Daniel H. Janzen


Daniel Hunt Janzen is an American evolutionary ecologist, and conservationist. He divides his time between his professorship in biology at the University of Pennsylvania, where he is the DiMaura Professor of Conservation Biology, and his research and field work in Costa Rica.
Janzen and his wife Winifred Hallwachs have catalogued the biodiversity of Costa Rica. Through a DNA barcoding initiative with geneticist Paul Hebert, they have registered over 500,000 specimens representing more than 45,000 species, which has led to the identification of cryptic species of near-identical appearance that differ in terms of genetics and ecological niche.
They helped to establish the Area de Conservación Guanacaste World Heritage Site, one of the oldest, largest and most successful habitat restoration projects in the world.

Early life and education

Daniel Hunt Janzen was born January 18, 1939 in Milwaukee, Wisconsin. His father, Daniel Hugo Janzen, grew up in a Mennonite farming community and served as Director of the United States Fish and Wildlife Service. His father and mother, Miss Floyd Clark Foster of Greenville, South Carolina, were married on April 29, 1937.
Janzen obtained his B.Sc. degree in biology from the University of Minnesota, in 1961, and his Ph.D. from the University of California, Berkeley in 1965.

Career

In 1963, Janzen attended a two-month course in tropical biology taught in several field sites throughout Costa Rica. This Advanced Science Seminar in Tropical Biology was the precursor to a Fundamentals in Tropical Biology course, which Janzen designed for the Organization for Tropical Studies, a consortium of several North American and Costa Rican universities. Janzen went back in 1965 as an instructor and has lectured in at least one of the three yearly courses every year since.
Janzen taught at the University of Kansas, the University of Chicago and at the University of Michigan before joining the faculty at the University of Pennsylvania. There he is the DiMaura Professor of Conservation Biology, and his research and field work in Costa Rica.
Janzen has also held teaching positions in Venezuela, and in Puerto Rico.

Research

Janzen's early work focused on the careful and meticulous documentation of species in Costa Rica, and in particular on ecological processes and the dynamics and evolution of animal-plant interactions.
In 1967, for example he described the phenological specialization of bee-pollinated species of Bignoniaceae, amongst them a "kind of mass flowering", which Alwyn Howard Gentry in his classification of flowering named Type 4 or "big bang" strategy.
Miguel Altieri in his textbook Agroecology: The Science of Sustainable Agriculture says: "Janzen's 1973 article on tropical agroecosystems was the first widely read evaluation of why tropical agricultural systems might function differently from those of the temperate zones".
In 1985, realizing that the area in which they worked was threatened, Janzen and Hallwachs expanded the focus of their work to include tropical forest restoration, expansion and conservation.
Through a DNA barcoding initiative with geneticist Paul Hebert, they have registered over 500,000 specimens representing more than 45,000 species, which has led to the identification of cryptic species of near-identical appearance that differ in terms of genetics and ecological niche.Janzen and Hallwachs have supported species barcoding initiatives at both national and international levels through the Instituto Nacional de Biodiversidad, CBOL and iBOL.

Coevolution of plants and animals

are the world's most threatened forest ecosystems. In middle America there were 550 000 km² of dry forests at the beginning of the 16th century; today, less than 0.08% remains. They have been cleared, burnt and replaced by pastures for cattle raising, at an ever-faster rate during the last 500 years.
In 1985, realizing that widespread development in northwestern Costa Rica was rapidly decimating the forest in which they conducted their research, Janzen and Hallwachs expanded the focus of their work. They began with the Parque Nacional Santa Rosa, which included of pasture and relictual neotropical dry forest and of marine habitat. This eventually became the Área de Conservación Guanacaste, located just south of the Costa Rica-Nicaragua border, between the Pacific Ocean and the Cordillera de Tilaran which integrated four different national parks. Together these house at least 15 different biotopes, viz and ca. 4% from world's plant, mammals, birds, reptiles, amphibians, fishes and insects diversity, all within an area less than. It is one of the oldest, largest and most successful habitat restoration projects in the world. As of 2019, it consists of. The park exemplifies their beliefs about how a park should be run. It is known as a center of biological research, forest restoration and community outreach.
Janzen and his wife helped to establish the Area de Conservación Guanacaste World Heritage Site, one of the oldest, largest and most successful habitat restoration projects in the world. As of 2019, it consists of, located just south of the Costa Rica-Nicaragua border, between the Pacific Ocean and the Cordillera de Tilaran. The park exemplifies their beliefs about how a park should be run. It is known as a center of biological research, forest restoration and community outreach.
Habitat restoration is not a simple matter. Not only must one fight against hundreds of years of ecological degradation, manifested in the form of altered drainage patterns, hard to eradicate pastures, compacted soils, exhausted seed banks, diminished adult and propagule stocks, proliferation of fire-resistant and unpalatable weeds from the old world tropics and sub-tropics.
Also one is faced with the difficulties of changing a culture which coevolved with, profited from and can become miserable with such a system.
For this reason ACG was conceived as a cultural restoration project, which, to paraphrase its natural counterpart, ought to be grown as well. ACG integrates complementary processes of experimentation, habitat restoration and cultural development.
The techniques used include:
Of his research partner and wife, Winifred Hallwachs, Janzen says "We did these things together," and "we are very much together in perceiving things the same things....Since I'm the vocal member, it's then attributed to me. But I would say these ideas and directions and thoughts and actions are easily fifty-fifty attributable."

Honorary distinctions

Janzen has been subject to recognition many times in the USA, as well as in Europe and Latin America; the monetary endowments of these prizes have been invested in the trust fund of the ACG or another of his conservation's projects in Costa Rica; amongst the 19 prizes and distinctions, the following are the most important:
The following are just a couple of the publications by Janzen not otherwise listed.
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