What is conservation Biology?

Conservation Biology came into existence as a distinct discipline in the 1970's when biologists began to describe the current scenario as a "biodiversity crisis". Extinction rates were seen to match those during megafaunal extinctions, e.g. the dinosaurs during the Cretaceous.

The journal Conservation Biology was only created in 1987 and the Society for Conservation Biology was founded in 1985.

Conservation biology arose from two opposed views of nature and our relationship to it.

1. The Romantic-Transcendental Conservation Ethic – from the writings of Ralph Waldo Emerson, Henry David Thoreau, and John Muir. Nature viewed in a quasi-religious sense and as a way to ‘cleanse the human soul. The tradition continues today in the Sierra Club.

2. The Resource Conservation Ethic – from Gifford Pinchot, this is the basis of much of the activities of government agencies like the Forest Service. It is anthropocentric, and views nature as resources to be used wisely.

The two opposing views have been joined in a third view. This view predominates in Conservation Biology today. It is called…

The Evolutionary-Ecological Land Ethic – Aldo Leopold is its source, clearly presented in A Sand County Almanac (1949). However, unlike Leopold, modern ecology/conservation biology views ecosystems in a non-equilibrium context.

Why is earth undergoing ‘megafaunal extinction’ rates? The reason: areas of greatest diversity, e.g. tropical rain forest and coral reefs, are also areas with the greatest numbers of as yet undescribed species and simultaneously under severe pressure from human activities.

Conservation biology is the scientific study of how to maintain diversity with increasing human population size and development. It is a synthetic science, built from ecology, population biology, population genetics, biogeography, economics, anthropology, and philosophy with the intention of developing principles and strategies to preserve diversity.

Here is why scientists worry about human impact. It’s a graphical depiction of our ecological footprint, i.e. human population density and degree of transformation of natural habitats…

A more complete view of how interdisciplinary conservation biology is:

The main objectives of Conservation Biology are:

• to investigate human impacts on global diversity

• to develop practical approaches to promote human development without extinguishing biological diversity.

Here’s another view of the basic principles, this one from a different introductory text by Primack (1994):

• Diversity of organisms is good; humans generally value and appreciate biodiversity. Human-mediated extinction of populations and species is bad.

• Ecological complexity is good and in many instances mandatory to species survival. Harm to one species may result in 'cascading' effects on others.

• Evolution is good.

• Biological diversity has intrinsic value.

There is another component in conservation biology, necessary to understand parts of answers to HOW, WHAT and WHERE for conservation. That subject is:

Biogeography.

Biogeography is the study of the distributions of species over space and time and the causes of those distributions.

It has two basic components: descriptive biogeography and ecological biogeography. The first part studies the geography of species and the second part deals in the causes of those distributions.

To answer many questions in biogeography and conservation biology we look to islands.

Island processes are seen as important in understanding the population dynamics and genetics of species having patchy distributions. Patchiness characterizes the distributions of almost all species.

‘Islands’ include those in oceans or fresh water, lakes in a terrestrial matrix, habitat islands, peninsulas, clumps of zebra mussels on lakebeds of the Great Lakes, and even patches in the distribution of species scattered widely over an area. Island concepts help in learning how to preserve species and communities as humans impose themselves on natural environments.

It is important to see the history of a subject to understand its development and future. So, here is a short history of biogeography and conservation biology…

Biogeography realistically began when it got past simply describing and naming new species, and into describing habitat characteristics, relationships among species, i.e. how distributions were affected by species interactions (competition, predation, mutualism), history (site(s) of origin, dispersal capabilities in relation to geological events, ecological variability, climate (including climate change), and continental drift.

The first attempts were phytogeography in the first two decades of the 19th century. In 1805 Alexander von Humboldt developed qualitative indicators of relationships between plant species and climate.

That first classification was developed further, particularly by DeCandolle in 1813. DeCandolle divided botany into subdisciplines, separating out 1) systematics and taxonomic description, 2) studies of species interactions, particularly with man, and 3) morphology, physiology and geography.

