PeerJ Preprints: Ecologyhttps://peerj.com/preprints/index.atom?journal=peerj&subject=1100Ecology articles published in PeerJ PreprintsDevelopment and application of a robotic zebra finch (RoboFinch) to study multimodal cues in vocal communicationhttps://peerj.com/preprints/28004v32019-12-302019-12-30Ralph SimonJudith VarkevisserEzequiel MendozaKlaus HochradelConstance ScharffKatharina RiebelWouter Halfwerk
Understanding animal behaviour through psychophysical experimentation is often limited by insufficiently realistic stimulus representation. Important physical dimensions of signals and cues, especially those that are outside the spectrum of human perception, can be difficult to standardize and control separately with currently available recording and displaying techniques (e.g. video displays). Accurate stimulus control is in particular important when studying multimodal signals, as spatial and temporal alignment between stimuli is often crucial. Especially for audiovisual presentations, some of these limitations can be circumvented by the employment of animal robots that are superior to video presentations in all situations requiring realistic 3D presentations to animals. Here we report the development of a robotic zebra finch, called RoboFinch, and how it can be used to study vocal learning in a songbird, the zebra finch.
Understanding animal behaviour through psychophysical experimentation is often limited by insufficiently realistic stimulus representation. Important physical dimensions of signals and cues, especially those that are outside the spectrum of human perception, can be difficult to standardize and control separately with currently available recording and displaying techniques (e.g. video displays). Accurate stimulus control is in particular important when studying multimodal signals, as spatial and temporal alignment between stimuli is often crucial. Especially for audiovisual presentations, some of these limitations can be circumvented by the employment of animal robots that are superior to video presentations in all situations requiring realistic 3D presentations to animals. Here we report the development of a robotic zebra finch, called RoboFinch, and how it can be used to study vocal learning in a songbird, the zebra finch.Discrete stochastic marine metapopulation disease modelhttps://peerj.com/preprints/264542019-11-282019-11-28Gorka BidegainTal Ben-Horin
Some marine microparasitic pathogens can survive several months in the water column to make contact with or to be absorbed or filtered by hosts. Once inside, pathogens invade the host if they find suitable conditions for reproduction. This transmission from the environment occurs via pathogens released from infected and dead infected animals. Some recent modeling studies concentrated on the disease dynamic imposed by this complex interaction between population and water column at the host-pathogen level in single populations. However, only when a marine disease can be understood at the metapopulation scale effective approaches to management will become routinely achievable. The discrete-time disease model in this paper investigates both spatial and temporal dynamics of hosts and waterborne pathogens in a metapopulation system of three patches. This system with a patch providing infective particles and susceptible and infected individuals by dispersal tries to imitate the effect of current forces in the ocean on the passive dispersal of organisms. The model detects behaviours that are not present in single population continuous-time and deterministic models.
Some marine microparasitic pathogens can survive several months in the water column to make contact with or to be absorbed or filtered by hosts. Once inside, pathogens invade the host if they find suitable conditions for reproduction. This transmission from the environment occurs via pathogens released from infected and dead infected animals. Some recent modeling studies concentrated on the disease dynamic imposed by this complex interaction between population and water column at the host-pathogen level in single populations. However, only when a marine disease can be understood at the metapopulation scale effective approaches to management will become routinely achievable. The discrete-time disease model in this paper investigates both spatial and temporal dynamics of hosts and waterborne pathogens in a metapopulation system of three patches. This system with a patch providing infective particles and susceptible and infected individuals by dispersal tries to imitate the effect of current forces in the ocean on the passive dispersal of organisms. The model detects behaviours that are not present in single population continuous-time and deterministic models.First confirmation of the shell-boring oyster parasite Polydora websteri (Polychaeta: Spionidae) in Washington State, USAhttps://peerj.com/preprints/276212019-11-212019-11-21Julieta MartinelliHeather LopesLorenz HauserIsadora Jimenez-HidalgoTeri L KingJacqueline Padilla-GaminoPaul RawsonLaura SpencerJason WilliamsChelsea Wood
Invasions by the spionid polychaete Polydora websteri have resulted in the collapse of oyster aquaculture industries in Australia, New Zealand, and Hawaii. These worms burrow into the shells of bivalves, creating unsightly mud blisters that are unappealing to consumers and, when nicked during shucking, release mud and detritus that can foul oyster meats. Recent sightings of mud blisters on the shells of Pacific oysters (Crassostrea gigas) in Puget Sound, Washington, suggest a new spionid polychaete invasion. To determine the identity of the polychaete causing these mud blisters, we obtained Pacific oysters from two locations in Puget Sound and examined them for blisters and burrows associated with spionid infection. We then extracted polychaetes and sequenced mitochondrial (cytochrome c oxidase I [COI]) and nuclear (18S rRNA) genes to obtain species-level identifications for a subset of these worms. Our data confirm that P. websteri is present in mud blisters of Puget Sound oysters, constituting the first confirmed record of this species in Washington State. The presence of non-native P. websteri could threaten the sustainability of oyster aquaculture in Washington, which currently produces more shellfish than any other US state.
