Pollinator preferences for yellow, orange, and red flowers of Mimulus verbenaceus and M. Cardinalis

Red. orange, and yellow morphs of Mimulus verbenaceus and M. cardinalis were field tested for pollinator preferences. The species are closely similar except that M. verbenaceus flowers have partially reflexed corolla lobes, whereas M. cardinalis flowers have fully reflexed corolla lobes. On the basis of over 6000 bumblebee and hummingbird visits, highly significant ( p Mimulus verbenaceus and M. cardinalis .     

Mimulus evanescens (Scrophulariaceae): a new annual species from the northern Great Basin

Recent taxonomic studies in Mimulus support the recognition of Mimulus evanescens , a new autogamous species morphologically allied with M. breviflorus and M. latidens . Initially known only from herbarium specimens, the most recent from 1958, M. evanescens was relocated in the field in 1990 in northern Lassen Co., CA. A second population was found in southern Lake Co., OR, in 1993. Mimulus evanescens is apparently confined to the Great Basin and its periphery, where it has been recorded from 10 localities across Idaho, Oregon, and California. Based on collection information and visits to the two extant populations, the new species appears to be restricted to vernally moist sites and fluctuating banks of intermittent streams or pools. Long-term utilization of such sites by livestock may have contributed to the present-day rarity of M. evanescens . The species should be added to federal and state lists of candidate endangered species pending the results of future field studies and surveys.     

Evolutionary divergence in closely related populations of Mimulus guttatus (Scrophulariaceae)

The evolutionary divergence of five closely related populations of the yellow monkey flower. Mimulus guttatus was compared with the length of time the populations could have occupied the site and with the ability of the populations to intercross. Populations from the younger sites were found to be morphologically intermediate to populations from the older sites. Ability to intercross was not correlated with morphological divergence at this stage of evolution.       

Ecological impacts of Pogonomyrmex on woody vegetation of a Larrea-Ambrosia shrubland

Discovery of distinct mid-elevational bands of blackbrush ( Coleogyne ramosissima Torr.) shrublands on desert mountain slopes in the Mojave Desert caused an investigation of the relationships between environmental factors and Coleogyne distribution. Environmental factors were quantitatively examined to determine which were significant predictors of Coleogyne density at upper-elevational limits (ecotones) in the Spring Mountains of southern Nevada. Path analysis revealed significant, direct causal effects of air temperature, soil moisture, soil depth, and percent litter cover on the distribution of Coleogyne . Specifically, air temperature was a significant positive predictor, while soil moisture, soil depth, and percent litter cover were significant negative predictors of Coleogyne density, with the effects of other environmental variables parceled out. Path analysis also indicated that indirect effects of soil pH, bulk density, compaction, percent pore space, organic matter, soil temperature, salinity, cryptogam, and percent bare soil and rock cover on Coleogyne density were substantially more potent than their direct casual effects. Environmental attributes associated with elevational changes correlate with and may determine the density of Coleogyne shrubs at upper ecotones in southern Nevada.     

Environmental attributes correlating with density of blackbrush ( Coleogyne ramosissima ) shurbs in the Spring Mountains of southern Nevada

Discovery of distinct mid-elevational bands of blackbrush ( Coleogyne ramosissima Torr.) shrublands on desert mountain slopes in the Mojave Desert caused an investigation of the relationships between environmental factors and Coleogyne distribution. Environmental factors were quantitatively examined to determine which were significant predictors of Coleogyne density at upper-elevational limits (ecotones) in the Spring Mountains of southern Nevada. Path analysis revealed significant, direct causal effects of air temperature, soil moisture, soil depth, and percent litter cover on the distribution of Coleogyne . Specifically, air temperature was a significant positive predictor, while soil moisture, soil depth, and percent litter cover were significant negative predictors of Coleogyne density, with the effects of other environmental variables parceled out. Path analysis also indicated that indirect effects of soil pH, bulk density, compaction, percent pore space, organic matter, soil temperature, salinity, cryptogam, and percent bare soil and rock cover on Coleogyne density were substantially more potent than their direct casual effects. Environmental attributes associated with elevational changes correlate with and may determine the density of Coleogyne shrubs at upper ecotones in southern Nevada.     

