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The principle of Uniformitarianism states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time. [2] A fundamental principle of geology advanced by the 18th century Scottish physician and geologist James Hutton, is that "the present is the key to the past ...
Cross-cutting relationships can be used to determine the relative ages of rock strata and other structures. Explanations: A – folded rock strata cut by a thrust fault; B – large intrusion (cutting through A); C – erosional angular unconformity (cutting off A & B) on which rock strata were deposited; D – volcanic dike (cutting through A, B & C); E – even younger rock strata (overlying ...
The black walnut secretes a chemical from its roots that harms neighboring plants, an example of competitive antagonism.. In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other.
The pygmy mammoth is an example of insular dwarfism, a case of Foster's rule, its unusually small body size an adaptation to the limited resources of its island home.. A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms.
These proposed relationships lead to the hypothesis that intermediate disturbance levels would be the optimal amount of disorder within an ecosystem. Once K-selected and r-selected species can live in the same region, species richness can reach its maximum. The main difference between both types of species is their growth and reproduction rate.
When a large distance separates the source and the target (a small activation site), the redundancy principle explains that this geometrical gap can be compensated by large number. Had nature used less copies than normal, activation would have taken a much longer time, as finding a small target by chance is a rare event and falls into narrow ...
The term sister group is used in phylogenetic analysis, however, only groups identified in the analysis are labeled as "sister groups".. An example is birds, whose commonly cited living sister group is the crocodiles, but that is true only when discussing extant organisms; [3] [4] when other, extinct groups are considered, the relationship between birds and crocodiles appears distant.
Coexistence theory attempts to explain the paradox of the plankton-- how can ecologically similar species coexist without competitively excluding each other?. Coexistence theory is a framework to understand how competitor traits can maintain species diversity and stave-off competitive exclusion even among similar species living in ecologically similar environments.