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477 results on '"Harder, Lawrence D."'

4. Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity

Author

O'Meara, Brian C, Smith, Stacey D, Armbruster, W Scott, Harder, Lawrence D, Hardy, Christopher R, Hileman, Lena C, Hufford, Larry, Litt, Amy, Magallón, Susana, Smith, Stephen A, Stevens, Peter F, Fenster, Charles B, and Diggle, Pamela K

Subjects
Biodiversity, Biological Evolution, Flowers, Magnoliopsida, Models, Biological, Phylogeny, Quantitative Trait, Heritable, Stochastic Processes, diversification, floral evolution, macroevolution, non-equilibrium, flower symmetry, pollination, Biological Sciences, Agricultural and Veterinary Sciences, Medical and Health Sciences
Abstract

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years.

Published
2016

8. Invasive bees and their impact on agriculture

Author

Aizen, Marcelo A., primary, Arbetman, Marina P., additional, Chacoff, Natacha P., additional, Chalcoff, Vanina R., additional, Feinsinger, Peter, additional, Garibaldi, Lucas A., additional, Harder, Lawrence D., additional, Morales, Carolina L., additional, Sáez, Agustín, additional, and Vanbergen, Adam J., additional

Published
2020
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9. Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance

Author

Garibaldi, Lucas A, Steffan-Dewenter, Ingolf, Winfree, Rachael, Aizen, Marcelo A, Bommarco, Riccardo, Cunningham, Saul A, Kremen, Claire, Carvalheiro, Luísa G, Harder, Lawrence D, Afik, Ohad, Bartomeus, Ignasi, Benjamin, Faye, Boreux, Virginie, Cariveau, Daniel, Chacoff, Natacha P, Dudenhöffer, Jan H, Freitas, Breno M, Ghazoul, Jaboury, Greenleaf, Sarah, Hipólito, Juliana, Holzschuh, Andrea, Howlett, Brad, Isaacs, Rufus, Javorek, Steven K, Kennedy, Christina M, Krewenka, Kristin M, Krishnan, Smitha, Mandelik, Yael, Mayfield, Margaret M, Motzke, Iris, Munyuli, Theodore, Nault, Brian A, Otieno, Mark, Petersen, Jessica, Pisanty, Gideon, Potts, Simon G, Rader, Romina, Ricketts, Taylor H, Rundlöf, Seymour, Colleen L, Schüepp, Christof, Szentgyörgyi, Hajnalka, Taki, Hisatomo, Tscharntke, Teja, Vergara, Carlos H, Viana, Blandina F, Wanger, Thomas C, Westphal, Catrin, Williams, Neal, and Klein, Alexandra M

Subjects
Agricultural, Veterinary and Food Sciences, Zoology, Crop and Pasture Production, Biological Sciences, Animals, Bees, Crops, Agricultural, Flowers, Fruit, Insecta, Pollination, General Science & Technology
Abstract

The diversity and abundance of wild insect pollinators have declined in many agricultural landscapes. Whether such declines reduce crop yields, or are mitigated by managed pollinators such as honey bees, is unclear. We found universally positive associations of fruit set with flower visitation by wild insects in 41 crop systems worldwide. In contrast, fruit set increased significantly with flower visitation by honey bees in only 14% of the systems surveyed. Overall, wild insects pollinated crops more effectively; an increase in wild insect visitation enhanced fruit set by twice as much as an equivalent increase in honey bee visitation. Visitation by wild insects and honey bees promoted fruit set independently, so pollination by managed honey bees supplemented, rather than substituted for, pollination by wild insects. Our results suggest that new practices for integrated management of both honey bees and diverse wild insect assemblages will enhance global crop yields.

Published
2013

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