Relationship Between Pollination Behavior of Invasive Honeybees and Native Bumblebees

Transcription

1 Relatinship Between Pllinatin Behavir f Invasive Hneybees and Native Bumblebees Carlyn Silverman Barnard Cllege, Clumbia University 7 Ec-Infrmatics Summer Institute HJ Andrews Experimental Frest Oregn State University

2 Mtivatin Plant-pllinatr netwrks: traditinally bipartite Ignres pssible relatinships within each grup Why d we care? Invasive hneybees may impact native bees Chice f Pllinatrs: Apis mellifera 0 species f Bmbus Ttal recrded interactins: 22.8% Apis and 9.6% Bmbus Generalist pllinatrs 2

3 Definitins/Ntatin mwy := meadw-watch-year (78 ttal) f := a single flwer species invlved in >9 scial bee interactins in a mwy A f := # f Apis interactins with f B f := # f Bmbus interactins with f Pssible classes fr each f interactin: Class E (Equal) := apprximately : A f t B f Class A (Apis) := at least 2: A f t B f Class B (Bmbus) := at least 2: B f t A f Observed Class and Andy Class 3

4 Questin : Hw are bserved classes related t Andy s expected classes? 4

5 Andy Class (based n flwer traits) is Related t Observed Class Observed Class Andy Class E A B Ttal E A B Ttal Pearsn s chi-squared test: X-squared = 40.4, df = 4, p-value < 2.2e-6 Prprtins by rw: Observed Class Andy Class E A B E A B

6 Questin 2: Hw d flwer traits and envirnmental factrs relate t Apis/Bmbus partitining f interactins? 6

7 Mdeling Apprach: Decisin Trees Class E Class 2 A Class 3 B % yes ExclusinVisibility = bright n % ExclusinTubePlantCde =,0,2,3,6, % ExclusinTubePlantCde =,0,3,6, % ExclusinTubePlantCde = 0,3,6, % % Bim.flwr >= 7 Bim.flwr < % Bim.flwr < % % % % % % % % Decisin tree fr Andy Class based n flwer traits 7

8 Methd AdaBst: An ensemble methd fr classificatin Linear Cmbinatin f weighted trees Outputs relative imprtance f each variable Fit 3 mdels using AdaBst t predict the bserved and Andy class 5 decisin trees per mdel Estimate misclassificatin rate thrugh crss-validatin Plt imprtance value f each predictr (nrmalized t sum t 00) 8

9 Observed Class Related t Envirnmental Cvariates Mdel Predictrs: Abund := #stalks * #flws/stalk ApisPrp := Prprtin f Apis t all scial bees in the mwy Day = day f year Andy Class Predictin Errr: 47.2% Observed Class Predictin Errr: 22.4% 9

10 Observed Class and Andy Class bth Related t Flwer Traits Mdel 2 Predictrs: Bim.flwr = bimass per flwer Tube = cde indicating tube length and extent f exclusivity (0 levels) Visibility = bright r red/dark Bim.flwr Funct Exclusin Flwer Frm Funct Exclusin Bim.flwr Flwer Frm Andy Class Predictin Errr:.3% Observed Class Predictin Errr: 20.8% 0

11 Observed Class Best Explained by Bth Envirnmental Cvariates and Traits Mdel 3 Predictrs: Day, Abund, ApisPrp, Bim.flwr, Tube, Visibility Funct Exclusin Bim.flwr Abund Day ApisPrp Flwer Frm Andy Class Predictin Errr: 3.3% Observed Class Predictin Errr: 4.9%

12 Findings & Interpretatin Apis and Bmbus (generalist pllinatrs) rarely interact equally with a flwer species in a given mwy Avidance? Cmpetitin? Flwer Preference? Andy Class predicted very well by 3 flwer traits Implies crrelatin between traits Envirnmental cvariates and flwer traits bth play a rle in the partitining f interactins Significant relatinship between pllinatr presence and the pllinatin activity f ther species 2

13 Thank Yu: Julia Jnes Rebecca Hutchinsn Andy Mldenke Kate Jnes EISI Participants 3

14 AdaBst: An Ensemble Methd fr Classificatin AdaBst = Adaptive Bsting Linear cmbinatin f weighted weak learners create a strng classifier Mdel utputs relative imprtance f each variable based n weight and Gini Index Gini Index = degree f inequality f predictrs fr each weak classifier Figure: Paul Vila 4