BIO3115 - midterm 1

What is Conservation Biology?

A multidisciplinary, crisis‑driven science focused on understanding biodiversity loss and developing solutions to prevent extinction and ecosystem degradation.

What are the main aims of conservation biology?

• Provide scientific principles for conserving biodiversity

• Identify conservation problems

• Develop corrective management strategies

• Bridge science and management

• Disseminate conservation knowledge widely and accurately

What is the declining population paradigm?

It focuses on identifying the causes of population declines and reversing them before extinction occurs.

What is the small population paradigm?

It focuses on risks faced by populations already reduced to small sizes and aims to maintain viability and prevent extinction.

How do the two paradigms differ (decline + small pop)?

• Declining population → why populations are decreasing

• Small population → how to prevent extinction once populations are already small

Why is conservation biology called a “crisis discipline”?

Because consequences of inaction are often worse than acting with incomplete information.

Why is conservation biology multidisciplinary?

It integrates ecology, genetics, economics, sociology, ethics, and politics.

What does it mean that conservation biology is value‑laden?

Conservation decisions are influenced by human values, priorities, and ethical beliefs.

Should uncertainty prevent conservation action? Why or why not?

No. Delaying action often increases extinction risk; proactive management generally improves species persistence.

How does reducing uncertainty affect conservation outcomes?

Reducing uncertainty can triple the effectiveness of management actions.

What is a major communication issue related to uncertainty in conservation science?

Scientists must communicate uncertainty clearly without paralyzing decision‑makers.

What is the Nero dilemma?

The risk that conservation inaction leads to irreversible loss, even when knowledge is incomplete.

Why is action often better than no action in the Nero dilemma?

Because no action greatly increases the probability of extinction.

What is the bottom‑line dilemma?

The difficulty of defining a precise conservation target (e.g., minimum protected area size).

Why is the bottom‑line dilemma problematic?

Because journalists and policymakers want clear thresholds, but science cannot always provide them.

What is the tragedy of the commons?

When individuals overuse a shared resource, causing long‑term collective harm.

Why does individual benefit conflict with collective benefit in this dilemma?

Individual short‑term gain leads to degradation of the shared resource.

How does Elinor Ostrom challenge Hardin’s view?

She showed that communities can sustainably manage commons through cooperation and governance.

What is the tyranny of small decisions?

When many minor decisions accumulate into major biodiversity loss.

Why is this tyranny of small décision dangerous?

• No single decision appears harmful

• Environmental safeguards are bypassed

• Ecological thresholds are crossed invisibly

• Leads to “extinction by a thousand cuts”

What are trade‑offs in conservation?

Situations where saving one species or ecosystem harms another due to limited resources.

Why are trade‑offs unavoidable?

Because resources (space, money, time) are limited.

What is intrinsic value of biodiversity?

Biodiversity has value simply by existing, regardless of human use.

What is instrumental (utilitarian) value of biodiversity?

Biodiversity is valuable because it provides benefits to humans.

Give examples of instrumental values.

• Goods: food, fiber, medicine

• Services: pollination, water purification, flood control

• Information: scientific knowledge

• Psycho‑spiritual: cultural and aesthetic benefits

How do indigenous cultures value biodiversity?

As an integral part of cultural identity, traditions, and spiritual life.

Why is granting rights to nature important in conservation?

It provides stronger legal protection and recognizes cultural and ethical values.

What is the ultimate goal of conservation biology?

The preservation of Earth’s biodiversity.

What two main aspects does biodiversity encompass?

Species richness and evenness

What is species richness

The number of species present per unit area or volume.

What is evenness?

How evenly individuals are distributed among species in a community.

What is α (alpha) diversity?

The number of species occurring at a single local site.

What factors lead to high α-diversity?

High habitat specialization and many species packed into a single habitat.

What is biodiversity conservation

The management of human interactions with biological diversity to maximize current benefits while maintaining the ability of ecosystems to meet future generations’ need

What is β (beta) diversity?

The difference in species composition among sites; species turnover along gradients.

What causes high β-diversity?

High habitat specificity and high species turnover between habitats.

What is γ (gamma) diversity?

Total species diversity across a large geographic region or multiple sites.

How does sampling effort affect observed species richness?

Species richness increases with sampling effort until a plateau is reached

Why must sampling effort be standardized when comparing sites?

Because differences in effort can falsely appear as differences in biodiversity.

What are biodiversity indicators

Measurable variables used to track changes in biodiversity over time or space.

What is an action threshold?

A predefined level of biodiversity loss at which conservation action should occur.

How is γ-diversity used in conservation planning?

To prioritize regions that maximize species representation across large areas.

