Question

1. why are islands of particular concern in conservation biology?

1. give two examples of species mentioned in the text that have gone extinct on islands.

1. why do smaller populations and lower genetic diversity make island species more prone to extinction?

1. how does the distance of an island from the mainland affect colonization rates?

1. what two main factors influence the extinction rate of species on islands? 6.

why do larger islands generally have lower extinction rates?

1. define \primary productivity.\ how is it measured?

Explanation:

1. Islands have isolated ecosystems with unique, often endemic species that evolved with limited predators/competition, making them highly vulnerable to disturbances like invasive species, habitat loss, and climate change. They also have small population sizes and limited genetic diversity, increasing extinction risk.
2. Common examples from conservation biology texts include the Dodo (Raphus cucullatus, from Mauritius) and the Moa (various species from New Zealand).
3. Smaller populations face higher risk of random demographic/genetic events (e.g., inbreeding depression, stochastic mortality). Lower genetic diversity reduces ability to adapt to environmental changes (e.g., new diseases, climate shifts).
4. Islands farther from the mainland have lower colonization rates: fewer species can disperse across greater distances, so fewer new organisms reach and establish populations there.
5. The two main factors are island size (smaller islands have higher extinction rates) and the number/size of resident populations (smaller populations are more at risk).
6. Larger islands have more available habitat and resources, supporting larger, more stable populations. They also have greater habitat diversity, reducing competition and providing refuges from disturbances.
7. Primary productivity is the rate at which autotrophs (plants, algae, cyanobacteria) convert inorganic carbon (via photosynthesis or chemosynthesis) into organic biomass. It is typically measured as:

• Gross Primary Productivity (GPP): Total carbon fixed by autotrophs, measured in units like $\frac{gC}{m^2 \cdot year}$ or $\frac{kg biomass}{m^2 \cdot year}$.
• Net Primary Productivity (NPP): GPP minus the energy autotrophs use for respiration (NPP = GPP - R), representing the biomass available to other trophic levels.

Answer:

1. Islands have isolated, endemic-rich ecosystems with small, vulnerable populations, making them highly susceptible to extinction threats.
2. A. Dodo (Raphus cucullatus, Mauritius), B. Moa (New Zealand species)
3. Small populations face stochastic risks; low genetic diversity limits adaptive capacity.
4. Farther islands have lower colonization rates due to limited dispersal ability of species.
5. A. Island size, B. Size of resident species populations
6. Larger islands have more habitat/resources, supporting larger, more stable populations.
7. Primary productivity is the rate autotrophs produce organic biomass. It is measured as gross (total carbon fixed) or net (biomass available to consumers) productivity, in units like $\frac{gC}{m^2 \cdot year}$ or $\frac{kg biomass}{m^2 \cdot year}$.