Data from: Rapid plastic breeding response to rain matches peak prey abundance in a tropical savannah bird
Hidalgo Aranzamendi, Nataly ; Hall, Michelle L. ; Kingma, Sjouke ; Pol, Martijn van de; Peters, Anne - \ 2019
trophic interactions - annual cycle - tropics - phenology - Timing of reproduction - Phenotypic Plasticity - avian life-history - unpredictable environment - Malurus coronatus
1. Changes in climate are shifting the timing of life cycle events in the natural world. Compared to northern-temperate areas, these effects are relatively poorly understood in tropical and southern regions, where there is limited information on how timing of breeding and food availability are affected by climatic factors, and where patterns of breeding activity are more unpredictable within and between years. 2. Combining a new statistical modelling approach with 5 years of continuous individual-based monitoring of a monsoonal tropical insectivorous bird, we quantified (i) the proximate climatic drivers at two trophic levels: timing of breeding and abundance of arthropod prey; (ii) the effect of climate variation on reproductive output and (iii) the role of individual plasticity. 3. Rainfall was identified as the main determinant of phenology at both trophic levels. Throughout the year, likelihood of egg laying increased very rapidly in response to even small amounts of rain during the preceding 0-3 weeks. Adult body mass and male sperm storage also increased rapidly after rain, suggesting high breeding preparedness. Additionally, females were flexible, since they were more likely to nest if their previous attempt was longer ago and unsuccessful. Arthropod abundance also increased after rainfall, but more slowly, with a peak around 10 weeks. Therefore, the peak food availability coincided with the presence of dependent fledglings. 4. Fitness benefits of nesting after more rain appeared to be linked to offspring quantity rather than quality: nest attempts following higher rainfall produced larger clutches, but showed no improvement in nestling mass or relative fledging success. The response of clutch size to rainfall was plastic, since repeated sampling showed that individual females laid larger clutches after more rain, possibly mediated by improved body mass. 5. Rapid, individually flexible breeding in response to rainfall and slower increase in arthropod abundance also as a response to rainfall, might buffer insectivorous species living in tropical seasonal environments from climate-change induced phenological trophic mismatches.
Rapid plastic breeding response to rain matches peak prey abundance in a tropical savanna bird
Hidalgo Aranzamendi, Nataly ; Hall, Michelle L. ; Kingma, Sjouke A. ; Pol, Martijn van de; Peters, Anne - \ 2019
Journal of Animal Ecology 88 (2019)11. - ISSN 0021-8790 - p. 1799 - 1811.
annual cycle - avian life-history - phenology - phenotypic plasticity - timing of reproduction - trophic interactions - tropics - unpredictable environment
Changes in climate are shifting the timing of life cycle events in the natural world. Compared to northern temperate areas, these effects are relatively poorly understood in tropical and southern regions, where there is limited information on how timing of breeding and food availability are affected by climatic factors, and where patterns of breeding activity are more unpredictable within and between years. Combining a new statistical modelling approach with 5 years of continuous individual-based monitoring of a monsoonal tropical insectivorous bird, we quantified (a) the proximate climatic drivers at two trophic levels: timing of breeding and abundance of arthropod prey; (b) the effect of climate variation on reproductive output and (c) the role of individual plasticity. Rainfall was identified as the main determinant of phenology at both trophic levels. Throughout the year, likelihood of egg laying increased very rapidly in response to even small amounts of rain during the preceding 0–3 weeks. Adult body mass and male sperm storage also increased rapidly after rain, suggesting high breeding preparedness. Additionally, females were flexible, since they were more likely to nest whether their previous attempt was longer ago and unsuccessful. Arthropod abundance also increased after rainfall, but more slowly, with a peak around 10 weeks. Therefore, the peak food availability coincided with the presence of dependent fledglings. Fitness benefits of nesting after more rain appeared to be linked to offspring quantity rather than quality: nest attempts following higher rainfall produced larger clutches, but showed no improvement in nestling mass or relative fledging success. The response of clutch size to rainfall was plastic, since repeated sampling showed that individual females laid larger clutches after more rain, possibly mediated by improved body mass. Rapid, individually flexible breeding in response to rainfall and slower increase in arthropod abundance also as a response to rainfall, might buffer insectivorous species living in tropical seasonal environments from climate change-induced phenological trophic mismatches.