On the relative importance of floral color, shape, and nectar rewards in attracting pollinators to Mimulus

Pollinator preferences were observed for the six species of section Erythranthe of the genus Mimulus using greenhouse-grown plants placed in a meadow in the Red Butte Canyon Natural Area, Salt Lake County, Utah. The principal pollinators were hummingbirds and bumble bees. Hummingbirds preferred the species with the most reflexed tubular flowers regardless of color, whereas bumblebees preferred pink. lavender, or yellow flowers to red flowers regardless of shape. Results for the six species were confirmed by observations of F 2 hybrid recombinant plants selected such that flower color could be held constant and flower shape varied and vice versa.     

Vertical distribution of liverwort communities and their relationship with environmental factors in a karst sinkhole in south-western China

ABSTRACT

Understanding the relationships between the vertical distribution of liverwort communities and associated environmental factors is vital for biodiversity conservation in karst sinkholes. The abundance index, α and β diversity indices were used to analyse the characteristics of liverwort communities in the Monkey-Ear Sinkhole (280 m deep, entrance diameter 300 m, width 280 m). A Generalised Linear Model was used to study the vertical distribution of liverwort communities, and the relationships between their vertical distribution and environmental factors were analysed with Canonical Correspondence Analysis. Forty-two liverwort taxa from 22 genera in 19 families were identified in the sinkhole. The liverwort assemblages were dominated by the families Plagiochilaceae and Lejeuneaceae. The α and β diversity appeared to fluctuate randomly among the four depths sampled. The highest degree of environmental heterogeneity was found at the lower-middle section of the sinkhole; liverwort community diversity at the base was much higher than that found at the upper, middle or lower-middle sections. The environment at the base of the sinkhole was more complex than at the other three depths, providing a range of habitats that facilitated the coexistence of multiple liverwort communities. The abundance of species, genera and families in liverwort communities followed the sequence: base > upper section > middle section > lower – middle section. There were significant differences in liverwort communities at the four depths. In the sinkhole, liverwort communities fell into three distribution groups: wide, moderate or narrow distribution along the vertical direction. The communities with a broad distribution, found from the upper section to the base, were affected by a combination of light, humidity and temperature, and were classified as mixed factor dependent; those with a moderate distribution found mostly in the mid and lower-middle sections were primarily dependent on temperature and humidity, and were classified as temperature and humidity dependent; and those with a narrow distribution found at the base of the sinkhole were mainly influenced by humidity, and were classified as humidity dependent.     

Arbuscular mycorrhizae in thermal-influenced soils in Yellowstone National Park

Mycorrhizae are common plant-fungal symbioses occurring in most land plants. Despite their ubiquity, little is known about the distribution of arbuscular mycorrhizae (AM) in extreme environments. We surveyed for the presence of AM in thermal sites in Yellowstone National Park (YNP) where soils are characterized by extreme pHs, elevated temperatures, and toxic element concentrations. Plants at 5 sites, growing in soils with rooting-zone temperatures up to 48°C and soil pH values as low as 3.4, were mycorrhizal (colonization levels from 4% to 34%). Soils from a sparsely vegetated thermal area and an adjacent, continuously vegetated transition area differed significantly in rooting-zone temperature (35°C vs. 26°C), acidity (pH 3.8 vs. 5.4), electrical conductivity (2.22 vs. 0.49 mmhos cm -1 ), Fe (181.3 vs. 48.5 mg kg -1 ),Mn (7.2 vs. 98.2 mg kg -1 ), and Zn (2.3 vs. 4.5 mg kg -1 ). Mycorrhizal infectivity potential (MIP) was 77% greater in the transition soils, with colonization levels of 26% and 46% in thermal and transition soils, respectively. Furthermore, colonization of Agrostis scabra , Dichanthelium lanuginosum , and Mimulus guttatus was found to be consistently high throughout the growing season (from 48% to 72%). It is possible that AM are essential for plant life on the edge of thermal areas, and that either or both symbionts are specifically adapted to their environment. Further research is required to elucidate AM function in and specific adaptations to YNP's thermal areas.     

