With the ongoing acceleration of global urbanization, an increasingly larger proportion of natural habitats are being transformed and utilized by humans. Urbanization has a substantial impact on animal populations, ex...With the ongoing acceleration of global urbanization, an increasingly larger proportion of natural habitats are being transformed and utilized by humans. Urbanization has a substantial impact on animal populations, exposing them to greater risks, but also presenting new opportunities and resources. Although the effects of urbanization and brood parasitism on the population dynamics and behavior of host birds have received considerable attention, there has been comparatively little research on how urbanization might affect the risk of brood parasitism on host birds. From April to August in 2023 and 2024, we investigated the risk of brood parasitism on Azure-winged Magpies (Cyanopica cyanus) breeding in the urban center, outskirt, and rural areas of Wuhan City, Hubei Province, China. The results revealed significant differences in the risk of brood parasitism among Azure-winged Magpies in the three regions, with the proportion of magpies parasitized by the Asian Koel (Eudynamys scolopaceus) being found to be significantly lower in the city center (0%) than that in outskirt (3.8%) and rural (11.4%) areas. Our results are consistent with the idea that cities can act as refuges that reduce the risk of brood parasitism experienced by host Azure-winged Magpies. Accordingly, breeding in cities enables Azure-winged Magpies to escape brood parasitism by the Asian Koel.展开更多
Rates of brood parasitism vary extensively among host species and populations of a single host species. In this study, we documented and compared parasitism rates of two sympatric hosts, the Oriental Reed Warbler （Ac...Rates of brood parasitism vary extensively among host species and populations of a single host species. In this study, we documented and compared parasitism rates of two sympatric hosts, the Oriental Reed Warbler （Acrocephalus orientalis） and the Reed Parrotbill （Paradoxornis heudei）, in three populations in China. We found that the Common Cuckoo （Cuculus canorus） is the only parasite using both the Oriental Reed Warbler and Reed Parrotbill as hosts, with a parasitism rate of 22.4%-34.3% and 0%-4.6%, respectively. The multiple parasitism rates were positively correlated with local parasitism rates across three geographic populations of Oriental Reed Warbler, which implies that higher pressure of parasitism lead to higher multiple parasitism rate. Furthermore, only one phenotype of cuckoo eggs was found in the nests of these two host species. Our results lead to two conclusions： （1） The Oriental Reed Warbler should be considered the major host of Common Cuckoo in our study sites; and （2） obligate parasitism on Oriental Reed Warbler by Common Cuckoo is specialized but flexible to some extent, i.e., using Reed Parrotbill as a secondary host. Further studies focusing on egg recognition and rejection behaviour of these two host species should be conducted to test our predictions.展开更多
Objective:To ascertain the level of intestinal parasites vis-a-vis the quality of housing and water supply,and sanitary conditions among the people of Kuraje village in Zamfara state. Methods:The study was cross secti...Objective:To ascertain the level of intestinal parasites vis-a-vis the quality of housing and water supply,and sanitary conditions among the people of Kuraje village in Zamfara state. Methods:The study was cross sectional in nature.Individual households were selected using systematic random sampling methods and pre-tested questionnaires were administered to all the members of each household.Stool samples were collected and processed using standard laboratory procedures.Housing conditions,sources of water and sanitary conditions of the households were also inspected.Results were analysed using Epi Info 2006 model.Results: The prevalence of intestinal parasites was 67.0%(347/519).72.3%(251/347),17.0%(59/347),and 10.7%(37/347) had one,two and three or more parasites,respectively.The associated factors with intestinal parasites were poor housing and sanitary conditions,lack of potable water and illiteracy.The commonest parasites encountered were hookworm(22.0%),Ascaris lumbricoides (18.5%),and Strongyloides stercoralis(15.6%) while the least common was Enterobius vermicularis (1.6%).Others were Giardia lamblia(5.7%),Hymenolepsis nana(5.0%),Trichuris trichiura(8.8%), Entamoeba histolytica(14.4%) and Schistosoma mansoni(8.4%).Conclusions:The infection rate of intestinal parasites in Kuraje village is high.More efforts should be intensified towards improvement in sanitary and housing standards,supply of potable water and institution of a more comprehensive literacy programme for the people of the community.展开更多
