Terrestrial Biodiversity Flashcards
Keystone Species:
A species that has a disproportionately large impact on its ecosystem relative to its abundance. The concept was introduced by Robert Paine in 1966. Examples include Pisaster sea stars and corals, though corals, despite having a large impact, are not considered keystone because of their high abundance.
Biodiversity:
This term refers to the variability among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part. It includes diversity within species, between species, and of ecosystems.
Genetic Diversity:
This term is not explicitly defined in the lecture notes, but it generally refers to the variety of genetic information contained in all of the individual organisms within a species. High genetic diversity allows species to adapt to changing environments.
Species Diversity:
Also not explicitly defined in the notes, this term refers to the variety of species within a certain region or ecosystem. It includes the number of different species (species richness) and the relative abundance of each species (species evenness).
Ecological Diversity (Ecosystem Diversity):
Although not defined in the notes, this term generally refers to the variety of ecosystems within a geographical location. It considers different habitats, biological communities, and ecological processes, as well as variation in the abiotic environment.
Habitat Destruction:
This is when natural habitat is no longer able to support the species present. Organisms that previously used the site are displaced or destroyed.
Habitat Degradation:
A decline in habitat quality that leads to reduced survival or reproductive success in a population.
Habitat Fragmentation:
Habitat loss results in the division of large, continuous habitats into smaller, more isolated remnants.
Invasive Species:
A non-native species that spreads widely and rapidly and becomes dominant in a community, interfering with the native community’s normal functions. Examples include the Emerald ash borer and European starling.
Explain the connections between biomes, and why some of these connections are particularly important to the long-term health of the biome.
Connections Between Biomes:
Biomes are interconnected both biotically and abiotically. For instance, animal migrations like that of salmon, move nutrients across biomes, impacting various ecosystems. Additionally, abiotic factors like dust movement influence soil and plant life in different biomes. These connections are vital for nutrient cycling, species diversity, and overall ecosystem health.
Explain why climate alone is insufficient to predict the plants or animals found in an area.
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Climate alone is insufficient to predict the plants or animals found in an area due to several factors. Firstly, species interactions can influence the presence or absence of certain species in areas where they are otherwise expected based on climate. For instance, some species depend on the presence of other species for survival, as seen in various food webs. This interdependence means that the absence or presence of one species can significantly impact the distribution of others, regardless of the climatic conditions.
Furthermore, other factors such as habitat destruction, alteration, or fragmentation can significantly impact biodiversity. Natural habitats that are no longer able to support their original species due to human activities or other disturbances can lead to a displacement or destruction of species. This results in changes in the distribution and abundance of species in a way that climate alone cannot predict.
The complexity of ecosystems and their interconnected nature, along with human impacts, mean that climate is just one of many factors influencing the distribution of plants and animals.
Identify if humans are a keystone species and justify your answer.
Humans are often considered a keystone species, but this classification is somewhat controversial. Keystone species are those that have a disproportionately large impact on their environment relative to their abundance. Humans certainly fit this definition, as they have immense influence on ecosystems worldwide through activities like agriculture, urbanization, and industrialization. These activities alter habitats, change species compositions, and impact global processes like the carbon cycle and climate. However, the term “keystone species” traditionally applies to species within a specific ecological context, and using it for humans, who are global changemakers, often extends beyond the usual scope of ecological studies.
Describe how the number of species on Earth can be estimated, and identify how many species there are on Earth (within a range).
The lecture notes from “Bio2485_Lecture05_TerrestrialBiodiv” do not provide specific information on the methods for estimating the number of species on Earth or the current range of these estimates.
However, generally, the number of species on Earth can be estimated using various methods, including:
Taxonomic Surveys and Sampling: These involve direct collection and identification of species in different habitats and regions. Scientists use these surveys to estimate species richness and extrapolate these findings to larger areas.
Genetic Analysis: Advances in genetic sequencing allow scientists to identify species based on genetic differences, even among very closely related organisms.
Mathematical Models: These models use known data, such as the rate of discovery of new species and the number of species in well-studied groups, to estimate the total number of species.
Estimates for the total number of species on Earth vary widely. Conservative estimates suggest there are about 8.7 million species (excluding bacteria and archaea), but the actual number could be much higher, potentially in the tens of millions. Many species remain undiscovered, particularly in understudied habitats like deep oceans and tropical rainforests. check
Describe the rate of extinction today compared to historical levels.
The lecture notes from “Bio2485_Lecture05_TerrestrialBiodiv” do not specifically quantify the current rate of extinction compared to historical levels. However, it is widely recognized in scientific literature that the current rate of species extinction is significantly higher than the natural or background rate.
Historically, extinction rates were much lower, occurring over longer geological time scales. Today, due to human activities such as habitat destruction, pollution, climate change, and overexploitation of resources, the rate of extinction has accelerated dramatically. This rapid loss of species has led many scientists to believe we are entering a sixth mass extinction event, the first to be caused largely by human activity. The current rate of extinction is estimated to be up to 1,000 times higher than the natural background rate.
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Explain how the Living Planet Index is calculated, and identify what the Index tells you, and what it cannot tell you.
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The Living Planet Index (LPI) is used to evaluate the health of the world’s biodiversity. It tracks the population size of almost 21,000 populations from 5,000 species using publicly available data. The index is set to 100% for the year 1970, and any values below 100% reflect an average loss of population size for all the species being monitored.
The LPI provides a measure of the state of global biodiversity by showing trends in vertebrate populations. However, it has limitations: it doesn’t provide information on the reasons for population changes, nor does it include all species or specific ecosystems. Also, the index is biased towards more studied species and regions, meaning it may not fully represent less known or studied species.
