geographic and taxonomic selectivity patterns in the distribution of rare southeastern endemics
TRANSCRIPT
Geographic and TaxonomicPatterns in the Distribution of Rare
Southeastern Endemics
James C. EstillUGA Center For Applied Genetic Technology
and Department of Plant Biology
Traits Increasing Extinction Risk
McKinney. 1997. Ann. Rev. Ecol. Syst. 28:495-516.
Short Term Goal : Use a biologically meaning definition of rarity to Identify the taxonomic and geographic patterns in the distribution of taxa potentially at risk of extinction in the southeastern US Ultimate Goal: Identify the traits associated with pattern
Ecological meaning of endemic:Species that are relatively spatially limited.
Rare Southeastern Endemics
Endemic 1st used in the medical literature to describe a disease that was limited to a certain geographic area
Jamie’s definition of rare endemic:“A species spatially limited to a biologically significant region with a limited number of occurrences”
Relative - As compared to other species… all species are endemic to Earth
Spatial limitation could be geographic or ecological
Defining the Geographic Area of Interest
When studying biogeographical trends in species richness, it is important to delineate areas that have biologically meaningful boundaries.
Goal: Delineate an area that had some sort of biologically meaningful borders.
Problem: Data that are available are typically delineated by political boundaries.
Defining the Geographic Area of Interest
States South of the Maximum Glacial Extent
Counties Occurringin the HT Domain - Bailey. 1998
1,231 Counties14 States
Obviously Not Perfect
Identifying Rare Southeastern Endemics
2. Distribution entirely limited to the geographic area of interest
3. Species that occur in less than 26 counties
1. Plant taxa that are commonly recognized at the species level (Kartesz, 1994 ). Including hybrids.
Data Sources
State Data Source
Arkansas (Smith 1988)
Florida (Wunderlin, Hansen et al. 1995)
Georgia (Jones and Coile 1988)(Patrick, Allison et al. 1995) (USDA 1999)
Kentucky (USDA 1999)
Louisiana (Thomas and Allen 1993; Thomas and Allen 1996; Thomas and Allen 1998)
North Carolina (Radford, Ahles et al. 1968) (USDA 1999)
South Carolina (Radford, Ahles et al. 1968)(Townsend and T.A.Mousseau )(USDA 1999)
Tennessee (Chester, Wofford et al. 1993; Chester, Wofford et al. 1997)State NHP
Texas (Carr and Diamond 1996) (Schneider 1999)
Virginia (Harvill, Bradley et al. 1992)(USDA 1999)
West Virginia (Strausbaugh and Core 1950s) (USDA 1999)
State Distributionshttp://plants.usda.gov
County DistributionsKral. R. 1983. State FlorasTaxonomic Monographs
Data Management in MS Access
SE Endemic Occurrence Data
Base data set of state occurrencesUSDA Plants Database: http://plants.usda.gov
• All data managed in MS Access
• Query of this database yielded initial list of 2,380 species limited to the 14 states of interest.
• County distribution info gained from numerous state floras and atlases
Species Removed- 766 Occur in dry domain of Texas- 329 Occur in Tropical Domain of Florida- 152 Occur outside United States- 326 Occur in >25 counties- 194 Nomenclature Problems- 117 Unresolved county distributions
482 Species(31 hybrids)
18
402
62ENDANGERED
THREATENED
NOT LISTED
Species: Federal Status
I have generated a unique data set.
Taxonomic Selectivity Patterns
McKinney. 1997. Ann. Rev. Ecol. Syst. 28:495-516.
Short Term Goal : Identify the taxonomic and geographic patterns in the distribution of rare southeastern taxa Ultimate Goal: Identify the traits leading to this pattern
Family Level Taxonomic Selectivity
Of the 307 families that occur in the SE United States, three have more endemics then predicted by a random selection model (p<0.001)
Family Number of SE Endemics
Asteraceae 78
Lamiaceae 38
Sarraceniaceae 14
http://www.masozravky.com/foto_galerie/fotosarracenia.htm
Sarraceniaceae Pitcher Plant Family
AsteraceaeSunflower Family
http://www.science.uwaterloo.ca/biology/jcsemple/heterotheca.htm http://www.uga.edu/~botgarden/GEPSN2b.html
LamiaceaeMint Family
Genus Level Taxonomic Selectivity
Of the 2,191 Genera of plants that occur in the Southeastern states, thirteen have outstanding numbers of rare southeastern endemics (p<0.001)
Genus Number of SE Endemics
Agalinis 8
Chrysopsis 7
Deeringothamnus 2
Dicerandra 7
Hexastylis 5
Leavenworthia 6
Lesquerella 7
Polygonella 4
Rudbeckia 6
Sarracenia 14
Scutellaria 11
Trillium 11
Triphora 3
Family
Scrophulariaceae
Asteraceae
Annonaceae
Lamiaceae
Aristolochiaceae
Brassicaceae
Brassicaceae
Bignoniaceae
Asteraceae
Sarraceniaceae
Lamiaceae
Liliaceae
Orchidaceae
Taxonomic Selectivity Patterns
McKinney. 1997. Ann. Rev. Ecol. Syst. 28:495-516.
