The term is split roughly into (intellectual) thirds: What is biodiversity? species & phylogenies and how is it patterned?

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1 The term is split roughly into (intellectual) thirds: What is biodiversity? species & phylogenies and how is it patterned? hollow curves Where is biodiversity? measurement, latitudinal gradients and why is it there? species-area curves, energy, etc. (Why) is biodiversity important? productivity, values of biodiversity How are those values expressed? legislation Evolutionary timescales Evolutionary and Ecological time scales Evolutionary and Ecological time scales 1 where are all these species (space)? Different patterns at different scales, so include both ecological and evolutionary time speciation and extinction immigration, species interactions, local extinctions Background reading for next few weeks: Purvis and Hector (2000) Getting the measure of Biodiversity First pattern: why do larger areas have more species? SC predict species richness, and can be used to predict current extinction rates... Rosenzweig, 95

2 SC predict species richness, and can be used to predict current extinction rates... Species-rea Curves. Issues include: 1.! Empirical note: Log-Log plot 2.! Three illuminating curves:! - among subplots of a biogeographic province! - among isolated islands within a province! - among independent biogeographic provinces Put all three on one graph, and then explore each in turn 1. Empirical note: Raw data is a curve of diminishing returns (power law with exponent z<1) # species S=c z species number high c area high z low z log(#spp) slope intercept LogS=zLog() + Log(c) high z = 0.15 low z = 0.1 Log(c)=1.75 Log(c)= low c rea log(rea) intercept is the expected richness at Log()=0 (and so obviously is scale dependent)

3 ll Species-rea relationships are governed by four forces: immigration, extirpation, speciation and extinction Rarefaction Question: How do B vs B' abundance distributions differ? log(#spp) within province 1 1 islands of 1 2 between provinces 1 and 2 Species observed not observed B B sample size log(rea) Number of individuals folks don t like this Biogeographic province: an area whose species-richness dynamics are governed principally by speciation and extinction Island: an area whose species-richness dynamics are governed most by immigration and extirpation within province curves tend to be relatively shallow! islands are steeper than their province!! between provinces the steepest within province 1 1 (One taxon's island is another's province) log(s) 1's islands 2 between provinces 1 and 2 log()

4 Three Species-rea Curves 1. Within provinces! Species-rea relationships for birds spatial scale (Gaston & Blackburn, 2000). Within provinces - nested subsets nested subset: larger samples are not independent of smaller samples, so statistical analyses are hard to do. z=0.11

5 . Within Provinces... 1 Possible hypotheses for intraprovincial curve: 1. Larger areas sample more individuals log(s) 2. Larger areas sample more habitats 2 Given all the bird data from the UK, how could we test the first, statistical artifact? bit of total area log() all of area 1 Why do we have fewer species in smaller subplots? 1. Census a small area - get average # spp and! record the average number of individuals 2. Draw the same number of individuals randomly from the entire Province (e.g. all the breeding pairs in the UK). Repeat 100 times to get a confidence interval. 3. Is it the same as your small area? If it is, this is consistent with the intraprovincial slope being a pure sampling issue. --could only do this in the UK! So, from Eastern Wood (16 ha in Surrey, censused 49-79): 168 breeding pairs per year, on average --average # spp: 31.8 (+/-2.6) -take samples of 168 from the 62, breeding pairs (!) of 540 spp of birds in Britain. --average number of spp: 45 (+/-3.4) spp....so actually get fewer than we expect based on sampling (and so the null model would predict a shallower slope than we see. There is something else to explain) What is our explanation?

6 So is the increase due to sampling more habitats? --weak test for Eastern Wood: Sample 168 from 51, pairs (of 80 spp) of deciduous wood species (100 times) -get 31.8 (+/-2.4) - exactly the same as average year at EW. So sampling more species than expected in larger samples may be due to sampling more habitats How often do you see grebes in a forest? -- evidence suggests that # of new habitats is a good, but not perfect predictor of species richness in subplots. Problem: area may be better predictor of habitat than habitat! Three Species-rea Curves Biogeographic ll Species-rea 'realms'/kingdoms relationships are governed by four forces: immigration, extirpation, speciation and extinction 1. Within provinces: often shallow auto-correlation (subsamples) sampling + habitat within provinces 1 2. mong provinces: log(s) 1's islands 2 between provinces bewildering taxonomy (provinces/regions, ecozones, etc.) log()

