Is it becoming harder to secure reviewers for peer review? A test with data from five ecology journals.

BACKGROUND: There is concern in the academic publishing community that it is becoming more difficult to secure reviews for peer-reviewed manuscripts, but much of this concern stems from anecdotal and rhetorical evidence. METHODS: We examined the proportion of review requests that led to a completed review over a 6-year period (2009-2015) in a mid-tier biology journal (Molecular Ecology). We also re-analyzed previously published data from four other mid-tier ecology journals (Functional Ecology, Journal of Ecology, Journal of Animal Ecology, and Journal of Applied Ecology), looking at the same proportion over the period 2003 to 2010. RESULTS: The data from Molecular Ecology showed no significant decrease through time in the proportion of requests that led to a review (proportion in 2009 = 0.47 (95 % CI = 0.43 to 0.52), proportion in 2015 = 0.44 (95 % CI = 0.40 to 0.48)). This proportion did decrease for three of the other ecology journals (changes in proportions from 2003 to 2010 = -0.10, -0.18, and -0.09), while the proportion for the fourth (Functional Ecology) stayed roughly constant (change in proportion = -0.04). CONCLUSIONS: Overall, our data suggest that reviewer agreement rates have probably declined slightly but not to the extent suggested by the anecdotal and rhetorical evidence.

A test of hybrid growth disadvantage in wild, free-ranging species pairs of threespine stickleback (Gasterosteus aculeatus) and its implications for ecological speciation.

Ecological speciation is the evolution of reproductive isolation as a direct or indirect consequence of divergent natural selection. Reduced performance of hybrids in nature is thought to be an important process by which natural selection can favor the evolution of assortative mating and drive speciation. Benthic and limnetic sympatric species of threespine stickleback (Gasterosteus aculeatus) are adapted to alternative trophic niches (bottom browsing vs. open water planktivory, respectively) and reduced feeding performance of hybrids is thought to have contributed to the evolution of reproductive isolation. We tested this "hybrid-disadvantage hypothesis" by inferring growth rates from otoliths sampled from wild, free-ranging benthic, limnetic, and hybrid sticklebacks in two lakes. There were significant differences in growth rate between lakes, life-history stages, and among years (maximum P = 0.02), as well as interactions between most factors, but not between hybrid and parental species sticklebacks in most comparisons. Our results provide little evidence of a growth disadvantage in hybrid sticklebacks when free-ranging in nature. Although trophic ecology per se may contribute less to ecological speciation than envisioned, it may act in concert with other aspects of stickleback biology, such as interactions with parasites, predators, competitors, and/or sexual selection, to present strong multifarious selection against hybrids.

An evaluation of the effectiveness of a commercial mechanical trap to reduce abundance of adult nuisance mosquito populations.

In this study, we explore the potential of a commercially available mechanical mosquito control device, the Liberty Plus Mosquito Magnet (hereafter referred to as Mosquito Magnet), to reduce the abundance of adult nuisance mosquito populations in public recreational areas. Mosquitoes were trapped on 2 replicate sites close to a campground at Brae Island Regional Park near Fort Langley, British Columbia, Canada. Each site comprised a treatment (Mosquito Magnets used) and control subsection (Mosquito Magnets not used). Mosquito numbers were assessed before and after the treatment period in both subsections at each site with Centers for Disease Control and Prevention (CDC) black light traps. Although nearly 200,000 mosquitoes from 14 different species were collected over 366 trap-nights from May 31 to July 31, 2008, the majority of those identified were Aedes sticticus (68%) and Ae. vexans (22%)-2 of the most notorious nuisance mosquito species in British Columbia. The number of mosquitoes captured by CDC black light traps increased overall during the study period due to natural seasonal variation. Nevertheless, a significant treatment effect (P = 0.0389) was associated with an average decrease of about 32% in the average number of adult mosquitoes collected per day. These results strongly suggest that Mosquito Magnets can reduce the abundance of nuisance mosquitoes, potentially reducing the biting pressure on the public, and providing another tool in mosquito control operations.

Little impact of hatchery supplementation that uses native broodstock on the genetic structure and diversity of steelhead trout revealed by a large-scale spatio-temporal microsatellite survey.

Artificial breeding programs initiated to enhance the size of animal populations are often motivated by the desire to increase harvest opportunities. The introduction of non-native genotypes, however, can have negative evolutionary impacts. These may be direct, such as introgressive hybridization, or indirect via competition. Less is known about the effects of stocking with native genotypes. We assayed variation at nine microsatellite loci in 902 steelhead trout (Oncorhynchus mykiss) from five rivers in British Columbia, Canada. These samples were collected over 58 years, a time period that spanned the initiation of native steelhead trout broodstock hatchery supplementation in these rivers. We detected no changes in estimates of effective population size, genetic variation or temporal genetic structure within any population, nor of altered genetic structure among them. Genetic interactions with nonmigratory O. mykiss, the use of substantial numbers of primarily native broodstock with an approximate 1:1 male-to-female ratio, and/or poor survival and reproductive success of hatchery fish may have minimized potential genetic changes. Although no genetic changes were detected, ecological effects of hatchery programs still may influence wild population productivity and abundance. Their effects await the design and implementation of a more comprehensive evaluation program.