Pollination experiments in the Mimulus cardinalis--M. lewisii complex

Experimental sets of Mimulus cardinalis and M. lewisii plants were (1) exposed to pollinators and (2) shielded from pollinators at study sties in Red Butte Canyon and Big Cottonwood Canyon, Wasatch Mountains, Utah. The exposed plants produced 1,535 seedlings and the shielded plants only 1. Clearly, seed production is dependent upon cross-pollination. A few syrphid flies were observed visiting the flowers but no hummingbirds or bumble bees, although the latter two have been reported as the main pollinators of M. cardinalis and M. lewisii , respectively. No interspecific hybrids were produced even though the species are fully interfertile, indicating that pollinators are faithful to their species or that different parts of their bodies pick up and carry pollen to the two different species.     

Remarkable waxing, waning, and wandering of populations of Mimulus guttatus : an unexpected example of global warming

Experimental sets of Mimulus cardinalis and M. lewisii plants were (1) exposed to pollinators and (2) shielded from pollinators at study sties in Red Butte Canyon and Big Cottonwood Canyon, Wasatch Mountains, Utah. The exposed plants produced 1,535 seedlings and the shielded plants only 1. Clearly, seed production is dependent upon cross-pollination. A few syrphid flies were observed visiting the flowers but no hummingbirds or bumble bees, although the latter two have been reported as the main pollinators of M. cardinalis and M. lewisii , respectively. No interspecific hybrids were produced even though the species are fully interfertile, indicating that pollinators are faithful to their species or that different parts of their bodies pick up and carry pollen to the two different species.     

Species-environment relationships among filter-feeding caddisflies (Trichoptera: Hydropsychidae) in Rocky Mountain streams

Species-environment relationships were determined for filter-feeding macroinvertebrates from 55 Rocky Mountain stream sites to establish species distribution patterns. Species abundance and 20 environmental variables were measured at each site with species-environment relationship determined using canonical correspondence analysis and stepwise multiple regression. Results suggest that the distribution of several taxa was strongly related to upstream-downstream environmental gradients. Arctopsyche grandis abundance increased with stream size (width and depth) and decreased with increasing turbulence (Reynolds number). Brachycentrus abundance also increased with stream size (depth). Hydropsyche abundance increased with increasing baseflow. Parapsyche elsis abundance also increased with stream size (depth). Hydropsyche abundance increased with increasing baseflow. Parapsyche elsis abundance demonstrated negative correlation with depth, Froude number, and conductivity. Taxa followed previously reported patterns, partitioning habitat according to stream size. Arctopsyche grandis , Brachycentrus , and Hydropsyche were found in larger (3rd- to 6th order) streams, while Parapsyche elsis was observed in small headwater (1st- and 2nd- order) streams. Other filter-feeding taxa such as Simulium, Pisidium and ostracods exhibited little or no apparent habitat partitioning among stream sites.     

Biotic and abiotic factors influencing the distribution of Coleogyne communities in southern Nevada

Woody plant community composition was analyzed throughout the range of Coleogyne ramosissima in the Spring and Sheep Mountain ranges of southern Nevada. The lower Coleogyne elevational boundary was analyzed in detail in Lucky Strike Canyon, on the eastern edge of the Spring Mountains. TWINSPAN (2-way indicator species analysis) identified 4 primary species and stand groups from the 2 mountain ranges (extensive survey). Analysis of DECORANA (detrended correspondence analysis) results indicated that elevation and soil depth were the environmental factors most significantly associated with distribution of species and stand groups in the extensive survey. Elevation was the only significant physical factor associated with distribution of species and stand groups in the intensive survey. Five vegetation zones form the 2 mountain ranges were identified based on their dominant species in 15 extensive transects. Coleogyne were subdivided into pure stands and upper and lower ecotones for further investigation of species distribution and environmental factors. Selected environmental factors appear to play an important role in structuring the Mojave Desert vegetation zones in southern Nevada.     

