5 research outputs found
Enhanced lithium depletion in Sun-like stars with orbiting planets
The surface abundance of lithium on the Sun is 140 times less than
protosolar, yet the temperature at the base of the surface convective zone is
not hot enough to burn Li. A large range of Li abundances in solar type stars
of the same age, mass and metallicity is observed, but theoretically difficult
to understand. An earlier suggestion that Li is more depleted in stars with
planets was weakened by the lack of a proper comparison sample of stars without
detected planets. Here we report Li abundances for an unbiased sample of
solar-analogue stars with and without detected planets. We find that the
planet-bearing stars have less than 1 per cent of the primordial Li abundance,
while about 50 per cent of the solar analogues without detected planets have on
average 10 times more Li. The presence of planets may increase the amount of
mixing and deepen the convective zone to such an extent that the Li can be
burned.Comment: 13 pages, 2 figure
Global urban environmental change drives adaptation in white clover
Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale
Global urban environmental change drives adaptation in white clover
Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale
Global urban environmental change drives adaptation in white clover
Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale