The role of functional constraints in nonrandom mating patterns for a dance fly with female ornaments

Most hypotheses to explain nonrandom mating patterns invoke mate choice, particularly in species that display elaborate ornaments. However, conflicting selection pressures on traits can result in functional constraints that can also cause nonrandom mating patterns. We tested for functional load‐lifting constraints during aerial copulation in Rhamphomyia longicauda, a species of dance fly that displays multiple extravagant female‐specific ornaments that are unusual among sexual traits because they are under stabilizing selection. R. longicauda males provide females with a nuptial gift before engaging in aerial mating, and the male bears the entire weight of the female and nuptial gift for the duration of copulation. In theory, a male's ability to carry females and nuptial gifts could constrain pairing opportunities for the heaviest females, as reported for nonornamented dance flies. In concert with directional preferences for large females with mature eggs, such a load‐lifting constraint could produce the stabilizing selection on female size previously observed in this species. We therefore tested whether wild‐caught male R. longicauda collected during copulation were experiencing load‐lift limitations by comparing the mass carried by males during copulation with the male's wing loading traits. We also performed permutation tests to determine whether the loads carried by males during copulation were lighter than expected. We found that heavier males are more often found mating with heavier females suggesting that whereas R. longicauda males do not experience a load‐lift constraint, there is a strong relationship of assortative mating by mass. We suggest that active male mate choice for intermediately adorned females is more likely to be causing the nonrandom mating patterns observed in R. longicauda.     

Heteroduplex molecules cause sexing errors in a standard molecular protocol for avian sexing

Molecular methods are a necessary tool for sexing monomorphic birds. These molecular approaches are usually reliable, but sexing protocols should be evaluated carefully because biochemical interactions may lead to errors. We optimized laboratory protocols for genetic sexing of a monomorphic shorebird, the upland sandpiper (Bartramia longicauda), using two independent sets of primers, P2/P8 and 2550F/2718R, to amplify regions of the sex‐linked CHD‐Z and CHD‐W genes. We discovered polymorphisms in the region of the CHD‐Z intron amplified by the primers P2/P8 which caused four males to be misidentified as females (n = 90 mated pairs). We cloned and sequenced one CHD‐W allele (370 bp) and three CHD‐Z alleles in our population: Z° (335 bp), Z′ (331 bp) and Z″ (330 bp). Normal (Z°Z°) males showed one band in agarose gel analysis and were easily differentiated from females (Z°W), which showed two bands. However, males heterozygous for CHD‐Z alleles (Z′Z″) unexpectedly showed two bands in a pattern similar to females. While the Z′ and Z″ fragments contained only short deletions, they annealed together during the polymerase chain reaction (PCR) process and formed heteroduplex molecules that were similar in size to the W fragment. Errors previously reported for molecular sex‐assignment have usually been due to allelic dropout, causing females to be misidentified as males. Here, we report evidence that events in PCRs can lead to the opposite error, with males misidentified as females. We recommend use of multiple primer sets and large samples of known‐sex birds for validation when designing protocols for molecular sex analysis.     

Optimizing Radio Retention and Minimizing Radio Impacts in a Field Study of Upland Sandpipers

Abstract: Two challenges in wildlife telemetry are optimizing the duration of transmitter attachment and minimizing the impacts of radios on the behavior and demography of the study animal. We tested 4 methods of radio attachment for a breeding population of upland sandpipers (Bartramia longicauda) under natural conditions at a tallgrass prairie site in Kansas, USA. To estimate radio retention and weekly survival rates, we used the nest survival model of Program MARK. Radio retention was lowest at the start and the end of the breeding period. The expected duration of radio retention was 1.8 years for a leg-loop harness, 40 days for radios glued to clipped feathers, 26 days for radios glued directly to feathers, and 7 days for radios glued to bare skin. Few radiomarked birds died during our study, but 4 of 8 mortality events were discovered within one week of radiomarking. Both glue and harnesses increased predation risk immediately after radio attachment. The weekly probability of survival was high after a 1-week acclimation period, and the expected survival for a 10-week breeding period was similar in males and females. Attachment of radios with glue had no effect on annual return rates. However, attachment of radios with leg harnesses resulted in lower return rates among radiomarked birds than birds without radios. Radios attached with glue were shed in <1 year but radios attached with harnesses were retained for up to 1-2 years. Our results indicate a tradeoff between optimizing radio retention and minimizing impacts on demography. Glue techniques had retention rates that were suitable for only short-term studies, but attachment with glue had no long-term effect on annual return rates. Leg harnesses provided effective radio retention that had little effect on survival rates during the stationary breeding period, but resulted in lower annual return rates. Robust estimates of radio retention and survival will assist researchers in selecting attachment techniques that best meet the study goals of future telemetry projects.     