Inoculation of susceptible and resistant potato plants with the late blight pathogen Phytophthora infestans : effects on an aphid and its parasitoid
Lazebnik, Jenny ; Tibboel, Marianne ; Dicke, Marcel ; Loon, Joop J.A. van - \ 2017
Entomologia Experimentalis et Applicata 163 (2017)3. - ISSN 0013-8703 - p. 305 - 314.
Aphididae - Aphidius colemani - Braconidae - genetic modification - Hemiptera - Hymenoptera - Myzus persicae - non-target effects - plant-pathogen-insect interactions - plant–insect interactions - Solanum tuberosum - trophic interactions
Plants are exposed to microbial pathogens as well as herbivorous insects and their natural enemies. Here, we examined the effects of inoculation of potato plants, Solanum tuberosum L. (Solanaceae), with the late blight pathogen Phytophthora infestans (Mont.) de Bary (Peronosporales: Pythiaceae) on an aphid species commonly infesting potato crops and one of the aphid's major parasitoids. We observed the peach-potato aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), and its natural enemy, the biocontrol agent Aphidius colemani Viereck (Hymenoptera: Braconidae), on potato either inoculated with water or P. infestans. Population growth of the aphid, parasitism rate of its natural enemy, and other insect life-history traits were compared on several potato genotypes, the susceptible cultivar Désirée and genetically modified (GM) isogenic lines carrying genes conferring resistance to P. infestans. Effects of P. infestans inoculation on the intrinsic rate of aphid population increase and the performance of the parasitoid were only found on the susceptible cultivar. Insect traits were similar when comparing inoculated with non-inoculated resistant GM genotypes. We also tested how GM-plant characteristics such as location of gene insertion and number of R genes could influence non-target insects by comparing insect performance among GM events. Different transformation events leading to different positions of R-gene insertion in the genome influenced aphids either with or without P. infestans infection, whereas effects of position of R-gene insertion on the parasitoid A. colemani were evident only in the presence of inoculation with P. infestans. We conclude that it is important to study different transformation events before continuing with further stages of risk assessment of this GM crop. This provides important information on the effects of plant resistance to a phytopathogen on non-target insects at various trophic levels.
The role of subtropical zooplankton as grazers of phytoplankton under different predation levels
Lacerot, G. ; Kruk, C. ; Lurling, M. ; Scheffer, M. - \ 2013
Freshwater Biology 58 (2013)3. - ISSN 0046-5070 - p. 494 - 503.
fish community structure - shallow lakes - jenynsia-multidentata - trophic interactions - size distribution - biomanipulation - dynamics - climate - restoration - cladocerans
1.Large zooplankton such as Daphnia play a fundamental role as consumers of phytoplankton in temperate lakes. These organisms are scarce in subtropical lakes where smaller cladocerans or copepods take this niche. However, such smaller grazers appear to be less able to exert an effective top-down control on the phytoplankton community. 2.We experimentally analysed the ability of zooplankton typical of subtropical, nutrient-rich lakes to graze effectively on the phytoplankton community. We conducted two outdoor mesocosm experiments in a hypertrophic lake, with combinations of three different zooplankton densities and three different omnivorous fish densities. In the first experiment, the zooplankton community was dominated by a small-sized cladoceran (Moina micrura) and in the second by a calanoid copepod (Notodiaptomus incompositus). The phytoplankton community also differed between experiments, with dominance of large size classes and less palatable species in the first experiment and edible sizes in the second. 3.In both experiments, the effect of fish on the largest zooplankton was strong and negative, and low fish densities were sufficient to eliminate the larger zooplankton. Fish presence had positive effects on the biovolume of the largest phytoplankton size fraction (30-100µm) in the first experiment. This effect was more pronounced in combination with high zooplankton biomass, suggesting that nutrient recycling by both fish and zooplankton may have been an important mechanism promoting phytoplankton growth. 4.None of the zooplankton communities tested had significant top-down effects on the phytoplankton community. In view of the phytoplankton species that dominated the communities at the end of both experiments, inedibility, toxicity and antigrazer defences may explain the absence of significant effects of zooplankton grazing. 5.Our results support the idea that in subtropical nutrient-rich lakes, drastic removal of small omnivorous fish may be needed to allow an increase in zooplankton biomass. In addition, our results imply that for such a change to result in effective top-down control of phytoplankton, a shift in zooplankton community composition is essential too, as the experimental increase in small-sized grazers had little effect on the phytoplankton communities.
