Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community. Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area. Relative species abundances tend to conform to specific patterns that are among the best-known and most-studied patterns in macroecology. Different populations in a community exist in relative proportions; this idea is known as relative abundance.
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👉 Species composition in the context of Climate proxy
In the study of past climates ("paleoclimatology"), climate proxies are preserved physical characteristics of the past that stand in for direct meteorological measurements and enable scientists to reconstruct the climatic conditions over a longer fraction of the Earth's history. Reliable global records of climate only began in the 1880s, and proxies provide the only means for scientists to determine climatic patterns before record-keeping began.
A large number of climate proxies have been studied from a variety of geologic contexts. Examples of proxies include stable isotope measurements from ice cores, growth rates in tree rings, species composition of sub-fossil pollen in lake sediment or foraminifera in ocean sediments, temperature profiles of boreholes, and stable isotopes and mineralogy of corals and carbonate speleothems. In each case, the proxy indicator has been influenced by a particular seasonal climate parameter (e.g., summer temperature or monsoon intensity) at the time in which they were laid down or grew. Interpretation of climate proxies requires a range of ancillary studies, including calibration of the sensitivity of the proxy to climate and cross-verification among proxy indicators.
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Species composition in the context of Association (ecology)
In phytosociology and community ecology an association is a type of ecological community with a predictable species composition and consistent physiognomy (structural appearance) which occurs in a particular habitat type. The term was first coined by Alexander von Humboldt and formalised by the International Botanical Congress in 1910.
An association can be viewed as a real, integrated entity shaped either by species interactions or by similar habitat requirements, or it can be viewed as merely a common point along a continuum. The former view was championed by American ecologist Frederic Clements, who viewed the association as a whole that was more than the sum of its parts, and by Josias Braun-Blanquet, a Swiss-born phytosociologist. On the other end of the argument was American ecologist Henry Gleason, who saw these groupings of plant species as a coincidence produced by the "fluctuation and fortuitous immigration of plants, and an equally fluctuating and variable environment".
Species composition in the context of Electrofishing
Electrofishing is a fishing technique that uses direct current electricity flowing between a submerged cathode and anode. This affects the movements of nearby fish so that they swim toward the anode, where they can be caught or stunned.
Electrofishing is a common scientific survey method used to sample fish populations to determine abundance, population density and species composition. When performed correctly, electrofishing results in no permanent harm to the fish, which return to their natural mobility state in as little as two minutes after being caught.