Population Adaptation and Evolution

Key Concept 1: Population Adaptation

• Populations adapt when gene variants (alleles) better suited for survival/reproduction increase in frequency, a process known as natural selection.

Key Concept 2: Genetic Diversity and Natural Selection

• Genetic diversity fuels natural selection.
• More diverse populations are more likely to contain individuals that can adapt or thrive under changing conditions.

Key Concept 3: Interdependent Species and Coevolution

• Interdependent species can mutually adapt via coevolution.
• If a species invades the habitat of another and they have not coevolved, the invaded species may lack necessary defenses.

Key Concept 4: Factors Influencing Evolution

• Genetic drift, bottleneck effect, and founder effect, along with natural selection, influence evolution.

Key Concept 5: Artificial Selection

• In artificial selection, humans selectively breed organisms to promote or eliminate certain traits.
• This has led to the evolution of resistant or tolerant populations.

Key Concept 6: Pace of Evolution and Extinction

• The pace of evolution and extinction is affected by habitat loss, climate change, invasive species, pollution, and selective pressures.
• Mass extinction events can eliminate well-adapted species and sever community connections.

Key Concept 7: Mass Extinction Rates

• Extinction rates were much higher during mass extinction events.
• Past mass extinctions are linked to catastrophic events; current human activity might be causing another.

Brown Tree Snakes in Guam

• Brown tree snakes, introduced in the 1940s, decimated native wildlife in Guam.
• This caused the extinction of bird, bat, and lizard species threatening ecosystems and causing issues like power outages.
• Efforts to control snakes included trapping, snake-sniffing dogs, poisoned bait drops, and public education.

Extinction

• Extinction happens when all individuals of a species die out.
• It can be caused by natural events (environmental changes) or human activities (habitat destruction, overhunting).

Selective Pressure and Differential Reproductive Success

• Selective pressure is an environmental factor (predation, climate) affecting survival and reproduction.
• It favors traits best suited to the environment and leads to differential reproductive success.
• Differential reproductive success means advantageous traits are passed to more offspring, driving evolution.

Natural Selection and Its Conditions

• Natural selection is the process where individuals with advantageous traits survive and reproduce more successfully.
• Conditions for natural selection include trait variation within a population, heritability, differential survival/reproduction, and environmental pressures that lead to competition.

Genes, Alleles, and Evolution

• Genes are DNA segments coding for traits.
• Alleles are different versions of a gene.
• During evolution, allele frequencies in a population change due to mechanisms like natural selection, genetic drift, or mutation.

Types of Natural Selection

• Directional Selection: Favors one extreme trait (e.g., giraffes with longer necks).
• Stabilizing Selection: Favors average traits, reducing extremes (e.g., human birth weights).
• Disruptive Selection: Favors both extreme traits over the average (e.g., finches with large or small beaks).

Selection of Individuals vs. Evolution of Populations

• Selection acts on individuals based on their traits.
• Evolution occurs at the population level. Allele frequencies change over time due to individual selection, leading to population-wide shifts.

Genetic Diversity and Adaptation

• Genetic diversity increases a population’s ability to adapt to environmental changes.
• Low diversity may lead to extinction if a population lacks suitable traits.
• Brown tree snakes can decimate uniform populations lacking defenses.

Genetic Mutations, Recombination, and Pocket Mice

• Genetic mutations introduce new alleles and traits.
• Recombination shuffles alleles which increasing genetic diversity and adaptation.
• Pocket mice with dark fur had better survival in lava flows and spread due to recombination.

Coevolution

• Coevolution occurs when two or more species reciprocally influence each other's evolution through interactions.
• It leads to specialized traits (e.g., hummingbird and flower coevolution).

Invasive Species

• Invasive species are non-native organisms that spread rapidly.
• Invasive species negatively impact native species due to competition, food web disruption, habitat alteration, and disease introduction.

Endemic Species

• Endemic species are native to and found only in a specific region, like Galápagos tortoises.
• Endemic species face the risk of extinction due to limited range, specialized adaptations, environmental changes, and invasive species.

