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Evolution of Homo antecessor. The last members of Paranthropus die out. 1 Ma First coyotes. 810 ka First wolves: 600 ka Evolution of Homo heidelbergensis. 400 ka First polar bears. 350 ka Evolution of Neanderthals. 300 ka Gigantopithecus, a giant relative of the orangutan from Asia dies out. 250 ka Anatomically modern humans appear in Africa.
Factors which have been identified as impeding the identification of pathogens include the following: 1. Lack of animal models: Experimental infection in animals has been used as a criterion to demonstrate a disease-causing ability, but for some pathogens (such as Vibrio cholerae, which causes disease only in humans), animal models do not exist ...
Viral evolution is a subfield of evolutionary biology and virology concerned with the evolution of viruses. [ 1 ] [ 2 ] Viruses have short generation times, and many—in particular RNA viruses —have relatively high mutation rates (on the order of one point mutation or more per genome per round of replication).
Life cycle of the black rot pathogen, the gram negative bacterium Xanthomonas campestris pathovar campestris. Plant pathology or phytopathology is the scientific study of plant diseases caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1]
1871; Thomas Taylor publishes the first USDA papers on microscopic plant pathogens [4] 1875; Mikhail Woronin identified the cause of clubroot as a "plasmodiophorous organism" and gave it the name Plasmodiophora brassicae [1] 1876; Fusarium oxysporum f.sp. cubense, responsible for Panama disease, discovered in bananas in Australia [5]
A representation by Robert Seymour of the cholera epidemic depicts the spread of the disease in the form of poisonous air.. The miasma theory was the predominant theory of disease transmission before the germ theory took hold towards the end of the 19th century; it is no longer accepted as a correct explanation for disease by the scientific community.
The idea of a tree of life arose from ancient notions of a ladder-like progression from lower into higher forms of life (such as in the Great Chain of Being).Early representations of "branching" phylogenetic trees include a "paleontological chart" showing the geological relationships among plants and animals in the book Elementary Geology, by Edward Hitchcock (first edition: 1840).
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...