Invasions by the spionid polychaete Polydora websteri have resulted in the collapse of oyster aquaculture industries in Australia, New Zealand, and Hawaii. These worms burrow into the shells of bivalves, creating unsightly mud blisters that are unappealing to consumers and, when nicked during shucking, release mud and detritus that can foul oyster meats. Recent sightings of mud blisters on the shells of Pacific oysters (Crassostrea gigas) in Puget Sound, Washington, suggest a new spionid polychaete invasion. To determine the identity of the polychaete causing these mud blisters, we obtained Pacific oysters from two locations in Puget Sound and examined them for blisters and burrows associated with spionid infection. We then extracted polychaetes and sequenced mitochondrial (cytochrome c oxidase I [COI]) and nuclear (18S rRNA) genes to obtain species-level identifications for a subset of these worms. Our data confirm that P. websteri is present in mud blisters of Puget Sound oysters, constituting the first confirmed record of this species in Washington State. The presence of non-native P. websteri could threaten the sustainability of oyster aquaculture in Washington, which currently produces more shellfish than any other US state.Comparative studies of Echinometra mathaei species complex (Echinoidea: Camarodonta: Echinometridae) from two sites in Western Visayas, Philippines (Taklong Island, Guimaras and Nabas, Aklan)https://peerj.com/preprints/279862019-10-282019-10-28Joseph Ricky TamayoMaria Celia D Malay
Echinometra mathaei is a species complex with its constituent reproductively-isolated species informally called A, B, C and D based on studies done in Okinawa and the Red Sea. Little research has been done on this genus, and to our knowledge no studies have been done on the E. mathaei complex in the Philippines. To help clarify species delineations in the E. mathaei complex, a comparative study was done between two localities in Western Visayas, Philippines: the Taklong Island National Marine Reserve, in Nueva Valencia, Guimaras and Barangay Unidos in Nabas, Aklan. Morphological characteristics (spine color, milled rings, and skin around the peristome) and tubefeet and gonad spicules were observed. Two or possibly three species of Echinometra were found in the two sites based on their morphology and spicules, namely: Echinometra sp. A, Echinometra sp. C, and Echinometra affinity C, which resembles sp. C but differs in the milled rings and gonad spicules. Echinometra sp. C and E. affinity C cannot be distinguished on the basis of field-visible characters, thus the two morphs are referred to as Echinometra VC for the purpose of field surveys. Echinometra VC and Echinometra sp. A exhibited differences in abundance (VC was much more common) and microhabitat (VC was restricted to rocky shores and never observed in coral communities). To study the abundance and distribution of Echinometra VC, 50 m by 2 m belt transects were surveyed along the rocky shores of both sites: two parallel transects (at 0 m and at 0.9 m) and a perpendicular transect (only in Nabas), each with three replicates. The transect data showed that the mean densities for 0 m and 0.9 m in Nabas are significantly higher in Taklong yielding p-values of 0.001 and 0.002, respectively, when analyzed using t-test.Of the two sites, only Nabas showed a significant difference between the mean densities at 0 m and 0.9 m, with the mean density at 0.9 m significantly higher than that of 0 m yielding a p-value of 0.02 when analyzed using two-sample t-test. A Poisson regression on the perpendicular transect data from Nabas showed a trend of increasing Echinometra density with increasing distance from the shore. In the future, DNA barcoding and cross-fertilization studies should be performed in order to confirm the species of Echinometra observed. Many factors can affect the density and distribution of Echinometra, so further studies must be conducted to explain observed differences in their distribution and abundance.
Echinometra mathaei is a species complex with its constituent reproductively-isolated species informally called A, B, C and D based on studies done in Okinawa and the Red Sea. Little research has been done on this genus, and to our knowledge no studies have been done on the E. mathaei complex in the Philippines. To help clarify species delineations in the E. mathaei complex, a comparative study was done between two localities in Western Visayas, Philippines: the Taklong Island National Marine Reserve, in Nueva Valencia, Guimaras and Barangay Unidos in Nabas, Aklan. Morphological characteristics (spine color, milled rings, and skin around the peristome) and tubefeet and gonad spicules were observed. Two or possibly three species of Echinometra were found in the two sites based on their morphology and spicules, namely: Echinometra sp. A, Echinometra sp. C, and Echinometra affinity C, which resembles sp. C but differs in the milled rings and gonad spicules. Echinometra sp. C and E. affinity C cannot be distinguished on the basis of field-visible characters, thus the two morphs are referred to as Echinometra VC for the purpose of field surveys. Echinometra VC and Echinometra sp. A exhibited differences in abundance (VC was much more common) and microhabitat (VC was restricted to rocky shores and never observed in coral communities). To study the abundance and distribution of Echinometra VC, 50 m by 2 m belt transects were surveyed along the rocky shores of both sites: two parallel transects (at 0 m and at 0.9 m) and a perpendicular transect (only in Nabas), each with three replicates. The transect data showed that the mean densities for 0 m and 0.9 m in Nabas are significantly higher in Taklong yielding p-values of 0.001 and 0.002, respectively, when analyzed using t-test.Of the two sites, only Nabas showed a significant difference between the mean densities at 0 m and 0.9 m, with the mean density at 0.9 m significantly higher than that of 0 m yielding a p-value of 0.02 when analyzed using two-sample t-test. A Poisson regression on the perpendicular transect data from Nabas showed a trend of increasing Echinometra density with increasing distance from the shore. In the future, DNA barcoding and cross-fertilization studies should be performed in order to confirm the species of Echinometra observed. Many factors can affect the density and distribution of Echinometra, so further studies must be conducted to explain observed differences in their distribution and abundance.Seasonality in ecology: Progress and prospects in theoryhttps://peerj.com/preprints/272352019-10-112019-10-11Easton R WhiteAlan Hastings
Seasonality is an important feature of essentially all natural systems but the consequences of seasonality have been vastly underappreciated. Early work emphasized the role of seasonality in driving cyclic population dynamics, but the consequences of seasonality for ecological processes are far broader. Yet, seasonality is often not explicitly included in either empirical or theoretical studies. Many aspects of ecological dynamics can only be understood when seasonality is included, ranging from the oscillations in the incidence of childhood diseases to the coexistence of species. Through several case studies, we outline what is now known about seasonality in an ecological context and set the stage for future efforts. We discuss approaches for incorporating seasonality in mathematical models, including Floquet theory. We argue, however, that these tools are still limited in scope and more approaches need to be developed.
Seasonality is an important feature of essentially all natural systems but the consequences of seasonality have been vastly underappreciated. Early work emphasized the role of seasonality in driving cyclic population dynamics, but the consequences of seasonality for ecological processes are far broader. Yet, seasonality is often not explicitly included in either empirical or theoretical studies. Many aspects of ecological dynamics can only be understood when seasonality is included, ranging from the oscillations in the incidence of childhood diseases to the coexistence of species. Through several case studies, we outline what is now known about seasonality in an ecological context and set the stage for future efforts. We discuss approaches for incorporating seasonality in mathematical models, including Floquet theory. We argue, however, that these tools are still limited in scope and more approaches need to be developed.Physical habitat modeling methodology and applicationshttps://peerj.com/preprints/280052019-10-032019-10-03Ravi Nalamothu
The water management districts in Florida are required by s. 373.042, F.S. to establish minimum flow and levels (MFLs) for a priority list of water bodies that is updated each year. These MFLs are established for water bodies to prevent “significant harm” to the water resources or ecology because of withdrawals for beneficial use, and can be an effective water resource management tool. Protection of the resource from significant harm is a benefit to the variety of existing users of the resource as well as the ecological systems supported by the water bodies. This article presents an overview of a modeling technique and an associated tool developed to protect the instream habitat from significant harm.
