Learning Objectives Biodiversity loss refers to the reduction of biodiversity due to displacement or extinction of species. According to a 2019 United Nations report, 1 million species at risk of extinction. Considering there are estimated to be 8-11 million species total,…
Learning Objectives Biodiversity is a broad term for the variety of life on Earth. Traditionally, ecologists have measured biodiversity by taking into account both the number of species and the number of individuals of each species. However, biologists now measure biodiversity…
Roughly 1.5 million species have been identified, and this is just a fraction of all the species on Earth. These species exist in a variety of ecosystems. Genetic differences among individuals within a species further contributes to the variety of…
Communities include all the different species living in a given area. Biotic interactions refer to the relationships among organisms. Competition occurs when organisms at the same trophic level use the the same resources, and one or both organisms is harmed.…
Learning Objectives Food Chains A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. Each organism in a food chain occupies a specific trophic level (energy level), its position in the food chain. The…
Learning Objectives Trophic interactions in a community can be represented by diagrams called food chains and food webs. Before discussing these representations in detail, we must first review the basics of energy. Energy flows through a community as a result of trophic interactions.…
Learning Objective Describe the difference between a community and an ecosystem Communities are composed of living organisms and their interactions with one another and include biotic (living) components. Ecosystems are communities that include the abiotic (non-living) components of the environment as well (Video ). These abiotic factors…
Learning Objective Describe community structure and succession Community Dynamics Community dynamics are the changes in community structure and composition over time, often following environmental disturbances such as volcanoes, earthquakes, storms, fires, and climate change. Communities with a relatively constant number of…
Learning Objectives Biodiversity, Species Richness, and Relative Species Abundance Biodiversity describes a community’s biological complexity: it is usually measured by the number of different species, or species richness, in a particular area and their relative abundance (evenness). However, genetic diversity is increasingly considered as a…
Learning Objectives Symbiosis Symbiotic relationships, or symbioses (plural), are close interactions between individuals of different species over an extended period of time which impact the abundance and distribution of the associating populations. Most scientists accept this definition, but some restrict the term…