frair (version 0.5.100)

gammarus: Gammarus Functional Response Data

Description

Functional response dataset for two species of Gammarus spp. (freshwater amphipods) eating Simulium spp. (black fly) larvae.

Usage

data(gammarus)

Format

A dataframe with the following structure:

density:	An integer. The initial density of prey	eaten:	An integer. The number of prey eaten
alive:	An integer. The number of prey left alive	spp:	A factor with levels G.d.celticus and G.pulex. The species of predator.

Details

This dataset is a stripped-down version of that presented in Paterson et al. 2014. It contains only Simulium spp. data with all other treatments (other than predator identity) pooled. The predators are amphipods which are either native (Gammarus duebeni celticus) or invasive (Gammarus pulex) to waterways in Ireland. Total experimental time was 40 hours.

Examples

data(gammarus)
str(gammarus) 

with(gammarus, 
    plot(density, eaten, type='n', 
	xlab='Density', ylab='No. Prey Eaten'))
with(gammarus[gammarus$spp=='G.d.celticus',], 
	points(density-0.2, eaten, pch=20, col=rgb(0,0.5,0,0.2)))
with(gammarus[gammarus$spp=='G.pulex',], 
	points(density+0.2, eaten, pch=20, col=rgb(0.5,0,0,0.2)))

legend(2,20, c('Native', 'Invasive'), pch=20, 
	col=c(rgb(0,0.5,0), rgb(0.5,0,0)))