13.4 - Exercises

Biodiversity encompasses three essential components: genetic diversity, species diversity, and ecological diversity. Genetic diversity refers to the variety of genes within a species, species diversity pertains to the different species within a particular area, and ecological diversity includes the different ecosystems that host these species.

Ecologists estimate the total number of species using several methods. They analyze existing databases of species, compare species richness in well-studied temperate regions with less studied tropical zones, and extrapolate findings to estimate the number of undiscovered species. They often rely on statistical models that use known species data as a baseline.

Three hypotheses explain why tropics have greater species richness: 1) Evolutionary Time Hypothesis - The tropics have remained in a stable environment for longer periods allowing more time for speciation. 2) Environmental Stability Hypothesis - Tropical climates are more stable and predictable, leading to greater specialization and diversity. 3) Solar Energy Hypothesis - More sunlight and energy in the tropics increase primary productivity, supporting a wider array of species.

The slope of regression in the species-area relationship indicates how species richness changes with area size. A steeper slope signifies that larger areas contain significantly more species, suggesting that habitat size contributes greatly to biodiversity. This relationship suggests conservation priorities should focus on protecting larger habitats.

The major causes of species loss include habitat destruction (like deforestation), over-exploitation of resources (such as excessive fishing), invasive species that outcompete native ones, and co-extinctions where loss of one species leads to the extinction of another species it depends on. These factors disturb ecosystems and impact biodiversity critically.

Biodiversity is crucial for ecosystem functionality as it enhances productivity, stability, and resilience against disturbances. Diverse ecosystems can better withstand changes such as climate shifts or diseases, ultimately providing essential services like clean air and water, pollination, and nutrient cycling.

Sacred groves are patches of forest that are protected by local communities due to their spiritual significance. These areas often contain a variety of flora and fauna, some of which may be endangered. Their conservation practices play a crucial role in preserving biodiversity and maintaining ecosystems.

Ecosystem services such as flood control and soil erosion prevention are facilitated by biotic components like plants and animals. Roots of plants stabilize soil, reducing erosion, while vegetation can absorb excess rainwater, minimizing flood risks. Biodiverse ecosystems typically enhance these services more effectively.

Animals exhibit greater diversification for several reasons; they often have complex behaviors and adaptations that allow them to exploit various niches, their ability to move allows them to escape unfavorable conditions, and they have more significant evolutionary pressures leading to speciation. In contrast, plant diversification may be somewhat limited due to their reliance on specific conditions for growth.

Deliberate extinction can occur when a species is invasive and poses a threat to native ecosystems. For example, if an alien species is dominating a habitat and driving native species to extinction, removing it could be justified to preserve the ecological balance. However, such actions should be handled with extreme caution.