancer treatment.

Examples of Biodiversity's Benefits

• Resistance to disease in crops
• Higher yield varieties of crops
• New food plants
• Medicines and technologies
• Example: Taq polymerase from Thermus aquaticus, essential for genetic engineering.

Loss of Genetic Diversity

• The loss of species equates to the loss of genes and genetic diversity.
• Enormous genetic diversity offers potential for human benefits.

Ecosystem Services

• Ecosystem services are processes by which natural ecosystems and species sustain human life.
• Examples:
  • Purification of air and water
  • Detoxification and decomposition of wastes
  • Cycling of nutrients
  • Carbon Sequestration
  • Moderation of weather extremes
  • Pest control
  • Pollinators

Importance to Humans

• Example: Pollination's total value exceeds $150 billion$ per year globally.
• Much of this is provided by unmanaged pollinators.

Aesthetic Reasons

• Human-centered aesthetic reasons have been historically important, particularly in the 19th century U.S.
• Experiences with nature were considered essential for emotional and psychological health.
• John Muir emphasized the need for experiences with the sublime and connection with a creator.

Ethical Considerations

• Ethical, aesthetic, and spiritual motivations drive many conservation efforts.
• Conservation in Thailand is rooted in Buddhist principles.

Conservation of Natural Monuments

• Many areas set aside for conservation in the U.S. are designated areas of natural beauty.
• Example: Rainbow Bridge National Monument in Arizona.

Threats to Biodiversity

• Major threats include:
  • Habitat destruction
  • Change in Ecosystem Processes Locally
  • Introduced species
  • Overharvesting
  • Global change

Habitat Destruction and Fragmentation

• Vast areas of grasslands and forests in the Northern Hemisphere were destroyed by the end of the 19th century.
• Grasslands in the southern hemisphere are vanishing, and tropical forests are disappearing at about $2$% per year.
• Habitat is fragmented into small pieces, separated by human-dominated land.

Fragmented Habitats

• Habitat fragments become biological "islands."
• Smaller islands support smaller populations.
• Small populations face extinction risks due to random events and reduced genetic variation.

Smaller Populations

• Reduced genetic variation leads to fixation of harmful alleles which inhibit ability to evolve in response to changing conditions

Fragmented Habitats and Ecosystem Processes

• Fire, grazing, and other ecological forces are altered.
• Edge effects change habitat conditions.
• Human habitation near preserves introduces weedy plants, fire control, domestic predators, and human disturbance.

Edge Habitats

• Certain species thrive in edge habitats, like coyotes and raccoons.
• Some species, like wolves and mountain lions, cannot tolerate edge environments.

Brown Headed Cowbird Example

• The brown-headed cowbird is a brood parasite that prefers edge habitats.
• Forest fragmentation increases cowbird access, harming forest interior species such as the bluebird.

Habitat Change and Disruption of Ecosystem Processes

• Surviving natural habitats often change due to human alteration of ecosystem processes.

Salmon Example

• Pacific salmon are ecologically and economically important off the West Coast of North America.
• Salmon populations have declined due to factors like hydroelectric dams and habitat modification from logging and agriculture.

Introduction of Exotics

• Human activities are creating worldwide faunal interchange.
• This is an uncontrolled experiment in community ecology, with the potential result of a massive loss of gamma diversity worldwide caused by the loss of endemic species.
• Most exotic species do not spread, but those that do can cause significant ecosystem changes and extinctions.

Brown Tree Snake Example

• Boiga irregularis, the brown tree snake, was introduced to Guam in the late 1940s.
• It has caused the extinction of most endemic birds on Guam because the bird fauna there evolved no natural defenses.
• It has reached high densities and causes power outages.

Overexploitation

• Steller's Sea Cow reached a length of 26 feet and could way seven thousand pounds or more.
• It was hunted to extinction within 30 years of its discovery.

Vulnerability to Extinction

• Factors include:
  • Endemism
  • Rarity
  • Small Population Size
  • Ecological Specialization
  • Beauty/Usefulness to Humans/Competitor with Humans

Endemism

• Species restricted to a small area are more vulnerable to extinction

Rarity