Alfred Russel Wallace arrived in Singapore in 1854 with a simple plan in mind. He would survey the region's wildlife and ship specimens back to London for sale to museums and wealthy collectors. His financial security rested on the foreign exotica for which Victorians had a seemingly insatiable appetite.

The British naturalist amassed thousands of insects and birds during eight years in southeast Asia. And though Wallace's strange creatures sold for good money back home, the collection had a more profound value. Through studying the animals, Wallace hit on one of the world's greatest scientific discoveries: the theory of evolution through natural selection.

Wallace's work on the theory, along with major insights into biodiversity, are described in thousands of pages of books, articles, drawings and paintings, which appear together for the first time today, in a web project directed by John van Wyhe, a historian at the National University of Singapore. The Wallace Online project was funded by an anonymous US donor, and comes ahead of next year's centenary of Wallace's death.

Wallace's publications were distributed among thousands of magazines and newspapers, and had never been collected together in one place. The project contains 28,000 pages of searchable documents and 22,000 images. They include stunning pictures of blue-throated bee eaters, asian fairy-bluebirds and meticulous drawings of butterflies and beetles.

The new bird of paradise that Wallace discovered, Wallace's standard-wing. Photograph: Wallace Online

Van Wyhe, who directed a similar project for Darwin's works several years ago, said the Wallace collection was intended as a reliable source of information on the naturalist whose name was so eclipsed by Darwin's. "This needed to be done for Wallace. He's far less well known than Darwin, and it's high time people had reliable material on his work," van Wyhe said.

The history of science is littered with names overlooked, but few so much as Wallace. In July 1858, the first papers on natural selection were read aloud at the Linnean Society in London, one from Darwin, the other from Wallace. Though both men announced the theory at the same time, Darwin's publication, On the Origin of Species, the following year was the seed of revolution that made senior scientists take notice.

The book was not the only factor. Victorian modesty played a part in Wallace's diminished place in history, and perhaps some deference to what he, a poor and unprivileged man, saw as the great figures of science. "The Victorians were falling over themselves to be more modest than everybody else. Modesty was a high virtue. So Wallace, from the very beginning, referred to it as Darwin's theory, and he never relented to the end of his life," said van Wyhe.

From 1855, Wallace published a series of articles that came ever closer to declaring the theory of evolution through natural selection. In the midst of a malarial fever, on the island of Ternate in Indonesia, he had a moment of clarity, that many are born, lots die, and only a few survive. He sent an essay from the island to Darwin, who passed it to the great geologist, Charles Lyell, who then proposed it to the Linnean Society alongside an essay from Darwin.

"It's one of the greatest ironies in history. Wallace sends his essay to the one man in the world who has been working on this for 20 years. And Darwin, again the perfect gent, passes it to Lyell, and they decide to publish essays from them both," said van Wyhe.

Wallace's thorough survey of wildlife led to another breakthrough in 1859, known today as the Wallace line. He noticed that species on either side of an invisible line between Australia and Asia were substantially different, despite being close geographical neighbours. The observation clashed with the thinking of the day, that species were created for their particular environment. Wallace proposed the animals came from two ancient, larger landmasses, a Super Asia and a Super Australia, which had long since sunk beneath the waves. "He couldn't have imagined plate tectonics, which is the real explanation, and that Australia started out in South America," said van Wyhe.

Among Wallace's other writings are notes on local cuisine. In a passage on the durian fruit, Wallace describes a large coconut-sized fruit with short, stout spines, liable to fall from trees and cause spectacular wounds to the unwary. "When brought into a house the smell is often so offensive that some persons can never bear to taste it. This was my own case when I first tried it in Malacca, but in Borneo I found a ripe fruit on the ground, and, eating it out of doors, I at once became a confirmed Durian eater," he writes. Having declared the taste almost impossible to describe, he offers "a rich butter-like custard, highly flavoured with almonds gives the best general idea of it, but intermingled with it come wafts of flavour that call to mind cream-cheese, onion-sauce, brown sherry, and other incongruities".

In other papers, Wallace laments the rate at which species are being forced to extinction, and makes one of the earliest calls for conservation. He likens species to letters that make up the volumes of Earth's history, and their loss obliterating an invaluable record of the past.

"Future ages will certainly look back upon us as a people so immersed in the pursuit of wealth as to be blind to higher considerations," he writes from the Malay archipelago in 1863.