Explain Biodiversity and Population Dynamics - Biology

Identify whether regulation is density-dependent: disease spreads faster as population density rises.

Density-dependent. Higher density increases contact rates and transmission.
What is functional diversity in an ecosystem?

The diversity of ecological roles and traits that affect ecosystem processes. Different functional roles contribute to ecosystem processes.
What is primary productivity and how can biodiversity influence it?

Rate of biomass production; higher diversity can increase productivity. Diverse plant communities often show greater total biomass production.
What is genetic drift and when is it strongest in population dynamics?

Random allele frequency change; strongest in small populations. Sampling effects dominate when few individuals reproduce.
What is the typical effect of higher biodiversity on ecosystem stability?

Higher biodiversity generally increases stability and resilience. Diverse communities buffer against environmental fluctuations.
What is bottom-up control in population dynamics?

Resource availability (producers/nutrients) limits higher trophic populations. Energy and nutrients flow up from primary producers.
Which option best predicts stability: A low evenness, B high evenness, assuming equal richness?

B high evenness. Balanced abundances create more stable community dynamics.
Identify whether regulation is density-independent: a hurricane reduces all populations in a region.

Density-independent. External forces affect populations regardless of their size.
Identify the expected trend: as species richness increases, what happens to food web redundancy?

Food web redundancy generally increases. More pathways provide backup when individual species fail.
What is a trophic cascade?

A chain of effects across trophic levels after a population change. Predator changes ripple through multiple feeding levels.
What is habitat fragmentation and its typical effect on biodiversity?

Breaking habitat into patches; it often reduces biodiversity and gene flow. Isolated patches lose connectivity and species diversity.
What is the typical effect of predator removal on prey population size?

Prey population size often increases, potentially reducing plant biomass. Released from predation pressure, prey populations expand.
Identify the expected trend: as habitat fragmentation increases, what happens to gene flow?

Gene flow usually decreases. Barriers reduce movement and genetic exchange between populations.
Identify the relationship between biodiversity and ecosystem resilience after disturbance.

Higher biodiversity usually increases the speed and likelihood of recovery. More species provide alternative pathways for ecosystem recovery.
What is species richness in a community?

The number of different species present. Counts distinct species without considering their relative abundances.
What is logistic growth in population dynamics?

Growth slows as $N$ approaches $K$ ; an S-shaped curve. Environmental resistance slows growth near carrying capacity.
What is density-independent regulation of population size?

Population limits act regardless of density (e.g., drought, storms). Environmental factors affect all individuals equally.
What is the "insurance effect" of biodiversity on population dynamics?

Multiple species can maintain function when one species declines. Functional redundancy maintains ecosystem services when species decline.
What is a population bottleneck and its effect on genetic diversity?

A sharp $N$ reduction that decreases genetic variation. Surviving individuals carry only a subset of original alleles.
What is density-dependent regulation of population size?

Population limits intensify as density increases (e.g., competition, disease). Higher crowding amplifies competition and resource depletion.
What is a limiting resource in population dynamics?

A resource that restricts population growth when scarce. Essential resources like food or space become bottlenecks.
What is ecological succession and how does biodiversity typically change over time?

Community change after disturbance; biodiversity often increases then stabilizes. Species accumulate during recovery from early to late stages.
What is biodiversity, as used in ecology when comparing communities?

The variety of life across genes, species, and ecosystems in an area. Encompasses genetic, species, and ecosystem variety in a defined region.
What is inbreeding depression and what population condition increases it?

Reduced fitness from inbreeding; more likely in small, isolated populations. Related mating increases homozygosity and harmful recessive expression.
State the per capita growth rate definition using $r$ in population ecology.

$r$ is the per-individual rate of increase (births minus deaths per capita). Birth and death rates determine net population change.
Identify the most likely result of a population bottleneck on future adaptability.

Reduced adaptability due to lower genetic variation. Fewer alleles limit evolutionary responses to future challenges.
What is competitive exclusion in population ecology?

Two species with identical niches cannot stably coexist. Complete niche overlap leads to competitive displacement.
What is carrying capacity ( $K$ ) of an environment?

