testing for size-dependent trade- offs of clustering in nephila clavipes laura sauvage (cmc ‘14) &...
TRANSCRIPT
- Slide 1
- Testing for size-dependent trade- offs of clustering in Nephila clavipes Laura Sauvage (CMC 14) & Haley Godtfredsen (Scripps 16)
- Slide 2
- Introduction Web ecology Prey capture Males Kleptoparasites Predation
- Slide 3
- Nephila clavipes LargeMediumSmall
- Slide 4
- Another component of web environment: Solitary (built alone)Clustered (attached to other webs)
- Slide 5
- Theoretical costs and benefits of cluster formation: Cost = competition for food Benefit = less predation risk per spider
- Slide 6
- Daniella Barraza, 2012 Cost: Medium spiders caught more prey if solitary than clustered. - No difference for small spiders. Benefit: Longer web tenure if clustered. - More so for medium than small spiders.
- Slide 7
- Sauvage & Godtfredsen, 2013 Hypothesis: Costs & benefits of clustering will be size-dependent. Preliminary data- Frequency of clustering Variation in web experience based on spider size and clustering
- Slide 8
- Methods Firestone Center for Restoration Ecology Baru, Costa Rica
- Slide 9
- Spider IDSolitary/ Clustered Date Found ColorNeighbor Females Spider Size (mm) Web Size (m) 1S7/5/2013N/A 1.780.18 2S7/5/2013N/A 4.740.43 3C7/5/2013Blue42.570.30 4C7/6/2013Green32.910.31 5S7/6/2013N/A 3.400.36 Initial Measurements (example data)
- Slide 10
- Spider ID DateWeb Condition # Prey# Legs# Neighbor Females 17/15/2013Good08N/A 27/15/2013Good28N/A 37/15/2013Poor071 47/15/2013Good081 57/15/2013Okay17N/A Monitoring Data (example data)
- Slide 11
- Measuring costs and benefits of cluster formation: Competition for food: prey capture rate Lower predation risk Web duration Leg autotomy Web condition Reason for disappearance
- Slide 12
- Clustering Clustered: 191 webs (48%) Solitary: 209 webs (52%) Frequencies of.
- Slide 13
- ClusteringLeg Autotomy Clustered: 191 webs (48%)No: 367 webs (94%) Solitary: 209 webs (52%)Yes: 25 webs (6%) Frequencies of.
- Slide 14
- ClusteringLeg AutotomyWeb Fate Clustered: 191 webs (48%)No: 367 webs (94%) Moved: 160 webs (65%) Solitary: 209 webs (52%)Yes: 25 webs (6%) Depredated: 86 webs (35%) Frequencies of.
- Slide 15
- ClusteringPrey Capture Leg Autotomy Spider/Web Fate Spider Size NS + Influence of spider size on NS = not significant + = positive correlation
- Slide 16
- ClusteringPrey Capture Leg Autotomy Spider/Web Fate Spider Size NS + Influence of spider size on Influence of clustering on Prey Capture Leg Autotomy Spider/Web Fate Clustered compared to Solitary NS
- Slide 17
- Significance Studying the costs/benefits of living in a group (cluster) Do these trade-offs differ with spider size?
- Slide 18
- Prey capture Preliminary Data Predation Spider Size Clustering X X X
- Slide 19
- To Be Determined Do size-dependent trade-offs exist in clusters? Frequency with which spiders of different sizes are clustered or solitary. Cluster formation Order of arrival Effect of size
- Slide 20
- Acknowledgements Keck Science Department Professor E. Ferree Professor D. McFarlane Greddy Arias-- Firestone Caretaker Pitzer College
- Slide 21
- Preliminary Results Mean web diameter (mm) Bigger spiders have bigger webs. n=17 n=183 n=138