Questions: Biodiversity Conservation and Extinction Threats

Question 1

Which of the following is currently considered the single greatest driver of species extinction globally?

• A. Direct overhunting and poaching of targeted species
• B. Pollution of freshwater and marine ecosystems
• C. Habitat destruction and fragmentation
• D. Competition pressure following climate-driven range shifts

Answer: (C)

Habitat destruction and fragmentation is consistently the dominant extinction driver across taxa. It eliminates the resources species need, reduces population sizes below minimum viable thresholds, and isolates populations so that local extinctions cannot be rescued by recolonization. Poaching and pollution are significant but secondary contributors in most assessments. This also addresses the misconception that direct killing is the primary cause.

Question 2

Protecting a charismatic umbrella species like the tiger automatically protects the full diversity of species that share its habitat.

• T. True
• F. False

Answer: False

The umbrella species concept has value but requires empirical validation for each case. Charismatic megafauna often have large ranges and specific habitat needs that do not align with the requirements of invertebrates, plants, fungi, and microbes sharing the same region. A reserve designed around tiger habitat may still miss wetlands, forest edges, or soil microhabitats critical to much of the local biodiversity. Umbrella species are tools that work in some contexts but not all.

Question 3

What is population viability analysis (PVA), and how does the concept of minimum viable population (MVP) translate PVA results into conservation action?

Model answer: PVA is a modeling approach that estimates the probability a population will persist over a specified time horizon, incorporating demographic rates, environmental variability, and genetic factors. MVP is the smallest population size at which a species has an acceptable long-term survival probability (commonly defined as ≥95% over 100 years). Together they allow conservationists to identify which populations are at imminent extinction risk and set quantitative targets for recovery.

These tools convert qualitative concern into actionable numbers. A population well below its MVP is vulnerable to stochastic extinction events — a bad breeding season, a disease outbreak — that a larger population would survive. PVA lets managers run 'what-if' scenarios (e.g., reducing poaching, restoring habitat) and compare their projected impact, enabling data-driven triage when resources are limited.