7 Holt et al., Science, 2013 Oceanic provinces (~10 per each of four 'realms') "Longhurst Biogeographic Provinces" (Bedford Oceanographic Institute) Map of the terrestrial zoogeographic realms and regions of the world. Zoogeographic realms and regions are the product of analytical clustering of phylogenetic turnover of assemblages of species, including 21,037 species of amphibians, nonpelagic birds, and nonmarine mammals worldwide. Dashed lines delineate the 20 zoogeographic regions identified in this study. Thick lines group these regions into 11 broad-scale realms, which are named. Color differences depict the amount of phylogenetic turnover among realms World s Birds (G&B,01) widespread species of tree, many insect spp r 2 = 0.71 limited range tree species, few insect spp z=0.66, log(c)=1.59 (very steep slope) Z=0.89, so like interprovincial: hypotheses? (Rz, 95)

8 Flowering plants at two scales z>1 within Britain Note: Steep among-province relationships hold within groups (birds, bats, fern-living insects,trees in wet forest) - So not just habitat variation at some gross scale. Interesting - (but...) Rosenzweig 95 Here, we are in the realm of evolutionary time --Note: new provinces have DIFFERENT species (different pools), but the pattern is one of numbers (the pattern is not cumulative like within province...) -- Bigger areas may support larger populations, and larger populations often have larger ranges ccording to Rosenzweig (1995, but still considered relevant): Larger areas = larger populations = less extinction Larger ranges are more likely to be bisected (allopatric speciation) Diversity leads to specialization, a more sedentary lifestyle, and more speciation How does this effect speciation and extinction? Obviously, this is pure conjecture (particularly the last one) We will return to diversification rate and province size when we consider the tropics next week...

9 Tropical bird (sub)species richness Dispersal ability may predict richness: high low high low high low high low high low Three Species-rea Curves 1. Within provinces:! often shallow!!! auto-correlation (subsamples)!!! sampling more individuals!!! turnover (beta) due to heterogeneity 2. mong provinces: not subsamples!!! steepest of three types of curve!!! higher speciation;lower extinction rate!!! -both!f(population size, range size)? 3. mong islands of a province: 33 Claire Salisbury et al., islands off the coast of UK Woodland "islands" for birds in UK (Gaston&Blackburn, 00) Eastern Wood, Surrey r 2 = 0.66 r 2 = 0.82 z=0.32, log(c)=1.17 z=0.28, log(c)=1.65

10 Island Biogeography Theory (Macrthur and Wilson, 63; Gotteli, 95) For one island based on four premises - (NB: pure ecology) s the number of species resident on an island increases: 1. The immigration rate decreases (fewer new species) 2. The extirpation rate increases (competition) (both absolute and per species rate) new species arrival rate (spp/yr) equilibrium species extirpation rate (spp/yr) s the size of the island increases: 3. The immigration rate increases (bigger target) 4. The extirpation rate decreases (larger populations) few # spp on island many Immigration and extirpation rate, Eastern Wood, Compare with bigger island species arrival rate big island- more species arrive species extirpation rate -and fewer are lost cross at 32 spp, where 3 new species arrive and 3 current species are lost = equilibrium point few # spp on island many higher equilibrium

11 This explains the positive slope, but why is the island curve steeper than the intraprovincial curve? Islands are separated from the mainland, which is the source of immigrants. The greater the separation, the more isolated an island is, reducing immigration rates. log(s) within province islands in On the mainland, habitat is continuous, allowing immigration rates to be higher. Many populations may be also be sinks - only there by virtue of continuous immigration from sources. This allows smaller areas to have more species. Mainland Island log(rea) For a subplot the same size as an island... and more species in mainland plots makes the mainland slope shallower new spp arrival rate (per year) few Immigration rates are greater species extirpation rate (per year) and fewer are lost Island # spp Mainland many logs within province islands in log rea Islands are farther away, and are also missing sink species, making the island slopes steeper

12 Which set of islands (red or blue) is likely farther from the mainland? Quiz What is the llee effect? Does it make managing small populations easier or harder? Why? 2. Describe two areas of biodiversity science where Ne is important. 3. What is an "independent contrast"? log(s) 4. Draw and clearly label two Relative Species bundance Curves on on the same axis for the same assemblage: one with a small sample size, and one with a large sample size. B 5. Purvis and Hector talk about "Numbers, Evenness and Difference" as facets of biodiversity in their Box 1. Give two examples of specific measures of "difference", preferably one that measures within a sample and one that measures across samples. log(rea) E2 E1 Wilson & Simberloff, 69

13 E2 (near) rthropods on mangrove islands red set is likely farther from the mainland note: it is not clear that the slopes must be different, though they usually are... log(s) E1 (far) B Fumigated islands Simberloff and Wilson, '69 log(rea) pomerine ants distant islands all of NGuinea closer islands Ok, can we infer when an island becomes a biogeographical province? Macrthur & Wilson, 1967 ta da - use phylogenies!