Background: The success of cuckoo parasitism is thought to depend largely on the extent of egg matching between cuckoo and host eggs, since poor-matching cuckoo egg would lead to more frequent egg rejection by the hos...Background: The success of cuckoo parasitism is thought to depend largely on the extent of egg matching between cuckoo and host eggs, since poor-matching cuckoo egg would lead to more frequent egg rejection by the host. In this study, we investigated how egg-spot matching between the Common Cuckoo(Cuculus canorus) and its host, the Oriental Reed Warbler(Acrocephalus orientalis) is affected by the local parasitism rate, nest availability in breeding synchronization and egg rejection.Methods: We used the paired design of parasitized and their nearest non-parasitized nests where breeding occurred simultaneously to compare egg-spot matching. The image analysis was used to compare four eggshell pattern variables, namely spot size, density, coverage on the different areas of egg surface, and the distribution on the whole egg surface. Egg recognition experiments were conducted to test the effect of egg spots on egg rejection by the host.Results: Our results show that much better matching in almost all spot parameters tested on the side of the egg and the spot distribution on the whole egg occurred in parasitized nests than in non-parasitized nests. Matching of spot density between cuckoo and host eggs in parasitized nests increased with the synchronization between temporal availability of nests and the egg-laying period of female cuckoos. Egg recognition experiments in which the warbler eggs were deliberately painted with extra spots led to a significantly higher egg rejection rate(78.3%) than of unpainted eggs.Conclusion: Our data suggest that both the high temporal encounter rate between cuckoo and warbler nests as well as the high egg rejection ability of the host are important factors for egg-spot matching of the cuckoos.展开更多
Ten populations of Radopholus similis from different ornamental hosts were tested for their parasitism and pathogenicity to water spinach （Ipomoea aquatic）, malabar spinach （Basella rubra）, and squash （Cucurbita ...Ten populations of Radopholus similis from different ornamental hosts were tested for their parasitism and pathogenicity to water spinach （Ipomoea aquatic）, malabar spinach （Basella rubra）, and squash （Cucurbita moschata） in pots. The re- sults showed all three plants were new hosts of R. similis. Growth parameters of plants inoculated with nematodes were significantly lower than those of healthy control plants. All R. similis populations were pathogenic to the three plants, but pathogenicity differed among populations from different hosts. The same R. similis populations also showed different pathogenic effects in the three different plants. RadN5 population from Anthurium andraeanum had the highest pathoge- nicity to the three studied plants. RadN1 from A. andraeanum had the lowest pathogenicity to squash and RadN7 from Chrysalidocarpus lutesens had the lowest pathogenicity to water spinach and malabar spinach. R. similis is usually associated with root tissues, but here we report that it could be found to move and feed in the stem bases of all three studied plants. Sequence and phylogenetic analyses of DNA markers of the 18S rRNA, 28S rRNA, ITS rRNA, and mitochondrial DNA gene sequences of ten R. similis populations revealed significant genetic diversity. RadN5 and RadN6 populations from anthurium showed a close genetic relationship and could be distinguished from other populations by PCR-RFLP. At the same time, RadN5 and RadN6 populations were the most pathogenic to three studied plants. These results confirm the existence of large biological variability and molecular diversity among R. similis populations from the same or different hosts, and these characteristics are related to pathogenic variability.展开更多
Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when...Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when the host“wins”the coevolutionary arms race.By recreating bygone species interactions,using artificial parasitism experiments,lingering defensive behaviors that evolved in the context of parasitism can be understood and may even be used to identify the unknown agent of parasitism past.Here we present the first study of this type by evaluating lingering“frontline”nest defenses that have evolved to prevent egg laying in a former brood parasite host.The Australian reed warbler Acrocephalus australis is currently not parasitized but is known to exhibit fine-tuned egg discrimination—a defensive behavior indicative of a past brood parasite–host arms race and common in closely related parasitized species.Here,using 3D-printed models of adult brood parasites,we examined whether the Australian reed warbler also exhibits frontline defenses to adult brood parasites,and whether we could use these defenses to identify the warbler’s“ghost of parasitism past.”Our findings provide evidence that the Australian reed warbler readily engages in frontline defenses that are considered adaptive specifically in the context of brood parasitism.However,individuals were unable to discriminate between adults of different brood parasite species at their nest.Overall,our results demonstrate that despite a relaxation in selection,defenses against brood parasitism can be maintained across multiple stages of the host’s nesting cycle,and further suggest that,in accordance with previous findings,that learning may be important for fine-tuning frontline defense.展开更多
