The interactions between herbivores and their host plants play a key role in ecological processes. Understanding the width and nature of these interactions is funda- mental to ecology and conservation. Recent research...The interactions between herbivores and their host plants play a key role in ecological processes. Understanding the width and nature of these interactions is funda- mental to ecology and conservation. Recent research on DNA-based inference of trophic associations suggests that the host range of phytophagous insects in the tropics may be wider than previously thought based on traditional observation. However, the reliability of molecular inference of ecological associations, still strongly dependent on PCR and thus exposed to the risk of contamination with environmental DNA, is under debate. Here, we explored alternative procedures to reduce the chance of amplification of external, nondiet DNA, including surface decontamination and analysis of mid/hind guts, comparing the results with those obtained using the standard protocol. We studied 261 specimens in eight species of Neotropical Chrysomelidae that yielded 316 psbA-trnH intergenic spacer sequences （cpDNA marker of putative diets） from unique and multiple-band PCR results. The taxonomic identity of these sequences was inferred using the automated pipeline BAGpipe, yielding results consistent with 31 plant families. Regardless of the proto- col used, a wide taxonomic spectrum of food was inferred for all chrysomelid species. Canonical Correspondence Analysis using these data revealed significant differences at- tributed mainly to species （expectedly, since they represent different ecologies）, but also to treatment （untreated vs. cleaned/gut samples） and PCR results （single vs. multiple bands）. Molecular identification of diets is not straightforward and, regardless of the species＇ niche breadth, combining approaches that reduce external contamination and studying multiple individuals per species may help increasing confidence in results.展开更多
Invasive species are a major threat to island biodiversity,and their eradications have substantially contributed to the conservation of island endemics.However,the consequences of eradications on the trophic ecology o...Invasive species are a major threat to island biodiversity,and their eradications have substantially contributed to the conservation of island endemics.However,the consequences of eradications on the trophic ecology of native taxa are largely unexplored.Here,we used the eradication of invasive black rats Rattus rattus and European rabbits Oryctolagus cuniculus from the Berlenga Island,in the western coast of Portugal,as a whole-ecosystem experiment to investigate the effects of the eradication of invasive mammals on the trophic niche and body dimensions of the island-restricted Berlenga wall lizard Podarcis carbonelli berlengensis over a 2-year period.Our results suggest an expansion of the isotopic niche and an intensification of the sexual dimorphism of the lizard following mammal eradication.Additionally,we found considerable variability in isotopic niche across the island and detected evidence of sex-specific and season-modulated nutritional requirements of this threatened reptile.Our findings support that the eradication of 2 of the planets most problematic invasive vertebrates led to changes in the lizard trophic niche and sexual dimorphism in just 2 years.This suggests that the ecological pressuresfor example,prey availability and habitat structureto which lizards are exposed have substantially changed post-eradication.Our study emphasizes the scientific value of island eradications as experiments to address a wide range of ecological questions and adds to the increasing body of evidence supporting substantial conservation gains associated with these restoration interventions.展开更多
This study measured stable carbon and nitro- gen isotope ratios in phytoplankton, zooplankton, five inver- tebrates species, eight fishes species and three seabirds spe- cies collected in Bohai Bay. δ 13C ranged from...This study measured stable carbon and nitro- gen isotope ratios in phytoplankton, zooplankton, five inver- tebrates species, eight fishes species and three seabirds spe- cies collected in Bohai Bay. δ 13C ranged from ?25.38‰ to ?11.08‰ showing a relative low enrichment in the food web from Bohai Bay. The mean δ 13C of mullet is higher than that of other organisms, and this might be due to that mullet is migration fish and feeds mainly on inshore sources. δ 15N ranged from 4.08‰ to 13.98‰, and showed a step-wise en- richment with trophic level of 3.8‰. The δ 15N enrichment factor was used to construct an isotopic food web model to establish trophic relationships within this marine food web. According to this model, exact trophic levels of all organisms were estimated as 1.46?2.10, 1.91?3.32, 2.55?4.23 and 2.98?4.28 for plankton, invertebrates, fishes, and seabirds.展开更多
The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body ...The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations （Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn）. We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni （4 700-16 000μg/g） and high values （5-34μg/g） for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni （〉 500μg/g）. The large number of high-Ni heteropterans adds to discoveries of others （from California USA and New Caledonia） and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran （Stenoscepa） contained 3 500 μg Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg （〉 2 800 μg/g）, one beetle with elevated Cu （〉 70 μg/g） and one heteropteran with an elevated level of Mn （〉 200 μg/g）. Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates.展开更多
