Ecology. Michael Begon

Ecology - Michael  Begon


Скачать книгу
allowed hypotheses that were once untestable to be critically evaluated. Evolutionary ecologists are not so focused now on whether or not sympatric speciation can happen, but rather how often and under what conditions.

      APPLICATION 1.3 Conservation significance of hot spots of endemism

An illustration of a map depicting the biodiversity hot spots. Twenty-five biodiversity hot spots identified because of their exceptional concentrations of endemic species that are undergoing exceptional levels of human induced habitat loss.

      Source: From Myers et al. (2000).

      The five most prominent hot spots, the tropical Andes, Sundaland, Madagascar, Brazil's Atlantic Forest and the Caribbean, contain 20% of the world's vascular plants and 16% of vertebrate species but together they comprise only 0.4% of the world's surface. Moreover, they are subject to some of the heaviest levels of habitat loss: the Caribbean retains only 11.3% of its primary vegetation, Madagascar 9.9%, Sundaland 7.8% and Brazil's Atlantic Forest 7.5%. There was reasonable congruence between levels of endemism of plants and vertebrates in the hot spots, but note that no invertebrates were included in the analysis. In a geographically more restricted study in South Africa, Bazelet et al. (2016) showed that there was congruence between hot spots of the rather circumscribed diversity of katydids (bush crickets) and the biodiversity hot spots already recognised for much wider groupings, indicating that the conservation of biodiversity hot spots may often also protect non‐target organisms.

      Myers et al. (2000) called for a more than 10‐fold increase in annual funding from governmental and international agencies to safeguard these hot spots.

      1.4.1 Movements of landmasses

Schematic illustration of continental drift that means that continents that are now separate were once joined to one another. (a) The ancient supercontinent of Gondwanaland began to break up about 150 million years ago. (b) About 50 Myr ago recognisable bands of distinctive vegetation had developed, and (c) by 32 Myr ago these had become more sharply defined. (d) By 10 Myr ago much of the present geography of the continents had become established but with dramatically different climates and vegetation from today; the position of the Antarctic ice cap is highly schematic.

      Source: After Norton & Sclater (1979), Janis (1993) and other sources.

      placental and marsupial mammals

Schematic illustration of the parallel evolution of marsupial and placental mammals. The pairs of species are similar in both appearance and habit, and usually in lifestyle.