Emergence of long distance bird migrations: a new model integrating global climate changes

During modern birds history, climatic and environmental conditions have evolved on wide scales. In a continuously changing world, landbirds annual migrations emerged and developed. However, models accounting for the origins of these avian migrations were formulated with static ecogeographic perspectives. Here I reviewed Cenozoic paleoclimatic and paleontological data relative to the palearctic–paleotropical long distance (LD) migration system. This led to propose a new model for the origin of LD migrations, the ‘shifting home’ model (SHM). It is based on a dynamic perspective of climate evolution and may apply to the origins of most modern migrations. Non-migrant tropical African bird taxa were present at European latitudes during most of the Cenozoic. Their distribution limits shifted progressively toward modern tropical latitudes during periods of global cooling and increasing seasonality. In parallel, decreasing winter temperatures in the western Palearctic drove shifts of population winter ranges toward the equator. I propose that this induced the emergence of most short distance migrations, and in turn LD migrations. This model reconciliates ecologically tropical ancestry of most LD migrants with predominant winter range shifts, in accordance with requirements for heritable homing. In addition, it is more parsimonious than other non-exclusive models. Greater intrinsic plasticity of winter ranges implied by the SHM is supported by recently observed impacts of the present global warming on migrating birds. This may induce particular threats to some LD migrants. The ancestral, breeding homes of LD migrants were not ‘northern’ or ‘southern’ but shifted across high and middle latitudes while migrations emerged through winter range shifts themselves. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

STEP WISE,MULTIPLE OBJECTIVE CALIBRATION OF A HYDROLOGIC MODEL FOR A SNOWMELT DOMINATED BASIN1

ABSTRACT: The ability to apply a hydrologic model to large numbers of basins for forecasting purposes requires a quick and effective calibration strategy. This paper presents a step wise, multiple objective, automated procedure for hydrologic model calibration. This procedure includes the sequential calibration of a model's simulation of solar radiation (SR), potential evapotranspiration (PET), water balance, and daily runoff. The procedure uses the Shuffled Complex Evolution global search algorithm to calibrate the U.S. Geological Survey's Precipitation Runoff Modeling System in the Yampa River basin of Colorado. This process assures that intermediate states of the model (SR and PET on a monthly mean basis), as well as the water balance and components of the daily hydrograph are simulated consistently with measured values.     

Functional reference in an alarm signal given during nest defence: seet calls of yellow warblers denote brood-parasitic brown-headed cowbirds

Field observations and model-presentation experiments have shown that yellow warblers (Dendroica petechia) produce seet calls preferentially in response to brood-parasitic brown-headed cowbirds (Molothrus ater). In this study, we investigated whether seet calls are functionally referential alarm calls denoting cowbirds by determining whether female warblers responded appropriately to seet calls in the absence of a cowbird, whether alarm calling by warblers varied with response urgency, and how warblers in a population allopatric with cowbirds responded to cowbird and avian predator models and seet playbacks. As a control, we presented chip calls, which are elicited by nest predators as well as by non-threatening intruders, but are not strongly associated with cowbirds. Yellow warblers responded differently to playbacks of seet than chip calls. To seet playbacks, almost 60% of females gave seet calls and rushed to sit in their nests, responses typically elicited by cowbirds, whereas these responses were given infrequently in response to chip calls. Yellow warblers seet called equally in situations that simulated low, medium and high risk of parasitism, which suggests that these calls did not vary with response urgency. In a population allopatric with cowbirds, seet calls were rarely produced in response to cowbird or avian nest predator models and never to seet playbacks. These results suggest that seet calls are functionally referential signals denoting cowbirds and that cowbird parasitism was a strong selective pressure in the evolution of functional referentiality in the seet call of yellow warblers.Communicated by W.A. Searcy     

Why do honey bees dance?

The honey bee dance language, used to recruit nestmates to food sources, is regarded by many as one of the most intriguing communication systems in animals. What were the ecological circumstances that favoured its evolution? We examined this question by creating experimental phenotypes in which the location information of the dances was obscured. Surprisingly, in two temperate habitats, these colonies performed only insignificantly worse than colonies which were able to communicate normally. However, foraging efficiency was substantially impaired in an Asian tropical forest following this manipulation. This indicates that dance language communication about food source locations may be important in some habitats, but not in others. Combining published data and our own, we assessed the clustering of bee forage sites in a variety of habitats by evaluating the bees’ dances. We found that the indicated sites are more clustered in tropical than in temperate habitats. This supports the hypothesis that in the context of foraging, the dance language is an adaptation to the particular habitats in which the honey bees evolved. We discuss our findings in relation to spatial aggregation patterns of floral food in temperate and tropical habitats.     

菲尔德斯半岛火山构造及其时空演化

菲尔德斯半岛火山活动有两个高峰期,相应分为两个亚族回.火山机构有二类,一类以火山颈相岩柱为标志,另一类发育着火口相、近火口相集块岩、集块熔岩.据形成时间又可分为早期和晚期火山机构.火山活动明显受区域构造控制,为典型的裂隙中心式喷发,形成本区NW向、间距约为2km的火山喷发带.早期活动遍及全区,具有自SW向NE迁移的总体演化趋势;晚期沿火山喷发带自NW向SE局部性迁移.     

Short-sighted evolution of virulence in parasitic honeybee workers (Apis mellifera capensis Esch.)

The short-sighted selection hypothesis for parasite virulence predicts that winners of within-host competition are poorer at transmission to new hosts. Social parasitism by self-replicating, female-producing workers occurs in the Cape honeybee Apis mellifera capensis, and colonies of other honeybee subspecies are susceptible hosts. We found high within-host virulence but low transmission rates in a clone of social parasitic A. m. capensis workers invading the neighbouring subspecies A. m. scutellata. In contrast, parasitic workers from the endemic range of A. m. capensis showed low within-host virulence but high transmission rates. This suggests a short-sighted selection scenario for the host-parasite co-evolution in the invasive range of the Cape honeybee, probably facilitated by beekeeping-assisted parasite transmission in apiaries.     

Earliest zygodactyl bird feet: evidence from Early Cretaceous roadrunner-like tracks

Fossil footprints are important in understanding Cretaceous avian diversity because they constitute evidence of paleodiversity and paleoecology that is not always apparent from skeletal remains. Early Cretaceous bird tracks have demonstrated the existence of wading birds in East Asia, but some pedal morphotypes, such as zygodactyly, common in modern and earlier Cenozoic birds (Neornithes) were unknown in the Cretaceous. We, herein, discuss the implications of a recently reported, Early Cretaceous (120–110 million years old) trackway of a large, zygodactyl bird from China that predates skeletal evidence of this foot morphology by at least 50 million years and includes the only known fossil zygodactyl footprints. The tracks demonstrate the existence of a Cretaceous bird not currently represented in the body fossil record that occupied a roadrunner (Geococcyx)-like niche, indicating a previously unknown degree of Cretaceous avian morphological and behavioral diversity that presaged later Cenozoic patterns. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

炼油化工废水处理技术进展

评述了国内外在炼油化工废水处理的活性污泥技术改进、微生物处理与物化处理组合技术、难降解废水无害化处理技术以及污水回用技术方面的新进展。