Catostomid fishes

17 p. : ill., map ; 26 cm.Includes bibliographical references (p. 15-17).Two new species of Catostomus (sensu stricto) are described from northwest Mexico. One inhabits northeastern headwater streams in the Río Yaqui drainage and the other is widely distributred in the southern and southeastern parts of the Río Yaqui and in the upper Río Mayo basin. These new taxa exhibit low pharyngeal tooth counts, possibly indicating a close relationship between them. They are hypothesized to be members of an old, regional ichthyofauna that stretches from central Mexico to northwest United States"--P. [1]

Filling a Geographical Gap: New Paleoecological Reconstructions From the Desert Southwest, USA

In 1916 the time stamp for quantitative palynology was set with Lennart von Post's initial paper on pollen analysis and environmental change in the Scandinavian peat bogs. In the 1930s, Von Post provided a map of the known palynological reconstructions. This map showed many conspicuous gaps of geographic coverage that have endured to this day. In particular, environmental reconstruction in arid lands remain much less known, largely due to the paucity of depositional environments in these areas as well as challenges with preservation in regions either uniformly dry or subjected to strong wet/dry phases. Over the last decade we have examined linkages between desert wetland development and episodes of wet and arid conditions. Desert wetland, or ciénegas, are recharged by groundwater and appear to be sensitive to climate-driven groundwater fluctuations. These systems appear to “grow” during wet periods potentially associated with enhanced El Niño activity, suggesting an important linkage with groundwater dynamics and the quantity and frequency of winter precipitation delivery. Hydrologic conditions in ciénegas are also important controls on the preservation of pollen, where episodes of aridity coincide with periods of poor pollen preservation. We assess modern El Niño events, as analogs of past wet conditions, to provide context on the atmospheric controls for delivery of moisture into the desert southwest during winter. Our analysis shows that anomalously high and persistent moisture delivery into the region during El Niño events enables the growth of ciénegas, improves preservation of pollen and promotes the growth of fuels necessary to support wildfire. This paper examines ciénega sites located in the southwestern region of North America at the US/Mexico Border and discusses results that addresses a geographical gap identified by Von Post's original work in paleoenvironmental research

Assessment of pollen rewards by foraging bees

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The removal of pollen by flower-visiting insects is costly to plants, not only in terms of production, but also via lost reproductive potential. Modern angiosperms have evolved various reward strategies to limit these costs, yet many plant species still offer pollen as a sole or major reward for pollinating insects. 2. The benefits plants gain by offering pollen as a reward for pollinating are defined by the behaviour of their pollinators, some of which feed on the pollen at the flower, while others collect pollen to provision offspring. 3. We explore how pollen impacts on the behaviour and foraging decisions of pollen-collecting bees, drawing comparisons with what is known for nectar rewards. This question is of particular interest since foraging bees typically do not ingest pollen during collection, meaning the sensory pathways involved in evaluating this resource are not immediately obvious. 4. Previous research focussed on whether foraging bees can determine the quality of pollen sources offered by different plant species, and attempted to infer the mechanisms underpinning such evaluations, mainly through observations of collection preferences in the field 5. More recent experimental research has started to focus on if pollen itself can mediate the detection of, and learning about, pollen sources and associated floral cues. 6. We review advancements in the understanding of how bees forage for pollen and respond to variation in pollen quality, and discuss future directions for studying how this ancestral floral food reward shapes the behaviour of pollinating insects

Morphological variability in the Cuatro Cienegas cichlid, Cichlasoma minckleyi

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75338/1/j.1095-8649.2003.00006.x.pd

Age-Specific Estimates Indicate Potential Deleterious Capture Effects and Low Survival of Stocked Juvenile Colorado Pikeminnow (\u3ci\u3ePtychocheilus lucius\u3c/i\u3e)

Hatcheries and stocking programs have become necessary to repatriate or augment populations of imperiled fishes worldwide. Over nearly two decades, millions of endangered juvenile Colorado Pikeminnow Ptychocheilus lucius have been stocked into the San Juan River (Colorado, New Mexico, and Utah); however, recruitment of these individuals to adult life stages (age ≥6) remains low. Using a mark–recapture data set collected from annual riverwide electrofishing efforts between 2003 and 2016, we investigated apparent survival and capture probabilities of stocked Colorado Pikeminnow to identify age‐specific bottlenecks contributing to this lack of recruitment. With relatively high capture rates, which averaged between 0.34 and 0.39 for the first 2 years after an individual\u27s first encounter, our results indicated that survival was consistently less than 0.25 for young age‐groups (i.e., ages 1–3), and no appreciable increase in survival occurred until fish had been in the river for at least 3 years (i.e., age ≥4+). Although age and capture effects were confounded for most age‐groups, capture appeared to reduce apparent survival for age‐2 fish by approximately 50%. The confounding effects of age, a completely hatchery‐origin population, and extensive environmental alterations to the San Juan River make it difficult to disentangle factors associated with this overall reduced juvenile survival

