….what is a species? DIVERSITY INVENTORY what should we count? - how many organisms are there in the world? - their distribution among the various groups? what is the quantitative composition of the world's biota? what should we count? ….what is a species? 12

mostly morphology + physiology - recall that "species" is not a standard unit [morphological; biological] - depends on kind of organism [available characteristics] -depends on analysis methods varying criteria - appearance; genetic community/ /continuity; lumpers & splitters; molecules some organisms don't have sex we know little more than appearance for HUGE majority of all organisms [molecules; cells; physiology; anatomy] mostly morphology + physiology 12

how many species are known in the world? certainly an underestimate so bearing in mind this imprecision…. how many species are known in the world? most estimates are in the order of 106 working total = 1.65 x 106 (used in pie-diagrams) the 1.65 x 106 value is that used in World Cons. Monitoring Syst.'s Global Biodiversity book. basis of all pies ACTUALLY, WE DON'T KNOW……. UNDERESTIMATE? inadequacy of search (see next) BUT ALSO speed of acquisition >>> speed of cataloguing: "Our museums are glutted with new species. We don’t have time to describe more than a small fraction of those pouring in each year." E. O. Wilson, The Diversity of Life) certainly an underestimate WHY? 12

-large, familiar, groups almost entirely known (though not quite….) -but most groups probably hugely more numerous than we yet know e.g. BACTERIA PROTISTS FUNGI NEMATODES MITES INSECTS Catagonus and s.e Asian forest ungulates simply difficulty of observation makes any small organisms probably greatly underestimated to some great extent, we know of them if & when they become apparent to us through damage, disease etc. Discovery of "silent" small creatures is a substantial technical and manpower problem. Decline of importance of taxonomy in universities... 12

-some kinds of habitats are barely known TROPICAL FOREST CANOPY OCEANS - floors & abyss; vents TROPICAL FOREST CANOPY 7% vs. >50%; 50-100m. SOILS (and deeper…) oceans cover 71% of earth's surface. average depth is 3700m!!! NEW ANIMAL PHYLA FROM OCEANS- Loricifera 1983; entirely independent communities NOT based in sunlight never imagined before discovered in vents until very recently, almost all bio-exploration manpower devoted to temperate latitudes….. both soils & bodies are very difficult to study. OTHERS' BODIES "entire universes…." 12

but there could easily be 10x to 100x how many species do we THINK there are? estimates vary from 107 to 1011 (meaning of these numbers) we have little help in choosing among them but there could easily be 10x to 100x what we currently know 1011 is the number of stars in our galaxy…... 12

where do estimates come from? some have tried to use description-rate number year asymptote asymptote must be long-term constant, or nearly-so (are all suitable habitats well-enough known & studied?) but for non-asymptotic curves, rediction is impossible….. 12

>8x106 spp. tropical canopy beetles others have used extrapolation from detailed regional studies e.g. Erwin's studies of canopy arthropods in C. & S. America insecticide "bug-bomb" 163 spp. beetles exclusive to Luehea How many beetles are found on many trees? How many trees show same level of exclusivity? How fixed is the exclusivity of Luehea - or any other tree? 50,000 forest tree species if Luehea typical….. >8x106 spp. tropical canopy beetles 12

Erwin claims 50-100x106 spp. arthropods worldwide in all habitats in many studies, beetles represent 40% of all arthropod species so all tropical canopy arthropods = 20 x 106 species canopy spp. = 2x ground spp. so tropical arthropods = 30 x 106 spp. are beetle proportions stable? is proportion of canopy vs. ground stable? how well do we know earth's tropics? Erwin claims 50-100x106 spp. arthropods worldwide in all habitats 12

how are taxa distributed among groups? (recall matter of classifications) following figures based on figures from World Conservation Monitoring Centre different classifications put species in different bins taking standard 5-Kingdom and numbers available about 8 years ago……. again depends on which lower category you count- answer depends on what you count 12

the five kingdoms, counting phyla Earth's biota: the five kingdoms, counting phyla protists bacteria animals what are phyla? plants fungi 12

the same, but counting species bacteria protists plants fungi animals “The imbalance in the proportion of microbes & animals undoubtedly reflects the way in which the attention of researchers has so far been concentrated on the animals rather than any real preponderance of the animal kingdom.” (Cox & Moore, 1993) clearly a very different picture from foregoing 12

now concentrating on eukaryotes though fungi and protists are certainly underdescribed, the relative diversity of plants and animals is probably fair - 3-4x as many animal spp. 12

ANIMAL DIVERSITY insects counting……. ORDERS 420 SPECIES 106+ major structural diversity (orders) by phyla is fairly evenly distributed but at species level, clear that most variations are on the Insect theme……. N.B. arthropods 12

* again, among vertebrates, most are bony fish ~47,000 spp. 12

Species composition of Mammals, by order 1000 together make up 70% spp. 1000 100 10 most mammals are rodents, or bats or insectivores (though we now know that "Insectivore" is not a natural group - trophic convergence has generated many superficially similar forms..…. Species composition of Mammals, by order ~4300 spp. 12

…and now the Birds - ~9500 spp. the vast majority are songbirds 12

this is a very general pattern in ecology, by now, most of you will have noticed a pattern in species abundances……. just a few groups contain most of the species but most groups contain few of the species species abundance is highly skewed among groups this is a very general pattern in ecology, found at most scales of analysis 12

few groups are sp.-rich; most are sp.-poor this is so regardless of total numbers 10 100 1000 note: log-scale number of spp. or indivs. per group number of groups with N spp. or individuals 12

NEXT CLASS: Global patterns in Species Richness 12