The Guiana Shield
The Guiana Shield comprises geologically ancient highlands in northeastern South America drained by headwaters of the Amazon, Orinoco and Essequibo rivers. Connections between
these drainages have shifted over time, making for complicated biogeographical patterns among fishes of the region. The western Guiana Shield (pictured), is where most of my research has been focused. This area comprises a large central plateau with many shear-sided, table-top mountains called tepuis. This stair-step topographical motif is the result of a vast underlying sedimentary formation being repeatedly uplifted and eroded. To learn more, read my book chapter here. Headwaters of many major drainages in this area are isolated from lowlands by large rapids or waterfalls, creating a broad division in fish biogeographical patterns. Highland fishes show patterns of dispersal via headwater capture, whereas lowland fish dispersal is mediated by environmental gradients, seasonally flooded wetlands and coastal plumes of freshwater between coastal river mouths.
GS collecting localities since 2003
I have led four expeditions to the upper Orinoco in Amazonas State, Venezuela, and participated in one expedition to Venezuela's Gran Sabana. These expeditions have cumulatively generated over 2,200 tissue samples for genetic analysis and 7,200 lots of whole fish voucher specimens. Over 5,800 of these lots are in North American museums: approximately 3,900 lots at AUM, 1,500 lots at ANSP and 400 lots at the ROM. These trips have also produced type material for at least 18 new species descriptions, 15 of which I have authored. For online repositories of fish photos from these expeditions, click here, here, and here. For more information on the products, sponsors and participants of each expedition, click on the following:
I have led four expeditions to the Guiana Shield highlands of western Guyana and participated in two expeditions to the Rupununi Savannahs, which form a low watershed divide between the Branco (Amazon) and Essequibo river drainages. These expeditions have generated over 1,000 tissue samples for genetic analysis and over 2,000 lots of whole fish voucher specimens at North American museums: approximately 1,700 lots at AUM, XXXX lots at ANSP and 400 lots at the ROM. These trips have also yielded type material for several new species descriptions, one of which I have authored. For more information on the products, sponsors
and participants of each expedition, click on the following: