The papers in this Special Issue examine tool use and manual gestures in primates as a window on the evolution of the human capacity for language. Neurophysiological research has supported the hypothesis of a close association between some aspects of human action organization and of language representation, in both phonology and semantics. Tool use provides an excellent experimental context to investigate analogies between action organization and linguistic syntax. Contributors report and contextualize experimental evidence from monkeys, great apes, humans and fossil hominins, and consider the nature and the extent of overlaps between the neural representations of tool use, manual gestures and linguistic processes. 相似文献
Ursolestes perpetior gen. et sp. nov. is a large purgatoriid plesiadapiform primate from the middle/late Puercan (earliest Paleocene) Simpson Quarry, Montana, USA. It differs from Purgatorius Van Valen and Sloan, 1965, the only other known purgatoriid and the oldest discovered primate, in its substantially larger body size as inferred from the dimensions of the known parts of its dentition, while resembling Purgatorius in possessing a large lower canine, unreduced p1, and in the upper molars, a protocone twist and weakly developed postprotocone fold; moreover, the m3 of U. perpetior possesses an expanded, plesiadapiform‐like posterior lobe of the talonid that supports the hypoconulid. The large lower canine and the greater development of trenchant molar crests suggest that U. perpetior was more insectivorous, differing appreciably from the omnivorous niche long hypothesized for Purgatorius and purportedly marking the insectivore–primate transition. Hence, U. perpetior adds significant new knowledge regarding the breadth of the adaptive zone occupied by purgatoriids in their position at the very beginnings of primate evolution. 相似文献
The role of environment and the relative significance of endogenous versus exogenous selection in shaping hybrid zones have been crucial issues in the studies of hybridization. Recent advances in ecological niche modeling (ENM) offer new methodological tools, especially in combination with the genotyping of individuals in the hybrid zone. Here, we study the hybrid zone between the widely known spices Origanum onites and Origanum vulgare ssp. hirtum in Crete. We analyze the genetic structure of both parental taxa and their hybrid Origanum × intercendens using AFLP markers on 15 sympatric and 12 allopatric populations and employ ecological niche modeling and niche similarity tests to study their niche patterns. We complement these analyses with seed viability measurements. Our study revealed that the hybridizing taxa O. onites and O. vulgare ssp. hirtum and the resulting genotypic classes showed geographical and environmental niche similarities based on the predictions of ENMs and the subsequent similarity tests. The occurrence of the hybrid zone is not directly dependent on environmental factors which favor the fitness of the hybrid compared to the parental taxa, but rather on aspects such as historical factors and management practices, which may contribute to the localization and maintenance of the contact zone between parental species. Our results suggest that if a minimum required niche differentiation between genotypic classes is not achieved, environmental dependence might not have a prominent role on the outcome of the hybridization. 相似文献
Hymenophyllaceae (filmy ferns) are typically plants of shady, constantly moist habitats. They attain greatest species diversity and biomass in humid tropical montane forests and temperate hyperoceanic climates. This paper presents ecophysiological data bearing on their worldwide ecological niche space and its limits.
Methods
Chlorophyll fluorescence was used to monitor recovery in desiccation experiments, and for measurements of 95 % saturating irradiance [photosynthetic photon flux density (PPFD95 %)] of photosynthetic electron flow and other parameters, in the New Zealand Hymenophyllum sanguinolentum, and three species each of Hymenophyllum and Trichomanes from forests in Trinidad and Venezuela.
Key Results
Hymenophyllum sanguinolentum was comparable in desiccation tolerance and light responses with the European species. The more common species in the two tropical forests showed PPFD95 % >100 µmol m−2 s−1, and withstood moderate desiccation (–40 MPa) for several days. The four most shade-adapted species had PPFD95 % ≤51 µmol m−2 s−1, and were sensitive to even mild and brief desiccation (–22 MPa for 3 d).
