how many species are there, globally? range of estimates: 2 – 100 million best estimate: 10...

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How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97% of all species are invertebrates, and within these, insects are by far the most numerous (an estimated 1-30 million species). In one study of just 19 trees in Panama, 1200 species of beetle were discovered , of which 80% were previously unknown to science. Within the vertebrates species: 23,500 ray-finned fish, 9000- 10,000 birds, 7,984 reptiles, 5400 amphibians, 4475-5000 mammals. 70% of the world's species occur in only 12 countries: Australia, Brazil, China, Columbia, Ecuador, India, Indonesia, Madagascar, Mexico, Peru, and Zaire. On average, 3 new species of birds are found each year An estimated 40 percent of freshwater fishes in South America have not yet been classified. The deep sea floor may contain as many as a million undescribed species. Hydrothermal vent communities, discovered less than two decades ago, >20 new families or subfamilies, 50 new genera, and 100 new

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Page 1: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

How many species are there, globally?

Range of estimates: 2 – 100 millionBest estimate: 10 million1.4 – 2 million species have a name.

An estimated 97% of all species are invertebrates, and within these, insects are by far the most numerous (an estimated 1-30 million species).

In one study of just 19 trees in Panama, 1200 species of beetle were discovered , of which 80% were previously unknown to science.

Within the vertebrates species: 23,500 ray-finned fish, 9000-10,000 birds, 7,984 reptiles, 5400 amphibians, 4475-5000 mammals.

70% of the world's species occur in only 12 countries: Australia, Brazil, China, Columbia, Ecuador, India, Indonesia, Madagascar, Mexico, Peru, and Zaire.

On average, 3 new species of birds are found each year

An estimated 40 percent of freshwater fishes in South America have not yet been classified.

The deep sea floor may contain as many as a million undescribed species.

Hydrothermal vent communities, discovered less than two decades ago, >20 new families or subfamilies, 50 new genera, and 100 new species were found.

Page 2: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

How to measure species diversity?

Counting the number of species has several challenges:

• species recognition (especially the small ones)• the influence of sampling effort and sample size

1 transect: 3 species

2 transects: 5 species

3 transects: 8 species

4 transects: 8 species

5 transects: 8 species

Page 3: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Number of individuals in sample

Nu

mb

er

of s

pe

cie

s in

sam

ple

The sampling artifact:A bigger sample usually contains more species.

Community 1

Community 2

Page 4: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

The sampling artifact:Can be avoided by using diversity indices, rather than species numbers.

Number of individuals in sample

community 2

Fisher’s does not change with sample size.

community 1

Fis

her’s

Page 5: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

How do you figure out how species numbers increase with area?

Nested sampling design:

Total species number in an area: 403 species.

403

Page 6: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Nested sampling design:

Average species number of 305.

341

280

312

4patches

288

Page 7: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

How do you figure out of species numbers increase with area?

Nested sampling design:

Average species number of 266.

220

305289245

269301

242

8patches

256

Page 8: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

How do you figure out of species numbers increase with area?

Nested sampling design:

Average species number of 188.

150

213

187

145

191

228

202

40patches

Page 9: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

How do you figure out of species numbers increase with area?

Nested sampling design:

Average species number of 160.

321

55

105

154

225

188

150

150patches

193

96

113

Page 10: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

0

50

100

150

200

250

300

350

400

450

0 200 400 600 800 1000 1200

Area size (ha)

Spe

cies

Num

ber

4

4.5

5

5.5

6

6.5

0 1 2 3 4 5 6 7 8Log Area

Log

Spe

cies

Num

ber

Page 11: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

cAzS logloglog

The increase in the log of species number is proportional to the increase in log area.

zcAS

4

4.5

5

5.5

6

6.5

0 1 2 3 4 5 6 7 8Log Area

Log

Spe

cies

Num

ber

Page 12: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Examples:

From Rosenzweig 1995

Page 13: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

• z-values are quite similar between taxa, continents, ecosystems.

• z-values are often in the range: 0.1-0.2.

• c-values vary, expressing systematic differences in biodiversity between taxa, ecosystems, etc.

Generalized species-area curve for nested samples within continents:

cAzS logloglog

Log area

Log

sp

eci

es

nu

mb

er

Page 14: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Productivity gradient:

More productive ecosystems usually have more species per area. But, highly productive ecosystems often have reduced diversity.