Nestmate recognition codes show remarkable chemical complexity, involving multiple biochemical pathways. This complexity provides the opportunity to evaluate the ecological and social conditions that favor the evoluti...Nestmate recognition codes show remarkable chemical complexity, involving multiple biochemical pathways. This complexity provides the opportunity to evaluate the ecological and social conditions that favor the evolution of complex signaling. We investigated how the chemical signatures of three populations of the social paper wasp Polistes biglumis differed in terms of concentration of hydrocarbons, proportions of branched hydrocarbons and overall variation. We tested whether the variation in chemical signatures among populations could be explained by the prevalence of social parasites or whether this was just an effect of local abiotic conditions which influenced the composition of the hydrocarbon cuticular layer. We studied the chemical signa- ture in three populations in which obligate social parasites differed in the selection pressures they imposed on host populations. Within each population, we restricted our analyses to non-parasitized hosts, to avoid potential short-term effects of parasite pres- ence on the host chemical signatures. We found that host colonies in parasitized populations had more diverse profiles than the parasite-free population. Moreover, the overall concentration of hydrocarbons and the relative proportion of branched hydrocar- bons were larger in the parasitized populations, relative to the non-parasitized one. This is to our knowledge the first evidence in favour of the hypothesis that different traits in the host chemical signatures as a whole undergo evolutionary changes resulting from directional or balancing selection imposed by social parasites. We conclude that obligate social parasites act as ＇engines of diversity＇ on host chemical signatures and operate in favor of a geographic mosaic of diverging communication codes展开更多
A fun dame ntal question in biology is how diversity evolves and why some clades are more diverse than others.Phenotypic diversity has often been shown to result from morphological adaptation to different habitats.The...A fun dame ntal question in biology is how diversity evolves and why some clades are more diverse than others.Phenotypic diversity has often been shown to result from morphological adaptation to different habitats.The role of behavioral interactions as a driver of broadscale phenotypic diversity has received comparatively less attention.Behavioral interactions,however,are a key agent of natural selection.Antagonistic behavioral interactions with predators or with parasites can have significant fitness consequences,and hence act as strong evolutionary forces on the phe no type of species,ultimately gen erating diversity betwee n species of both victims and exploiters.Avian obligate brood parasites lay their eggs in the nests of other species,their hosts,and this behavioral interaction between hosts and parasites is often considered one of the best examples of coevolution in the natural world.In this review,we use the coevolution between brood parasites and their hosts to illustrate the potential of behavioral interactions to drive evolution of phenotypic diversity at different taxonomic scales.We provide a bridge between behavioral ecology and macroevolution by describing how this interaction has increased avian phenotypic diversity not only in the brood parasitic clades but also in their hosts.展开更多
Background:Red-winged Blackbirds(Agelaius phoeniceus),hereafter red-wings,are much less frequently parasitized by Brown-headed Cowbirds(Molothrus ater)in eastern North America than in central North America and had not...Background:Red-winged Blackbirds(Agelaius phoeniceus),hereafter red-wings,are much less frequently parasitized by Brown-headed Cowbirds(Molothrus ater)in eastern North America than in central North America and had not been recorded as hosts in our study area in southeastern Pennsylvania.Although hosts of Old World cuckoos(Cuculidae)often show geographic variation in egg rejection behavior,cowbird hosts typically exhibit uniform responses of all acceptance or all rejection of cowbird eggs.Thus,geographic variation in cowbird parasitism frequencies might reflect a different behavioral response to parasitism by hosts where only some populations reject parasitism.In this study,we tested whether egg rejection behavior may explain the lack of parasitism observed in our eastern red-wing population,which may provide insight into low parasitism levels across eastern North America.Methods:We parasitized red-wing nests with model cowbird eggs to determine their response to parasitism.Nests were tested