A sink host allows a specialist herbivore to persist in a seasonal source.

In seasonal environments, sinks that are more persistent than sources may serve as temporal stepping stones for specialists. However, this possibility has to our knowledge, not been demonstrated to date, as such environments are thought to select for generalists, and the role of sinks, both in the field and in the laboratory, is difficult to document. Here, we used laboratory experiments to show that herbivorous arthropods associated with seasonally absent main (source) habitats can endure on a suboptimal (sink) host for several generations, albeit with a negative growth rate.

Complex and Diverse Drivers of Parasite Loads in a Cosmopolitan Insect.

The goal of parasite epidemiologists is to understand the factors that determine host infection levels. Potential infection determinants exist at many scales, including spatial and temporal environmental variation, among-host differences, and interactions between symbionts infecting the same host. All of these factors can impact levels of parasitism, but frequently only a subset is considered in any host-parasite system.

Sexual selection constrains the body mass of male but not female mice.

Sexual size dimorphism results when female and male body size is influenced differently by natural and sexual selection. Typically, in polygynous species larger male body size is thought to be favored in competition for mates and constraints on maximal body size are due to countervailing natural selection on either sex; however, it has been postulated that sexual selection itself may result in stabilizing selection at an optimal mass. Here we test this hypothesis by retrospectively assessing the influence of body mass, one metric of body size, on the fitness of 113 wild-derived house mice ) residing within ten replicate semi-natural enclosures from previous studies conducted by our laboratory.

Host specificity of a parasitic fluke: is Posthodiplostomum minimum a centrarchid-infecting generalist or specialist?

Parasite host specificity has important implications for species diversity estimates, food web dynamics, and host shifts. "White grub" is the metacercaria stage of a fluke ( Posthodiplostomum minimum ) that occurs in many fish species, but no attempt has been made to quantify variation in host use by this worm. Here we used 2 approaches to evaluate host specificity within the strain that infects centrarchids ( P.

Fitness effects of a selfish gene (the Mus t complex) are revealed in an ecological context.

In wild house mice, genes linked to the t transmission distortion complex cause meiotic drive by sabotaging wild-type gametes. The t complex is consequently inherited at frequencies higher than 90%. Yet, for unclear reasons, in wild mouse populations this selfish DNA is found at frequencies much lower than expected.

Effects of Trichinella spiralis on survival, total mass, and organ mass of oldfield mice (Peromyscus polionotus).

Trichinella spiralis is a parasitic nematode that infects many mammals, including humans. Hosts may experience significant physiological changes or may die because of acute inflammatory immune responses toward the parasite. In this study, oldfield mice (Peromyscus polionotus) were used as a new experimental host for T.

GENETIC DIVERSITY AND CAPILLARIA HEPATICA (NEMATODA) PREVALENCE IN MICHIGAN DEER MOUSE POPULATIONS.

There have been few field tests of the hypothesis that homozygous populations are prone to high levels of disease. I tested for a negative correlation between genetic diversity and parasitism by estimating the allozyme heterozygosity, population density, and proportion of individuals infected by Capillaria hepatica (Nematoda) in nine Michigan populations of deer mice (Peromyscus maniculatus). Parasite prevalence was correlated negatively with heterozygosity when the effects of density were held constant, but was not correlated with population density after controlling for the effects of genetic diversity.