Assessing the Diversity Along an Urban Gradient Using as a Model

William Kish & Sujan Henkanaththegedara Department of Biological & Environmental Sciences Longwood University, Farmville, Virginia Background

 Urbanization generally cause loss of native diversity (Blair 1996).  Urbanization may also promote a few urban- adapted taxa and lead to biotic Southern House (Kukulcania hibernalis) homogenization (Blair 1996).  Little attention has been given to explore how urban development affects the diversity and abundance of including spiders (Shochat et al. 2004).

Common House Spider (Parasteatoda tepidariorum) Intermediate Disturbance Hypothesis

 The highest diversity is reported in moderately disturbed locations (Connell 1978). Background

 The United States supports a considerable diversity of spiders (~4,000 species, Bradley, 2013). Tuft-legged Orbweaver  Many aspects of spider habitat use, and niche ( placida) specialization are poorly documented (Howell and Jenkins 2004).  Additionally, the species diversity of spiders in the eastern United States is poorly documented (Howell and Jenkins 2004).

Canopy Jumping Spider (Phidippus otiosus) Effects of Urbanization

 Compared bird species distribution and abundance across urban gradient

 Species richness, Shannon diversity and biomass was highest at moderately disturbed habitats

 Support for intermediate disturbance hypothesis

(Blair 1996) Effects of Urbanization

 Diversity was highest in desert remnants habitat (dominated by native vegetation, no built structures)

 Diversity was lowest in mesic yards (>50% lawns, exotic plants, and irrigation) (Shochat et al. 2004) Research Objectives

1) Study spider diversity and abundance along an urban gradient

- Test the Intermediate Disturbance Hypothesis

2) Explore the relationships between environmental conditions and the diversity of spiders.

3) Compile a checklist of spiders in the Longwood Lancer Park flood plain. Study Area

 Longwood University in Farmville, Virginia at the Lancer Park Flood Plain.  This ~30-acre area with both aquatic and terrestrial habitats containing:  Third order stream  Seasonal pools and several man-made ponds  Eastern deciduous forests  Grasslands and hedge habitats  Buffer habitat with parking lots and roads Research Design

 Three 5m x 5m study plots representing forested habitat (non- urban), grassy habitat (transitional), and urban habitat. Field Data Collection • Fall 2018 (N=5) and Spring 2019 (N=7)

• Collected using visual observations and sweep nets.

• Photographed and released back to the original capture location.

• Environmental data were also collected (temperature, humidity, light intensity and height) Distribution of the experimental plots Field Data Collection  Spiders were identified using field guides and identification keys provided by Bradley (2013), Gaddy (2009), and Howell and Jenkins (2004)  Reported to iNaturalist online species repository (https://www.inaturalist.org) Data Analysis

 Diversity was determined using the Shannon-Wiener Diversity Index.  Data was analyzed statistically using R statistical software program.  Two way ANOVAs and Simple Linear Regressions were used. Results • 11 Families, 51 Genera, 76 Taxa, and 345 Individuals • Most abundant families and Taxa: A B • Salticidae (17.4%); White-jawed Jumping Spider (Hentzia mitrata) (20) (A)

• Lycosidae (16.2%); Rabid Wolf C D Spider (Rabidosa rabida)(8) (B) • Oxyopidae (15.7%); Lynx Spider (Oxyope sp.) (48) (C) • Araneidae (13.0%); Humped Trashline Orbweaver (Cyclosa turbinate) (20) (D) Results: Species richness

 Fall 2018: Highest number of species in grassland habitat.

12 P = 0.0188 F = 6.217 10

8

6

4

2 Number ofSpecies 0 Urban Grassland Forest

High Disturbance Low Disturbance Results: Abundance

 Fall 2018: Highest abundance was in the grassland habitat

P < 0.001 35 F = 15.00 30 25 20 15

Abundance 10 5 0 Urban Grassland Forest High Disturbance Low Disturbance Results: Shannon-Wiener Diversity

 Fall 2018: No significant differences among habitats.

2 P = 0.172 1.8 F = 1.99 1.6 1.4 1.2 1

Wiener Wiener Index (H') 0.8 - 0.6 0.4 0.2 Shannon 0 Urban Grassland Forest

High Disturbance Low Disturbance Results: Species Richness

 Spring 2019: Highest number of species in forested habitat

7

6 P = 0.832 F = 0.186 5 4 3 2

Number ofSpecies 1 0 Urban Grassland Forest Results: Abundance

 Spring 2019: Highest abundance was in the grassland

10 9 P = 0.689 8 F = 0.38 7 6 5 4

Abundance 3 2 1 0 Urban Grassland Forest High Disturbance Low Disturbance Results: Shannon-Wiener Diversity

 Spring 2019: No significant differences among habitats.

1.8 1.6 1.4 P = 0.405 F = 0.951 1.2 1

0.8 Wiener Wiener Index (H') - 0.6 0.4 0.2 Shannon 0 Urban Grassland Forest Results: Effects of humidity

 Abundance had a significant positive correlation with relative humidity. 45 40 R² = 0.1283 P = 0.0273 35 30 25 20

15 Abundance 10 5 0 0 20 40 60 80 100 Humidity (%) Results: Effects of light intensity

 Abundance had a significant negative correlation with light intensity

45 R² = 0.1478 40 P = 0.0188 35 30 25 20

Abundance 15 10 5 0 0 50000 100000 150000 Light Intensity (Lux) Results: Effects of height

 Abundance had a significant negative correlation with height

45 R² = 0.1195 40 P = 0.0335 35 30 25 20

15 Abundance 10 5 0 0 50 100 150 200 Height (cm) Results: Effects of light intensity

 Number of species had a significant negative correlation with light intensity

14 R² = 0.1245 P = 0.0322 12 10 8 6 4

Number ofSpecies 2 0 0 50000 100000 150000 Light Intensity (Lux) Conclusions and Discussion

 11 Families, 51 Genera, 76 Taxa, and 345 Individuals  Rural habitats support diverse spider communities

 Less diversity and abundance in urban habitats in fall 2018  Provides evidence for negative impacts of urbanization

 Support for IDH with fall 2018 data but not with spring 2019  Possibly due to lack of “mature spider community” after winter

 More spiders in humid, low elevation and dark habitats Discussion

Limitations  Seasonality of spiders  Extreme weather Spotted Orbweaver (Neoscona crucifera) Future Directions Yellow Garden Spider  Continue sampling to increase sample size (Argiope aurantia)  Analyze the seasonal variation  Sample throughout the year

https://www.inaturalist.org/projects/lancer-park-spiders-fall-2018 https://www.inaturalist.org/projects/lancer-park-spiders-spring-2019 Acknowledgments We would like to thank,  Data collection: Griffin Mayo and Zachary Taylor  Funding: Longwood CURIO Program and Virginia Academy of Science (Undergrad Research Scholarship)  This study was conducted as an extension of Longwood BioBlitz (https://blogs.longwood.edu/longwoodbioblitz/) under VDGIF Scientific Collecting Permit # 059601. References

 Blair, R.B. 1996. Land use and avian species diversity along an urban gradient. Ecological Applications 6:506-519.  Bradley, R. A. 2013. Common Spiders of North America. University of California Press, Berkeley and Los Angeles, CA.  Connell, J.H. Diversity in Tropical Rain Forests and Coral Reefs. Science199: 1302- 1310.  Gaddy, L.L. 2009. Spiders of the Carolinas. Stensaas + Kollath Publishing, Duluth, Minnesota, USA.  Howell, W. M., and Jenkins, R. L. 2004. Spiders of the Eastern United States. Pearson Education, Boston, Massachusetts, USA.  Shochat, E, W.L. Stefanov, M.E.A. Whitehouse, S.H. Faeth. 2004. Urbanization and spider diversity: influences of human modification of habitat structure and productivity. Ecological Applications 14: 268–280 Questions?