across three nest stages and compared to control nests with no manipulations.Because rejection differed significantly by stage,we compared responses separately for each nest stage.We also monitored other songbird nests to identify parasitism frequencies on all potential hosts.Results:Red-wings showed significantly more rejections during the building stage,but not for the laying and incubation stages.Rejections during nest building involved mostly egg burials,which likely represent a continuation of the nest building process rather than true rejection of the cowbird egg.Excluding these responses,red-wings rejected 15%of cowbird eggs,which is similar to rejection levels from other studies and populations.The overall parasitism frequency on 11 species surveyed in our study area was only 7.4%.Conclusions:Egg rejection behavior does not explain the lack of parasitism on red-wings in our eastern population.Alternatively,we suggest that cowbird preference for other hosts and the low abundance of cowbirds in the east might explain the lack of parasitism.Future research should also explore cowbird and host density and the makeup of the host community to explain the low levels of parasitism on red-wings across eastern North America because egg rejection alone is unlikely to explain this broad geographic trend.展开更多
The Plaintive Cuckoo(Cacomantis merulinus) is a widespread brood parasite in Asia, but no data on host species utilization in Bangladesh exist. By searching for nests of all possible host species of the Plaintive Cuck...The Plaintive Cuckoo(Cacomantis merulinus) is a widespread brood parasite in Asia, but no data on host species utilization in Bangladesh exist. By searching for nests of all possible host species of the Plaintive Cuckoo at Jahangirnagar university campus, north of Dhaka, we were able to determine which hosts were used in this area. We found that the Common Tailorbird(Orthotomus sutorius) was the only potential host used by Plaintive Cuckoos, and parasitism rate was rather high(31.3 %, n = 16). However, both host and cuckoo breeding success was poor(0 %, n = 16) due to frequent nest predation. Details on host and cuckoo egg appearance are provided. Our findings indicate that Common Tailorbirds are common hosts of the Plaintive Cuckoo in Central Bangladesh.展开更多
Common Cuckoos(Cuculus canorus) parasitize nests of small passerines.e Cuckoo chicks cause the death of their nest-mates when evicting eggs or nestlings from the nests;consequently,hosts su er from a high loss of repr...Common Cuckoos(Cuculus canorus) parasitize nests of small passerines.e Cuckoo chicks cause the death of their nest-mates when evicting eggs or nestlings from the nests;consequently,hosts su er from a high loss of reproduction.Host adaptations against parasitism,e.g.,by egg discrimination behavior,and cuckoo counter-adaptations to hosts,e.g.,by mimetic eggs,are often regarded as a result of the arms race between the two interacting species.In Hungary Great Reed Warblers(Acrocephalus arundinaceus) are the main hosts of cuckoos,su ering from heavy parasitism(ca.40-65%).e Oriental Reed Warbler(A.orientalis),formerly a subspecies of the Great Reed Warbler(A.a.orientalis),is also a highly parasitized host in Japan(25-40%).We compared main characteristics of Cuckoo parasitism in these two distant areas from the Western and Eastern Palearctic by comparing cuckoo egg mimicry.We measured color characteristics of host and parasitic eggs by spectrophotometer.Visual modeling revealed lower chromatic distances between Cuckoo and host eggs in Hungary than in Japan,but high variation both in host and Cuckoo eggs may cause matching problems in Hungary.Achromatic(brightness) di erence between host and Cuckoo eggs were lower in Japan than in Hungary,and it proved to be the most important factor a ecting egg rejection.Hosts rejected Cuckoo eggs at similar frequencies(37% and 35% in Hungary and Japan,respectively).Host adaptation,i.e.,egg rejection behavior,seems to be preceding Cuckoo counter-adaptations to hosts in Japan.We suggest that the Cuckoo-Great/Oriental Reed Warbler relationships developed in alternative ways in Japan and Hungary,and they represent di erent stages of their arms race.展开更多
A double parasitism(isopod Cymothoidae and copepod Pennellidae) on black-barred halfbeak fish,Hemiramphus far,was recorded from Pazhayar coastal waters(southeast coast of India) during September 2008.This is the first...A double parasitism(isopod Cymothoidae and copepod Pennellidae) on black-barred halfbeak fish,Hemiramphus far,was recorded from Pazhayar coastal waters(southeast coast of India) during September 2008.This is the first report from this region and the infection is discussed in relation to environmental and biological parameters.展开更多
基金supported by the National Key R&D Program of China(2023YFF1304600)supported by the National Natural Science Foundation of China(No.32160242 to JL,32470513 and 32270526 to WL)supported by the 2023 Ningxia Hui Autonomous Region Youth Science and Technology Support Talent Training Project.