Conclusions
Light and desiccation responses of filmy ferns can be seen as an integrated package. At low light and windspeed in humid forests, net radiation and saturation deficit are low, and diffusion resistance high. Water loss is slow and can be supported by modest conduction from the sub-stratum. With higher irradiance, selection pressure for desiccation tolerance increases progressively. With low light and high humidity, the filmy fern pattern of adaptation is probably optimal, and the vascular plant leaf with mesophyll and stomata offers no advantage in light capture, water economy or CO2 uptake. Trade-offs between light adaptation and desiccation tolerance, and between stem conduction and water absorption through the leaf surface, underlie adaptive radiation and niche differentiation of species within the family. Hymenophyllaceae are a rare example of an evolutionary shift of adaptive strategy from typical vascular plant adaptation to the poikilohydry most typical of bryophytes. 相似文献
Sequences of the ITS region of nrDNA were analyzed for the seven genera of Papaveraceae subf. Chelidonioideae s.str. Three major clades can be recognized. These are 1.Chelidonium/Hylomecon/Stylophorum, 2.Eomecon/Sanguinaria, and 3.Bocconia/Macleaya. The monophyly of genera in the first of these three clades is doubtful, and clades two and three are sister to each other. Use of the ITS phylogeny of the subfamily to trace its morphological and ecological evolution shows that morphological change is concentrated in theBocconia/Macleaya clade, and probably related to the evolution of wind-pollination from insect-pollination in these two genera after habitat shift. 相似文献
Homoploid hybrid speciation occurs through stabilization of a hybrid segregate (or segregates) isolated by premating and/or postmating barriers from parent taxa. Theory predicts that ecological and spatial isolation are of critical importance during homoploid hybrid speciation, and all confirmed homoploid hybrid species are ecologically isolated from their parents. Until recently, such species have been identified long after they originated, and consequently it has not been possible to determine the relative importance of spatial and ecological isolation during their origin. Here we present evidence for the recent origin (within the past 300 years) of a new homoploid hybrid species, Senecio squalidus (Asteraceae), in the British Isles, following long-distance dispersal of hybrid material from a hybrid zone between S. aethnensis and S. chrysanthemifolius on Mount Etna, Sicily, Italy. Historical records show that such hybrid material from Sicily was introduced to the Oxford Botanic Garden in Britain in the early part of the 18th century and that S. squalidus began to spread from there after approximately 90 years. A survey of randomly amplified polymorphic DNA/intersimple sequence repeats (RAPD/ISSR) marker variation demonstrated that S. squalidus is a diploid hybrid derivative of S. aethnensis and S. chrysanthemifolius that grow at high and low altitudes, respectively, on Mount Etna and that form a hybrid zone at intermediate altitudes. Senecio squalidus contained 11 of 13 RAPD/ISSR markers that were recorded at high frequency in S. chrysanthemifolius but were absent or occurred at low frequency in S. aethnensis, and 10 of 13 markers for which the reverse was true. Bayesian admixture analysis showed that all individuals of S. squalidus surveyed were of mixed ancestry with relatively high mean proportions of ancestry derived from both S. chrysanthemifolius and S. aethnensis (0.644 and 0.356, respectively). We argue that long-distance isolation of hybrid material from its parents on Mount Etna would have helped favor the origin and establishment of S. squalidus in the British Isles, regardless of whether the initial hybrid material introduced to Britain was preadapted to local conditions. 相似文献
The brain of Echiniscus viridissimus , Peterfi, 1956 is composed of a series of orthogonally arranged neuropils. The most anterior neuropils are rireumbuccal, positioned dorso-and ventrolateral to the buccal tube and are associated with ganglia for sensory receptors of the mouth cone. Posterior to these are neuropils and ganglia for the (1) internal cirri and (2) cephalic papillae, external cirri, cirri A and clavae. They are joined by two pairs of vertical tracts to neuropils lateral to the buccal tube. A model based on the postcephalic organization of the tardigrade nervous system is used to propose a transformation of segmental ganglia that gives an arrangement congruent with the pattern of neuropils in the brain. The analysis suggests that the brain is derived from nervous elements of four segments with the fourth segment having contributed paired dorsal ganglia and their connecting vertical tracts to the first trunk ganglia of the ventral chain. The organization of the head of tardigrades is compared with that of other lobopods and arthropods and several possible key evolutionary innovations are offered. In addition homologous characters for the heads of tardigrades and other lobopods and arthropods are proposed and the nomenclature for the tardigrade cephalic nervous system is discussed. 相似文献