Stabilizing sexual selection for female ornaments in a dance fly

Ornamental traits function by improving attractiveness and are generally presumed to experience directional selection for mating success. However, given the greater investment of females in offspring than males, female-specific ornaments can in theory signal fecundity yet be constrained by fecundity costs. Theoretical work predicts that such constraints can lead to stabilizing selection via male choice for intermediately ornamented females. Female dance flies Rhamphomyia longicauda (Diptera: Empididae) display two female-specific ornaments in mating swarms - inflatable abdominal sacs and pinnate tibial scales. We investigated the intensity and form of sexual selection on female traits including ornaments and found no evidence for directional sexual selection. Instead, we found marginally nonsignificant quadratic selection for all three measures of ornament expression. Canonical analysis confirmed that the strongest vectors of nonlinear selection were associated with ornamental traits, although the significance of the quadratic coefficients associated with these vectors depended on the statistical approach. Direct Mitchell-Olds and Shaw tests for the location of the maximum fitted fitness value for both raw morphological traits and canonical axes revealed only one marginally nonsignificant result for the multivariate axis loading most heavily on pinnate leg scales. Together, these results provide the first tentative support for stabilizing selection on female-specific ornaments.     

New genera and species of Leptophlebiidae (Ephemeroptera) from New Zealand

Abstract

New genera Isothraulus, Arachnocolus, and Penniketellus are established for three species of leptophlebiid mayfly from New Zealand. Each genus is monotypic and endemic to New Zealand. Isothraulus and Arachnocolus are known only from the northern North Island, and Penniketellus is known only from the Arthur's Pass area of the central South Island. The male and female imago, nymph, and egg of Isothraulus abditus n.sp., the male imago, male subimago, and nymph of Arachnocolus phillipsi n.sp., and the male and female imago, female subimago, and egg of Penniketellus insolitus n.sp. are described. The relationships of each genus and the ecology of nymphs of each species are discussed.     

中国猎舞虻亚属二新种(双翅目,舞虻科)

记述我国猎舞虻亚属2新种.模式标本保存在中国农业大学昆虫博物馆.     

A NEW METHOD FOR OBTAINING NUCLEAR GENE SEQUENCES FROM FIELD SAMPLES AND TAXONOMIC REVISIONS OF THE PHOTOSYNTHETIC EUGLENOIDS LEPOCINCLIS (EUGLENA) HELICOIDEUS AND LEPOCINCLIS (PHACUS) HORRIDUS (EUGLENOPHYTA)1

One of the foremost issues in the field of algal taxonomy is the inability to acquire, grow, and sequence new taxa. This problem is particularly true in the study of photosynthetic euglenoids where most of the distinct taxa in culture collections have been sequenced, and many other taxa of interest have been resistant to culturing, and thus, sequencing. In an effort to address this problem, we have utilized a new technique, novel to the field of taxonomy, which allows for the sequencing of nuclear genes from a very small number of cells. Through this procedure, a DNA extraction followed by a multiple displacement amplification (MDA), taxa obtained by field collection had their genomic DNA (gDNA) amplified many fold to microgram quantities. The DNA was then used as template DNA for PCR reactions, and multiple nuclear genes were amplified successfully from several different taxa. By applying this procedure, we were able to shed new light on taxa that have been historically difficult to classify, resulting in the assignment of Euglena helicoideus (C. Bernard) M. S. Benn. et Triemer and Phacus horridus (Pochm.) M. S. Benn. et Triemer to the genus Lepocinclis.