文摘With the ongoing acceleration of global urbanization, an increasingly larger proportion of natural habitats are being transformed and utilized by humans. Urbanization has a substantial impact on animal populations, exposing them to greater risks, but also presenting new opportunities and resources. Although the effects of urbanization and brood parasitism on the population dynamics and behavior of host birds have received considerable attention, there has been comparatively little research on how urbanization might affect the risk of brood parasitism on host birds. From April to August in 2023 and 2024, we investigated the risk of brood parasitism on Azure-winged Magpies (Cyanopica cyanus) breeding in the urban center, outskirt, and rural areas of Wuhan City, Hubei Province, China. The results revealed significant differences in the risk of brood parasitism among Azure-winged Magpies in the three regions, with the proportion of magpies parasitized by the Asian Koel (Eudynamys scolopaceus) being found to be significantly lower in the city center (0%) than that in outskirt (3.8%) and rural (11.4%) areas. Our results are consistent with the idea that cities can act as refuges that reduce the risk of brood parasitism experienced by host Azure-winged Magpies. Accordingly, breeding in cities enables Azure-winged Magpies to escape brood parasitism by the Asian Koel.
基金supported by a grant from NIH(R01AI132695)to RM。
文摘Chronic wasting disease—a prion disease affecting cervids:Many neurological conditions,including Alzheimer's and Parkinson's diseases,amyotrophic lateral sclerosis,frontotemporal dementias,among others,are caused by the accumulation of misfolded proteins in the brain.These diseases affect not only humans,but also animals.
文摘通过传统形态分类结合DNA条形码方法对寄生性天敌伲姬小蜂属Necremnus Thomson(姬小蜂科Eulophidae)进行整合分类研究,查明东帕米尔高原伲姬小蜂属资源状况,为该属物种的快速准确鉴定以及生物学、系统发育等研究奠定基础。于2021-2023年以网扫和黄盘诱集为主要采集方法获得东帕米尔高原的伲姬小蜂属标本;在数码体视显微镜下观察测量标本的形态特征,进行形态分类学研究;在传统形态鉴定的基础上,利用无损伤提取法提取物种基因组DNA,获得COI序列,并与数据库中该属物种COI序列比对,分析其碱基组成和遗传距离,基于最大似然法构建系统发育树,进行系统发育分析。本研究发现东帕米尔高原伲姬小蜂属5种,其中一个新种—暗黑伲姬小蜂Necremnus nigra Xi&Hu, sp.nov.,对该新种进行了形态描述,并提供了形态特征图。DNA条形码分析结果表明,暗黑伲姬小蜂与潜叶蛾伲姬小蜂亲缘关系更近。
基金supported by the National Natural Science Foundation of China(31071938 and 31272328 to WL,31101646 and 31260514 to CY)Program for New Century Excellent Talents in University(NCET-10-0111 to WL)the United Foundation for Natural Science of National Natural Science Foundation of China and People's Government of Guangdong Province(U0833005 to ZZ)
文摘Rates of brood parasitism vary extensively among host species and populations of a single host species. In this study, we documented and compared parasitism rates of two sympatric hosts, the Oriental Reed Warbler （Acrocephalus orientalis） and the Reed Parrotbill （Paradoxornis heudei）, in three populations in China. We found that the Common Cuckoo （Cuculus canorus） is the only parasite using both the Oriental Reed Warbler and Reed Parrotbill as hosts, with a parasitism rate of 22.4%-34.3% and 0%-4.6%, respectively. The multiple parasitism rates were positively correlated with local parasitism rates across three geographic populations of Oriental Reed Warbler, which implies that higher pressure of parasitism lead to higher multiple parasitism rate. Furthermore, only one phenotype of cuckoo eggs was found in the nests of these two host species. Our results lead to two conclusions： （1） The Oriental Reed Warbler should be considered the major host of Common Cuckoo in our study sites; and （2） obligate parasitism on Oriental Reed Warbler by Common Cuckoo is specialized but flexible to some extent, i.e., using Reed Parrotbill as a secondary host. Further studies focusing on egg recognition and rejection behaviour of these two host species should be conducted to test our predictions.
文摘Objective:To ascertain the level of intestinal parasites vis-a-vis the quality of housing and water supply,and sanitary conditions among the people of Kuraje village in Zamfara state. Methods:The study was cross sectional in nature.Individual households were selected using systematic random sampling methods and pre-tested questionnaires were administered to all the members of each household.Stool samples were collected and processed using standard laboratory procedures.Housing conditions,sources of water and sanitary conditions of the households were also inspected.Results were analysed using Epi Info 2006 model.Results: The prevalence of intestinal parasites was 67.0%(347/519).72.3%(251/347),17.0%(59/347),and 10.7%(37/347) had one,two and three or more parasites,respectively.The associated factors with intestinal parasites were poor housing and sanitary conditions,lack of potable water and illiteracy.The commonest parasites encountered were hookworm(22.0%),Ascaris lumbricoides (18.5%),and Strongyloides stercoralis(15.6%) while the least common was Enterobius vermicularis (1.6%).Others were Giardia lamblia(5.7%),Hymenolepsis nana(5.0%),Trichuris trichiura(8.8%), Entamoeba histolytica(14.4%) and Schistosoma mansoni(8.4%).Conclusions:The infection rate of intestinal parasites in Kuraje village is high.More efforts should be intensified towards improvement in sanitary and housing standards,supply of potable water and institution of a more comprehensive literacy programme for the people of the community.
