The biodiversity crisis:myth or reality?

Philippe BouchetNational Museum of Natural History, Paris

« We are responsible for the largest mass extinction of species known in the history of the planet. »

E.O. Wilson, 2002. The Future of Life. 2002.

« Each and every species is doomed to extinction. Ammonites and dinosaurs, for instance, did not need man to become extinct »

• The magnitude of bidoversity: known, unknown

• Measuring extinctions

• Predictions and speculations

The magnitude of biodiversity: changing paradigm

• « Scientists have described 1.6 million species and there might be the same number still undescribed »

• « Scientists have described 1.8 million species but the real number may be around 10 to 100 million »

PROTOCTISTA 80 000Incl.: Actinopoda 6000

Foraminifera 10 000Ciliophora 8000Sporozoa 5000Rhodophyta (red algae) 5000Gamophyta (green algae) 10 000Bacillariophyta (diatoms) 12 000

PLANTS 270 000Incl.: Bryophyta 16 000

Pteridophyta 10 000Spermatophyta 240 000

FUNGI 72 000

 ANIMALS 1 320 000Incl.: Porifera 10 000

Cnidaria 10 000Plathyelminthes 14 000Nematoda 20 500Arthropoda 1 085 000Incl.: Crustacea 75 000

Arachnida 75 000Insecta 950 000Incl.: Coleoptera 400 000

Diptera 120 000Hymenoptera 130 000Lepidoptera 150 000

Mollusca 70 000Annelida 12 000Echinodermata 6000Chordata 56 000Incl.: Pisces 27 683

Amphibia 5200Reptilia 8163Aves 9913Mammalia 4629Incl.: Chiroptera 925

Rodentia 2021

Number of described species

Contexte et enjeux – Un nouveau paradigmeMain groups of organisms:described species

From WCMC, 1992. Global biodiversity assessment. Chapman & Hall

Procaryota 0.2 %

Protozoa 2.4 %

Coleoptera 23.8 %

Algae 2.4 %

Lepidoptera 8.9 %

Hymenoptera 7.7 %

Diptera 7.1 %

Other insects 8.9 %

Arachnida 4.5 %

Crustacea 2.4 %Other arthropoda 1.2 %

Other invertebrates 4.0 %Mollusca 4.2 %

Nematoda 0.9 % Vertebrates 2.7 %

Plants 14.3 %

Fungi 4.2 %

Saola Pseudoryx nghetinhensis

Wollemi pineWollemia nobilis

Ethmia mariannae, Rhodes Island

Cycloscala sardellaeLifou, South Pacific

Gyrodactylus teuchis, France

Average yearly number of new species descriptions

Vertebrates

400

Insects

7000

Other animals

4000

Plants

2300

Other organisms

2000

TOTAL: ca. 16 000

8000

10 000

0

12 000

2000

4000

6000

1750 1800 1850 1900 1950 2000 2050

World birds

1750 1800 1850 1900 1950 2000 2050

8000

6000

4000

2000

0

European Diptera

Data : Coleoptera sampling on 19 trees 1143 spp

Step 1 : Number of host-specificColeoptera species

162 spp

Step 2 : nb of Coleoptera speciesspecific of 50,000 tree species 8 000 000 spp

Step 3 : Adding othercanopy insect species 20 000 000 spp

Step 4 : Adding ground-dwelling insects

30 000 000 spp

Tropical insects diversity estimate (Erwin 1982)

SANTO 2006 Expedition

Measuring extinctions:

• Counting

• Predicting

Red Lists :

Source : Liste Rouge 2004

Dodo Raphus cucullatus(1662)

Sylviornis neocaledoniae (3500 BP)

New Caledonian Lorikeet Charmosyna diadema(1913)

Extinctions counted since 1600

Species duration in the paleontological records

Average species lifespan(million years)

Mammals 1 Silurian graptolites 2Echinodermata 6Planctonic foraminifera 7Cenozoic bivalves 10

Species lifespan : 5-10 million years5-10 million species

1-2 naturally-induced extinctions per year, i.e. 405-810 since 1600

Same order of magnitude as the counted number of extinctions(844 species)

But: Only 1.7 million described species

0.1-0.3 naturally-induced extinctions per year,i.e. 40-120 since 1600

Higher hypothesis: 1-2 million years lifespan

1-2 naturally-induced extinctions per year,i.e. 400-800 since 1600

Lower hypothesis: 5-10 million years lifespan

But: Well-studied species: mammals and birds only(ca. 15,000 species, 1-2 million years lifespan)

0.007-0.015 naturally-induced extinctions per year,i.e. 3-6 since 1600

210 mammals and birds species known as extinct since 1600= 35-70 times the « noise » of naturally-induced extinctions

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

5000-6000 experts

…

Specialist group(Orthoptera)

Specialist group(Cetaceans)

Specialist group(China plants)

Specialist group(Rotifera)

120 specialist groups

…

Species SurvivalCommission

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

5000-6000 experts

…

Specialist group(Orthoptera)

Specialist group(Cetaceans)

Specialist group(China plants)

Specialist group(Rotifera)

120 specialist groups

…

Species SurvivalCommission

Expert

Expert

Anceyodonta gatavakensisMangareva

Peltiera nitidaMadagascar

Meligethes aeneusItalian Alps

Pseudoyersinia brevipennis : last seen in 1860 near Hyères (France)

Measuring extinctions:

• Counting

• Predicting

Prediction: species/area relationship

Application of the insular biogeography theoryto tropical forests

With this parameters, a loss of 50% of tropical forests surface would induce the extinction of three million species : 1000 times the « natural » extinction rate.

Slope and origin may change:

?

?

??

Large range of uncertainty, but that does not change the results of this approach: the extinction rate is 1,000 to 10,000 times higher than the natural extinction rate

•« One third to half of the living species could have disappeared by 2050 »•« One species is going extinct every 15 minutes »•« 100 000 species are vanishing every year »•« 2-8% of the living species will become extinct between 1990 and 2015 »

Discoglossus pictus

Hula valley

Ramsar Convention on Wetlands - Ramsar site no. 868