Physiological and behavioral sexual maturity of female red deep-sea crabs Chaceon quinquedens (Smith, 1879) (Decapoda: Brachyura: Geryonidae) in the Mid-Atlantic Bight

We describe the physiological and behavioral maturity of the red deep-sea crab, Chaceon quinquedens (Smith, 1879), using ovary and oocyte development and morphological features to estimate the size at 50% sexual maturity (SM50) for females in the Mid-Atlantic Bight. This economically important species inhabits the continental shelf and slope of the western Atlantic from Nova Scotia, Canada to the Gulf of Mexico. Samples were collected by trawling in 2011–2013 and by traps in 2014–2016. We used histological analysis to describe the stages of ovarian development. Five stages of ovarian development were identified: 1, immature; 2, early maturing; 3, late maturing; 4, mature; and 5, redeveloping. A logistic model was used to estimate the SM50 using maximum likelihood methods. Physiological SM50 varied among geographic locations and was estimated at 61.2 mm CL and 70.8 mm CL for females collected near Hudson Canyon and Baltimore and Norfolk canyons, respectively. Behavioral SM50 decreased with latitude and was estimated at 53.9 mm CL, 62.5 mm CL and 65.5 mm CL for Hudson, Baltimore, and Norfolk canyons, respectively. Results implied asynchrony between physiological and behavioral sexual maturity, suggesting that mating occurs prior to completion of ovarian development. This study provides the first evidence of a latitudinal trend in sexual maturity for C. quinquedens. Further investigation is needed to understand the cause of the latitudinal trend as our study presented limitations. Results provide useful information for fisheries management about the reproductive biology of C. quinquedens.

Dynamics of dissolved inorganic carbon and co2 fluxes between water and atmosphere in the main channel of the ob river

The results of investigation of the carbonate system parameters dynamics in the middle and lower reaches of the Ob River in July 2016 were analyzed. The distributions of the carbonate characteristics of the river waters were found to follow a steady latitudinal trend determined by the landscape-geochemical conditions of the drainage basin and by the permafrost distribution. The first field data on the magnitude and direction of the CO2 fluxes in the river water-atmosphere system in this region were presented. It was shown that the waters in the middle and lower reaches of the river are multiply supersaturated with CO2 with respect to its atmospheric content, and the daily average evasion reaches 625,9 mmol m-2 day-1 at an average value of 102,1 mmol m-2 day-1. It was determined that the waters of the Ob River in the studied reaches are a significant CO2 source to the atmosphere; according to conservative estimates, the total flux in July was 2 ⋅ 1011 g of carbon in the form of CO2.

Beryllium-10 dating of the Foothills Erratics Train in Alberta, Canada, indicates detachment of the Laurentide Ice Sheet from the Rocky Mountains at ~15 ka

The Foothills Erratics Train consists of large quartzite blocks of Rocky Mountains origin deposited on the eastern slopes of the Rocky Mountain Foothills in Alberta between ~53.5°N and 49°N. The blocks were deposited in their present locations when the western margin of the Laurentide Ice Sheet (LIS) detached from the local ice masses of the Rocky Mountains, which initiated the opening of the southern end of the ice-free corridor between the Cordilleran Ice Sheet and the LIS. We use 10Be exposure dating to constrain the beginning of this decoupling. Based on a group of 12 samples well-clustered in time, we date the detachment of the western LIS margin from the Rocky Mountain front to ~14.9 ± 0.9 ka. This is ~1000 years later than previously assumed, but a lack of a latitudinal trend in the ages over a distance of ~500 km is consistent with the rapid opening of a long wedge of unglaciated terrain portrayed in existing ice-retreat reconstructions. A later separation of the western LIS margin from the mountain front implies higher ice margin–retreat rates in order to meet the Younger Dryas ice margin position near the boundary of the Canadian Shield ~2000 years later.

Phenological Advance, Stasis, and Delay

This chapter begins by distinguishing phenology from seasonality. Phenology is defined as the study of the occurrence of phenomena in relation to time. In contrast, seasonality refers to temporal variation in abiotic environmental conditions. The chapter then presents the central findings of four major reviews of phenological change over the past several decades. This overview shows that, first, in general, recent phenological trends in plants and animals tend overwhelmingly to be negative—that is, species across a diverse array of taxa appear to have tended toward earlier timing of springtime activity in concert with recent climatic warming. Second, however, it demonstrates that there has not been a universal tendency toward earlier timing of springtime phenological events with warming. Lastly, the overview reveals that there is, indeed, some evidence for a latitudinal trend in rates of phenological advance. The chapter also looks at phenological dynamics across taxa, latitude, and time.

Detecting trends in body size: empirical and statistical requirements for intraspecific analyses

Attributing biological explanations to observed ecogeographical and ecological patterns require eliminating potential statistical and sampling artifacts as alternative explanations of the observed patterns. Here, we assess the role of sample size, statistical power, and geographic inclusivity on the general validity and statistical significance of relationships between body size and latitude for 3 well-studied species of turtles. We extend those analyses to emphasize the importance of using statistically robust data in determining macroecological patterns. We examined intraspecific trends in body size with latitude in Chelydra serpentina, Chrysemys picta, and Trachemys scripta using Pearson’s correlations, diagnostic tests for influential points, and resampling. Existing data were insufficient to ascertain a latitudinal trend in body size for C. serpentina or T. scripta. There was a significant relationship for C. picta, however, resampling analyses show that, on average, 16 of the 23 available independent populations were needed to demonstrate a significant relationship and that at least 20 of 23 populations were required to obtain a statistically powerful correlation between body size and latitude. Furthermore, restricting the latitudes of populations resampled shows that body size trends of C. picta were largely due to leveraging effects of populations at the edge of the species range. Our results suggest that broad inferences regarding ecological trends in body size should be made with caution until underlying (intraspecific) patterns in body size can be statistically and conclusively demonstrated.

Global geographic patterns of sexual size dimorphism in birds: Support for a latitudinal trend?

Sexual size dimorphism (SSD) is widespread among animals, and is a common indication of differential selection among males and females. Sexual selection theory predicts that SSD should increase as one sex competes more fiercely for access to mates, but it is unclear what effect spatial variation in ecology may have on this behavioral process. Here, we examine SSD across the class Aves in a spatial and phylogenetic framework, and test several a priori hypotheses regarding its relationship with climate. We mapped the global distribution of SSD from published descriptions of body size, distribution, and phylogenetic relationships across 2581 species of birds. We examined correlations between SSD and nine predictor variables representing a priori models of physical geography, climate, and climate variability. Our results show guarded support for a global latitudinal trend in SSD based on a weak prevalence of species with low or female-biased SSD in the North, but substantial spatial heterogeneity. While several stronger relationships were observed between SSD and climate predictors within zoogeographical regions, no global relationship emerged that was consistent across multiple methods of analysis. While we found support for a global relationship between climate and SSD, this support lacked consistency and explanatory power. Furthermore the strong phylogenetic signal and conspicuous lack of support from phylogenetically corrected analyses suggests that any such relationship in birds is likely due to the idiosyncratic histories of different lineages. In this manner, our results broadly agree with studies in other groups, leading us to conclude that the relationship between climate and SSD is at best complex. This suggests that SSD is linked to behavioral dynamics that may at a global scale be largely independent of environmental conditions.