Not long afterward, Lyell proposed gradual change in geographical features of the earth. He developed the concept of uniformatarianism, the idea that processes today are identical to processes operating in the past. It is that concept that allows us to infer history from observations made in contemporary time.

Darwin and Wallace, in their separate collecting trips in the new world and southeast Asia respectively, observed species distributions which were critical to the development of the theory of evolution. They used uniformatarianism to understand how some aspects of these distribution arose.

Ernst Haeckel applied the theory of evolution to species distributions directly. He named a special discipline called chorology, which was the study of the spatial distributions of organisms and their causes. One of the major components explaining the change in species' distributions was evolution, and we now call the subject biogeography.

Alfred Russell Wallace, who should be credited as a co-developer of evolution, is regarded as the father of zoogeography. Because animals are mobile, and because so long was spent simply categorizing insects (because there are so many), 'animal biogeography' took longer to get off the ground.

Wallace's master work, The Geographical Distribution of Animals described the transition in terrestrial fauna between Australia, with its associated islands, and the islands extending out from southeast Asia towards Australia.

Other lines have since been drawn to demark this transition. Weber's line encloses the region in which the mammalian fauna is exclusively Australasian, and west of the Celebes, between Bali and Lompok, is Wallace's line, which marks the outer limit of the Asian (or Oriental) mammalian fauna. In the narrow zone between these boundaries there is limited mixing; the area is called Wallacea.

During the late 19th and early 20th centuries, a number of important descriptive rules for animal (particularly mammal) anatomy developed, generally related to climates:

1.Bergmann's rule which states that warm blooded animals from cooler climates have larger body sizes and lower surface to volume ratios.

2.Allen's rule which says that warm blooded animals will have more compact extremities in cold climates than in warm ones.

In the same time frame, plant communities were classified. Merriam classified altitudinal and latitudinal vegetation types and zones, termed life zones, and their relationship to temperature and rainfall. Most modern diagrams of Merriam's zonation present it as a three axis system, in which the climatic axis is potential evapotranspiration.

Merriam attempted to generalize his classification scheme to animals, and failed.

During the 20th century two major developments have influenced the development of biogeography: the recognition of continental drift and the development of a quantitative theory of island biogeography.

Continental drift was first described by Wegener in 1912. Its acceptance took quite a while. Philip Darlington published a monograph (The Biogeography of the Southern End of the World) in 1957 that did not accept continental drift and created ‘fanciful’ explanations for relations among the southern continents. He published a revision about a decade later that used continental drift explanations.

Finally, we come to the quantitative theory of biogeography, traceable to MacArthur and Wilson. It is from quantitative biogeography that conservation biology arose.

Human ImpactsHumans (native Americans and Inuit) are widely regarded as responsible for the extinction of a variety of large mammals in North America including mastodons, tapirs, glyptodonts, and giant ground sloths.

Humans have long cut forests. In Greek times, the forests of the Baltic area and those in southern Asia were cut for ship building. Tropical forest has been cut for centuries in the course of slash and burn agriculture. The contemporary problem is the effect of increased population size, meaning larger areas cut and more frequent exhaustion of areas.

References Candolle, A. de. 1855. Géographie botanique raisonée. 2 vol. Paris, Masson Editeur.

Clausen, Keck, and Heisey. 1948. Experimental studies on the nature of species. III. Environmental responses of climatic races of Achillea. Carnagie Institute, Pub. no.581.

Darlington, P. 1957. Biogeography of the Southern End of the World. Harvard Univ. Press, Cambridge, MA.

Hardin, G. 1968. The tragedy of the commons. Science 162:1243-1248.

MacArthur, R.H. and E.O. Wilson. 1963. An equilibrium theory of insular zoogeography. Evolution 17:373-387.

MacArthur, R.H. and E.O. Wilson. 1967. The Theory of Island Biogeography. Princeton Univ. Press. 203p., Princeton, NJ.

Groom, M.J., G. Meffe, and C.R. Carroll. 2006. Principles of Conservation Biology. 3rd ed. Sinauer, Sunderland, MA.

Primack, R.B. 1994. Essentials of Conservation Biology. Sinauer, Sunderland, MA.