Evolution and Biodiversity — Key Concepts & Conservation

Key Concepts:
- a) Populations adapt to changing environments when individuals with inherited traits that improve survival or reproduction leave more offspring on average than less-suited individuals (natural selection).
- b) Individuals do not evolve; populations do. A population evolves if the frequency of genes (alleles) in descendants differs from that in ancestors.

Individuals within a population are genetically different.
Same basic genes in a species: DNA directs production of proteins and influences traits.
Variation arises because there can be more than one form (alleles) of each gene.
Alleles account for trait diversity (e.g., attachment of earlobes).
Environment changes create selective pressures.
Selective pressure: nonrandom influence that affects survival or reproduction.
Differential reproductive success: fit individuals leave more offspring.

Natural selection: organisms best adapted to the environment survive to reproduce, changing gene frequencies across generations.
Introduced by Darwin and Wallace; primary driving force of evolution.
Modes: stabilizing, directional, or disruptive.
More successful individuals reproduce more, shifting gene frequencies.
Example: color variation in beetles affects predation and survival; camouflage influences outcomes.

Key Concept a: Two species can become highly adapted to one another when each becomes the selective pressure that favors traits in the other (coevolution).
Key Concept b: Species that never coevolved with a predator may lack needed defenses.
Coevolution: reciprocal natural selection between interacting species (e.g., predator and prey).

Random processes also shape evolution: genetic drift, bottleneck, founder effects.
Genetic drift: random shifts in allele frequencies; reduces genetic variation; strongest in small populations.
Bottleneck effect: drastic reduction in population size reduces genetic diversity.
Founder effect: a small group colonizes a new area with a subset of the original population's genes.

Evolutionary pace is generally slow; influenced by population size, genetic diversity, reproductive rate, generation time, and selective pressures.
r-selected species often evolve faster; many endangered species are K-selected.
Extinctions can be gradual or rapid; rapid losses disrupt community connections.

Artificial selection: humans decide which individuals breed to produce desired traits.
Works like natural selection but pressure is human-driven.
Examples: domesticated dogs; antibiotic- or pesticide-resistant populations.

Biodiversity = genetic, species, and ecological diversity.
Rainforests host high biodiversity; total species estimates range widely (uncertainty remains).
Insects are the most diverse group; vertebrates are a small fraction of all life.
Biodiversity underpins ecosystem services and human well-being.

Biodiverse ecosystems provide cultural, provisioning, and regulating services; global value estimated in trillions of dollars.

Five main threats: habitat destruction, climate change, pollution, invasive species, overexploitation.
Habitat destruction and fragmentation reduce biodiversity and ecosystem services.
Isolation increases extinction risk; invasive species displace natives.

Single-species conservation: focuses on individual species (flagship or charismatic species).
Ecosystem-based conservation: protects habitats to safeguard all species.
Protected areas: national parks, refuges, reserves; marine protected areas.
Landscape conservation: protect ecosystems by safeguarding a suite of indicator species across a landscape.

Conservation genetics helps identify endangered populations and track illegal trade (e.g., ivory).
Key treaties and laws:
- CITES: regulates international trade of endangered/threatened species.
- CBD: promotes sustainable use of all biodiversity; enforcement challenges exist.
- ESA: U.S. Endangered Species Act protects listed species and habitats.
- Lacey Act, Ramsar Convention: additional protections.

Ecotourism and debt-for-nature swaps provide funding and incentives for conservation.
Consumers can support sustainable products and reduce impact on biodiversity.
Citizen science and volunteering contribute to conservation efforts.

Invasive brown tree snake linked to rapid seabird declines on Guam.
Evidence includes geography, predator-prey interactions, and ancillary species losses.
Management efforts illustrate challenges of rapid, human-caused ecological change.

Palm oil expansion drives large-scale deforestation and biodiversity loss.
Environmental costs: habitat destruction, climate impacts, erosion, water pollution, and loss of species (e.g., orangutans).
RSPO and sustainable palm oil efforts aim to reduce impacts; consumer choices influence supply.
Comparison: natural tropical forests vs. oil palm plantations show drastic biodiversity differences.

Education and informed consumer choices help protect biodiversity.
Support sustainable products and practices; reduce resource use and carbon footprint.
Enjoy biodiversity through responsible consumption and participation in conservation.

IUCN Red List classifies threat levels from least concern to extinct.
Protected areas (land and sea) are essential for long-term biodiversity protection.
National and international laws support protection and habitat preservation.

Education and everyday decisions are central to conserving biodiversity; action at local and global levels is needed to maintain ecosystem services and human well-being.