From Today in Science History:
Ernst Mayr (Born 5 Jul 1904; died 3 Feb 2005). German-born American biologist known for his work in avian taxonomy, population genetics, and evolution. In 1928, he led the first of three expeditions to New Guinea and the Solomon Islands where he studied the effects of geographic distribution among various animal species. He led development of the modern synthetic theory of evolution (the interplay of gene mutation and recombination, changes in structure and function of chromosomes, reproductive isolation and natural selection). In 1940, he proposed a definition of species that became accepted in scientific circles. He began bird watching as a young boy, and by the age of ten, he could recognize all of the local bird species by call as well as sight.
[ "Darwin's Influence on Modern Thought" by Ernst Mayr, and his books here, Johnson, Kristin. "Ernst Mayer, Karl Jordan, and the History of Systematics," History of Science 43 (2005): 1-35, Haffer, Jurgen and Franz Bairlein, "Ernst Mayr – ‘Darwin of the 20th century’," Journal of Ornithology 145 (2004): 161-162, and Haffer, Jurgen. Ornithology, Evolution, and Philosophy: The Life and Science of Ernst Mayr 1904-2005 (Springer, 2007)]
Robert Fitzroy (Born 5 Jul 1805; died 30 Apr 1865) British naval officer, hydrographer, and meteorologist who commanded the voyage of HMS Beagle, aboard which Charles Darwin sailed around the world as the ship’s naturalist. That voyage provided Darwin with much of the material on which he based his theory of evolution. Fitzroy retired from active duty in 1850 and from 1854 devoted himself to meteorology. He devised a storm warning system that was the prototype of the daily weather forecast, invented a barometer, and published The Weather Book (1863). His death was by suicide, during a bout of depression.
A Fitzroy podcast from the Royal Society.