Bài giảng what is biodiversity

Dimensions of biodiversityGenetic component Spatial component Functional component Temporal component within individuals within populations between populations between species

What is Biodiversity?

the variety of life on Earth at all its levels,

from genes to ecosystems, and the ecological

and evolutionary

processes that sustain it

Biodiversity is:

Source: ©AMNH-CBC

Dimensions of biodiversity

Genetic

component

Spatial component

Functional component

Temporal component

within individuals

within populations

between

populations

between species

communities ecosystems landscapes ecoregions

biogeographic regions

e.g reproductive behavior, predation, parasitism

daily seasonal annual geological or evolutionary

Phyla Classes Orders Families Genera Species Subspecies Population Individuals

Organismal diversity

Biomes Bioregions Landscapes Ecosystems Habitats Niches Population

Ecological diversity

Population Individuals Chromosomes Genes Nucleotides

Genetic diversity

Hierarchy of Biodiversity

Source: Yves Samyn

Elements of biodiversity form nested hierarchies

Hierarchy of

Biodiversity

Source: Yves Samyn

Genetic Diversity

The variation in the nucleotides, genes, chromosomes, or whole genomes of organisms

Source: Human Genome Project, Department of Energy

Variation in genome size

A greater total number of genes

might not correspond with a

greater complexity in the

anatomy and physiology of

thale cress 25,498 Arabidopsis

Genome Initiative (2000)

nematode  19,000 C elegans

Sequencing Consortium (1998)

Drosophila melanogaster

fruit fly 13,600 Adams et al

(2000)

Homo sapiens human ca 30,000-40,000 International

Human Genome Sequencing Consortium (2001) Source: U.S Dept of Energy, Human Genome Project

http://www.ornl.gov/hgmis

Phenotypic Diversity

Phenotype - the physical constitution of an organism that

results from its genetic constitution (genotype) and the

action of the environment on the expression of the genes

An Example of Genetic Variation

Source: ©AMNH-CBC

Morphological diversity within and

between natural populations: An example

Morphological diversity within and between natural populations: Vietnam’s examples

Nguyen et al 2009

A population is:

• a group of individuals of the same species that share

aspects of their genetics or demography more closely with each other than with other groups of individuals of that species

• a more practical way of defining a population and

measuring its diversity is by the space it occupies Thus a

population may be defined as a group of individuals of

the same species occupying a defined area at the same

time (Hunter, 2002).

Cryptic Species

• taxonomically cryptic

species look very

similar to other species

• may be misidentified (and hence overlooked

as being a different species)

Source: Bain ©AMNH-CBC

Population Diversity

• Variation in the quantitative and spatial characteristics between populations

Proportion of total genetic variation within species due to genetic differences between

geographic populations (from Avise, 1994)

Importance of population

variation

Loss of isolated populations along with

their unique component of genetic

variation is considered by some scientists

to be one of the greatest but most

overlooked tragedies of the biodiversity

crisis.

– Therefore, each definition has a different effect

on how we plan conservation.

Species concepts

Species diversity vs richness

•Species richness: the number of species present in a given area

• Species diversity: species number weighted by measure of importance, such as

abundance, productivity or size

For example:

Shannon’s diversity index (H) = - i ln i

i is the proportion of the total number of specimens of species i expressed

as a proportion of the total number of specimens for all species in the ecosystem

Many people use the term “species diversity” when they mean species richness

Ecosystem A

SR = 4 H' = 1.3086

SE = 0.94

Ecosystem B

SR = 3 H' = 1.0807

SE = 0.98

Ecosystem C

SR = 3 H' = 1.0323

SE = 0.94

Adapted from: Hunter, M Jr 2002 Fundamentals of Conservation Biology Second Edition Blackwell Science, Massachusetts, U.S.A.

Developing this idea further

• An ecosystem with representative species from many different higher taxa present (e.g from

different families or orders) possess more

taxonomic or phylogenetic diversity than

another with fewer higher taxa but many more species

• Marine ecosystems frequently have more

different phyla but fewer species than

terrestrial ecosystems; i.e higher taxonomic

diversity but lower species diversity

Community Diversity

• Variation in the groups of populations and species that share an environment

Ecosystem Diversity

• An ecosystem is a community plus the physical

environment that it occupies at a given time

Some examples of ecosystems

Inter-species interactions underpin ecosystem diversity

• There are very many potential interactions among

species, such as:

– predation,

– competition,

– parasitism,

– mutualism

• Some of these involve very close ecological and

evolutionary associations between the organisms and are an important component of community and

ecosystem biodiversity

– consider for example plant pollinators and seed dispersers

Examples of distinct communities and ecosystems

• Species associated with:

ripening figs in a tropical

forest,

• Species clustered around

a hydrothermal vent on

the ocean floor,

• Species in the spray zone

of a waterfall,

• Species under warm

stones in the alpine zone

on a mountaintop

Source: ©AMNH

- “a relatively large unit of land or water containing a

geographically distinct assemblage of species, natural communities, and environmental conditions” (WWF, 1999)

Biodiversity hotspot

Spatial scales and diversity

• Alpha-diversity

– Measured locally, at a

single site

• Beta-diversity

– Measures the uniqueness;

the difference between

two sites

• Gamma-diversity

– Measured over a large

scale, same concept as

alpha-diversity

Adapted from: Meffe et al 2002 Ecosystem management:

adaptive, community-based conservation Island Press,

Washington, D.C., U.S.A.

Gamma Diversity

• Gamma diversity is a measure of the

overall diversity for all ecosystems within a large region.

May be considered to be “geographic-scale” species diversity

Alpha, beta and gamma diversity for hypothetical species of birds (A-N) in

three different ecosystems.

Can gamma diversity = alpha diversity?

and a small

cushion-forming plant or pearlwort,

Colobanthus quintensis.

• These species usually

co-occur.

Contrast Antarctica with a

landscape in Vietnam

Lunde © AMNH/CBC

Endemism in Madagascar

The island of Madagascar is often considered to be

an area of high conservation priority in the world because the majority of species are endemic

Source: Koy ©AMNH-CBC

Endemism in Madagascar

– 52% birds – 80% flowering plants – 95% reptiles

– 99% amphibians

–100% primates

Source: Ersts ©AMNH-CBC

Source: Frey ©AMNH-CBC

Endemism in Vietnam

– 6% mammals – 25% amphibians – 21% reptiles

Case Study: Global biodiversity consequences of local introductions:

Lake Victoria cichlids

Source: Boulenger, G.A (1907) Zoology of Egypt: the fishes

of the Nile Plate 91 Hugh Rees Limited, London

British Government introduced the

Nile perch (Lates niloticus) to Lake

Victoria in 1954.

Source: ©AMNH

Nile perch population exploded

in the 1980s; native cichlid

populations then crashed

Alpha vs Gamma Diversity

Local Diversity (alpha) increased initially, then

crashed:

• Hundreds of cichlids native to the Lake Victoria

• Humans introduced 1 species, which increased the alpha biodiversity until the perch population

exploded in the 1980s and decimated the cichlids

Global Diversity (gamma) decreased: perhaps 200 species lost globally

Mac Hunter (University of Maine), Raoul Bain, Kevin Koy, Ned Horning, Ho-Ling Poon, and Armistead Booker

(American Museum of Natural History) provided

assistance for production of images and accompanying text

This is a product of the Network of Conservation Educators and Practitioners (NCEP)

http://ncep.amnh.org