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Course: AP®︎/College Environmental science > Unit 1
Lesson 4: Intro to biodiversity and biogeographySpecies diversity and ecosystem resilience
Review your understanding of species diversity, ecosystem resilience, and the impacts of habitat loss on generalist and specialist species in this free article aligned to AP standards.
Key points
- Biodiversity describes the enormous variety of life on Earth. An ecosystem's biodiversity includes genetic, species, and habitat diversity. But, because species are the basic units of biological classification, biodiversity is most commonly associated with species diversity.
- A measurement of species diversity includes two components: species richness and species evenness.
- Species richness is the number of different species in an area. An ecosystem with more species has a higher species richness.
- Species evenness describes species' relative abundance in an area. An ecosystem that contains roughly equal numbers of individuals across multiple species has a higher species evenness than an ecosystem that is dominated by a single species.
- Species diversity increases with both species richness and species evenness.
- Ecosystem resilience is the ability of an ecosystem to absorb change and return to the same equilibrium state after a temporary disturbance.
- Ecosystems with higher species diversity tend to be more resilient. If an ecosystem has a diverse community of organisms, they are not all likely to be affected by a disturbance in the same way. So, if one species is nearly killed off, a functionally similar species can take its place, maintaining the function of the ecosystem as a whole.
- The effect of an ecological disturbance on a species depends on its role in the ecosystem, or its ecological niche. Niches can be used to classify species as either generalists or specialists.
- Specialist species have narrow niches. They may live only in one type of habitat, use just a few types of food, or tolerate a narrow range of environmental conditions. Specialist species have a competitive advantage in their undisturbed environment, but they are highly sensitive to habitat loss. As a result, many specialist species are becoming threatened, endangered, and extinct due to human activities.
- Generalist species have broad niches. They can live in different types of habitats, eat a variety of foods, or tolerate a wide variety of environmental conditions. Generalist species are affected by habitat loss, but adapt more quickly than specialists, and are more likely to spread into new environments.
Want to join the conversation?
How can we increase Species richness on urban areas?(6 votes)
Provide Wildlife Corridors and Connections Between Green Spaces.
Use Organic Maintenance Methods and Cut Back On Lawns.
Use a Native Plant Palette and Plant Appropriately.
Utilize Existing Green Space Connections.
Be Mindful of Non-Native Predators.(15 votes)
- Urbane areas kill wildlife.(2 votes)
Not necessarily. My Grandparents live in an urban area and they see plenty of wildlife.(1 vote)
- How come generalists require less from the ecosystems but specialists require more, what makes it so hard for specialist to adapt(1 vote)
i think its because for specialists, they have to have a certain kind of environment but and if they don´t its really hard for them to adapt because they have lived a specific way for so long.
Like if you were suddenly driven from the only home you had ever known, it would a struggle to adapt. and some species cant adapt at all, unlike generalists, who adapt very easy.
does that help?(2 votes)
- What is the difference between evolving and adapting?(1 vote)
I think generally they can mean the same thing, but if we're being technical, adapting might be a little more short-term and immediate. Like, an animal or a lifeform adapts to a change in their environment. But evolution is a much longer timespan that referes to the gradual changes in genetics, features, etc., that take place over hundreds of thousands and millions of years.
Hope this helps! :)(2 votes)
If there are more animals (a larger population size) in an ecosystem, does it implicate that the ecosystem is more suitable for life, and thus, the species richness increases?(1 vote)- It can; to support large numbers of a single species or smaller numbers of many species, an environment has to have a high productivity; however, if one species becomes dominant then species evenness will decrease, and the environment won't be able to support other species with similar habits.(2 votes)