The water management districts in Florida are required by s. 373.042, F.S. to establish minimum flow and levels (MFLs) for a priority list of water bodies that is updated each year. These MFLs are established for water bodies to prevent “significant harm” to the water resources or ecology because of withdrawals for beneficial use, and can be an effective water resource management tool. Protection of the resource from significant harm is a benefit to the variety of existing users of the resource as well as the ecological systems supported by the water bodies. This article presents an overview of a modeling technique and an associated tool developed to protect the instream habitat from significant harm.Endless forms of sexual selectionhttps://peerj.com/preprints/275842019-10-012019-10-01Willow R LindsayStaffan AnderssonBadreddine BererhiJacob HöglundArild JohnsenCharlotta KvarnemoErica H LederJan T LifjeldCalum E NinnesMats OlssonGeoff A ParkerTommaso PizzariAnna QvarnströmRebecca J SafranOla SvenssonScott Edwards
In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of a “stock-taking” workshop on sexual selection and conflict. Our aim is to identify and deliberate on outstanding questions and to stimulate discussion rather than provide a comprehensive overview of the entire field. These questions are organized into four thematic sections we deem essential to the field. First we focus on the evolution of mate choice and mating systems. Variation in mate quality can generate both competition and choice in the opposite sex, with implications for the evolution of mating systems. Limitations on mate choice may dictate the importance of direct vs. indirect benefits in mating decisions and consequently, mating systems, especially with regard to polyandry. Second, we focus on how sender and receiver mechanisms shape signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are challenging to measure. We view the neuroethology of sensory and cognitive receiver biases as the main key to signal form and the ‘aesthetic sense’ proposed by Darwin. Since a receiver bias is sufficient to both initiate and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate ‘null model’ of sexual selection. Thirdly, we focus on the genetic architecture of sexually selected traits. Despite advances in modern molecular techniques, the number and identity of genes underlying performance, display and secondary sexual traits remains largely unknown. In-depth investigations into the genetic basis of sexual dimorphism in the context of long-term field studies will reveal constraints and trajectories of sexually selected trait evolution. Finally, we focus on sexual selection and conflict as drivers of speciation. Population divergence and speciation are often influenced by an interplay between sexual and natural selection. The extent to which sexual selection promotes or counteracts population divergence may vary depending on the genetic architecture of traits as well as the covariance between mating competition and local adaptation. Additionally, post-copulatory processes, such as selection against heterospecific sperm, may influence the importance of sexual selection in speciation. We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection, and we offer potential avenues of research to advance this progress.
In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of a “stock-taking” workshop on sexual selection and conflict. Our aim is to identify and deliberate on outstanding questions and to stimulate discussion rather than provide a comprehensive overview of the entire field. These questions are organized into four thematic sections we deem essential to the field. First we focus on the evolution of mate choice and mating systems. Variation in mate quality can generate both competition and choice in the opposite sex, with implications for the evolution of mating systems. Limitations on mate choice may dictate the importance of direct vs. indirect benefits in mating decisions and consequently, mating systems, especially with regard to polyandry. Second, we focus on how sender and receiver mechanisms shape signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are challenging to measure. We view the neuroethology of sensory and cognitive receiver biases as the main key to signal form and the ‘aesthetic sense’ proposed by Darwin. Since a receiver bias is sufficient to both initiate and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate ‘null model’ of sexual selection. Thirdly, we focus on the genetic architecture of sexually selected traits. Despite advances in modern molecular techniques, the number and identity of genes underlying performance, display and secondary sexual traits remains largely unknown. In-depth investigations into the genetic basis of sexual dimorphism in the context of long-term field studies will reveal constraints and trajectories of sexually selected trait evolution. Finally, we focus on sexual selection and conflict as drivers of speciation. Population divergence and speciation are often influenced by an interplay between sexual and natural selection. The extent to which sexual selection promotes or counteracts population divergence may vary depending on the genetic architecture of traits as well as the covariance between mating competition and local adaptation. Additionally, post-copulatory processes, such as selection against heterospecific sperm, may influence the importance of sexual selection in speciation. We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection, and we offer potential avenues of research to advance this progress.Biogeographic patterns of belemnite body size responses to episodes of environmental crisishttps://peerj.com/preprints/280002019-09-302019-09-30Patrícia RitaJosé C. García-RamosPascal NeigeLaura PiñuelaRobert WeisLuís V. DuarteChristof ÜbelackerKenneth De Baets