基金supported by the National Natural Science Foundation of China (Nos.31301888 and 31672316 to DL)the General Scientific Research Project of the Education Department of Liaoning Province (L2015196 to DL)the Open Fund of the Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, Beijing Normal University (K1401 to DL)
文摘Background: The success of cuckoo parasitism is thought to depend largely on the extent of egg matching between cuckoo and host eggs, since poor-matching cuckoo egg would lead to more frequent egg rejection by the host. In this study, we investigated how egg-spot matching between the Common Cuckoo(Cuculus canorus) and its host, the Oriental Reed Warbler(Acrocephalus orientalis) is affected by the local parasitism rate, nest availability in breeding synchronization and egg rejection.Methods: We used the paired design of parasitized and their nearest non-parasitized nests where breeding occurred simultaneously to compare egg-spot matching. The image analysis was used to compare four eggshell pattern variables, namely spot size, density, coverage on the different areas of egg surface, and the distribution on the whole egg surface. Egg recognition experiments were conducted to test the effect of egg spots on egg rejection by the host.Results: Our results show that much better matching in almost all spot parameters tested on the side of the egg and the spot distribution on the whole egg occurred in parasitized nests than in non-parasitized nests. Matching of spot density between cuckoo and host eggs in parasitized nests increased with the synchronization between temporal availability of nests and the egg-laying period of female cuckoos. Egg recognition experiments in which the warbler eggs were deliberately painted with extra spots led to a significantly higher egg rejection rate(78.3%) than of unpainted eggs.Conclusion: Our data suggest that both the high temporal encounter rate between cuckoo and warbler nests as well as the high egg rejection ability of the host are important factors for egg-spot matching of the cuckoos.
基金funded by the National Natural Science Foundation of China (31071665)the Special Fund for Agro-Scientific Research in the Public Interest, China (200903040)
文摘Ten populations of Radopholus similis from different ornamental hosts were tested for their parasitism and pathogenicity to water spinach （Ipomoea aquatic）, malabar spinach （Basella rubra）, and squash （Cucurbita moschata） in pots. The re- sults showed all three plants were new hosts of R. similis. Growth parameters of plants inoculated with nematodes were significantly lower than those of healthy control plants. All R. similis populations were pathogenic to the three plants, but pathogenicity differed among populations from different hosts. The same R. similis populations also showed different pathogenic effects in the three different plants. RadN5 population from Anthurium andraeanum had the highest pathoge- nicity to the three studied plants. RadN1 from A. andraeanum had the lowest pathogenicity to squash and RadN7 from Chrysalidocarpus lutesens had the lowest pathogenicity to water spinach and malabar spinach. R. similis is usually associated with root tissues, but here we report that it could be found to move and feed in the stem bases of all three studied plants. Sequence and phylogenetic analyses of DNA markers of the 18S rRNA, 28S rRNA, ITS rRNA, and mitochondrial DNA gene sequences of ten R. similis populations revealed significant genetic diversity. RadN5 and RadN6 populations from anthurium showed a close genetic relationship and could be distinguished from other populations by PCR-RFLP. At the same time, RadN5 and RadN6 populations were the most pathogenic to three studied plants. These results confirm the existence of large biological variability and molecular diversity among R. similis populations from the same or different hosts, and these characteristics are related to pathogenic variability.