In the Croatian Adriatic, Arca noae occurs from the low intertidal to a depth of 60 m; it can live for > 15 years and is either solitary or forms byssally attached clumps with Modiolus barbatus. The shell is anteriorly foreshortened and posteriorly elongate. The major inhalant flow is from the posterior although a remnant anterior stream is retained. There are no anterior but huge posterior byssal retractor muscles and both anterior and posterior pedal retractors. The ctenidia are of Type B(1a) and the ctenidial–labial palp junction is Category 3. The ctenidia collect, filter and undertake the primary sorting of potential food in the inhalant water. The labial palps are small with simple re‐sorting tracks on the ridges of their inner surfaces. The ciliary currents of the mantle cavity appear largely concerned with the rejection of particulate material. The mantle margin comprises an outer and an (either) inner or middle fold. The outer fold is divided into outer and inner components that secrete the shell and are photo‐sensory, respectively. The latter bears a large number of pallial eyes, especially posteriorly. The inner/middle mantle fold of A. noae, possibly representative of simpler, more primitive conditions, may have differentiated into distinct folds in other recent representatives of the Bivalvia. 相似文献
The effects of Beauveria bassiana strains on coffee berry borers (CBB), which emerge from infested berries left on soil, and its impact on the infestation of coffee berries on tree branches were evaluated at two Experimental Stations (Naranjal-Caldas and Paraguaicito-Quindio) in the Colombian coffee zone. Using a completely randomized design with 10 repetitions, 50 coffee berries artificially infested with CBB were placed on the base of a coffee tree. Four treatments including B. bassiana strain Bb9205, a mixture of Cenicafé strains (Bb9001, Bb9024 and Bb9119), a commercial formulation of B. bassiana and a control (water) were sprayed with 1×109 conidia per tree. After 30 days, all fungal strains lowered the infestation levels of the coffee berries on the trees at both locations. The mixture of Cenicafé strains decreased the tree infestation between 50 and 30% at both locations. In the berries dissected from each treated tree, insect mortality was about 40% at both locations compared to 15% in the control. B. bassiana strains also decreased the insect population inside the newly infested berries on the trees by 55–75%. The mixture of Cenicafé strains was the most effective for decreasing insect populations. B. bassiana significantly decreased CBB populations that emerged from fallen, infested, coffee berries and reduced future insect generations. 相似文献
Blood-sucking arthropods are vectors responsible for the transmission of several pathogens and parasites to vertebrate animals. The horn fly Haematobia irritans irritans (Diptera: Muscidae) and the tick Boophilus microplus are important hematophagous ectoparasites that cause losses in cattle production. A serine protease inhibitor from a thorax extract of the fly H. irritans irritans (HiTI) was previously isolated, characterized and cloned. In the present study we described the expression, purification, and characterization of the recombinant HiTI (rHiTI) and its possible role in the control of different endogenous and bacterial proteases. rHiTI was successfully expressed using the pPIC9 expression vector with a yield of 4.2 mg/L of active rHiTI. The recombinant HiTI purified by affinity chromatography on trypsin-Sepharose had a molecular mass of 6.53 kDa as determined by LS-ESI mass spectrometry and inhibition constants (Kis) similar to those of native HiTI for bovine trypsin and human neutrophil elastase of 0.4 and 1.0 nM, respectively. Purified rHiTI also showed inhibitory activity against the trypsin-like enzyme of H. i. irritans using its possible natural substrates, fibrinogen and hemoglobin; and also inhibited the OmpT endoprotease of Escherichia coli using fluorogenic substrates. The present results confirm that HiTI may play a role in the control of fly endogenous proteases but also suggest a role in the inhibition of pathogen proteases. 相似文献
A new and phylogenetically basal species of Carpolestes, the youngest and most derived genus of the plesiadapoid family Carpolestidae in North America, is described from a late Tiffanian (Ti-5) site in Sweetwater County, Wyoming, USA. Carpolestids differ from closely related plesiadapoid clades in having an enlarged, multicuspidate, blade-like P4 that is partly convergent on that of multituberculates and other mammals showing plagiaulacoid dental adaptations. With some notable exceptions, the evolutionary history of North American carpolestids is characterized by the progressive development of larger and more elaborate P4 blades through time. In particular, species of the monophyletic genus Carpolestes differ from species assigned to the earlier and apparently paraphyletic genus Carpodaptes in terms of both the size and shape of their P4. A geometric morphometric analysis reveals that, with respect to P4 shape, the closest approximation to the highly derived morphology of Carpolestes is made by Carpodaptes hobackensis, which is one of the smallest known species of Carpodaptes. In contrast, the largest known species of Carpodaptes, Carpodaptes jepseni, has a P4 that falls within the metric range of variation for species of Carpolestes, yet Carpodaptes jepseni shows a uniquely derived P4 shape that seems to exclude it from any special phylogenetic relationship with Carpolestes. A phylogenetic analysis based on dental characters reconstructs Carpodaptes hobackensis as the sister group of the Carpolestes clade. Shape seems to have been a more important factor than size during the final transformation of the blade-like P4 of North American carpolestids.
