BIODIVERSITY
ECOSYSTEM SERVICES
ISLAND BIOGEOGRAPHY
TOLERANCE AND EVOLUTION
SUCCESSION
CHALLENGE
100
THE TOTAL NUMBER OF DIFFERENT SPECIES IN AN ECOSYSTEM
Species Richness
100
NAME TWO ECOSYSTEM SERVICES
Provisioning, regulating, cultural, and supporting services
100
WHAT SHOULD GO ON THE X-AXIS?
Island Area / Size (Positive correlation with number of species)
100
WHAT IS THEIR TOLERANCE RANGE?
-5°C to 47°C / 48°C
100
NAME TWO PIONEER SPECIES IN SECONDARY SUCCESSION
Grasses
Weeds / Annual plants (e.g., crabgrass, horseweed)
Fast-growing shrubs
100
GIVE AN EXAMPLE OF AN ANTHROPOGENIC ACTIVITY THAT PUSHES AN ORGANISM OUTSIDE OF ITS TOLERANCE RANGE
Deforestation / Urban heat island effect:
Burning fossil fuels (Ocean Acidification):
Agricultural runoff (Eutrophication / Hypoxia):
Industrial thermal pollution:
200
HOW DOES A HIGHER GENETIC DIVERSITY INCREASE RESILIENCE?
Higher trait variety increases the chance that some individuals survive stressors (like disease or drought) and reproduce.
200
THE ECOSYSTEM SERVICE THAT INCLUDES SPORT HUNTING
Cultural services (specifically recreation/ecotourism)
200
WHAT SHOULD GO ON THE X-AXIS?
Distance from mainland / Isolation
200
WHAT IS THE HIGHEST TEMPERATURE THEY CAN LIVE IN BEFORE ECOLOGICAL STRESS?
22°C (or 22.5°C / 23°C) — the upper boundary of the optimum range before entering the zone of physiological stress.
200
WHICH TYPE OF SUCCESSION IS THE FASTEST AND WHY?
Fastest Type:
Secondary succession
Why:
Pre-existing soil: Soil and its seed bank/organic nutrients remain intact after the disturbance, eliminating the long soil-formation process required in primary succession.
Surviving pioneer seeds and roots: Plant propagules, roots, spores, and underground vegetative structures are often already present and ready to regrow immediately.
200
EXPLAIN HOW NATURAL DISTURBANCES CAN INCREASE BIODIVERSITY
Intermediate Disturbance Hypothesis: Moderate levels of disturbance prevent dominant species from monopolizing resources, allowing weaker competitors to survive alongside them.
Creates habitat heterogeneity: Disturbances (e.g., fires, blowdowns) generate a mosaic of microenvironments and successional stages across the landscape.
Prevents competitive exclusion: Disruption resets local populations before a single species can outcompete others for limited light, nutrients, or space.
300
WHAT CONCEPT DO THESE GRAPHS DEPICT?
Ecosystem Resistance (low resistance on the left vs. high resistance on the right).
300
NAME A REGULATING SERVICE DISRUPTED BY DEFORESTATION
Climate regulation / Carbon sequestration
Water cycle regulation / Flood control
Erosion control / Soil retention
Air quality regulation / Air purification
Water purification / Filtration
300
WHY DO LARGER ISLANDS HAVE A HIGHER BIODIVERSITY?
Higher habitat diversity / more ecological niches
Lower extinction rates (larger populations, more resources)
Higher immigration rates / larger target area for dispersing species
300
HOW COULD A SPECIES INCREASE THEIR TOLERANCE RANGE?
Genetic mutation: Random changes in DNA that produce new traits/alleles suited for wider environmental conditions.
Natural selection / Adaptation: Selection pressures over multiple generations favoring individuals with broader physiological thresholds.
Phenotypic plasticity / Acclimatization: Individual organisms adjusting their physiology, behavior, or morphology within their lifetime in response to environmental changes (without genetic change).
300
DESCRIBE A CLIMAX COMMUNITY
Stable and self-sustaining: Final, mature stage of ecological succession that remains relatively unchanged until a major disturbance occurs.
High biodiversity and structural complexity: Features a diverse array of plant and animal species occupying specialized ecological niches.
Dominated by late-successional species: Composed of slow-growing, shade-tolerant, K-selected species (e.g., large canopy trees like hardwoods or conifers).
Balanced energy flow: Gross primary productivity (GPP) is roughly equal to total ecosystem respiration (R), maintaining a stable biomass.
300
HOW DOES THE CONCEPT OF PRIMARY SUCCESSION AND THE THEORY OF ISLAND BIOGEOGRAPHY OVERLAP?
Bare substrate colonization: Both start on uninhabited areas (bare rock vs. new oceanic islands).
Distance impacts immigration: Isolation determines how quickly pioneer species' spores and seeds reach the new area.
Habitat modification: Early pioneers establish and build soil, allowing later immigrating species to survive.
Island size affects succession: Larger islands collect more pioneer species and have lower extinction rates as communities develop.
400
HAVING THIS TYPE OF DIVERSITY ALLOWS FOR MORE SPECIES DIVERSITY
Habitat (or Ecosystem) Diversity
400
WHAT TYPE OF ECOSYSTEM SERVICE WOULD CATEGORIZE PLANTS THAT FILTER OUT POLLUTANTS?
Regulating service (water purification / air purification)
400
WHY ARE ISLAND-DWELLING SPECIES MORE SUSCEPTIBLE TO EXTINCTION?