Short Term Goal : Identify the taxonomic and geographic patterns in the distribution of rare southeastern taxa Ultimate Goal: Identify the traits leading to this pattern
Occurrence of Endemics
0
10
20
30
40
50
60
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Total Counties of Occurrence
Nu
mb
er o
f S
pec
ies
Endemics in States
State Rare SE Endemics in StateTotal Number of County
OccurrencesProportion of Counties Containing Endemics
Florida 227 1,370 1.00
Georgia 126 607 0.89
North Carolina 90 399 0.70
Alabama 87 268 0.88
South Carolina 71 165 0.85
Tennessee 64 216 0.60
Texas 55 315 0.71
Louisiana 43 161 0.80
Virginia 31 110 0.31
Mississippi 23 50 0.24
Kentucky 16 53 0.43
Arkansas 16 101 0.65
Oklahoma 10 20 0.12
West Virginia 8 21 0.20
Richness of Rare Southeastern Endemics
Corrections for Species Richness ?
Corrections for total plant species richness are currently not possible given the inconstancies of the data
• Inconsistency in sampling among states- Data not available for AL, MS, and OK- Primary data not available for most states
The county level distribution of most of the native US plants is unknown, and is becoming increasingly unknowable
• Inconsistency in sampling within counties- Distance to herbaria and interstates are currently great indicators of species richness
Epidemic Loss of Herbaria
Data derived from Index Herbariorum (http://www.nybg.org/bsci/ih/ih.html) .
Richness of Rare Southeastern Endemics
Richness of Rare Southeastern Endemics
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0 500 1000 1500 2000
99.9 % Confidence
Observed I
Spatial Autocorrelation of Endemic Species Richness
Lag Distance (km)
Glo
bal
Mo
ran
’s I
Local Indicators of Spatial Autocorrelation
The counties contributing to the positive global spatial autocorrelation at the 0-60km lag distance.
Global Moran’s I = 0.430
Rarity Weighted Richness Index (RWRI)
∑ == n
ii
county hRWRI
1
1
In addition to richness may want to consider rarity of the endemic species flora for that county
hi = the number of counties that species i occurs inn = number of endemic species in that county
The contribution of any species to the RWRI for a county will range from 0.04 to 1.00
Identifying Outstanding Endemic Floras
Can identify counties with “outstanding endemic floras” by comparing theEndemic Richness to the RWRI.
Outside of 95% and 99% confidence intervals of a linear model
R2 = 0.8836
0
2
4
6
8
10
12
0 10 20 30 40 50 60
Endemic Species Richness
Rar
ity-
Wei
gh
ted
Ric
hn
ess
Ind
ex (
RW
RI)
Significantly More Unique Significantly Less Unique
Geographic Centers of Endemic Species Richness
Gulf Coastal Plain
Central BasinSouthern Appalachians
AppalachicolaFlorida Panhandle
Central Pennisular Florida
Atlantic Coastal Plain
Combining the geographic analyses allows for the identification of six centers of endemic species richness
Geographic Centers of Endemic Species Richness
Ouachita Mts.
Two minor centers of endemism are also less apparent
NE Alabama
Summary
• Taxonomic selectivity exists for rare southeastern endemics at the Family and Genus level
• Geographic selectivity exists for rare southeastern endemics with well defined centers of endemism
• Overall species richness at the county level is relatively unknown, thus it is difficult to determine the association between endemism and overall species richness
• Now the real work begins
I’d be happy to answer any questions or concernsJamie Estill: [email protected]
Estill, J.C and Cruzan M.B. 2001. Phytogeography of Rare Plant Species Endemic to the Southeastern United States. Castanea. 66(1-2): 3-23.