The mating game: do opposites really attract?

When selecting a mate, females of many species face a complicated decision: choosing a very closely related mate will lead to inbreeding, while choosing a mate who is too genetically dissimilar risks breaking up beneficial gene complexes or local genetic adaptations. To ensure the best genetic quality of their offspring, the perfect compromise lies somewhere in between: an optimally genetically dissimilar partner. Empirical evidence demonstrating female preference for genetically dissimilar mates is proof of the adage 'opposites attract'. In stark contrast, Chandler & Zamudio (2008) show in this issue of Molecular Ecology that female spotted salamanders often choose males that are genetically more similar to themselves (although not if the males are small). Along with other recent work, these field studies highlight the broad spectrum of options available to females with respect to relatedness in their choice of mate that belies this rule of thumb.

Development of microsatellite markers in the St Lucia anole, Anolis luciae.

Anolis lizards are important models in studies of ecology and evolution. Here we describe 13 polymorphic microsatellites for use in population screening in the St Lucia anole, Anolis luciae, that can be used as a natural replicate to Anolis roquet on Martinique to study processes involved in population differentiation and speciation. Genotyping of 32 individuals using M13 tails and FAM-labelled universal M13 primers showed that all loci were polymorphic with high genetic diversity, averaging at 16.8 alleles per locus. Genotypic frequencies conformed to Hardy-Weinberg expectations, and there were no instances of linkage disequilibrium between loci.

Quantifying the constraining influence of gene flow on adaptive divergence in the lake-stream threespine stickleback system.

The constraining effect of gene flow on adaptive divergence is often inferred but rarely quantified. We illustrate ways of doing so using stream populations of threespine stickleback (Gasterosteus aculeatus) that experience different levels of gene flow from a parapatric lake population. In the Misty Lake watershed (British Columbia, Canada), the inlet stream population is morphologically divergent from the lake population, and presumably experiences little gene flow from the lake. The outlet stream population, however, shows an intermediate phenotype and may experience more gene flow from the lake. We first used microsatellite data to demonstrate that gene flow from the lake is low into the inlet but high into the outlet, and that gene flow from the lake remains relatively constant with distance along the outlet. We next combined gene flow data with morphological and habitat data to quantify the effect of gene flow on morphological divergence. In one approach, we assumed that inlet stickleback manifest well-adapted phenotypic trait values not constrained by gene flow. We then calculated the deviation between the observed and expected phenotypes for a given habitat in the outlet. In a second approach, we parameterized a quantitative genetic model of adaptive divergence. Both approaches suggest a large impact of gene flow, constraining adaptation by 80-86% in the outlet (i.e., only 14-20% of the expected morphological divergence in the absence of gene flow was observed). Such approaches may be useful in other taxa to estimate how important gene flow is in constraining adaptive divergence in nature.

Contrasting hybridization rates between sympatric three-spined sticklebacks highlight the fragility of reproductive barriers between evolutionarily young species.

Three-spined sticklebacks (Gasterosteus aculeatus) are a powerful evolutionary model system due to the rapid and repeated phenotypic divergence of freshwater forms from a marine ancestor throughout the Northern Hemisphere. Many of these recently derived populations are found in overlapping habitats, yet are reproductively isolated from each other. This scenario provides excellent opportunities to investigate the mechanisms driving speciation in natural populations. Genetically distinguishing between such recently derived species, however, can create difficulties in exploring the ecological and genetic factors defining species boundaries, an essential component to our understanding of speciation. We overcame these limitations and increased the power of analyses by selecting highly discriminatory markers from the battery of genetic markers now available. Using species diagnostic molecular profiles, we quantified levels of hybridization and introgression within three sympatric species pairs of three-spined stickleback. Sticklebacks within Priest and Paxton lakes exhibit a low level of natural hybridization and provide support for the role of reinforcement in maintaining distinct species in sympatry. In contrast, our study provides further evidence for a continued breakdown of the Enos Lake species pair into a hybrid swarm, with biased introgression of the 'limnetic' species into that of the 'benthic'; a situation that highlights the delicate balance between persistence and breakdown of reproductive barriers between young species. A similar strategy utilizing the stickleback microsatellite resource can also be applied to answer an array of biological questions in other species' pair systems in this geographically widespread and phenotypically diverse model organism.

A high incidence of clustered microsatellite mutations revealed by parent-offspring analysis in the African freshwater snail, Bulinus forskalii (Gastropoda, Pulmonata).

Genotyping of 11 microsatellites in 432 offspring from 28 families of the hermaphroditic, freshwater snail Bulinusforskalii detected 10 de novo mutant alleles. This gave an estimated mutation rate of 1.1 x 10(-3) per locus per gamete per generation. There was a trend towards repeat length expansion and, unlike most studies, multi-step mutations predominated, suggesting that the microsatellite mutation process does not conform to a strict stepwise mutation model. Interestingly, the ten mutant alleles appear to have arisen from only six independent germline mutation events within the microsatellite array, with seven of them residing in three mutational clusters. Our results extend observations of clustered microsatellite mutations to another taxonomic group and type of mating system, self-fertile gastropods, and provide compelling evidence of premeiotic germline mutations, a phenomenon that could greatly impact upon our understanding of mutation dynamics but which has received little attention.