Evolution in isolation / Loss of defensive adaptations (lack of natural predators leads to naivety and vulnerability to introduced invasive species)
High proportion of specialist species (narrow niches and specific food/habitat requirements)
Small population sizes (makes them highly vulnerable to genetic bottlenecks, inbreeding depression, and environmental catastrophes)
Limited geographic range / Spatial constraints (cannot migrate or relocate when their habitat is altered or destroyed)
400
HOW WILL THE CHANGING ENVIRONMENT AFFECT EVOLUTION?
Accelerated rates of evolution / Directional selection: Rapid environmental shifts create strong selection pressures, favoring individuals with advantageous traits and speeding up evolutionary change.
Increased extinction rates: Species with narrow tolerance ranges, low genetic diversity, or long generation times may be unable to adapt quickly enough, leading to local or global extinction.
Shifts in geographic distribution (Range shifts): Populations will migrate toward more favorable conditions (e.g., higher latitudes or elevations), altering gene flow and driving speciation in new environments.
Selection for phenotypic plasticity / Generalist traits: Changing environments favor organisms with flexible traits or broader ecological niches over narrow specialists.
400
EXPLAIN HOW SOIL IS FORMED DURING PRIMARY SUCCESSION
Chemical and physical weathering: Bare rock is broken down over time by wind, rain, and temperature fluctuations.
Action of pioneer species: Lichens and mosses secrete acids that chemically weather rock while physically anchoring into cracks.
Organic matter accumulation: As pioneer species die and decompose, organic matter mixes with the weathered rock fragments.
Nutrient cycling: Decomposers build a fertile topsoil layer over time, enabling larger plants (grasses, shrubs) to take root.
400
DESCRIBE A WAY TO COMBAT THE PROBLEM OF LOW GENETIC DIVERSITY WITHIN A POPULATION
Wildlife corridors: Habitat bridges connect fragmented populations, promoting gene flow between isolated groups.
Artificial translocation / Relocation: Moving individuals from distinct wild populations to introduce new alleles into a localized gene pool.
Captive breeding and release: Breeding individuals in controlled programs to maximize genetic variance before reintroducing offspring into the wild.
Habitat restoration / Expansion: Enlarging accessible habitat allows population size to grow, reducing the risk of genetic bottlenecks.
500
WHAT IS IT CALLED WHEN ORGANISMS BREED WITH CLOSE FAMILY MEMBERS AND INCREASE THE PROBABILITY OF OFFSPRING EXPRESSING RARE MUTANT PHENOTYPES?
Inbreeding depression (or inbreeding)
500
MAKE AN EFFECTIVE ARGUMENT WHY ECOSYSTEM SERVICES CAN JUSTIFY CONSERVATION
Economic Value / Cost Savings: Preserving natural services (like wetlands filtering water or bees pollinating crops) is far cheaper than building artificial infrastructure or manually replacing these functions.
Human Survival & Well-being: Ecosystems provide essential, non-replaceable goods and functions—such as clean air, fresh water, climate regulation, and disease control—that directly support public health and civilization.
Preserving Future Potential (Option Value): Maintaining intact ecosystems protects undiscovered resources, such as potential medicines, genetic traits for crops, and future economic opportunities.
500
WHICH ISLAND WOULD HAVE THE HIGHEST BIODIVERSITY AND WHY?
Isabela Island
Why:
Largest Surface Area / Size: According to the theory of island biogeography, larger islands support lower extinction rates because they have higher population capacities and more resources.
Greater Habitat & Niche Diversity: Being significantly larger than the surrounding islands, it features more varied microclimates, topographies (multiple active volcanoes), and diverse ecological niches.
Proximity to Mainland / Central Position: It is close to other islands and relatively close to the South American mainland source pool, resulting in higher colonization/immigration rates.
Island-hopping (or stepping stone) effect can come in to play.
500
EXPLAIN WHY ORGANISMS CAN’T EVOLVE TO COPE WITH ISSUES LIKE POLLUTION AND CLIMATE CHANGE
Environmental change outpaces reproduction: Climate change and pollution occur faster than multi-generational evolutionary rates.
Lack of pre-existing genetic variation: Natural selection requires pre-existing traits; without tolerant alleles, adaptation cannot occur.
Small populations lack evolutionary potential: Reduced population sizes lead to low genetic diversity and bottlenecks.
Physiological trade-offs: Energy spent coping with environmental stress reduces energy available for reproduction and survival.
Novel human-made stressors: Organisms have no evolutionary history or biological adaptations to withstand synthetic pollutants.
500
WHAT STAGE OF SUCCESSION IS THIS? JUSTIFY YOUR ANSWER.
Climax / Late-successional stage at the far right end of the graph)
Justification:
Presence of Mosses as pioneers: The graph begins with mosses—pioneer organisms capable of living on bare rock to form soil—which uniquely indicates primary succession.
Order of plant community turnover: Proceeds sequentially from mosses ---> grasses ---> shrubs ---> pine trees ---> oak trees, demonstrating the replacement of early-successional r-selected pioneers by late-successional, shade-tolerant K-selected species over time.
500
EXPLAIN HOW HABITAT FRAGMENTATION REDUCES SPECIES DIVERSITY ACCORDING TO THE THEORY OF ISLAND BIOGEOGRAPHY.
Creates habitat "islands": Fragmented patches function like isolated islands surrounded by human-dominated land.
Decreases immigration rates: Increased distance between patches reduces the movement of organisms to new areas.
Increases extinction rates: Smaller patch sizes support smaller populations, making them more vulnerable to localized extinction.