Effects of Autotomy on Locomotion in Cellar Spiders
Mentor 1
Kerri Wrinn
Location
Union Wisconsin Room
Start Date
24-4-2015 10:30 AM
End Date
24-4-2015 11:45 AM
Description
There is variation among spider species in their abilities to perform autotomy of appendages and subsequent regeneration, both of which are processes widespread across the animal kingdom. Therefore, spiders provide an excellent model system to study the evolution of these processes. We hypothesized that the costs and benefits of autotomy and regeneration reflect variation in the ecology of the species. Our short-term research goal was to test this by examining the effects of these processes on locomotion across species tested in an ecologically relevant way. We began to study this by working with the species, Pholcus phalangiodes, (family Pholcidae, cellar spiders) which are capable of autotomy, but not regeneration. We conducted a general survey of this species in homes in the Janesville area and recorded how many spiders were missing legs, number and position of missing legs, and the spider's sex. Our survey showed that 22% of the spiders we found were missing a leg. In our following experiment we only used spiders that had all of their legs intact. In our experiment we focused on the effects of autotomy on locomotion. We measured the speed of males and females traveling on horizontal and vertical surfaces both before and after autotomy of a front leg. These spiders tend to build webs on walls in buildings and thus spend a considerable amount of time climbing, making this an ecologically relevant measure. Data were analyzed after the trials using analysis of variance (ANOVAS) to compare change in average speed between horizontal and vertical trials for each spider and between the initial trials (intact) and second trials (autotomized for experimental subjects). Most importantly, we found that autotomy of the leg did not affect the speed of locomotion on a flat surface. However, autotomy did affect the speed of both sexes by slowing them down on the vertical surface. Therefore, we can conclude that, for locomotion, there is a cost to losing a leg. However, ecologically, perhaps for this species, this cost doesn’t outweigh the energy required to regenerate their legs. Further studies and comparisons need to be made between spiders that can and cannot regenerate their legs in order to validate our hypothesis. Our long-term goal is to map out the autotomy and regeneration abilities and their effects onto an evolutionary phylogeny across Araneae, the order of spiders.
Effects of Autotomy on Locomotion in Cellar Spiders
Union Wisconsin Room
There is variation among spider species in their abilities to perform autotomy of appendages and subsequent regeneration, both of which are processes widespread across the animal kingdom. Therefore, spiders provide an excellent model system to study the evolution of these processes. We hypothesized that the costs and benefits of autotomy and regeneration reflect variation in the ecology of the species. Our short-term research goal was to test this by examining the effects of these processes on locomotion across species tested in an ecologically relevant way. We began to study this by working with the species, Pholcus phalangiodes, (family Pholcidae, cellar spiders) which are capable of autotomy, but not regeneration. We conducted a general survey of this species in homes in the Janesville area and recorded how many spiders were missing legs, number and position of missing legs, and the spider's sex. Our survey showed that 22% of the spiders we found were missing a leg. In our following experiment we only used spiders that had all of their legs intact. In our experiment we focused on the effects of autotomy on locomotion. We measured the speed of males and females traveling on horizontal and vertical surfaces both before and after autotomy of a front leg. These spiders tend to build webs on walls in buildings and thus spend a considerable amount of time climbing, making this an ecologically relevant measure. Data were analyzed after the trials using analysis of variance (ANOVAS) to compare change in average speed between horizontal and vertical trials for each spider and between the initial trials (intact) and second trials (autotomized for experimental subjects). Most importantly, we found that autotomy of the leg did not affect the speed of locomotion on a flat surface. However, autotomy did affect the speed of both sexes by slowing them down on the vertical surface. Therefore, we can conclude that, for locomotion, there is a cost to losing a leg. However, ecologically, perhaps for this species, this cost doesn’t outweigh the energy required to regenerate their legs. Further studies and comparisons need to be made between spiders that can and cannot regenerate their legs in order to validate our hypothesis. Our long-term goal is to map out the autotomy and regeneration abilities and their effects onto an evolutionary phylogeny across Araneae, the order of spiders.