Genetic Drift

• Genetic drift is the random change in allele frequencies not due to fitness.
• Unlike natural selection, drift is non-selective.
• Small populations have drastic changes because random events have a larger impact on allele frequencies.

Bottleneck and Founder Effects

• Bottleneck Effect: A population shrinks severely, reducing genetic diversity. Cheetahs are an example, leading to diversity and health issues.
• Founder Effect: A small group starts a new population with reduced diversity. Amish populations show high rates of genetic disorders as a result.
• The bottleneck effect reduces an existing population while the founder effect starts a new one. Both limit diversity.
• Human actions such as habitat destruction and colonization/migration cause bottleneck and founder effects.

Artificial Selection vs. Natural Selection

• Artificial Selection: Humans selectively breed organisms.
• Natural Selection: Driven by environmental pressures.
• Artificial selection is often faster and intentional, unlike random natural selection.
• Dog breeding is an example of artificial selection.

Pesticide/Antibiotic Resistance

• Pesticide/antibiotic resistance is a form of artificial selection, killing most target organisms.
• Some organisms with resistant traits survive and reproduce. Repeated exposure increases resistance (e.g., MRSA, resistant insects).

Factors Affecting Evolution's Pace

• Mutation Rate: Higher mutation rates increase genetic variation, speeding evolution.
• Selection Pressure: Intense selection pressure accelerates trait selection.
• Generation Time: Shorter generation times lead to faster evolution.
• Genetic Diversity: Higher diversity provides more material for adaptation.
• Population Size: Smaller populations evolve faster but risk extinction.

Evolution vs. Extinction Pace

• Evolution is typically gradual as extinction can be rapid or gradual.
• Extinction can outpace evolution, especially when environmental changes exceed a species' ability to adapt.
• Human impacts are accelerating extinction rates.

r-Selected vs. K-Selected Species

• r-Selected Species: High reproduction rates and rapid adaptation (e.g., insects, mice)
• K-Selected Species: Few offspring, long lifespans, and slow adaptation (e.g., elephants, whales).
• K-selected species are more vulnerable to habitat loss and slow evolution, increasing extinction risk.

Impact of Bird Loss in Guam

• Guam bird loss disrupted ecosystems and seed dispersal decreased, and spider populations grew out of control.

Mass Extinction Events

• Mass extinction Events include loss of >50% of species in a geological short time.
• Five events have happened in the past.
  • Ordovician, Devonian, Permian, Triassic, and Cretaceous Extinctions.
• Ordovician-Silurian (~440 Mya): Climate change, glaciation.
• Devonian (~375 Mya): Ocean anoxia, possibly volcanic activity.
• Permian-Triassic (~252 Mya): Volcanic activity, global warming, ocean acidification.
• Triassic-Jurassic (~201 Mya): Volcanism, climate shifts.
• Cretaceous-Paleogene (~66 Mya): Asteroid impact, volcanic activity, climate change.

Background Extinction

• Background extinction has a low rate due to environmental changes, and competition.
• Extinction is balanced by speciation.
• Human activities have increased extinction rates by 1,000–10,000x.
• This accelerated pace threatens biodiversity and ecosystem survival.

Sixth Mass Extinction

• Species extinction rates compare to those comparable to past mass extinctions and causing biodiversity loss as a result.
• Up to 50% of species may be extinct by 2100.
  • Habitat Destruction, Climate Change, Overexploitation, Invasive Species, and Pollution resulting from human activities.
• Human-driven extinction is termed as “Anthropocene extinction” for its scale and speed.

Flashcard Key Terms

• Biodiversity: Variety of all life on Earth.
• Ecosystem Services: Human benefits from ecosystems (clean air/water, pollination, climate regulation).
• Instrumental Value: Usefulness of a species/ecosystem to humans (food/medicine).
• Intrinsic Value: Inherent worth unrelated to human use.
• Genetic Diversity: Variation in genes within a species.
• Species Diversity: Variety of species in an area.
• Ecological Diversity: Variety of ecosystems in an area.
• Endemic: Found only in a specific area.
• Biodiversity Hotspot: High endemic species and habitat loss.
• Endangered Species: At risk of extinction.
• Habitat Fragmentation: Division of continuous habitat.

