1. ….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

2. 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

3. 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

4. -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

5. -some kinds of habitats are barely known TROPICAL FOREST CANOPY
OCEANS - floors & abyss; vents
TROPICAL FOREST CANOPY
7% vs. >50%; m.
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

6. 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

7. 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

8. >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

9. 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 x106 spp.
arthropods worldwide in all habitats 12

10. 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

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

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

13. 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

14. 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

15. *
again, among vertebrates, most are bony fish
~47,000 spp. 12

16. 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

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

18. 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

19. 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

20. NEXT CLASS:
Global patterns in
Species Richness 12