文摘Coevolutionary arms races between brood parasites and hosts provide tractable systems for understanding antagonistic coevolution in nature;however,little is known about the fate of frontline antiparasite defenses when the host“wins”the coevolutionary arms race.By recreating bygone species interactions,using artificial parasitism experiments,lingering defensive behaviors that evolved in the context of parasitism can be understood and may even be used to identify the unknown agent of parasitism past.Here we present the first study of this type by evaluating lingering“frontline”nest defenses that have evolved to prevent egg laying in a former brood parasite host.The Australian reed warbler Acrocephalus australis is currently not parasitized but is known to exhibit fine-tuned egg discrimination—a defensive behavior indicative of a past brood parasite–host arms race and common in closely related parasitized species.Here,using 3D-printed models of adult brood parasites,we examined whether the Australian reed warbler also exhibits frontline defenses to adult brood parasites,and whether we could use these defenses to identify the warbler’s“ghost of parasitism past.”Our findings provide evidence that the Australian reed warbler readily engages in frontline defenses that are considered adaptive specifically in the context of brood parasitism.However,individuals were unable to discriminate between adults of different brood parasite species at their nest.Overall,our results demonstrate that despite a relaxation in selection,defenses against brood parasitism can be maintained across multiple stages of the host’s nesting cycle,and further suggest that,in accordance with previous findings,that learning may be important for fine-tuning frontline defense.
文摘Nestmate recognition codes show remarkable chemical complexity, involving multiple biochemical pathways. This complexity provides the opportunity to evaluate the ecological and social conditions that favor the evolution of complex signaling. We investigated how the chemical signatures of three populations of the social paper wasp Polistes biglumis differed in terms of concentration of hydrocarbons, proportions of branched hydrocarbons and overall variation. We tested whether the variation in chemical signatures among populations could be explained by the prevalence of social parasites or whether this was just an effect of local abiotic conditions which influenced the composition of the hydrocarbon cuticular layer. We studied the chemical signa- ture in three populations in which obligate social parasites differed in the selection pressures they imposed on host populations. Within each population, we restricted our analyses to non-parasitized hosts, to avoid potential short-term effects of parasite pres- ence on the host chemical signatures. We found that host colonies in parasitized populations had more diverse profiles than the parasite-free population. Moreover, the overall concentration of hydrocarbons and the relative proportion of branched hydrocar- bons were larger in the parasitized populations, relative to the non-parasitized one. This is to our knowledge the first evidence in favour of the hypothesis that different traits in the host chemical signatures as a whole undergo evolutionary changes resulting from directional or balancing selection imposed by social parasites. We conclude that obligate social parasites act as ＇engines of diversity＇ on host chemical signatures and operate in favor of a geographic mosaic of diverging communication codes
基金McKenzie Fellowship from University of Melbourne.N.E.L.the Australian Research Council grant DPI80100021a Wolfson Merit Award from the Royal Society.
文摘A fun dame ntal question in biology is how diversity evolves and why some clades are more diverse than others.Phenotypic diversity has often been shown to result from morphological adaptation to different habitats.The role of behavioral interactions as a driver of broadscale phenotypic diversity has received comparatively less attention.Behavioral interactions,however,are a key agent of natural selection.Antagonistic behavioral interactions with predators or with parasites can have significant fitness consequences,and hence act as strong evolutionary forces on the phe no type of species,ultimately gen erating diversity betwee n species of both victims and exploiters.Avian obligate brood parasites lay their eggs in the nests of other species,their hosts,and this behavioral interaction between hosts and parasites is often considered one of the best examples of coevolution in the natural world.In this review,we use the coevolution between brood parasites and their hosts to illustrate the potential of behavioral interactions to drive evolution of phenotypic diversity at different taxonomic scales.We provide a bridge between behavioral ecology and macroevolution by describing how this interaction has increased avian phenotypic diversity not only in the brood parasitic clades but also in their hosts.
基金provided by a BEARS Grant and a Neag Undergraduate Research Grant from Kutztown University
文摘Background:Red-winged Blackbirds(Agelaius phoeniceus),hereafter red-wings,are much less frequently parasitized by Brown-headed Cowbirds(Molothrus ater)in eastern North America than in central North America and had not been recorded as hosts in our study area in southeastern Pennsylvania.Although hosts of Old World cuckoos(Cuculidae)often show geographic variation in egg rejection behavior,cowbird hosts typically exhibit uniform responses of all acceptance or all rejection of cowbird eggs.Thus,geographic variation in cowbird parasitism frequencies might reflect a different behavioral response to parasitism by hosts where only some populations reject parasitism.In this study,we tested whether egg rejection behavior may explain the lack of parasitism observed in our eastern red-wing population,which may provide insight into low parasitism levels across eastern North America.Methods:We parasitized red-wing nests with model cowbird eggs to determine their response to parasitism.Nests were tested across three nest stages and compared to control nests with no manipulations.Because rejection differed significantly by stage,we compared responses separately for each nest stage.We also monitored other songbird nests to identify parasitism frequencies on all potential hosts.Results:Red-wings showed significantly more rejections during the building stage,but not for the laying and incubation stages.Rejections during nest building involved mostly egg burials,which likely represent a continuation of the nest building process rather than true rejection of the cowbird egg.Excluding these responses,red-wings rejected 15%of cowbird eggs,which is similar to rejection levels from other studies and populations.The overall parasitism frequency on 11 species surveyed in our study area was only 7.4%.Conclusions:Egg rejection behavior does not explain the lack of parasitism on red-wings in our eastern population.Alternatively,we suggest that cowbird preference for other hosts and the low abundance of cowbirds in the east might explain the lack of parasitism.Future research should also explore cowbird and host density and the makeup of the host community to explain the low levels of parasitism on red-wings across eastern North America because egg rejection alone is unlikely to explain this broad geographic trend.
