Conservation Biology and Biodiversity Overview

Biodiversity Levels: Comprehended at three scales: genetic diversity (variation within/between populations), species diversity (organismal hierarchy), and ecological diversity (community/ecosystem levels).
Tree of Life: Biodiversity represents the evolutionary relationships among all life forms; extinctions remove tips and branches from this tree.
Genetic Diversity Importance: Essential for microevolution and adaptation. It assists in taxonomy for wildlife protection laws and identifying population history, such as inbreeding or population bottlenecks.
Species Richness: As of 2014, approximately $1,244,360$ species were described, including: * Animalia: $953,434$ * Plantae: $215,644$ * Fungi: $43,271$ * Bacteria: $10,358$

Hypotheses of Diversity: Graphs illustrate different models of how species numbers affect ecosystem function: Diversity-stability, Rivet, Redundancy, and Idiosyncratic hypotheses.
Productivity: Higher species richness generally increases Net Primary Productivity (NPP) through: * Resource use efficiency: More photosynthesis occurring in diverse plots. * Facilitation: Specific species aiding the growth of others. * Sampling effects: High-species plots are more likely to contain highly productive species.
Stability Metrics: * Resistance: Power of a community to withstand disturbance. * Resilience: Speed at which a community recovers after a disturbance.

Taxon-Specific Surveys: Terry Erwin used canopy-dwelling beetles from Luehea seemannii trees to estimate $30$ million tropical arthropod species ( $600$ arthropods/tree $\times$ $50,000$ tree species).
Species-Area Relationships: Global abundance can be predicted using the function: $S = cA^z$ .
Mora et al. (2011) Study: Used higher taxonomic classification to predict a total of $8,750,000$ eukaryotes ( $\pm 1.3$ million). * $2.2$ million species are marine. * $85\%$ of terrestrial and $91\%$ of marine species remain undescribed. * Current discovery rate: approximately $13,000$ new species/year.

Current Status: Humans are causing a sixth mass extinction. Recent extinctions include species like Walter’s Duiker and Torquigener albomaculosus.
Extinction Rates: Current rates are $100$ to $1,000\times$ higher than the background rate ( $1$ species every $1,000$ years).
IUCN Tally of Threatened Species (2012): * Amphibians: $41\%$ * Mammals: $25\%$ * Birds: $13\%$
Top Threat: Habitat Destruction: * $98\%$ of global tropical forests and $93\%$ of coral reefs are gone or severely damaged. * Borneo experienced rapid deforestation between 1900 and 2010, impacting species like Orangutans. * In the USA, prairies are essentially gone, and $90\%$ of riparian communities in CA, AZ, and NM are destroyed.