How does habitat structural complexity affect α-diversity?

α-diversity increases with structural complexity due to more niches and microhabitats.

Why do high α-diversity habitats tend to have smaller population sizes per species?

Because resources are divided among more species.

What determines species richness on islands according to island biogeography theory?

A balance between immigration and extinction rates.

Does equilibrium apply to species composition or richness?

It applies only to species richness, not species composition.

How does distance from the mainland affect island species richness?

Farther islands have lower immigration rates and fewer species.

How does island size affect species richness?

Larger islands support more species due to lower extinction rates and higher habitat diversity.

What is the species–area relationship?

Species richness increases with area, often following a log–log relationship.

Why does species richness increase with area?

Larger areas contain more habitats and can support more populations.

How does time since isolation affect island biodiversity?

Recently isolated islands tend to have higher species richness due to past immigration opportunities.

How do land bridges affect species–area curves?

They increase immigration rates, leading to higher species richness.

What are the two main types of factors influencing population persistence?

• Demographic (ecological) factors: act over short timescales (decades) and affect population size.

• Evolutionary factors: act over long timescales (generations) and affect genetic composition.

Give examples of demographic factors.

Intrinsic growth rate (r₀), immigration, emigration, age structure, birth and death rates.

Give examples of evolutionary factors.

Genetic variability, population structure, natural selection.

When are evolutionary factors most important for population survival?

When the generation time is similar to or shorter than the rate of environmental change.

When are evolutionary factors largely irrelevant?

When environmental changes occur faster than the species’ generation time.

Why is genetic variability important for population persistence?

It determines a population’s ability to adapt to selection and changing environments.

How does low genetic variability affect extinction risk?

Low variability → low adaptive potential → higher extinction risk over evolutionary timescales.

What is heterozygosity (H)?

The proportion of individuals that are heterozygous at a gene (have different alleles).

What does high total heterozygosity (HT) indicate?

High overall genetic variability within a species.

What is effective population size (Ne)?

The number of individuals that actually contribute genes to the next generation.

Why is Ne often smaller than the actual population size?

Due to skewed sex ratios, mating behavior, unequal reproductive success, or non‑breeding adults.

How does Ne relate to genetic variability?

Genetic variability (heterozygosity) increases as Ne increases.

Why is Ne more important than census size for conservation genetics?

Because genetic processes depend on the number of breeders, not total individuals.

What is genetic drift?

Random changes in allele frequencies caused by chance sampling of gametes.

Why is genetic drift stronger in small populations?

Chance events have a greater impact when fewer individuals contribute genes.

What is the long‑term effect of genetic drift?

Loss of genetic variation and fixation of alleles.

How does genetic drift affect homozygosity?

It increases homozygosity over generations.

Why is inbreeding more common in small populations?

There are fewer unrelated mates available.

What is inbreeding?

Mating between genetically related individuals.

What is the inbreeding coefficient (F)?

A measure of the degree of inbreeding in a population.

How does inbreeding affect heterozygosity?

It reduces heterozygosity and increases homozygosity.

What is inbreeding depression?

Reduced survival and fertility of offspring from related parents.

Why does inbreeding depression occur?

Because harmful recessive alleles are expressed in homozygous individuals.

What life‑history traits are affected by inbreeding depression?

Juvenile mortality, fertility, disease resistance, overall fitness.

What is the founder effect?

Loss of genetic variability when a new population is started by a small number of individuals.

Which alleles are most likely lost during founder events?

Rare alleles from the original population.

What is a population bottleneck?

A severe, temporary reduction in population size.

How do founder effects and bottlenecks affect genetic variability?

They drastically reduce genetic variability through drift and inbreeding.

What determines how much genetic variation remains after a bottleneck?

Severity of the bottleneck and number of surviving breeders.

How does immigration affect genetic variability within populations?

It increases variability within populations.

How does immigration affect genetic differences among populations?

It reduces genetic differentiation between populations.

What is genetic rescue?

Improvement in fitness and genetic variability due to immigration of unrelated individuals.

How much immigration can be sufficient to reduce genetic loss?

Even a few unrelated individuals per generation can have a large effect.

What is outbreeding depression?

Reduced fitness caused by hybridization between genetically distinct populations.

Why can outbreeding reduce fitness?

Local adaptations are disrupted, producing poorly adapted hybrids.

Give an example of outbreeding depression from the lecture.

Tatra ibex: hybrids bred at the wrong time of year, causing reproductive failure.

Why are small populations especially vulnerable to extinction?

They experience stronger drift, inbreeding, loss of variability, and reduced adaptability.

Why is maintaining genetic connectivity important in conservation?

It preserves genetic diversity and reduces extinction risk.