14 nalysis of an evolutionary species-area relationship (Losos&Schluter,Nature 408:847, 00) two different processes? Cuba Hispaniola Jamaica Puerto Rico Breakpoint at 3000km 2 (L&S,00-fig3) Hispaniola 8 spp Hispaniola ln(spp) St.Croix 2spp Martinique 3spp log() 8 spp ln(spp) St.Croix 2spp Martinique 3spp log() What processes (immigration, extirpation, speciation, extinction) are implied by these different trees?

15 Perhaps in situ speciation on large island, but only immigration on smaller islands Non-zero speciation rate starts at 3000 km 2 dd a time axis, and you can calculate speciation rate (L&S,00-fig2) -So, whereas island dynamics (and subsamples of provinces) are governed mainly by: immigration, extirpation, Province dynamics are governed mainly by: So, what happens when we create Islands on the mainland? speciation, extinction and for nolis lizards, Cuba and Hispaniola and Jamaica are not islands

16 Cadiz Township, Wisconsin Faunal Collapse Contiguous Habitat (intraprovincial SC) Log # Species smaller areas lose more species Log rea From Macrthur and Wilson 1967, after Curtis 1956 Extirpations From Parks Species-rea relationships: which z to use? Parks lose mammal species due to faunal collapse W.D. Newmark 1987 (Nature) log(s) Intraprovincial 's islands Interprovincial log() '

17 because -ln(x) is close to 1-x for x near 1 ln S' S = z ln ' S'/S is prop(sppleft)... area gets smaller ln(1! prop(spplost)) =!prop(spplost) =!z ln( ' ) prop(lost) = z * prop(arealost) same substitution for area proportion species lost per year ~ z(proportion area lost per year) most common z used is 0.25 or 0.3, the island curve (see, e.g. Woodruff, 2001, Pimm, 2002). Here is an example using z~0.15 Eastern North merica: in 1870, forest was at low point, = 0.5 (so proportion lost was 0.5) So proportion species lost = 0.15 x 0.5 = 0.07, or 7% There were 30 species endemic to the area, so we expect 2-3 extinctions (for endemics, this area is their "province"). PIMM SL, SKINS R FOREST LOSSES PREDICT BIRD EXTINCTIONS IN ESTERN NORTH-MERIC P NTL CD SCI US 92: (1995) nd we lost 4 and are losing one more... Given the Passenger Pigeon was also heavily persecuted, this suggests at least 3 extinction due primarily to habitat loss, making z > 0.15 not unreasonable in this specific case. (This may just be a lucky example.) Martha, 1914 (wiki) Bachman's warbler (Vermivora bachmani) Passenger pigeon (Ectopistes migratorius) red-cockaded woodpecker (Picoides borealis) Endangered but doing better Ivory-billed woodpecker (Campephilus principalis)* The problem is, we have witnessed many fewer extinctions due to habitat loss than SR predicts Carolina parakeet (Conuropsis carolinensis) 68

18 Old alarmist projections of Extinction based on habitat loss: "One species per hour to one species a day" Myers, N. The Sinking rk: New Look at the Problem of Disappearing Species (Pergamon, 1979) "33 50% of all species between the 1970s and 2000" Lovejoy, T. E. in The Global 2000 Report to the President: Entering the Twenty-First Century (study director Barney, G. O.) "from half to several million species by 2000" National Research Council. Research Priorities in Tropical Biology (National cademy of Sciences, 1980) He and Hubbell (2011, 2012, 2013) point out something important Counting species when you first see them is different from counting species when you last see them! "50% of species by 2000" Ehrlich,P.R.&Ehrlich,.H.Extinction:The Causes and Consequences oft he Disappearance of Species (Random House, 1981) ER=endemics area relationship 69 He and Hubbell (2011) Hanski et al., 2013 make a different point first time you encounter a species (SR z) ln(spp) island curve last time you encounter species (ER z) ln(spp) But landscapes are not just getting smaller, but also fragmented! So z should be STEEPER! ln(area) For imminent extinctions, it is only when the entire range is gone that the species goes extinct...and this happens much more slowly with area - so, the z you use to calculate extinction should be LESS than SR z. ln(area) 72

19 nd Rosenzweig (2001) goes much further: both intraprovincial and island curves are based on source-sink dynamics Early stage: local endemics lost Ultimate drop should be based on interprovincial curves (area is lost forever, dynamics are speciation and extinction). Later stage: poor dispersers lost minor losses log(s) 's islands major losses log(s) 1 between provinces and here z approaches unity... This is much worse... log() ' log() ' How much land are we losing presently? Lets look at the tropics: Millennium Ecosystem ssessment (2005) published 0.25% of humid tropical forest conversion per year chard et al. (2002) suggest 0.52%/yr. Pimm (2002) suggests 1%/yr nd the tropics are special: -most species live there! This would suggest we sentence up 0.25 to 1% of tropical species to extinction, every year!