Potential landscape-scale pollinator networks across Great Britain: structure, stability and influence of agricultural land cover

Understanding spatial variation in the structure and stability of plant-pollinator networks, and their relationship with anthropogenic drivers, is key to maintaining pollination services and mitigating declines. Constructing sufficient networks to examine patterns over large spatial scales remains challenging. Using biological records (citizen science), we constructed potential plant-pollinator networks at 10km resolution across Great Britain, comprising all potential interactions inferred from recorded floral visitation and species co-occurrence. We calculated network metrics (species richness, connectance, pollinator and plant generality) and adapted existing methods to assess robustness to sequences of simulated plant extinctions across multiple networks. We found positive relationships between agricultural land cover and both pollinator generality and robustness to extinctions under several extinction scenarios. Increased robustness was attributable to changes in plant community composition (fewer extinction-prone species) and network structure (increased pollinator generality). Thus, traits enabling persistence in highly agricultural landscapes can confer robustness to potential future perturbations on plant-pollinator networks

A simple and distinctive microbiota exclusively associated with honey bees and bumble bees

Abstract: Specialized relationships with bacteria often allow animals to exploit a new diet by providing a novel set of metabolic capabilities. Bees are a monophyletic group of Hymenoptera that transitioned to a completely herbivorous diet from the carnivorous diet of their wasp ancestors. Recent culture-independent studies suggest that a set of distinctive bacterial species inhabits the gut of the honey bee, Apis mellifera. Here we survey the gut microbiotae of diverse bee and wasp species to test whether acquisition of these bacteria was associated with the transition to herbivory in bees generally. We found that most bee species lack phylotypes that are the same or similar to those typical of A. mellifera, rejecting the hypothesis that this dietary transition was symbiont-dependent. The most common bacteria in solitary bee species are a widespread phylotype of Burkholderia and the pervasive insect associate, Wolbachia. In contrast, several social representatives of corbiculate bees do possess distinctive bacterial phylotypes. Samples of A. mellifera harboured the same microbiota as in previous surveys, and closely related bacterial phylotypes were identified in two Asian honey bees (Apis andreniformis and Apis dorsata) and several bumble bee (Bombus) species. Potentially, the sociality of Apis and Bombus species facilitates symbiont transmission and thus is key to the maintenance of a more consistent gut microbiota. Phylogenetic analyses provide a more refined taxonomic placement of the A. mellifera symbionts. apis mellifera | bacterial microbiota | insect symbiosis | microbiology | molecula

Waterfall Formation at a Desert River-Reservoir Delta Isolates Endangered Fishes

Unforeseen interactions of dams and declining water availability have formed new obstacles to recovering endemic and endangered big-river fishes. During a recent trend of drying climate and declining reservoir water levels in the southwestern United States, a large waterfall has formed on two separate occasions (1989-1995 & 2001-present) in the transition zone between the San Juan River and Lake Powell reservoir because of deposited sediments. Because recovery plans for two large-bodied endangered fish species, razorback sucker (Xyrauchen texanus) and Colorado pikeminnow (Ptychocheilus lucius), include annual stockings in the San Juan River, this waterfall potentially blocks upstream movement of individuals that moved downstream from the river into the reservoir. To quantify the temporal variation in abundance of endangered fishes aggregating downstream of the waterfall and determine population demographics, we remotely monitored and sampled in spring 2015, 2016, and 2017 when these fish were thought to move upstream to spawn. Additionally, we used an open population model applied to tagged fish detected in 2017 to estimate population sizes. Colorado pike minnow were so infrequently encountered (\u3c 30 individuals) that population estimates were not performed. Razorback sucker captures from sampling (335) and detections from remote monitoring (943) showed high abundance across all three years. The razorback sucker population estimate for 2017 alone was 755 individuals and, relative to recent population estimates ranging from ~2000 to ~4000 individuals, suggests a substantial population exists seasonally downstream of this barrier. Barriers to fish movement in rivers above reservoirs are not unique, thus the formation of this waterfall exemplifies how water development and hydrology can interact to cause unforeseen changes to a riverscape