No abstract

We identified bacteria collected from the ejaculates and cloacae of male Red-winged Blackbirds (Agelaius phoeniceus) and from the cloacae of their mates during two breeding seasons and at three geographic locations with two distinct breeding habitats in each. In all, 42% of 233 ejaculates contained at least one bacteria species. Analysis of control samples suggested that some bacteria come from contamination during collection, but most are either carried within the ejaculate or are present on the male cloaca. As in an earlier study of Agelaius phoeniceus, we recorded many different species with considerable diversity between samples. We tested several explanations for this diversity. We found no overlap in either the presence of bacteria or the species found in multiple ejaculates obtained from the same male. We also found no association between bacteria in the ejaculate and those in the cloaca from the same male, or in samples collected from a male and those from the females nesting on his territory. Surveys of ejaculates from three locations, Kentucky, New York, and Wisconsin, yielded similar patterns of prevalence and diversity. Ejaculate samples from males inhabiting relatively dry upland habitats contained a similar number of bacteria and array of species as males inhabiting relatively wet, marshy territories. Many of the isolated bacteria are probably benign, but pathological effects of some species have been recorded in some circumstances. Our results suggest that acquiring pathogenic bacteria represents a potential cost to multiple mating by females, but the potential benefits of some microbes may offset these risks. Bacterias en el Sistema Reproductivo de Agelaius phoeniceus Resumen. Identificamos bacterias aisladas del semen eyaculado y de las cloacas de machos de la especie Agelaius phoeniceus y de las cloacas de sus parejas hembras durante dos estaciones y en tres áreas geográficas, con dos tipos de hábitat en cada área. En general, el 42% de las 233 muestras de eyaculaciones presentó por lo menos una especie de bacteria. El análisis de las muestras control sugiere que algunas bacterias provienen de contaminación ambiental durante la colecta, pero la mayoría de las bacterias provienen del semen o están presentes en la cloaca del macho. Al igual que en un estudio anterior con Agelaius phoeniceus, registramos muchas especies distintas, con bastante diversidad entre las muestras. Pusimos a prueba algunas hipótesis que podrían explicar esta diversidad. No encontramos coincidencia ni en la presencia de bacterias ni en las especies encontradas entre múltiples muestras obtenidas de un mismo macho. Tampoco encontramos correspondencia entre las bacterias presentes en las muestras de semen y de la cloaca de un mismo macho, ni entre las muestras colectadas de los machos y de las hembras que se encuentran anidando en su territorio. El estudio de muestras de eyaculaciones provenientes de tres localidades, Kentucky, New York, y Wisconsin, produjo patrones similares de prevalencia y diversidad. Muestras de semen de machos que habitan ambientes relativamente secos en tierras altas presentaron números de bacterias y especies similares a las muestras colectadas de machos que habitan territorios pantanosos. Probablemente, muchas de las bacterias son benignas, pero en ciertas circunstancias se han registrado efectos patológicos de algunas especies. Nuestros resultados sugieren que adquirir bacterias patológicas es un posible costo del apareamiento múltiple de las hembras, pero los posibles beneficios de algunos microbios podrían compensar estos riesgos.

Few studies have measured multivariate sexual selection acting on the sexual signals of male insects in wild populations. Sagebrush crickets are ideally suited to such investigations because mating imposes an unambiguous phenotypic marker on males arising from nuptial feeding by females. However, an important assumption underlying such studies is that males collected as virgins and those collected as non-virgins had equal opportunities to mate, an assumption that may be violated if males eclose (i.e. emerge following pupation) at different times of the breeding season. If mated males are those in the population that eclosed earlier and hence had a longer period to obtain matings than males in the virgin group, then differences in the songs of virgin and mated males could simply be an artifact of age-related changes in male morphology as opposed to a causal factor underlying variation in male mating success. Accordingly, we conducted a mark-recapture study to determine if there is an association between first appearance in the population and the likelihood of mating in free-living males. We captured all of the virgin males calling in the study population and marked them uniquely with a numbered tag. Subsequently, we tracked the mating success of 98 male subjects through the mid-point of the breeding season. There was no significant effect of date of capture (a proxy for time of eclosion) on time to mating. We conclude, therefore, that any differences in the songs of virgin and mated males stems from their effect on male mating success and not from any age-related effects.

The field of behavioral ecology has recently been reinvigorated by the addition of the notion of behavioral syndromes (a.k.a. animal personality). Behavioral syndromes imply the existence of individual variation in behavioral expression that is consistent across distinct functional contexts (e.g. foraging, mating, anti-predator). The syndromes paradigm suggests that the behavioral phenotype is best viewed as an integrated phenomenon wherein any given behavior can only be fully understood by studying selection pressures in all contexts. Here we report on a pilot study on behavioral syndromes in the Sagebrush cricket (Cyphoderrris strepitans), an acoustic Orthopteran insect that inhabits high altitude sagebrush meadows of Grand Teton National Park. The results of our preliminary analysis suggest very little consistent repeatability in the mating behavior of C. strepitans. In addition, we make note of the synergistic collaboration in our group between faculty researchers and graduate, undergraduate and high school research collaborators.