Nymphs of Stenoscepa sp. feed on leaves of the Ni hyperaccumulator Berkheya coddii at serpentine sites in Mpumalanga Province, South Africa. These sites contain Ni hyperaccumulators, Ni accumulators, and plants with N...Nymphs of Stenoscepa sp. feed on leaves of the Ni hyperaccumulator Berkheya coddii at serpentine sites in Mpumalanga Province, South Africa. These sites contain Ni hyperaccumulators, Ni accumulators, and plants with Ni concentrations in the normal range. We conducted studies to： （i） determine the whole-body metal concentration of nymphs （including those starved to empty their guts）; （ii） compare Stenoscepa sp. nymphs against other grasshoppers in the same habitat for whole-body metal concentrations; and （iii）compare the suitability of Ni hyperaccumulator and Ni accumulator plants as food sources for Stenoscepa sp. and other grasshoppers. Stenoscepa nymphs had extremely high whole-body Ni concentrations （3 500μg Ni/g）. This was partly due to food in the gut, as starved insects contained less Ni （950 pg Ni/g）. Stenoscepa nymphs survived significantly better than other grasshoppers collected from either a serpentine or a non-serpentine site when offered high-Ni plants as food. In a host preference test among four Berkheya species （two Ni hyperaccumulators and two Ni accumulators）, Stenoscepa sp, preferred leaves of the Ni hyperaccumulator species. A preference experiment using leaves of three Senecio species （of which one species, Senecio coronatus, was represented by both a Ni hyperaccumulator and a Ni accumulator population） showed that Stenoscepa sp. preferred Ni accumulator Senecio coronatus leaves to all other choices. We conclude that Stenoscepa sp. is extremely Ni-tolerant. Stenoscepa sp. nymphs prefer leaves of hyperaccumulator Berkheya species, but elevated Ni concentration alone does not determine their food preference. We suggest that the extremely high whole-body Ni concentration of Stenoscepa nymphs may affect food web relationships in these serpentine communities.展开更多
A summary of a long-term research of Lake Kinneret zooplankton distribution is presented. During 1969-2002 several prominent changes have been recorded in the Kinneret ecosystem. This paper is an attempt aimed at anal...A summary of a long-term research of Lake Kinneret zooplankton distribution is presented. During 1969-2002 several prominent changes have been recorded in the Kinneret ecosystem. This paper is an attempt aimed at analyzing the impact of these ecological changes on the zooplankton communities. The impacts of Phytoplankton, Bacteria, Protozoa, Temperature, Nutrient composition and fish predation on zooplankton dynamics are analyzed. It was found that periodical fluctuations of zooplankton density were mostly affected by fish predation as well as by temperature increase and food availability. Ecological conditions in Lake Kinneret have been modified since early 1990’s and the new conditions were consequently accompanied by zooplankton Homeostatic response. Moreover, as a result of the ecological changes fish intensified their pressure on zoo-plankton. The flexibility of food resource preference by zooplankton enabled its existence but fish predation predominantly controlled their density.展开更多
文摘The interactions between herbivores and their host plants play a key role in ecological processes. Understanding the width and nature of these interactions is funda- mental to ecology and conservation. Recent research on DNA-based inference of trophic associations suggests that the host range of phytophagous insects in the tropics may be wider than previously thought based on traditional observation. However, the reliability of molecular inference of ecological associations, still strongly dependent on PCR and thus exposed to the risk of contamination with environmental DNA, is under debate. Here, we explored alternative procedures to reduce the chance of amplification of external, nondiet DNA, including surface decontamination and analysis of mid/hind guts, comparing the results with those obtained using the standard protocol. We studied 261 specimens in eight species of Neotropical Chrysomelidae that yielded 316 psbA-trnH intergenic spacer sequences （cpDNA marker of putative diets） from unique and multiple-band PCR results. The taxonomic identity of these sequences was inferred using the automated pipeline BAGpipe, yielding results consistent with 31 plant families. Regardless of the proto- col used, a wide taxonomic spectrum of food was inferred for all chrysomelid species. Canonical Correspondence Analysis using these data revealed significant differences at- tributed mainly to species （expectedly, since they represent different ecologies）, but also to treatment （untreated vs. cleaned/gut samples） and PCR results （single vs. multiple bands）. Molecular identification of diets is not straightforward and, regardless of the species＇ niche breadth, combining approaches that reduce external contamination and studying multiple individuals per species may help increasing confidence in results.
基金Funding was provided by the Portuguese Foundation for Science and Technology to R.Rebelo(UID/BIA/00329/2019)M.Mota-Ferreira(SFRH/BD/95202/2013)+1 种基金ARDITI-Madeira's Regional Agency for the Development of Research,Technology and Innovation to R.Rocha(M1420-09-5369-FSE-000002)the LIFE+Berlengas project.M.Mota-Ferreira was also supported by the Interreg Europe project INVALIS-Protecting European Biodiversity from Invasive Alien Species(PGI05271)。
文摘Invasive species are a major threat to island biodiversity,and their eradications have substantially contributed to the conservation of island endemics.However,the consequences of eradications on the trophic ecology of native taxa are largely unexplored.Here,we used the eradication of invasive black rats Rattus rattus and European rabbits Oryctolagus cuniculus from the Berlenga Island,in the western coast of Portugal,as a whole-ecosystem experiment to investigate the effects of the eradication of invasive mammals on the trophic niche and body dimensions of the island-restricted Berlenga wall lizard Podarcis carbonelli berlengensis over a 2-year period.Our results suggest an expansion of the isotopic niche and an intensification of the sexual dimorphism of the lizard following mammal eradication.Additionally,we found considerable variability in isotopic niche across the island and detected evidence of sex-specific and season-modulated nutritional requirements of this threatened reptile.Our findings support that the eradication of 2 of the planets most problematic invasive vertebrates led to changes in the lizard trophic niche and sexual dimorphism in just 2 years.This suggests that the ecological pressuresfor example,prey availability and habitat structureto which lizards are exposed have substantially changed post-eradication.Our study emphasizes the scientific value of island eradications as experiments to address a wide range of ecological questions and adds to the increasing body of evidence supporting substantial conservation gains associated with these restoration interventions.
