Дэниел Янзен: Эволюционный эколог и пионер тропической биологии.

American evolutionary ecologist
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. 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. 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 (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).

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. amongst them a "kind of mass flowering", which Alwyn Howard Gentry in his classification of flowering named Type 4 or "big bang" strategy. 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". 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. As of 2017, some 10,000 new species in the Area de Conservacion Guanacaste have been identified thanks to the efforts of parataxonomists. 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).

Janzen is known for proposing "characteristically imaginative and unorthodox" hypotheses. These hypotheses have received varying degrees of support, 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. 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. Another influential idea comes from Janzen's 1967 paper 'Why mountain passes are higher in the tropics'. 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', 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, but the idea has been widely incorporated into studies of vertebrate feeding from humans to dinosaurs.

Coevolution of a mutualistic system in New World tropics between species of Acacia (Mimosoideae; Leguminosae), v. gr., Acacia cornigera, and the ant Pseudomyrmex ferruginea (Formicidae). Acacia spp in the Neotropics are protected by ants against defoliation; for this, the ants are rewarded by means of special organs and physiology that Acacia has evolved.

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