Daniel H. Janzen

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Daniel H. Janzen
Daniel Janzen (3214457162) (cropped).jpg
Janzen in 2009
Born
Daniel Hunt Janzen

(1939-01-18)January 18, 1939
Alma mater University of Minnesota, University of California, Berkeley
Known forTropical ecology, biodiversity development
Spouse Winifred Hallwachs
Awards Kyoto Prize
Scientific career
Institutions University of Pennsylvania, Guanacaste Dry Forest Conservation Fund, Área de Conservación Guanacaste (ACG)
External videos
Nuvola apps kaboodle.svg “Costa Rica : Paradise Reclaimed”, Profile of Dan Janzen in Nature, MacArthur Foundation (WNET Television station : New York, N.Y., 1987)
Nuvola apps kaboodle.svg “Spark: Heroes, commentary by Rob Pringle”, Day’s Edge Productions, December 29, 2016

Daniel Hunt Janzen (born January 18, 1939, in Milwaukee, Wisconsin [1] ) 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.

Contents

Janzen and his wife Winifred Hallwachs have catalogued the biodiversity of Costa Rica. Through a DNA barcoding initiative, Janzen and geneticist Paul Hebert 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 developed some of the most influential hypotheses in ecology that continue to influence research more than 50 years later. [2] [3]

Janzen and Hallwachs 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. [1] His father, Daniel Hugo Janzen, [4] grew up in a Mennonite farming community and served as Director of the United States Fish and Wildlife Service. [1] His father and mother, Miss Floyd Clark Foster of Greenville, South Carolina, were married on April 29, 1937. [5]

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. [6]

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 (OTS), 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. [6]

Janzen taught at the University of Kansas (1965–1968), the University of Chicago (1969–1972), and the University of Michigan (1972–1976) before joining the faculty at the University of Pennsylvania. [7] There he is the DiMaura Professor of Conservation Biology, and his research and field work in Costa Rica. [8]

Janzen has also held teaching positions in Venezuela (Universidad de Oriente, Cumaná in 1965–66; Universidad de los Los Andes, Mérida in 1973), and in Puerto Rico (Universidad de Puerto Rico, Río Piedras, 1969). [9]

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. [6] :426 [10] In 1967, for example he described the phenological specialization of bee-pollinated species of Bignoniaceae, [11] amongst them a "kind of mass flowering", which Alwyn Howard Gentry in his classification of flowering named Type 4 or "big bang" strategy. [12] Janzen proposed many hypotheses that inspired decades of work by tropical and temperate ecologists (see below).

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". [13] [14]

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 (through land purchases) and conservation. [15] [16] They employed the help of local Costa Ricans, converting their farming skills into parataxonomy, a term they coined in the late 1980s. [17] [18] As of 2017, some 10,000 new species in the Area de Conservacion Guanacaste have been identified thanks to the efforts of parataxonomists. [18]

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. [19] [20] [21] Janzen and Hallwachs have supported species barcoding initiatives at both national and international levels through the Instituto Nacional de Biodiversidad (INBio), CBOL (Consortium for the Barcode of Life) and iBOL (International Barcode of Life). [22] [23] [24]

Influential hypotheses

Janzen is known for proposing "characteristically imaginative and unorthodox" hypotheses. [25] These hypotheses have received varying degrees of support, [26] but are notable for having inspired a large and sustained body of research, as evidenced by the extremely high citation rates of many of his papers for decades after they are published. [3]

One of Janzen's most famous ideas (from his most highly cited paper) [3] is now known as the Janzen-Connell hypothesis, as Janzen and Joseph Connell independently proposed the idea in 1970-1971. They both suggested that the high diversity of tropical trees was due, in part, to specialist enemies attacking seeds or seedlings that were particularly close to the parent tree or particularly densely clustered, thus preventing any one species from becoming dominant. [27]

Another influential idea [2] comes from Janzen's 1967 paper 'Why mountain passes are higher in the tropics'. [28] It proposes that tropical mountains are more of a barrier to species dispersal than temperate mountains because tropical species are less able to tolerate changes in temperature with elevation, having evolved and lived in relatively stable climates.