Body size changes have been investigated through episodes of environmental crisis among several groups of organisms but the relative contribution of within-lineage size changes, selective extinction and origination of taxa on these patterns is still being debated. Rapid warming, anoxia, and perturbations of the carbon cycle linked with volcanic activity, as well as their impact on marine diversity are well documented for the Pliensbachian-Toarcian (Pli-Toa) boundary and for the Toarcian Oceanic Anoxic Event (T-OAE). Belemnites were a very abundant and successful cephalopod group in the Mesozoic oceans playing a paramount role in the oceanic trophic webs. Belemnites have mainly been studied from a geochemical perspective during this interval. Newly collected data from three northern and western Iberian sections (Peniche, Rodiles and Lastres) allowed an analysis of the belemnite body size dynamics across the Pli-Toa boundary and the T-OAE and a comparison with other European basins. In Peniche (Lusitanian Basin, Portugal), a significant reduction in belemnite body size was recognized across the Pli-Toa boundary at the assemblage level (i.e. community scale of organization). From the analysis of the different taxa recorded, it seems that adult specimens of Pseudohastites longiformis are driving the body size pattern observed (13% rostrum size decrease). The uppermost Polymorphum-Levisoni zones interval is characterized by a dramatic decrease on both belemnite abundance and diversity. Only 4 specimens of the genus Acrocoelites were found, increasing the body size at the assemblage level. In the Asturian Basin (N Spain), on the other hand, a body size increase at the assemblage level is recognized across the Pli-Toa boundary caused by a within-lineage effect mainly related to adult specimens of Passaloteuthis and Pseudohastites genera. During the onset of the T-OAE, belemnite body size increases due to the appearance of Acrocoelites genus. To summarize, the increase in rostrum size at the assemblage level across the T-OAE is associated with the radiation of a large-sized taxon (Acrocoelites genus) and the extinction of various other species. On the other hand, across the Pli-Toa boundary, the belemnite body size changes are dominated by within-lineage mechanisms. This suggests that species might have been able to cope within the early warming phase (Pli-Ta boundary), but were more affected by the subsequent warming and anoxia during the T-OAE. Our preliminary results indicate that this pattern might also be recognized in other western European sections, such as Cleveland Basin, western Paris Basin (Normandy) and Southern Germany sections. The biotic and abiotic drivers of belemnite body size changes still need to be comprehensively analyzed.
Body size changes have been investigated through episodes of environmental crisis among several groups of organisms but the relative contribution of within-lineage size changes, selective extinction and origination of taxa on these patterns is still being debated. Rapid warming, anoxia, and perturbations of the carbon cycle linked with volcanic activity, as well as their impact on marine diversity are well documented for the Pliensbachian-Toarcian (Pli-Toa) boundary and for the Toarcian Oceanic Anoxic Event (T-OAE). Belemnites were a very abundant and successful cephalopod group in the Mesozoic oceans playing a paramount role in the oceanic trophic webs. Belemnites have mainly been studied from a geochemical perspective during this interval. Newly collected data from three northern and western Iberian sections (Peniche, Rodiles and Lastres) allowed an analysis of the belemnite body size dynamics across the Pli-Toa boundary and the T-OAE and a comparison with other European basins. In Peniche (Lusitanian Basin, Portugal), a significant reduction in belemnite body size was recognized across the Pli-Toa boundary at the assemblage level (i.e. community scale of organization). From the analysis of the different taxa recorded, it seems that adult specimens of Pseudohastites longiformis are driving the body size pattern observed (13% rostrum size decrease). The uppermost Polymorphum-Levisoni zones interval is characterized by a dramatic decrease on both belemnite abundance and diversity. Only 4 specimens of the genus Acrocoelites were found, increasing the body size at the assemblage level. In the Asturian Basin (N Spain), on the other hand, a body size increase at the assemblage level is