Spatial patterns of biodiversity:

Latitudinal gradient:

Biodiversity decreases between the species-rich equatorial tropics and the species-poor polar regions.

Habitat heterogeneity gradient:

More spatially variable environments have more species per area.

Island patterns:

Islands have fewer species per area than their associated mainlands.The further away the island, the fewer species.

Page 15: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Productivity gradient.

Productivity

From Rosenzweig 1995

Cold & dry

Moist & warm

Page 16: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Habitat heterogeneity gradient.

Number of plants per 300 m2 plot beside the Hood River, Canada.

From Rownsend, Begon and Harper 2003

Page 17: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Habitat heterogeneity gradient.

Bird diversity in two continents

From Rosenzweig 1995

Page 18: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Latitudinal gradient:

From Rosenzweig 1995

Page 19: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%
Page 20: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Islands have fewer species than equal areas on the adjacent mainland.

Species-area curves for islands are different:

Page 21: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

mainlandislands

403

305

266

Islands have fewer species than equal areas on the adjacent mainland.

Species-area curves for islands are different:

188160

55

42

141

180

Page 22: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

From Rosenzweig 1995

Islands:

Mainland:

Page 23: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

New Guinea:

New Guinea islands:

From Rosenzweig 1995

Page 24: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

mainlandislands

403

188160

266

305

42

141

180

19

110

166

Island further from the mainland have fewer species than islands of equal size closer to the mainland.

Species-area curves for islands are different:

Page 25: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%
Page 26: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

• z-values for islands are usually greater than for mainlands. Generally, z = 0.2 – 0.6.

• z-values are greater with the farther they are from the mainland.

Generalized species-area curve for islands and their associated mainlands:

cSzS logloglog mainland

Log area

Log

sp

eci

es

nu

mb

er

close farislands

Page 27: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Rosenzweig 1997

Interprovincial species-area curve:

• larger continents (provinces) also have more species and the z-value for interprovincial species-area curves is 1 or greater.

Page 28: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

The three biological scales of species–area curves.

Rosenzweig M L PNAS 2001;98:5404-5410

Page 29: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Temporal patterns of biodiversity:

In evolutionary time:

Over millions of years diversity stays relatively constant. That means, relatively fast recovery from mass extinction events.

In succession:

Diversity increases in the course of succession.

In the history of life on earth:

Over hundreds of millions of years, diversity increased.

With disturbance frequency:

Intermediate disturbance frequencies have highest diversity.

Page 30: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Succession:

Page 31: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Disturbance frequency:

Disturbance

From Rosenzweig 1995

Page 32: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Algae and barnacles on rocks of different sizes

From Rosenzweig 1995

Disturbance frequency:

Page 33: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Evolutionary time:

Page 34: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Evolutionary time:

From Rosenzweig 1995

Page 35: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Uintatherium

Hyracotherium

From Rosenzweig 1995

Page 36: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

From Rosenzweig 1995

Page 38: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Townsend, Begon and Harper 2003

Page 39: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Other patterns:

Food web gradient:

Higher trophic levels usually have lower diversity than lower trophic levels. Exception: there are more animal than plant species. There are more

parasite than host species.

Body size:

Within a taxon, there are more intermediate-size species than either very large or very small species.

Page 40: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Food web gradients:

From Rosenzweig 1995

Page 41: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Patterns with body size

From Rosenzweig 1995

Dragonflies and Damselflies

Page 42: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Patterns with body size

From Rosenzweig 1995

Page 43: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Patterns with body size

From Rosenzweig 1995

Page 44: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Patterns in space

Log areaLog

spe

cies

num

ber

productivity

# sp

ecie

s

Habitat variety

# sp

ecie

s

Latitude

# sp

ecie

s

mainland

Log area

Log

spe

cies

num

ber

close farislands

Page 45: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Time during successionSpe

cie

s nu

mbe

r

Disturbance frequencySpe

cie

s nu

mbe

r

Millions of years

Spe

cie

s nu

mbe

r

Patterns in time

Hundreds of Millions of years

Spe

cie

s nu

mbe

r

Page 46: How many species are there, globally? Range of estimates: 2 – 100 million Best estimate: 10 million 1.4 – 2 million species have a name. An estimated 97%

Trophic level

# sp

ecie

s

Two more patterns

Body size within taxon

# sp

ecie

s