Do cytotypes of black flies of the complex (Diptera: Simuliidae) arise from sibling species?
To better understand the evolutionary radiation of the complex of black flies (Diptera: Simuliidae), we compared the geographic distributions of present-day larvae to their sex-chromosome diversity. We used the 5 known data sets including collections and sex-chromosome analysis from 307 geographic locations of 31 taxa of approximately 20,000 larvae from throughout the geographic range of distribution of the complex, from Alaska, western Canada, and the western United States to southern California, Arizona, and New Mexico. Siblings (reproductively isolated in sympatry) have considerably larger geographic distributions than do cytotypes (not reproductively isolated in sympatry), suggesting that the former may have been in existence longer than the latter. (the oldest member of the complex), (standard noninverted sex chromosomes), (sex determination on the X chromosome), and s. s. (IIL-3) share geographic distributions with all other siblings. Notably, 21 of 22 cytotypes share geographic distributions within those of siblings. Cytotypes are almost always discovered within the geographic distributions of siblings, suggesting that the former might be arising sympatrically.
AN INVERTEBRATE ECOSYSTEM ENGINEER UNDER THE UMBRELLA OF SAGE-GROUSE CONSERVATION
Conservation practitioners often rely on areas designed to protect species of greatest conservation priority to also conserve co-occurring species (i.e., the umbrella species concept). The extent to which vertebrate species may serve as suitable umbrellas for invertebrate species, however, has rarely been explored. Sage-grouse ( spp.) have high conservation priority throughout much of the rangelands of western North America and are considered an umbrella species through which the conservation of entire rangeland ecosystems can be accomplished. Harvester ants are ecosystem engineers and play important roles in the maintenance and function of rangeland ecosystems. We compared indices of the abundance of western harvester ants () and Greater Sage-Grouse () at 72 sites in central Wyoming, USA in 2012. The abundance of harvester ant mounds was best predicted by a regression model that included a combination of local habitat characteristics and the abundance of sage-grouse. When controlling for habitat-related factors, areas with higher abundances of sage-grouse pellets (an index of sage-grouse abundance and/or habitat use) had higher abundances of ant mounds than areas with lower abundances of sage-grouse pellets. The causal mechanism underlying this positive relationship between sage-grouse and ant mound abundance at the fine scale could be indirect (e.g., both species prefer similar environmental conditions) or direct (e.g., sage-grouse prefer areas with a high abundance of ant mounds because ants are an important prey item during certain life stages). We observed no relationship between a broad-scale index of breeding sage-grouse density and the abundance of ant mounds. We suspect that consideration of the non-breeding habitat of sage-grouse and finer-scale measures of sage-grouse abundance are critical to the utility of sage-grouse as an umbrella species for the conservation of harvester ants and their important role in rangeland ecosystems.
ANTIOXIDANT CAPACITY OF WYOMING BIG SAGEBRUSH ( SSP. ) VARIES SPATIALLY AND IS NOT RELATED TO THE PRESENCE OF A SAGEBRUSH DIETARY SPECIALIST
Sagebrush ( spp.) in North America is an abundant native plant species that is ecologically and evolutionarily adapted to have a diverse array of biologically active chemicals. Several of these chemicals, specifically polyphenols, have antioxidant activity that may act as biomarkers of biotic or abiotic stress. This study investigated the spatial variation of antioxidant capacity, as well as the relationship between a mammalian herbivore and antioxidant capacity in Wyoming big sagebrush (). We quantified and compared total polyphenols and antioxidant capacity of leaf extracts from sagebrush plants from different spatial scales and at different levels of browsing by a specialist mammalian herbivore, the pygmy rabbit (). We found that antioxidant capacity of sagebrush extracts was positively correlated with total polyphenol content. Antioxidant capacity varied spatially within and among plants. Antioxidant capacity in sagebrush was not related to either browsing intensity or duration of association with rabbits. We propose that the patterns of antioxidant capacity observed in sagebrush may be a result of spatial variation in abiotic stress experienced by sagebrush. Antioxidants could therefore provide a biomarker of environmental stress for sagebrush that could aid in management and conservation of this plant in the threatened sagebrush steppe.
Courtship behavior of the meadow jumping mouse ()
We describe the first recorded observations of courtship behavior of the meadow jumping mouse () made in wild-caught and captive-reared animals. Male meadow jumping mice performed a series of courtship behaviors upon approach to the female, including rapid fanning of the muzzle with the forelimbs, self-grooming, muzzle fanning, retreat, and eventual mounting attempts. During courtship, female jumping mice may retreat, ignore the courting male, or bat at the male with forelimbs until the male retreats. Active rejection of courting males by the female is suggestive of female mate choice in this species.