The effect of elevation on the distribution of sibling species in the Simulium arcticum complex (Diptera: Simuliidae)

At least 5 sibling species and an additional 11 cytotypes of the Simulium arcticum complex occur in Montana. Consequently, this speciose complex might allow study of environmental correlates with genetic differentiation. We used conventional methods of collection and cytogenetic analysis to study 1128 male larvae of the Simulium arcticum complex at 15 sites within 5 drainages in western Montana to test the hypothesis that distribution of siblings is associated with elevation. We sampled at the mouth, at the headwaters, and at an intermediate site to span the range of elevations within each drainage. We restricted our analyses to the most abundant taxa of the S. arcticum complex within our study area and observed a statistically significant presence of S. apricarium at low-elevation sites. Simulium arcticum IIL-18 appeared more frequently than expected at high elevation sites. Simulium brevicercum and S. arcticum sensu strictu appeared to be distributed randomly. We suggest potential causal reasons for these distributions including differential use of habitats along these elevational gradients.     

Classification and ordination of Coleogyne communities in southern Nevada

Woody plant community composition was analyzed throughout the range of Coleogyne ramosissima in the Spring and Sheep Mountain ranges of southern Nevada. The lower Coleogyne elevational boundary was analyzed in detail in Lucky Strike Canyon, on the eastern edge of the Spring Mountains. TWINSPAN (2-way indicator species analysis) identified 4 primary species and stand groups from the 2 mountain ranges (extensive survey). Analysis of DECORANA (detrended correspondence analysis) results indicated that elevation and soil depth were the environmental factors most significantly associated with distribution of species and stand groups in the extensive survey. Elevation was the only significant physical factor associated with distribution of species and stand groups in the intensive survey. Five vegetation zones form the 2 mountain ranges were identified based on their dominant species in 15 extensive transects. Coleogyne were subdivided into pure stands and upper and lower ecotones for further investigation of species distribution and environmental factors. Selected environmental factors appear to play an important role in structuring the Mojave Desert vegetation zones in southern Nevada.     

Variance and replenishment of nectar in wild and greenhouse populations of Mimulus

We compared nectar production in wild populations and greenhouse-grown populations of the monkey flower species of section Erythranthe of the genus Mimulus . Nectar was sampled from over 1000 flowers. For each flower the volume of nectar was measured with a calibrated micropipette and the percentage of sugar with a hand refractometer. Percentage of sugar varied little from flower to flower in both field and greenhouse studies, but volume varied markedly from flower to flower in field studies and even more in greenhouse studies. This high variance in nectar volumes appears to be intrinsic. The amount of nectar in greenhouse populations tended to increase with time in the absence of pollinators. The amount of nectar in field populations tended to remain the same to pollinator withdrawals. The latter conclusion was corroborated by sampling nectar at 2-h intervals all day and comparing the total volume produced by a flower to the volume of nectar produced in control flowers sampled only at the end of the day.     

Classification and ordination of the alpine plant communities of Railroad Ridge, White Cloud Peaks, Idaho

Alpine vegetation of Railroad Ridge in the White Cloud Peaks, Custer County, Idaho, was investigated to ascertain native communities and describe their distribution with respect to important environmental factors. Percent cover of all species and environmental information were recorded for 69 plots. Data were analyzed by TWINSPAN and CANOCO, which provided a classification and an ordination, respectively. Predominant communities are dominated by (1) Phlox pulvinata , (2) Carex elynoides , and (3) Ceum rossii , and other communities of lesser importance are dominated by (4) Artemisia campestris , (5) Eriogonum ovalifolium and Silene acaulis , and (6) Ivesia gordonii . Although the Artemisia campestris community occupies a relatively small portion of the study area, it is noteworthy because it is a community type not previously known for Idaho. The community co-dominated by Eriogonum ovalifolium and Silene acaulis is also unique and has not been documented in other Idaho alpine studies. Community distribution showed the strongest correlation with exposure, substrate type, and slope. In general, the study area supports fellfield communities that are representative of alpine areas in Idaho and some Great Basin mountain ranges, and dense turflike communities similar to ones found throughout western North America's temperate alpine regions.     