The clinical symptoms of Alzheimer disease (AD) include a gradual memory loss and subsequent dementia, and neuropathological deposition of senile plaques and neurofibrillary tangles. At the molecular level, AD subjects present overt amyloid β (Aβ) production and tau hyperphosphorylation. Aβ species have been proposed to overactivate the phosphoinositide3‐kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) axis, which plays a central role in proteostasis. The current study investigated the status of the PI3K/Akt/mTOR pathway in post‐mortem tissue from the inferior parietal lobule (IPL) at three different stages of AD: late AD, amnestic mild cognitive impairment (MCI) and pre‐clinical AD (PCAD). Our findings suggest that the alteration of mTOR signaling and autophagy occurs at early stages of AD. We found a significant increase in Aβ (1–42) levels, associated with reduction in autophagy (Beclin‐1 and LC‐3) observed in PCAD, MCI, and AD subjects. Related to the autophagy impairment, we found a hyperactivation of PI3K/Akt/mTOR pathway in IPL of MCI and AD subjects, but not in PCAD, along with a significant decrease in phosphatase and tensin homolog. An increase in two mTOR downstream targets, p70S6K and 4EBP1, occurred in AD and MCI subjects. Both AD and MCI subjects showed increased, insulin receptor substrate 1, a candidate biomarker of brain insulin resistance, and GSK‐3β, a kinase targeting tau phosphorylation. Nevertheless, tau phosphorylation was increased in the clinical groups. The results hint at a link between Aβ and the PI3K/Akt/mTOR axis and provide further insights into the relationship between AD pathology and insulin resistance. In addition, we speculate that the alteration of mTOR signaling in the IPL of AD and MCI subjects, but not in PCAD, is due to the lack of substantial increase in oxidative stress.
Renal impairment is associated with CNS dysfunctions and the accumulation of uremic toxins, such as indoxyl sulfate, in blood. To evaluate the relevance of indoxyl sulfate to CNS dysfunctions, we investigated the brain-to-blood transport of indoxyl sulfate at the blood-brain barrier (BBB) using the Brain Efflux Index method. [(3)H]Indoxyl sulfate undergoes efflux transport with an efflux transport rate of 1.08 x 10(-2)/min, and the process is saturable with a Km of 298 microm. This process is inhibited by para-aminohippuric acid, probenecid, benzylpenicillin, cimetidine and uremic toxinins, such as hippuric acid and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid. RT-PCR revealed that an OAT3 mRNA is expressed in conditionally immortalized rat brain capillary endothelial cell lines and rat brain capillary fraction. Xenopus oocytes expressing OAT3 were found to exhibit [(3)H]indoxyl sulfate uptake, which was significantly inhibited by neurotransmitter metabolites, such as homovanillic acid and 3-methoxy-4-hydroxymandelic acid, and by acyclovir, cefazolin, baclofen, 6-mercaptopurine, benzoic acid, and ketoprofen. These results suggest that OAT3 mediates the brain-to-blood transport of indoxyl sulfate, and is also involved in the efflux transport of neurotransmitter metabolites and drugs. Therefore, inhibition of the brain-to-blood transport involving OAT3 would occur in uremia and lead to the accumulation of neurotransmitter metabolites and drugs in the brain. 相似文献
Imposex, i.e. the development of additional male sex organs (penis and/or vas deferens), in females of gonochorist marine
and freshwater gastropods, is known to be caused by tributyltin (TBT), and it has been widely used as a biomonitoring tool
in environmental surveys for TBT pollution assessment. In this study, we experimentally tested the potential to induce imposex
by another endocrine disruptor (polychlorinated biphenyls [PCBs] mixture—Aroclor 1260). Adults of Hexaplex trunculus with low imposex level, coming from an Italian Marine Protected Area, were injected separately with different doses of tributyltin
chloride (TBTCl) and Aroclor 1260. The compounds were dissolved in ethanol and the organisms were narcotised by immersion
in MgCl2 solution before injection. Before and after the experiment, butyltin compounds (BuTs) and PCB tissue concentrations were
determined. A significant increase in imposex with respect to non-treated organisms was observed in all treatments, including
artefact controls. No clear correlation was observed between BuTs and PCB tissue concentrations and indices of imposex incidence.
Based on these results, no assumption can be formulated about PCB effect on imposex development. Nevertheless, they suggest
that the imposex level increase, at least in H. trunculus, in laboratory conditions might not be caused by TBT only, but it would rather be a non-specific response to different stress
stimuli. 相似文献