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Crescentin was discovered in 2009 by Christine Jacobs-Wagner in Caulobacter crescentus (now vibrioides), an aquatic bacterium which uses its crescent-shaped cells for enhanced motility. [1] The crescentin protein is located on the concave face of these cells and appears to be necessary for their shape, as mutants lacking the protein form rod ...
Convergent evolution—the repeated evolution of similar traits in multiple lineages which all ancestrally lack the trait—is rife in nature, as illustrated by the examples below. The ultimate cause of convergence is usually a similar evolutionary biome , as similar environments will select for similar traits in any species occupying the same ...
For example, when leaves alternate up a stem, one rotation of the spiral touches two leaves, so the pattern or ratio is 1/2. In hazel the ratio is 1/3; in apricot it is 2/5; in pear it is 3/8; in almond it is 5/13. [56] Animal behaviour can yield spirals; for example, acorn worms leave spiral fecal trails on the sea floor. [57]
The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions.
It also assists scientists in classifying organisms based on similar characteristics of their anatomical structures. A common example of comparative anatomy is the similar bone structures in forelimbs of cats, whales, bats, and humans. All of these appendages consist of the same basic parts; yet, they serve completely different functions.
For example, Agrobacterium tumefaciens is a plant pathogen, Brucella abortus is an animal pathogen, and Sinorhizobium meliloti is a soil bacterium that invades, and becomes a symbiont in, plant root nodules that fix nitrogen yet most of the proteins of the Caulobacter cell cycle control are also found in these species. The specific coupling ...
This is even more obvious in some species of dogs, such as malamutes and huskies, who appear even more physically and behaviorally similar. [17] There is a divergent genomic sequence of the mitochondrial DNA of wolves and dogs dated to over 100,000 years ago, which further supports the theory that dogs and wolves have diverged from shared ancestry.
One might predict that the loss of photosynthesis or cellular respiration would allow for the complete loss of the plastid genome or the mitochondrial genome respectively. [ 25 ] [ 30 ] [ 33 ] While there are numerous examples of mitochondrial descendants ( mitosomes and hydrogenosomes ) that have lost their entire organellar genome, [ 50 ] non ...