In a 1977 paper 'Why fruits rot, seeds mould, and meat spoils', [29] Janzen proposed that microbes render food inedible (or at least distasteful) to vertebrates not just as a by product of microbe-microbe competition or accidental waste products, but as an evolutionary strategy to repel vertebrates consumers, who would otherwise eat the food resource and the microbes themselves. Evidence is mixed, and it is hard to test whether compounds evolved to deter other microbes or vertebrates, [30] but the idea has been widely incorporated into studies of vertebrate feeding from humans [31] to dinosaurs. [32]

Coevolution of plants and animals

Tropical habitat restoration

Tropical dry forests 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% (440 km2 ) remains. [33] They have been cleared, burnt and replaced by pastures for cattle raising, [34] at an ever-faster rate during the last 500 years. [33]

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. Janzen and his wife helped to establish the Area de Conservación Guanacaste World Heritage Site (ACG), one of the oldest, largest and most successful habitat restoration projects in the world. They began with the Parque Nacional Santa Rosa, which included 100 km2 (25,000 acres) of pasture and relictual neotropical dry forest and 230 km2 (57,000 acres) of marine habitat. [15] 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 (mangroves, dry forest and shrubs, ephemeral, rainy season, and permanent streams, fresh water and littoral swamps, evergreen rain- and cloud forests...) and ca. 4% from world's plant, mammals, birds, reptiles, amphibians, fishes and insects diversity, all within an area less than 169,000 hectares (420,000 acres). [35] It is one of the oldest, largest and most successful habitat restoration projects in the world. As of 2019, it consists of 169,000 hectares (420,000 acres). [35] 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. [19]

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. [36] Also one is faced with the difficulties of changing a culture which coevolved with, profited from and can become miserable with such a system. [37] [38] [39]

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. [17] :89–91 [40] The techniques used include:

Personal life

Janzen is married to ecologist Winifred Hallwachs, who is also his frequent research partner. Of Hallwachs, Janzen has said, "We did these things together," [17] :132–136 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." [17] :134

Honorary distinctions

Janzen has been subject to recognition many times in the US, 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. Prizes and distinctions garnered by Janzen include:

See also

Publications

The following is a selection of Janzen's publications that are not otherwise listed.

Related Research Articles

<span class="mw-page-title-main">Guanacaste National Park (Costa Rica)</span> National park in northern Costa Rica

Guanacaste National Park, in Spanish Parque Nacional Guanacaste is a national park in northern Costa Rica. The park is part of the Area de Conservación Guanacaste World Heritage Site, and stretches from the slopes of the Orosí and Cacao volcanoes west to the Interamerican Highway where it is adjacent to the Santa Rosa National Park. It was created in 1989, partially due to the campaigning and fund-raising of Dr. Daniel Janzen to allow a corridor between the dry forest and rain forest areas which many species migrate between seasonally. The park covers an area of approximately 340 square kilometers, and includes 140 species of mammals, over 300 birds, 100 amphibians and reptiles, and over 10,000 species of insects that have been identified. It was this high density of bio-diversity that encouraged the Costa Rican government to protect this area. The Guanacaste National Park weaves the neighboring Santa Rosa National Park with the high altitude forests of the two volcanoes, Orosi and Cacao, and the rainforest of the Caribbean in the country's north.

<span class="mw-page-title-main">Guanacaste Conservation Area</span> Conservation area in northern Costa Rica

Guanacaste Conservation Area is an administrative area which is managed by the Sistema Nacional de Areas de Conservacion (SINAC) of Costa Rica for conservation in the northwestern part of Costa Rica. It contains three national parks, as well as wildlife refuges and other nature reserves. The area contains the Area de Conservación Guanacaste World Heritage Site, which comprises four areas.

Asturodes is a genus of snout moths in the subfamily Spilomelinae of the family Crambidae. The genus is placed in the tribe Margaroniini.

Parataxonomy is a system of labor division for use in biodiversity research, in which the rough sorting tasks of specimen collection, field identification, documentation and preservation are conducted by primarily local, less specialized individuals, thereby alleviating the workload for the "alpha" or "master" taxonomist. Parataxonomy may be used to improve taxonomic efficiency by enabling more expert taxonomists to restrict their activity to the tasks that require their specialist knowledge and skills, which has the potential to expedite the rate at which new taxa may be described and existing taxa may be sorted and discussed. Parataxonomists generally work in the field, sorting collected samples into recognizable taxonomic units (RTUs) based on easily recognized features. The process can be used alone for rapid assessment of biodiversity.