The maximum population size the environment can sustainably support. Environmental capacity determines long-term population stability.
What is a disturbance and how can it affect biodiversity and populations?

A disruptive event that changes resources; it can reset succession and $N$ . Opens niches and creates opportunities for colonization.
What is exponential growth in population dynamics?

Growth proportional to $N$ ; a J-shaped increase when resources are abundant. Unlimited resources allow maximum reproductive potential.
Identify the relationship: if biodiversity increases, what usually happens to variation in total ecosystem biomass over time?

Variation usually decreases (biomass becomes more stable). Portfolio effects from multiple species reduce temporal variability.
What is an extinction vortex in small populations?

A reinforcing cycle of small $N$ , low diversity, and rising extinction risk. Multiple factors compound to accelerate population decline.
Choose the correct outcome: if a keystone predator is removed, what happens to prey diversity?

Prey diversity often decreases due to competitive dominance by one prey species. One superior competitor excludes others without predation pressure.
What is gene flow and how does it affect genetic diversity?

Movement of alleles between populations; it typically increases diversity. Migrants introduce new alleles and counteract drift effects.
What is functional redundancy and how does it affect population stability?

Multiple species share roles; it buffers ecosystem function against declines. Backup species maintain function when others decline.
What is edge effect and how can it influence population dynamics in fragments?

Edge conditions alter survival and reproduction near habitat boundaries. Boundary zones create different microclimates and species interactions.
What is K-selected life history strategy in population dynamics?

Lower reproduction, later maturity, higher parental care; stable near $K$ . Emphasizes survival and competitive ability in stable environments.
Choose the correct link: if pollinator diversity declines, what happens to plant reproduction rates?

Plant reproduction rates often decrease. Pollinator loss directly reduces plant reproductive success.
What is the rescue effect in metapopulation dynamics?

Immigration reduces local extinction risk in small populations. Migrants prevent local populations from declining to extinction.
What is niche partitioning and how does it relate to biodiversity?

Species use different resources; it reduces competition and supports diversity. Resource specialization allows coexistence and maintains diversity.
What is r-selected life history strategy in population dynamics?

High reproduction, early maturity, low parental care; rapid growth. Maximizes reproductive output in unpredictable environments.
What is the direct relationship between biodiversity and disease spread risk?

Lower biodiversity can increase disease transmission in some systems. Fewer hosts can concentrate disease transmission pathways.
What is the dilution effect hypothesis for infectious disease?

Higher host diversity can reduce transmission by diluting competent hosts. Non-competent hosts interrupt transmission chains to susceptible species.
What is an invasive species in terms of biodiversity and populations?

A nonnative species that spreads and disrupts native populations and diversity. Outcompetes natives and alters community structure.
What is species evenness in a community?

How evenly individuals are distributed among species. Measures whether species abundances are balanced or skewed.
What is the founder effect and how can it change biodiversity within a population?

A new population starts from few individuals, altering allele frequencies. Random sampling of alleles creates genetic differences from source.
What is top-down control in population dynamics?

Predators regulate prey populations and can shape community composition. Predation pressure constrains lower trophic level abundance.
What is a keystone species?

A species with a disproportionately large effect on its ecosystem. Their ecological role exceeds their numerical abundance.
What is a metapopulation in population ecology?

A set of subpopulations linked by dispersal among habitat patches. Interconnected patches allow recolonization after local extinctions.
Identify the relationship between biodiversity loss and food web complexity.

Biodiversity loss typically simplifies food webs and reduces redundancy. Fewer species create simpler, less stable food networks.
What is population size ( $N$ ) in population dynamics?

The total number of individuals in a population. Fundamental measure for tracking population changes over time.
What is population density in ecology?

Number of individuals per unit area or volume. Measures crowding intensity in a given space.
What is the minimum viable population (MVP) concept?

The smallest population size likely to persist long term. Critical threshold for avoiding demographic and genetic risks.
What is the diversity–stability hypothesis in one sentence?

More diverse ecosystems tend to show more stable functioning over time. More species provide functional backup during disturbances.

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