基金supported by a grant through‘Quota Scheme’at Norwegian University of Science and Technology(NTNU)
文摘The Plaintive Cuckoo(Cacomantis merulinus) is a widespread brood parasite in Asia, but no data on host species utilization in Bangladesh exist. By searching for nests of all possible host species of the Plaintive Cuckoo at Jahangirnagar university campus, north of Dhaka, we were able to determine which hosts were used in this area. We found that the Common Tailorbird(Orthotomus sutorius) was the only potential host used by Plaintive Cuckoos, and parasitism rate was rather high(31.3 %, n = 16). However, both host and cuckoo breeding success was poor(0 %, n = 16) due to frequent nest predation. Details on host and cuckoo egg appearance are provided. Our findings indicate that Common Tailorbirds are common hosts of the Plaintive Cuckoo in Central Bangladesh.
基金supported by the bilateral project of the Japan Society for the Promotion of Science (JSPS)the Hungarian Academy of Sciences to F.T. and C.M. 2003-2005+1 种基金by the Hungarian Scienti c Research Fund (OTKAgrant No.T35015,48397 and 83217) to C.M. e Duna-Ipoly and Kiskunság National Parks provided permissions for research
文摘Common Cuckoos(Cuculus canorus) parasitize nests of small passerines.e Cuckoo chicks cause the death of their nest-mates when evicting eggs or nestlings from the nests;consequently,hosts su er from a high loss of reproduction.Host adaptations against parasitism,e.g.,by egg discrimination behavior,and cuckoo counter-adaptations to hosts,e.g.,by mimetic eggs,are often regarded as a result of the arms race between the two interacting species.In Hungary Great Reed Warblers(Acrocephalus arundinaceus) are the main hosts of cuckoos,su ering from heavy parasitism(ca.40-65%).e Oriental Reed Warbler(A.orientalis),formerly a subspecies of the Great Reed Warbler(A.a.orientalis),is also a highly parasitized host in Japan(25-40%).We compared main characteristics of Cuckoo parasitism in these two distant areas from the Western and Eastern Palearctic by comparing cuckoo egg mimicry.We measured color characteristics of host and parasitic eggs by spectrophotometer.Visual modeling revealed lower chromatic distances between Cuckoo and host eggs in Hungary than in Japan,but high variation both in host and Cuckoo eggs may cause matching problems in Hungary.Achromatic(brightness) di erence between host and Cuckoo eggs were lower in Japan than in Hungary,and it proved to be the most important factor a ecting egg rejection.Hosts rejected Cuckoo eggs at similar frequencies(37% and 35% in Hungary and Japan,respectively).Host adaptation,i.e.,egg rejection behavior,seems to be preceding Cuckoo counter-adaptations to hosts in Japan.We suggest that the Cuckoo-Great/Oriental Reed Warbler relationships developed in alternative ways in Japan and Hungary,and they represent di erent stages of their arms race.
基金Supported by the Chinese Academy of Sciences Research Fellowship for International Young Researchers to M Rajkumar hosted by J Sun,and the Knowledge Innovation Program of Chinese Academy of Sciences(Nos.KZCX2-YW-QN-205 and KZCX2-YW-213-2)
文摘A double parasitism(isopod Cymothoidae and copepod Pennellidae) on black-barred halfbeak fish,Hemiramphus far,was recorded from Pazhayar coastal waters(southeast coast of India) during September 2008.This is the first report from this region and the infection is discussed in relation to environmental and biological parameters.