基金This work was supported by the National Basic Research Program of China(Grant No.2003CB415004)the National Natural Science Foundation of China(Grant No.40021101)the Japanese Intermational Cooperation Agency.
文摘This study measured stable carbon and nitro- gen isotope ratios in phytoplankton, zooplankton, five inver- tebrates species, eight fishes species and three seabirds spe- cies collected in Bohai Bay. δ 13C ranged from ?25.38‰ to ?11.08‰ showing a relative low enrichment in the food web from Bohai Bay. The mean δ 13C of mullet is higher than that of other organisms, and this might be due to that mullet is migration fish and feeds mainly on inshore sources. δ 15N ranged from 4.08‰ to 13.98‰, and showed a step-wise en- richment with trophic level of 3.8‰. The δ 15N enrichment factor was used to construct an isotopic food web model to establish trophic relationships within this marine food web. According to this model, exact trophic levels of all organisms were estimated as 1.46?2.10, 1.91?3.32, 2.55?4.23 and 2.98?4.28 for plankton, invertebrates, fishes, and seabirds.
文摘The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations （Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn）. We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni （4 700-16 000μg/g） and high values （5-34μg/g） for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni （〉 500μg/g）. The large number of high-Ni heteropterans adds to discoveries of others （from California USA and New Caledonia） and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran （Stenoscepa） contained 3 500 μg Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg （〉 2 800 μg/g）, one beetle with elevated Cu （〉 70 μg/g） and one heteropteran with an elevated level of Mn （〉 200 μg/g）. Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates.
文摘Nymphs of Stenoscepa sp. feed on leaves of the Ni hyperaccumulator Berkheya coddii at serpentine sites in Mpumalanga Province, South Africa. These sites contain Ni hyperaccumulators, Ni accumulators, and plants with Ni concentrations in the normal range. We conducted studies to： （i） determine the whole-body metal concentration of nymphs （including those starved to empty their guts）; （ii） compare Stenoscepa sp. nymphs against other grasshoppers in the same habitat for whole-body metal concentrations; and （iii）compare the suitability of Ni hyperaccumulator and Ni accumulator plants as food sources for Stenoscepa sp. and other grasshoppers. Stenoscepa nymphs had extremely high whole-body Ni concentrations （3 500μg Ni/g）. This was partly due to food in the gut, as starved insects contained less Ni （950 pg Ni/g）. Stenoscepa nymphs survived significantly better than other grasshoppers collected from either a serpentine or a non-serpentine site when offered high-Ni plants as food. In a host preference test among four Berkheya species （two Ni hyperaccumulators and two Ni accumulators）, Stenoscepa sp, preferred leaves of the Ni hyperaccumulator species. A preference experiment using leaves of three Senecio species （of which one species, Senecio coronatus, was represented by both a Ni hyperaccumulator and a Ni accumulator population） showed that Stenoscepa sp. preferred Ni accumulator Senecio coronatus leaves to all other choices. We conclude that Stenoscepa sp. is extremely Ni-tolerant. Stenoscepa sp. nymphs prefer leaves of hyperaccumulator Berkheya species, but elevated Ni concentration alone does not determine their food preference. We suggest that the extremely high whole-body Ni concentration of Stenoscepa nymphs may affect food web relationships in these serpentine communities.
文摘A summary of a long-term research of Lake Kinneret zooplankton distribution is presented. During 1969-2002 several prominent changes have been recorded in the Kinneret ecosystem. This paper is an attempt aimed at analyzing the impact of these ecological changes on the zooplankton communities. The impacts of Phytoplankton, Bacteria, Protozoa, Temperature, Nutrient composition and fish predation on zooplankton dynamics are analyzed. It was found that periodical fluctuations of zooplankton density were mostly affected by fish predation as well as by temperature increase and food availability. Ecological conditions in Lake Kinneret have been modified since early 1990’s and the new conditions were consequently accompanied by zooplankton Homeostatic response. Moreover, as a result of the ecological changes fish intensified their pressure on zoo-plankton. The flexibility of food resource preference by zooplankton enabled its existence but fish predation predominantly controlled their density.
