Exhaustive Guide to Biodiversity, Extinction, and Conservation Biology

Definition and Scope of Conservation Biology - Conservation biology is the scientific study of the nature and status of Earth's biodiversity. - The primary aim of this field is to protect species, their habitats, and entire ecosystems from excessive rates of extinction. - It also seeks to prevent the erosion of biotic interactions, which are the complex relationships between living organisms. # Patterns of Biodiversity and Speciation - Adaptive Radiation: This is defined as a rapid branching through speciation of a phylogenetic clade into many closely related species. - During adaptive radiation, species migrate and radiate into different habitats and niches to occupy available ecological roles. - Endemic Species: These are species that are found naturally in only one specific geographical area and nowhere else on Earth. # Extinction: Natural Processes and Mass Events - The total number of species currently on Earth is the result of two continuous evolutionary processes: the birth of new species and the death (extinction) of existing ones. - Both speciation and extinction are considered natural birth and death processes of evolution. - Background Extinction: This refers to the typical, naturally occurring low rate of species extinction. - Mass Extinction: This refers to a significant rise in extinction rates that is substantially above the background level. - Historical Events: The late-Devonian and end-Triassic extinction events are noted as being particularly poorly understood by scientists. # Recent Extinctions and the Red List - Current Era: The present period of extinction is often referred to as the Holocene Extinction or the Anthropocene Extinction. - The International Union for Conservation of Nature (IUCN): This organization maintains the "red list," which is a comprehensive record of extinct and endangered species. - Calculation Challenges: Estimates of extinction rates are often hampered by the fact that many extinctions likely occur without ever being observed by humans. - Rate Comparisons: - The background extinction rate is approximately $1$ per million species per year. - Current species are becoming extinct at a rate $100 ext{ to } 1000$ times faster than the period before human dominance. - Future rates are expected to grow to $10000$ times higher than background rates. - Distinguishing Features of the Current Mass Extinction: - It is the only mass extinction event triggered by a single species: Homo sapiens. - Recovery of biodiversity takes millions of years because humans are currently utilizing the resources that new species would require to evolve. # Economic Value of Biodiversity - Direct Economic Value: This includes resources required for human survival, such as sources of food, medicine, clothing, energy, and shelter. - Genetic variation in food crops is a crucial resource. - Medicinal Extracts: Approximately $40\%$ of all prescription and nonprescription drugs have active ingredients extracted from plants. - Examples include Aspirin and various cancer-fighting drugs. - Madagascar Periwinkle: This plant is the source of vinblastine and vincristine, which are effectively used to treat common forms of childhood leukemia. These drugs have increased the survival rate for these cancers from $20\%$ to over $95\%$. - Pacific Yew: Taxol, another potent cancer-fighting drug, was developed from the bark of this tree. - Indirect Economic Value: This is derived from essential ecosystem services, including: - Pollination and water quality maintenance. - Buffering against environmental disasters like storms and droughts. - Prevention of mineral and nutrient loss. - Moderation of local and regional climates. - Promotion of organic waste breakdown and mineral cycling. - Tropical Rainforests: These forests provide significantly more economic benefit if they are left standing rather than being destroyed for alternative land uses. # The Economics and Dilemmas of Ecosystem Services - Evaluation Issues: - There is no definitive estimate for the total monetary value of all services provided by global ecosystems. - A significant socio-economic problem is that those who benefit from environmental degradation are often not the same individuals who pay the costs of that degradation. - Case Study: New York City Water: - $90\%$ of the water for $9 ext{ million}$ people comes from the Catskill Mountains and the Delaware River. - The city faced a dilemma: protect the functioning ecosystem or build a filtration plant. - Cost of construction: $6 ext{ billion dollars}$. - Annual operating cost: $300 ext{ million dollars per year}$. - Alternative: Spend $1 ext{ billion dollars}$ over a period of $10 ext{ years}$ to preserve the natural ecosystem. - Global Estimates: In $2011$, researcher Costanza et al. estimated the global value of ecosystem services at $145 ext{ trillion dollars per year}$. - Currently, we are losing an estimated $4 ext{ to } 20 ext{ trillion dollars per year}$ in ecosystem value. # Ethical and Aesthetic Values - Ethical considerations are based on human conscience and the belief that every species has an intrinsic value of its own, regardless of its economic utility to humans. # Factors Responsible for Extinction (HIPPCO) - The causes for extinction are categorized by the acronym HIPPCO: - H: Habitat loss. - I: Introduced species (invasive species). - P: Population growth (human). - P: Pollution (such as plastics). - C: Climate change. - O: Overexploitation. # Habitat Loss and Fragmentation - Habitat Fragmentation: This occurs when a habitat is divided into small, unconnected areas. - This has disastrous consequences due to the direct relationship between range size and extinction rates. - Edge Effects: These involve changes in the microclimate along the edge of a habitat, which can negatively impact species adapted to the interior. - Species-Area Relationships: Scientific models suggest that if a habitat area is reduced by $90\%$, at least half ($50\%$) of all species in that area will be lost. - Extent of Loss: - In $14$ identified biodiversity hotspots, only $15\%$ or less of the original habitat remains. - Madagascar has lost $90\%$ of its original forest. - The Brazilian Atlantic coast forest has lost $95\%$ of its original footprint. # Overexploitation and Introduced Species - Overexploitation Examples: - The extinction of the Passenger Pigeon. - The $1986$ worldwide moratorium on commercial whale killing; while some whale species are recovering, others are not. - Bat Caves: Human visitations to bat caves (specifically four visits per month) caused an $86\% ext{ to } 95\%$ decline in population size. - Introduced Species: This refers to the process of colonization where a species expands its geographical range. - While naturally a rare process, human activity has made it common. - Ecological interactions are often destructive because native species have not evolved defenses or adjustments to the presence of the new species (Invasive Species). - Impact in the United States: Approximately $50000$ species have been introduced. - Economic cost of invasive species: $140 ext{ billion dollars per year}$. - Human health impact: Spread of diseases like West Nile fever. - Impact in Hawaii: The introduction of mosquitoes carrying malaria led to the extinction or restriction of $70\%$ of native fauna to high elevations. # Climate Change and the Greenhouse Effect - Distinction: Weather refers to short-term changes (temperature, air pressure, precipitation, wind), while Climate is the average of these conditions in an area over a long period. - Greenhouse Effect: - Greenhouse gases absorb heat radiated by the Earth and emit infrared radiation that warms the atmosphere. - Without this natural effect, Earth would be too cold for life. # Oceans: Warming and Acidification - Role of Oceans: They remove approximately $\frac{1}{3}$ of $CO_2$ from the atmosphere. - Warming: Over the last century, oceans have seen a temperature increase of $0.6 ext{ to } 1.2\,^\circ\text{F}$. - Warmer oceans absorb less $CO_2$, which hastens atmospheric warming further. - Ocean Acidification: - Surface water acidity has increased by $30\%$. - $CO_2$ combines with water to form carbonic acid ($H_2CO_3$). - This process threatens corals, snails, organisms with shells, and phytoplankton. # Sea Level Rise and Coastal Consequences - Projections: Sea levels are projected to rise between $0.5 ext{ and } 1.5\,m$ by the year $2100$. - Predicted Effects: - Degradation and loss of $\frac{1}{3}$ of coastal estuaries, wetlands, and coral reefs. - Disruption of coastal fisheries. - Flooding of low-lying barrier islands, coastal areas, and agricultural lowlands and deltas.