Introduction to Biodiversity Self Made Review

2.1 Introduction to Biodiversity ● Biodiversity can include: - Genetic: The total number of genetic characteristics in the genetic makeup of a species. - Species: The number of different species that are represented in a given community. - Habitat: The range of habitats present in a region. ● Little genetic diversity means a species is susceptible to environmental change. ● A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts or human activities. - This can lead to loss of genetic diversity. ● Ecosystems with more species are more likely to recover from disruptions. ● Loss of habitat leads to loss of specialist species followed by loss of generalist species. Reduced number of species with large territorial requirements. ● Species richness is the number of species found in an eocsystem. ● Latitudinal Gradient- More species richness near the equator (typically more evenness as well). ● Transition zones have high biodiversity. 2.2 Ecosystem Services ● Four categories of ecosystem services: - Provisioning: The products obtained from ecosystems, including, for example, genetic resources, food and fiber, and freshwater. - Regulating: The benefits obtained from the regulation of ecosystem processes, including, for example, the regulation of climate, water, and some human diseases. - Cultural: Non-material benefits people obtain from nature. They include recreation, aesthetic enjoyment, physical and mental health benefits and spiritual experiences. - Supporting: Necessary for the production of all other ecosystem services. Some examples include biomass production, production of atmospheric oxygen, soil formation and retention, nutrient cycling, water cycling, and provisioning of habitat. ● Anthropogenic activities can disrupt ecosystem services, potentially resulting in economic and ecological consequences. 2.3 Island Biogeography ● Island biogeography is the study of the ecological relationships and distribution of organisms on islands, and of these organisms’ community structures. ● Many island species have evolved to be specialists versus generalists because of the limited resources, such as food and territory, on most islands. The long-term survival of specialists may be jeopardized if and when invasive species, typically generalists, are introduced and outcompete the specialists. ● Distance Effect- Farther island = less immigration thus fewer species ● Target Size- Lager Island= higher immigration because there is more room to spread out ● ● Differential Extinction- Larger Island= less extinction because of the large populations Edge Effect- Impacts because the conditions along a fragments edge don't align with the interior. 2.4 Ecological Tolerance ● Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can endure before injury or death results. ● Applies to individuals AND species. 2.5 Natural Disruptions to Ecosystems ● Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions. ● Earth system processes operate on a range of scales in terms of time. Processes can be periodic, episodic, or random. ● Earth’s climate has changed over geological time for many reasons. ● Sea level has varied significantly as a result of changes in the amount of glacial ice on Earth over geological time. ● Major environmental change or upheaval commonly results in large swathes of habitat changes. 2.6 Adaptations ● Organisms adapt to their environment over time, both in short- and long-term scales, via incremental changes at the genetic level. ● Environmental changes, either sudden or gradual, may threaten a species’ survival, requiring individuals to alter behaviors, move, or perish. 2.7 Ecological Succession ● There is both secondary and primary succession. ● A keystone species is a species whose activities have a particularly significant role in determining community structure. ● An indicator species displays if a certain aspect of an ecosystem is present. ● ● Pioneer members of an early successional species commonly move into unoccupied habitat and over time adapt to its particular conditions, which may result in the origin of new species. Succession in a disturbed ecosystem will affect the total biomass, species richness, and net productivity over time.