To see a World in a Grain of Sand And a Heaven in a Wild Flower,
Hold Infinity in the palm of your hand And Eternity in an hour. William Blake (1757-1827)
jueves, 27 de julio de 2017
Unconscious selection drove seed enlargement in vegetable crops
Domesticated grain crops evolved from wild plants under human
cultivation, losing natural dispersal mechanisms to become dependent
upon humans, and showing changes in a suite of other traits, including
increasing seed size. There is tendency for seed enlargement during
domestication to be viewed as the result of deliberate selection for
large seeds by early farmers. However, like some other domestication
traits, large seeds may have evolved through natural selection from the
activities of people as they gathered plants from the wild, or brought
them into cultivation in anthropogenic settings. Alternatively, larger
seeds could have arisen via pleiotropic effects or genetic linkage,
without foresight from early farmers, and driven by selection that acted
on other organs or favored larger plants. We have separated these
unconscious selection effects on seed enlargement from those of
deliberate selection, by comparing the wild and domesticated forms of
vegetable crops. Vegetables are propagated by planting seeds, cuttings,
or tubers, but harvested for their edible leaves, stems, or roots, so
that seed size is not a direct determinant of yield. We find that
landrace varieties of seven vegetable crops have seeds that are 20% to
2.5-times larger than those of their closest wild relatives. These
domestication effect sizes fall completely within the equivalent range
of 14% to 15.2-times for grain crops, although domestication had a
significantly larger overall effect in grain than vegetable crops. Seed
enlargement in vegetable crops that are propagated vegetatively must
arise from natural selection for larger seeds on the occasions when
plants recruit from seed and are integrated into the crop gene pool, or
via a genetic link to selection for larger plants or organs. If similar
mechanisms operate across all species, then unconscious selection during
domestication could have exerted stronger effects on the seed size of
our staple crops than previously realized.
Comparisons of seed mass between landraces and wild accessions of (A)
cereals (annual grass crops), (B) pulses (grain legumes), and (C)
vegetables. The seed mass in domesticated crop plants is expressed as a
multiple of that in wild plants (i.e., a value of two indicates a
twofold increase in seed mass under domestication). Points represent
mean ± 95% confidence interval and the red line denotes a value of 1.0
(i.e., no effect of domestication).
"None of the human faculties should be excluded from scientific activity. The depths of intuition, a sure awareness of the present, mathematical profundity, physical exactitude, the heights of creative reason and sharpness of understanding, together with a versatile and ardent imagination and a loving delight in the world of the senses, they are all essential for a lively and productive apprehension of the moment." J. W. Goethe (1749 - 1832)
Ecology has been eminently a descriptive science despite some pioneering work by theoreticians such as Lotka, Volterra, Nicholson, and others. Description is a first step toward understanding a system. However, such a first step needs to be accompanied by the development of a theoretical framework in order to achieve real insight and, whenever possible, predictive power.
Ricard V. Solé and Jordi Bascompte, 2006 (Self-Organization in Complex Ecosystems).
Animal Liberation Front
"Toda pregunta es siempre más que una pregunta, está probando una carencia, una ansiedad por llenar un hueco intelectual o psicológico, y hay muchas veces en que el hecho de encontrar una respuesta es menos importante que haber sido capaz de vivir a fondo la pregunta, de avanzar ansiosamente por las pistas que tiende a abrir en nosotros"
Julio Cortázar. Desafíos.
If we throw mother nature out the window, she comes back in the door with a pitchfork.
"The State represents violence in a concentrated and organized form. The individual has a soul, but as the State is a soulless machine, it can never be weaned from violence to which it owes its very existence". -Mahatma Gandhi
“If our means of investigation became more and more incisive, we would discover the simple under the complex, then the complex under the simple, then again the simple under the complex, and so on, without being able to predict which state would ultimately prevail” Jules Henri Poincaré (1854 –1912)