Benefits of biodiversity n Dr John A Finn, Dept of Agriculture. Lecture outcomes n What is biodiversity? n How much of it is there? n Why does it matter- what are the benefits of biodiversity?

What is biodiversity? n The variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequency. For biodiversity, these items are organised at many levels, ranging from complete ecosystems to the chemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, genes and their relative abundance.

What is biodiversity? Other definitions n The genetic taxonomic and ecosystem variety in living organisms of a given area, environment, ecosystem or the whole planet n the total diversity and variability of living things and of the systems of which they are a part. This covers the total range of variation in and variability among systems and organisms, at the bioregional, landscape, ecosystem and habitat levels, at the various organismal levels down to species populations and individuals, and at the level of the population and genes.

How much biodiversity is there? n How does one measure the number of species on Earth? n Only about 1 million species described, and only about 100,000 are well known. n Erwin and Stork: fogging samples of Tropical insects: –163 species of canopy-dwelling beetles specific to one tree species –about 50,000 tree species – 8 million species of canopy-dwelling beetles –about 40% of insects are beetles 20 million canopy insects

HOTSPOTS n Biodiversity hotspots refer to regions of the world that are high in endemic species (and are usually threatened) n Endemic species refers to a species native to a particular place and only found there n see o/h on hotspots and human population

Biodiversity Decline n Species extinction is currently greater than ever before: –background rate: 100 sp. per year –current rate: 1,800 to 30,000 species per year n Causes –Habitat destruction 36% –Hunting 23% –Accidental introductions 39% Consequences ?

Why does biodiversity matter? n Source of marketable commodities n Provision of non-marketable services and goods n It is of intrinsic value [From Does biodiversity matter?, Book chapter by Kunin and Lawton (1996), In: Biodiversity: a biology of numbers and difference by Gaston, K.J.] n Stabilises the provision of non-marketable services and goods- the insurance effect n It is threatened

Biodiversity as a source of marketable products n food (wild and cultivated sources) –Zea diploperennis; n medicinal compounds –Rosy periwinkle (flower) ; aspirin discovered in meadowsweet; hirudin in leeches; –in US, quarter of all prescriptions are substances derived from plants n biological control n source of materials of industrial value n harvesting (hunting/ fishing- recreational) n culturing (e.g. gardening)

Provision of non-marketable services and goods n Earth's biota can affect our environment n Ecosystems provide a variety of functions that in turn provide, directly or indirectly, a range of benefits to humans. –the regulation of climatic processes –regulation of population processes – breakdown of wastes and recycling of nutrients –maintenance of soil fertility –the provision of natural resources – production of food, timber and natural products n Current estimates put the global worth of such ecosystem services at 33 trillion US$ per year (Costanza et al, 1997). n see o/h and h/o on ecosystem services

Ecosystem function low high lowhigh Species richness null rivet idiosyncraticredundant Hypotheses: Relationship between diversity and function

n Redundant: Species richness is largely irrelevant: what is important is that the biomass of primary producers, consumers, decomposers etc. is maintained, and ecological processes will function normally with very few species. n Rivet: all species contribute to the integrity of an ecosystem in a small but significant way such that a progressive loss of species steadily damages ecosystem function. n Idiosyncratic hypothesis: ecosystem function changes as species richness changes, but the magnitude and direction of the change is unpredictable because the roles of individual species are complex and varied n Null hypothesis: ecosystem function is insensitive to species additions or deletions

The insurance hypothesis n Many current experiments examine ecosystem processes under average environmental conditions. n The next step is to ask 'Can higher biodiversity help ecosystems to withstand and recover from extreme events?'. n More diverse systems have a greater probability than less diverse systems of containing species that are suited to the changed prevailing conditions- the insurance hypothesis n By chance, more diverse biological systems should better withstand changes in environmental conditions

Environmental fluctuations 6 spp1 spp The insurance hypothesis- contd. 7 spp 1 spp Stable conditions

Biodiversity is of intrinsic value n Because it is of intrinsic value, humankind has moral and ethical responsibilities towards it.

References n Sutherland W.J. 1998, Conservation science and action. Chapters 1 and 2. n Does biodiversity matter?, Book chapter by Kunin and Lawton (1996), In: Biodiversity: a biology of numbers and difference by Gaston, K.J. n The Diversity of Life by E.O. Wilson. See Chapters 11, 12, 13, 14. Excellent book and easy to read.