An all-taxa biodiversity inventory, or ATBI, is an attempt to document and identify all biological species living in some defined area, usually a park, reserve, or research area. The term was coined in 1993, in connection with an effort initiated by ecologist Daniel Janzen to document the diversity of the Guanacaste National Park in Costa Rica.

<i>Ethmia blaineorum</i> Species of moth

Ethmia blaineorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from the Pacific side of Cordillera de Guanacaste at altitudes ranging from sea level to 600 meters. The habitat consists of dry forests.

<i>Ethmia millerorum</i> Species of moth

Ethmia millerorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from 1,150 to 1,300 meters in the Cordillera Volcánica de Guanacaste. The habitat consists of rain forests.

<i>Ethmia adrianforsythi</i> Species of moth

Ethmia adrianforsythi is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from middle elevations on the Caribbean slope of the Cordillera Volcánica de Guanacaste and in the lowlands of Sarapiquí. The habitat consists of rain forests.

<i>Ethmia dimauraorum</i> Species of moth

Ethmia dimauraorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded at altitudes between 700 and 1,300 meters on the Pacific slope of the Cordillera de Guanacaste, at 750 meters (2,460 ft) in the Cordillera Central and at 1,000 meters (3,300 ft) at the Caribbean side of the Cordillera de Tilarán.

<i>Ethmia helenmillerae</i> Species of moth

Ethmia helenmillerae is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from the Pacific slope of the Cordillera de Guanacaste at altitudes ranging from 0 to 579 meters. The habitat consists of dry forests.

<i>Ethmia johnpringlei</i> Species of moth

Ethmia johnpringlei is a moth in the family Depressariidae. It is found in northern Costa Rica, where it has been recorded from the western sides of the Cordillera de Guanacaste at altitudes between 300 and 600 meters. The habitat consists of dry forests and rain forests.

<i>Ethmia laphamorum</i> Species of moth

Ethmia laphamorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from both slopes of the Cordillera Volcánica de Guanacaste and Península de Nicoya at altitudes between 20 and 600 meters. The habitat consists of dry forests.

<i>Ethmia turnerorum</i> Species of moth

Ethmia turnerorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from both sides of the Cordillera Volcánica de Guanacaste at altitudes ranging from 242 to 832 meters. The habitat consists of dry forests and rain forests.

<i>Ethmia hendersonorum</i> Species of moth

Ethmia hendersonorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from the Caribbean slope at an altitude of 600 meters (2,000 ft). The habitat consists of dry forests.

<i>Ethmia tilneyorum</i> Species of moth

Ethmia tilneyorum is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from the Pacific slope of the Cordillera Volcánica de Guanacaste and on the Península de Nicoya at altitudes between 50 and 160 meters. Its habitat consists of dry forests.

<i>Ethmia miriamschulmanae</i> Species of moth

Ethmia miriamschulmanae is a moth in the family Depressariidae. It is found in Costa Rica, where it has been recorded from the Pacific side of the Cordillera Volcánica de Guanacaste and on the Península de Nicoya at altitudes ranging from 25 to 700 meters. The habitat consists of dry forests.

Jennifer S. Powers is an American ecologist and full professor in the departments of ecology, evolution and behavior, and plant and microbial biology at the University of Minnesota. Powers' research has advanced the understanding of global change consequences, ecosystem ecology, restoration and conservation of tropical dry forests. She also has been very active on several editorial boards, and in 2019 became the editor-in-chief of Biotropica, a scientific journal from the Association of Tropical Biology and Conservation (ATBC).

<span class="mw-page-title-main">Winifred Hallwachs</span> U.S. entomologist and tropical ecologist

Winifred Hallwachs is an American tropical ecologist who helped to establish and expand northwestern Costa Rica's Área de Conservación Guanacaste (ACG). The work of Hallwachs and her husband Daniel Janzen at ACG is considered an exemplar of inclusive conservation.

<span class="mw-page-title-main">Reforestation in Costa Rica</span> Conservation program

Reforestation efforts are being made in Costa Rica to recondition its biodiversity and ecosystems that were affected by heavy deforestation in the 1900s.

<span class="mw-page-title-main">Robert M. Pringle</span> American biologist and conservationist

Robert Mitchell Pringle is an American biologist and conservationist.

References

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