Biology ETDs

Publication Date

Spring 4-22-1996


Biotic and abiotic factors were considered as the potential factors influencing the activity pattern of Galapagos snakes. Three hypothesis are tested in this study in order to examine the causes of variation in snake activity. The first hypothesis (variation in the number of snakes active throughout the day is caused by distribution and abundance of their prey) is rejected because snakes and lizards have different patterns of activity. Moreover, Chi-square Goodness-of-Fit test and 2 x 2 Contingency tables show significant differences between these patterns of activity. However there are hours of the day when lizard activity could influence snake activity. The alternate hypothesis (variation in the number of snakes active throughout the day is caused by the effect variation in environmental temperature on body temperatures of snakes) is partially falsified because low levels of activity of snakes during the midday do not correspond with the periods when the body temperatures of snakes are outside of the range of temperatures that provides fast sprint-speeds. The later hypothesis (decrease in activity of snakes during midday is response to avoiding overheating) is supported because levels of activity of the snakes are significantly greater during cloudy periods than during sunny periods. Moreover, this is supported by the Chi-square Goodness-of-Fit test. In summary, the analyses indicate that there is not a single answer to the question of rather biotic or abiotic factors contribute more. Rather it appears that there is a mix of the two.

Project Sponsors

USAID, Latin American Institute




Galapagos Snakes, Biotic Factors, Abiotic Factors

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UNM Biology Department

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Biology Commons