Biodiversity and Conservation

Causes of Species Loss
- There is a mix of causes threatening the loss of most species.
- Notable example: habitat loss is generally the primary cause of amphibians' decline.

Goals of Conservation Biologists
- Seek to understand the causes of biodiversity loss.
- Devise plans for the protection and restoration of biological diversity.
Conservation Genetics
- Conservation geneticists apply principles of population genetics to ascertain how small a population can become before succumbing to inbreeding depression.

Definition
- Inbreeding depression is the reduced survival or reproduction resulting from the breeding of closely related individuals.
Mechanism of Inbreeding
- When closely related individuals breed, deleterious recessive alleles, typically hidden in heterozygous (Aa) individuals within large populations, are expressed, leading to negative fitness consequences.
Factors Influencing Inbreeding Depression
- The severity of inbreeding depression depends on the extent of genetic variability in a population.
- Populations with minimal genetic variability are more seriously impacted by the deleterious effects of a bottleneck event.

Impact of Bottleneck Events
- Bottleneck events cause a reduction in population size.
- The likelihood of mating with close relatives increases, leading to a further loss of genetic diversity through genetic drift as small populations continue to decrease.

Introduction
- The ESA was established in 1973 to protect imperiled species and their ecosystems.
- It prohibits actions that may destroy individuals of imperiled species by the government or citizens.
Protected Categories
- Endangered: Species with numbers so low that extinction is imminent.
- Threatened: Species whose populations are declining and likely to risk extinction in the near future.
Notable Example - Ridley Turtle
- Greatest threat comes from incidental capture in fishing gear, particularly in shrimp trawls.
Successes of the ESA
- Early successes include the recovery of species such as the bald eagle, peregrine falcon, and brown pelican following the ban of DDT (Dichlorodiphenyltrichloroethane).

Statistical Data
- The number of pairs of bald eagles increased from 0 in 1963 to approximately 10,000 by 2006, following the enactment of the ESA and DDT ban.

Federal Enforcement Issues
- Between 1973 and 1994, 108 species in the United States went extinct.
- Example: Lava hau kuahiwi (Hawaii) declared extinct in 1998.
Recent Additions to Extinction List (2023)
- 21 species including the Ohio madtom catfish have been added to the ESA extinction list, which includes a total of 650 extinct plants or animals as of 2023.
- Example: Scioto madtom, native to Big Darby Creek in Ohio, declared extinct in 2023.
ESA Listing Duration
- Approximately 1,300 species recognized as endangered and around 300 as threatened by the ESA.
- The listing process takes about 12 years, which is significantly longer than the 2 years stipulated by law.

Land Development and ESA
- The ESA does not preclude all land development projects harming listed species.
- Habitat Conservation Plans: Allow landowners to harm certain individuals if overall habitat preservation or improvement occurs.
- Safe Harbor Agreements: Government will not take legal action against landowners if they engage in activities that assist in the recovery of a species.

Global Species at Risk
- International Union for Conservation of Nature lists:
- 16,118 endangered species.
- 44,000 threatened species.

Convention on International Trade in Endangered Species of Wild Fauna and Flora:
- Bans international transport of rare species, including parts of flora and fauna.
Convention on Biological Diversity:
- Treaty that funds and incentivizes conservation in developing nations.

Importance of Captive Breeding
- Zoos and botanical gardens have become crucial for captive breeding programs aimed at endangered species, such as black rhinos.
Statistics & Facts
- Currently, 65 plant and animal species exist only in captivity.
California Condor Case Study
- Historically affected by hunting and lead poisoning, with numbers dropping to 60 individuals by 1967.
- First species to be listed under the ESA.
- Population dwindled to 22 individuals by 1982 but later recovered due to successful captive breeding.
- Over 250 individuals have been reintroduced to the wild, with more than 150 remaining in captivity.

Cloning Example
- The first cloned endangered species, the black-footed ferret, was produced in 2020 from DNA collected around 1985.
Forensic Science Applications
- Forensic science is now used to identify the origins of biological specimens recovered from black markets.
Market Monitoring
- Techniques are also applied to determine whether whale meat sold in Asian markets is sourced from endangered species or collected from protected areas.

Private Organizations and Government Entities
- Numerous private organizations collaborate with government agencies to advance conservation efforts, such as the World Wildlife Federation.
Flagship Species Initiatives
- Conservation efforts often focus on large, charismatic animals, termed flagship species, which serve as umbrella species protecting various other species in their habitats.
Example: Serengeti Wildebeest
- Protecting the wildebeest indirectly safeguards many other species due to its expansive home range.

Historical Perspective
- Traditionally, developed nations focused on conserving ecosystems in developing countries, frequently neglecting local citizens' welfare.
Contemporary Strategies
- Current conservation strategies involve local communities, such as the Maasai in Kenya, to create conservation plans that balance human and wildlife needs.