recognized across the Pli-Toa boundary caused by a within-lineage effect mainly related to adult specimens of Passaloteuthis and Pseudohastites genera. During the onset of the T-OAE, belemnite body size increases due to the appearance of Acrocoelites genus. To summarize, the increase in rostrum size at the assemblage level across the T-OAE is associated with the radiation of a large-sized taxon (Acrocoelites genus) and the extinction of various other species. On the other hand, across the Pli-Toa boundary, the belemnite body size changes are dominated by within-lineage mechanisms. This suggests that species might have been able to cope within the early warming phase (Pli-Ta boundary), but were more affected by the subsequent warming and anoxia during the T-OAE. Our preliminary results indicate that this pattern might also be recognized in other western European sections, such as Cleveland Basin, western Paris Basin (Normandy) and Southern Germany sections. The biotic and abiotic drivers of belemnite body size changes still need to be comprehensively analyzed.Leveraging eDNA to detect and monitor hybrid zoneshttps://peerj.com/preprints/279962019-09-302019-09-30Kathryn StewartScott A. Taylor
Hybrid zones are important windows into evolutionary processes and our understanding of their significance and prevalence in nature has expanded quickly. Yet most hybridization research has restricted temporal and spatial resolution, limiting our ability to draw broad conclusions about evolutionary and conservation related outcomes. Here, we argue rapidly advancing environmental DNA (eDNA) methodology should be adopted for studies of hybrid zones to increase temporal sampling (contemporary and historical), to refine and geographically expand sampling density, and to collect data for taxa that are difficult to directly sample. Genomic data in the environment offer the potential for near real-time biological tracking and eDNA provides broad, as yet untapped potential to address eco-evolutionary questions.
Hybrid zones are important windows into evolutionary processes and our understanding of their significance and prevalence in nature has expanded quickly. Yet most hybridization research has restricted temporal and spatial resolution, limiting our ability to draw broad conclusions about evolutionary and conservation related outcomes. Here, we argue rapidly advancing environmental DNA (eDNA) methodology should be adopted for studies of hybrid zones to increase temporal sampling (contemporary and historical), to refine and geographically expand sampling density, and to collect data for taxa that are difficult to directly sample. Genomic data in the environment offer the potential for near real-time biological tracking and eDNA provides broad, as yet untapped potential to address eco-evolutionary questions.Mapping ecological trends by keywords in the last 20 yearshttps://peerj.com/preprints/279942019-09-302019-09-30Lei Shi
Background. An effective bibliometric analysis based on the Science Citation Index (SCI) published by the Institute of Scientific Information (ISI) was carried out to identify the trend of ecological research between 1992 and 2016. Methods. This study emphases on the high-frequency keywords and their relationships to reveal the hotspots and developing trends of ecological research fields . Results. The result shows that the hotpots of ecology has changed a lot during the last 25 years, but some topics occupied an important position in ecological research consistently. Especially, “Biodiversity” and “Climate change” have been obtained more and more attention, so their ranks also have been changed greatly. As well as, we find that the relationship of the most frequently used keywords become more closely and complicated compared to before. Another interesting and amazing result shows that the keywords related to anthropogenic increased sharply. Finally, keywords analysis was an effective approach for mapping ecological research. We guess that anthropogenic keywords may be a potential guide for future research.
Background. An effective bibliometric analysis based on the Science Citation Index (SCI) published by the Institute of Scientific Information (ISI) was carried out to identify the trend of ecological research between 1992 and 2016. Methods. This study emphases on the high-frequency keywords and their relationships to reveal the hotspots and developing trends of ecological research fields . Results. The result shows that the hotpots of ecology has changed a lot during the last 25 years, but some topics occupied an important position in ecological research consistently. Especially, “Biodiversity” and “Climate change” have been obtained more and more attention, so their ranks also have been changed greatly. As well as, we find that the relationship of the most frequently used keywords become more closely and complicated compared to before. Another interesting and amazing result shows that the keywords related to anthropogenic increased sharply. Finally, keywords analysis was an effective approach for mapping ecological research. We guess that anthropogenic keywords may be a potential guide for future research.