SLOSS Debate
Encyclopedia
The SLOSS Debate was a debate in ecology
and conservation biology
during the 1970s and 1980s as to whether a single large or several small (SLOSS) reserves were a superior means of conserving biodiversity
in a fragmented habitat
.
In 1975 Jared Diamond
suggested some "rules" for the design of protected areas, based on Robert MacArthur
and E. O. Wilson
's book The Theory of Island Biogeography
. One of his suggestions was that a single large reserve was preferable to several smaller reserves whose total areas were equal to the larger.
Since species richness
increases with habitat
area, a larger block of habitat would support more species than any of the smaller blocks. This idea was popularised by many other ecologists, and has been incorporated into most standard textbooks in conservation biology, and was used in real-world conservation planning. This idea was challenged by Wilson's former student Daniel Simberloff
who pointed out that this idea relied on the assumption that smaller reserves had a nested
species composition - it assumed that each larger reserve had all the species presented in any smaller reserve. If the smaller reserves had unshared species, then it was possible that two smaller reserves could have more species than a single large reserve.
Simberloff and Abele expanded their argument in subsequent paper in the journal The American Naturalist stating neither ecological theory nor empirical data exist to support the hypothesis that subdividing a nature reserve would increase extinction rates, basically negating Diamond as well as MacArthur and Wilson. Bruce A. Wilcox and Dennis L. Murphy responded to this paper in the same journal pointing out flaws in their argument while providing a comprehensive definition of habitat fragmentation
. Wilcox and Murphy also argued that habitat fragmentation likely is the major threat to the loss of global biological diversity.
This helped set the stage for fragmentation research as an important area of conservation biology
. The SLOSS debate ensued as to the extent to which smaller reserves shared species with one another, leading to the development of nested subset theory by Bruce Patterson
and Wirt Atmar in the 1980s and to the establishment of the Biological Dynamics of Forest Fragments Project
(BDFFP) near Manaus
, Brazil
in 1979 by Thomas Lovejoy
and Richard Bierregaard.
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and conservation biology
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
during the 1970s and 1980s as to whether a single large or several small (SLOSS) reserves were a superior means of conserving biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
in a fragmented habitat
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
.
In 1975 Jared Diamond
Jared Diamond
Jared Mason Diamond is an American scientist and author whose work draws from a variety of fields. He is currently Professor of Geography and Physiology at UCLA...
suggested some "rules" for the design of protected areas, based on Robert MacArthur
Robert MacArthur
Robert Helmer MacArthur was an American ecologist who made a major impact on many areas of community and population ecology....
and E. O. Wilson
E. O. Wilson
Edward Osborne Wilson is an American biologist, researcher , theorist , naturalist and author. His biological specialty is myrmecology, the study of ants....
's book The Theory of Island Biogeography
The Theory of Island Biogeography
The Theory of Island Biogeography is a 1967 book by Edward O. Wilson and Robert MacArthur which laid the foundations for the study of island biogeography. An edition with a new preface by Edward O. Wilson was published in 2001 ....
. One of his suggestions was that a single large reserve was preferable to several smaller reserves whose total areas were equal to the larger.
Since species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
increases with habitat
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...
area, a larger block of habitat would support more species than any of the smaller blocks. This idea was popularised by many other ecologists, and has been incorporated into most standard textbooks in conservation biology, and was used in real-world conservation planning. This idea was challenged by Wilson's former student Daniel Simberloff
Daniel Simberloff
Daniel Simberloff is a biologist and ecologist who earned his Ph.D. from Harvard University in 1969.Simberloff started his studies in ecology as a student of the biologist E. O. Wilson, one of the co-authors of the theory of Island biogeography . For his Ph.D...
who pointed out that this idea relied on the assumption that smaller reserves had a nested
Nestedness
Nestedness is a measure of order in an ecological system, referring to the order in which the number of species is related to area or other factors. The more a system is "nested" the more it is organized....
species composition - it assumed that each larger reserve had all the species presented in any smaller reserve. If the smaller reserves had unshared species, then it was possible that two smaller reserves could have more species than a single large reserve.
Simberloff and Abele expanded their argument in subsequent paper in the journal The American Naturalist stating neither ecological theory nor empirical data exist to support the hypothesis that subdividing a nature reserve would increase extinction rates, basically negating Diamond as well as MacArthur and Wilson. Bruce A. Wilcox and Dennis L. Murphy responded to this paper in the same journal pointing out flaws in their argument while providing a comprehensive definition of habitat fragmentation
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
. Wilcox and Murphy also argued that habitat fragmentation likely is the major threat to the loss of global biological diversity.
This helped set the stage for fragmentation research as an important area of conservation biology
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
. The SLOSS debate ensued as to the extent to which smaller reserves shared species with one another, leading to the development of nested subset theory by Bruce Patterson
Bruce Patterson
Bruce Patterson was a Scottish cricketer. He took his first two wickets in a competition in June 2004 against Holland. He participated in three One-day internationals in May 1999 and played List A cricket from 1988 to 2002...
and Wirt Atmar in the 1980s and to the establishment of the Biological Dynamics of Forest Fragments Project
Biological Dynamics of Forest Fragments Project
The Biological Dynamics of Forest Fragments Project, originally called the Minimum Critical Size of Ecosystems Project is a large-scale ecological experiment looking at the effects of habitat fragmentation on tropical rainforest. The experiment, which was established in 1979 is located near Manaus,...
(BDFFP) near Manaus
Manaus
Manaus is a city in Brazil, the capital of the state of Amazonas. It is situated at the confluence of the Negro and Solimões rivers. It is the most populous city of Amazonas, according to the statistics of Brazilian Institute of Geography and Statistics, and is a popular ecotourist destination....
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
in 1979 by Thomas Lovejoy
Thomas Lovejoy
Dr. Thomas Eugene Lovejoy III is chief biodiversity adviser to the president of the World Bank, senior adviser to the president of the United Nations Foundation, and president of the Heinz Center for Science,...
and Richard Bierregaard.