Key Concept Flashcard Fill-Ins-

• Humans know more about well-studied groups such as birds and mammals than more diverse groups like insects on Earth.
• Biodiversity contributes to ecosystem stability which support human and cultural benefits.
• All genetic, species enhance and ecological diversity enhances the ability of a ecosystem to adapt.
• Protecting Biodiversity Hotspots is a cost-effective way to protect many endangered species.
• Genetic Diversity reduces risk that populations might go extinct.
• Biodiversity loss threatens ecosystems because of human activities threatening the services such as food.

Palm Oil

• Palm oil is a vegetable used in food, cosmetics, and biofuels.
• Palm oil production causes deforestation and habitat loss.

Ecosystems

• Indonesia has rainforests, coral reefs, and volcanic mountains creating major ecosystems.

Major Species Threats-

• Habitat loss, pollution, and climate change, and invasive species.

Biodiversity is related to-

• Ecosystem Services, Polination and Water Purification.

Loss of Biodiversity-

• Can lead to infectious diseases as a result of transmission.

Economic Benefits of Biodiversity-

• Tourism, agriculture, and pharmaceuticals, worth trillions of dollars for cultural economic benefits.
• Instrumental value is Humans using medicinal plants in order for medicinal plants to take care of disease.

Irish potato famine-

• Illustrates lack of genetic diversity caused potato famine from crop wiped out.

Species extinction-

• Affects ecosystems services.

Human isolation-

• Is used with habitat fragmentation and introduction.
• Wildlife corridors help animals connected .

Threats to Biodiversity-

• Habitat loss, pollution, invasive species.

Humans Reduce Threats-

• Pollution and actions that protect habitats.

Temperature increase can result in-

• Different climates.

Warmer planets can result in-

• Rising sea levels, melting glaciers.

Greenhouse gases-

• Trap heat in the atmosphere.

Measuring Present climate changes-

• Proxy data measures present climate changes.

Greenhouse gases aren't only forcuses-

• Surface albedo.

Current warming-

• Cannot be explained with natural climate forces.

Climate include-

• Intense heat events.

Responding to climate change-

• To reduce warming will entail mitigation, adaptation, and inevitable climate changes.

Matthew Hauer's Finding-

• Matthew Hauer's research highlights could displace 1.5 to 13 million to the US areas in 2100 due to sea level rising.

Weather and Climate Differences-

• Weather Is short term atmospheric conditions.
• Climatre is longer term averages, for seasons.

Isle de jean charles, Louisiana-

• Lost 98% of land because of SLR in 1950s.

Newtok, and Alaska:

• A Yukon village erosion due to stronger permafrost.

Climate Change, Reasons with small temperature increases-

• Long-term changes in the global area due to fossil fuel burning and increased greenhouse concentrations.

Effects of Global Warming-

• Hurricanes and Storms.
• Rising sea levels.

Climate change predicts:

• Rising Temperatures, Sea Level
• Biodiversity Impacts, Loss of polar bears from habitat

What is a climate force example?-

• Alters earths balance such as GHG that warm the planet ( methane gas).

GHG examples

• Trapping Heat (CO, CH4).

Danger of Enhanced Greenhouse Effects-

• Human Activities of concentration.

Fossil Fuel Link-

• Burning fossil fuel of Co2 increases greenhouse effect.

What type of proxy data is related to sediment?-

• Pollen which indicate vegetation.

Difference between Negative and Positive Feedback Loops-

• Opposite feedbacks, increasing plant growth.

Amplifying the change occurs with-

• Melting of Arctic ice reduces reflectivity and warms Earth.

How are Milankovitch Cycle used?-

• Effects radiation and long term shifts to see how years shift.

Climate refugees by 2050?-

• 200 million to 1 Billion could be displaced by droughts.

Climate models of the earth-

• Combine climate systems to create data.

The Vulnerable of Climates-

• High areas, glacier loss, shifts.

Climate Mitigations-

• Reducing of renewable energy, reforestation.

Climate Adaptational Adaptation-

• Adjusting current/expected with building walls.