Biodiversity Lecture Notes

Biodiversity Lecture Notes

• Biodiversity is the variety of life in genes, species, ecosystems, and ecosystem processes. It's essential for life on Earth.
• Biodiversity is variation at all levels of biological organization. It encompasses genetic, species, and ecosystem diversity, along with functional diversity.
• The lecture outlines the concept of biodiversity, distribution of biodiversity, biodiversity and balance of nature, benefits of biodiversity, threats to biodiversity, and the future of biodiversity studies.

Levels of Biodiversity

• Genetic diversity: The number of genes in organisms ranges over three orders of magnitude. Within species, the potential combinations of genes vastly exceeds the number of individuals. Genetic diversity is the ultimate source of biodiversity at all levels.

• Species diversity: Species richness is the number of species in a given area. Species diversity is a set of individuals that can mate and produce fertile offspring. Estimates range from 8 to 100 million species (likely 10-14 million), with 2 million identified. A significant portion (~50%) of species in endangered tropical rainforests.

• Ecosystem diversity: Ecosystems are biological communities of interacting organisms and their physical environment. A biome is a collection of different ecosystems sharing similar characteristics. Different environmental conditions lead to selective pressures and adaptations, resulting in diverse species.

• Functional diversity: This encompasses the biological and chemical processes (like energy flow and matter recycling) vital for the survival of species, communities, and ecosystems.

Speciation

• One species can split into two or more that cannot interbreed and produce fertile offspring; this is speciation.
• Geographic isolation and reproductive isolation are crucial factors separating species.

Factors Affecting Biodiversity

• Genetic diversity, species diversity, ecosystem diversity, and functional diversity all influence biodiversity.
• Other factors include habitat loss, fragmentation, prolonged droughts, increased radiation, parasites, viral and fungal diseases, pollution, climate change; competition from nonnative species. Many poorly known groups exist (insects, nematodes, mites), and many unknown species remain, especially in tropical regions.

Keystone Species

• Keystone species play significant roles in food webs, impacting the abundances of other species in an ecosystem. Removing them can drastically alter ecosystem structure and function.
• Pollinators and top predators are examples of keystone species.

Extinction

• Biological extinction: Occurs when an entire species is lost.
• Local extinction: A species vanishes from a specific area.
• Endemic species: Species vulnerable to extinction.
• Background extinction rate: The normal rate of extinction. Speciation often outpaces extinction.
• Mass extinction: Large-scale loss of species over a short period. The Earth has experienced several mass extinctions in the past.
• Current human activities significantly contribute to premature extinction and the degradation of habitats.

How to Study Biodiversity in Older Times

• Fossils, including mineralized and petrified remains, skeletons, bones, shells, leaves, and seeds, provide insights into past life forms and ecosystems. The fossil record is incomplete (about 1% of all species).

Population Changes Over Time

• Populations evolve (change genetically) over time through mutations (random changes in DNA) and spontaneous mutations or through external agent (radiation).
• Genetic variability drives populations to adapt or evolve to change in environment.
• Populations can adapt through evolution, migrate, or become extinct.

Natural Selection

• Adaptive traits are genetically favorable traits that enhance the probability of survival and reproduction.
• These traits often lead to differential reproduction in response to environmental conditions, leading to evolutionary change, adaptation, or migration.
• Natural selection doesn't result in perfection but in adaptation to existing conditions.
• Populations do not evolve intentionally or consciously, but as a response to selective pressures.

Biodiversity and Human Activities

• Human activities negatively affect biodiversity through habitat destruction.
• This also disrupts natural habitats (and biomes) and diminishes the earth's biodiversity.

Levels of Biodiversity: Ecosystem

• Ecosystems include interacting organisms and their physical environment. Biomes encompass large collections of distinct ecosystems with similar characteristics. Differences in geographic location and climate result in numerous biomes and ecosystems.

Ecological Niches

• Each species plays a specific ecological role known as an ecological niche.
• This includes the resources (water, sunlight, space, temperatures, and food requirements) that the species needs to survive and reproduce. Generalist species have broad niches, while specialist species have narrow niches.

Evolution

• Evolution explains how life on Earth has changed over time through changes to genes passed across generations in populations, through mutation or adaptation, driven by natural selection.

Current Human Activities and Biodiversity

• Human activities negatively impact biodiversity by destroying or degrading habitats.
• The result is the premature extinction of species.

Future of Biodiversity in Saudi Arabia

• The biodiversity of species in Saudi Arabia is presented and analyzed. The details of specific species and areas are included. The status and conservation efforts are present in the discussion.

Summary

• Diversity displays different levels.
• Each level includes various contributing factors, and all levels are interconnected.
• Dedicated programs to conserve biodiversity are crucial to prevent widespread loss.

Explore the fundamental concepts of biodiversity, including genetic, species, and ecosystem diversity. This quiz covers the distribution of biodiversity, its importance for ecological balance, and the threats it faces. Test your knowledge on the benefits and future of biodiversity studies.