Faltering lemming cycles reduce productivity and population size of a migratory Arctic goose species
Nolet, B.A. ; Bauer, S. ; Feige, N. ; Kokorev, Y. ; Popov, I.Y. ; Ebbinge, B.S. - \ 2013
Journal of Animal Ecology 82 (2013)4. - ISSN 0021-8790 - p. 804 - 813.
geese branta-bernicla - nyctea-scandiaca nests - brent geese - clutch size - climate-change - b.-bernicla - reproductive-performance - trophic interactions - incubation behavior - northeastern taimyr
1. The huge changes in population sizes of Arctic-nesting geese offer a great opportunity to study population limitation in migratory animals. In geese, population limitation seems to have shifted from wintering to summering grounds. There, in the Arctic, climate is rapidly changing, and this may impact reproductive performance, and perhaps population size of geese, both directly (e.g. by changes in snow melt) or indirectly (e.g. by changes in trophic interactions). 2. Dark-bellied brent geese (Branta bernicla bernicla L.) increased 20-fold since the 1950s. Its reproduction fluctuates strongly in concert with the 3-year lemming cycle. An earlier analysis, covering the growth period until 1988, did not find evidence for density dependence, but thereafter the population levelled off and even decreased. The question is whether this is caused by changes in lemming cycles, population density or other factors like carry-over effects. 3. Breeding success was derived from proportions of juveniles. We used an information-theoretical approach to investigate which environmental factors best explained the variation in breeding success over nearly 50 years (1960–2008). We subsequently combined GLM predictions of breeding success with published survival estimates to project the population trajectory since 1991 (year of maximum population size). In this way, we separated the effects of lemming abundance and population density on population development. 4. Breeding success was mainly dependent on lemming abundance, the onset of spring at the breeding grounds, and the population size of brent goose. No evidence was found for carryover effects (i.e. effects of conditions at main spring staging site). Negative density dependence was operating at a population size above c. 200 000 individuals, but the levelling off of the population could be explained by faltering lemming cycles alone. 5. Lemmings have long been known to affect population productivity of Arctic-nesting migratory birds and, more recently, possibly population dynamics of resident bird species, but this is the first evidence for effects of lemming abundance on population size of a migratory bird species. Why lemming cycles are faltering in the last two decades is unclear, but this may be associated with changes in winter climate at Taimyr Peninsula (Siberia). Key-words: bird migration, climate change, dark-bellied brent goose, density dependence, reproductive success
Dietary overlap between the potential competitors herring, sprat and anchovy in the North Sea
Raab, K.E. ; Nagelkerke, L.A.J. ; Boeree, C. ; Rijnsdorp, A.D. ; Temming, A. ; Dickey-Collas, M. - \ 2012
Marine Ecology Progress Series 470 (2012). - ISSN 0171-8630 - p. 101 - 111.
engraulis-encrasicolus l. - central baltic sea - clupea-harengus - feeding-behavior - intraguild predation - trophic interactions - population-dynamics - mediterranean sea - fish eggs - irish sea
European anchovy Engraulis encrasicolus increased its abundance and distribution in the North Sea during the mid-1990s and may consume similar zooplankton to and/or compete with other occupants of the North Sea like herring Clupea harengus and sprat Sprattus sprattus. The diets of adult anchovy, sprat and juvenile herring of comparable sizes, sampled close in time and space, were compared to understand how the 3 species prey on zooplankton and establish whether their diets overlap or not. Anchovy was found to be more generalist, consuming a higher diversity of prey items. Herring was more specialized, with low diversity of food items. Sprat was intermediate between anchovy and herring. The dietary overlap between anchovy and sprat was highest, followed by herring and sprat before anchovy and herring. The mean weight of stomach contents did not differ between species. We conclude that of the 3 species, anchovy is likely to be the least affected by changing plankton communities.
Complexity in quantitative food webs
Banasek-Richter, C. ; Bersier, L.F. ; Cattin, M.F. ; