Determining basis for pit size variation in Myrmeleon immaculatus between two lakeshores of Northern Michigan.

Abstract

Behavioral EcologyEnvironmental factors influencing pit-building behavior of the antlion Myrmeleon immaculatus are fairly well studied. The purpose of this study was to identify and differentiate environmental, genetic, and possible organizational or early learning factors influencing different behavioral phenotypes of two populations at Douglas Lake and Sturgeon Bay in northern Michigan, USA. We collected 60 antlions from each site and measured pit diameters in a common garden design. We distinguished treatments by feeding frequency, site, and day for a total of 22 days under a controlled laboratory setting with a regular disturbance regime. Sturgeon Bay antlions built larger pits that Douglas Lake antlions, animals that were subjected to a higher feeding frequency built smaller pits than a lower feeding frequency, and no apparent trend was gleaned from the day effect due to a presumed temperature effect. As a follow-up experiment we measured the effects of temperature on pit-building using light-bulb warming stations on 64 of our animals. Antlion pits that were given supplemental heat grew at a faster rate than controls. We also compared weight and pit diameters of at least 15 animals from seven sites between Sturgeon Bay and Pine Point. No significant difference was found between any site or lakeshore, though our data suggested that the original Sturgeon Bay study site displayed a larger pit size than any other site. These results indicate that genetic effects on these animals are unlikely, due to the close proximity of all populations. We suggest that organizational or early learning effects are significant determinants of pit-building behavior in this species.http://deepblue.lib.umich.edu/bitstream/2027.42/101736/1/Niemisto_Maura_2013.pd