Ants from northern Arizona and southern Utah

Ants of 22 species were collected in can pit-traps from 16 different vegetative associations to determine distribution, seasonal and annual occurrence, and population as bases for monitoring environmental impact. Thirteen species were sufficiently abundant and distributed to qualify as indicator species. Myrmecocystus mexicanus was the most widespread ecologically. Pogonomyrmex occidentalis was the most abundant species, but second in ecological distribution. The greatest number of species was found in the juniper- Ephedra -grass association, and the fewest species in Ephredra-Coleogyne-Grayia.        

Evidence for a geographical gradient selection in the distribution of breeding Podicipedidae and Rallidae in the south-western Mediterranean

ABSTRACT

Knowledge of factors influencing waterbird distribution is a crucial step that would help wetland managers to target their conservation efforts. In this work, we used a 2-year survey in 25 wetlands distributed throughout Morocco to model Podicipedidae and Rallidae spatial distribution and to assess the relevance of a set of environmental and anthropogenic factors in predicting site occupancy, by means of generalised linear mixed models (GLMM). In Podicipedidae, little grebes and great crested grebes were the most commonly detected species, while in Rallidae the most common species was the common moorhen. Geographical location (measured mainly as distance to the coastline and elevation) was the major predictor of the occurrence probability of breeding Podicipedidae and Rallidae species in Morocco. Statistical analyses also provide evidence that there exists a geographical selection gradient in wetland occupancy. Indeed, Podicipedidae species (great crested grebes and black-necked grebes) tend to use continental mountain wetlands, while Rallidae (purple swamphens and Eurasian coots) tend instead to use coastal wetlands. However, none of the considered environmental and anthropogenic factors explained the distribution patterns of the red-knobbed coot. The pursuit of the investigations, while considering other explanatory factors such as water quality (limnological data), diet, predation and conservation status, is of great importance for understanding basic, large-scale geographical distribution patterns of Moroccan waterbird populations.     

Horizontal and vertical distribution of Dolichopodidae (Diptera) in a woodland ecosystem

The horizontal and vertical distribution of dolichopodid flies in a deciduous woodland ecosystem was investigated by means of white-water traps during a nearly 8-month period. Eighteen traps were installed along a light intensity/soil humidity gradient (three zones) and from 0 to 80cm high (six levels). Six environmental features were recorded on several occasions. The dolichopodid data were analysed by means of two multivariate techniques, detrended correspondence analysis (DCA) and two-way indicator species analysis (TWINSPAN). The DCA revealed four distinct species groups, which also proved to be clearly different on a broader ecological basis. The horizontal distributions in many species could be explained by the different environmental conditions in the zones. Although nearly all species were unequally distributed over the traps, their stratification patterns generally showed no significant correlation with the recorded biotic and abiotic features. It is therefore suggested that the observed vertical distributions are the results of a combination of specific and environmental characteristics.     

Patterns of asymmetry in body traits and genitalia in two distant populations of a Neotropical scorpion

The ability of a genotype to control the stable development of a phenotype under different environmental conditions may explain the level of developmental instability. An indicator to developmental instability is Fluctuating Asymmetry. Traits under pressures of sexual selection exhibit greater values of asymmetry that others. These traits have more physiological requirements during morphogenesis and a more complex development. The aims of this work are to analyze asymmetry patterns of genitalic and somatic traits in the scorpion Bothriurus bonariensis (Bothriuridae) and to compare these values between central and peripheral populations of its distribution. We observed that types of asymmetry in genitalic traits differed in both populations. Also, traits of the hemispermatophores (two halves that constitute the spermatophore) showed the highest levels of fluctuating asymmetry, particularly in those characteristics with important role for insemination success. This work offers fundamental baseline knowledge for further works focused on asymmetry of genitalia and mating success in scorpions.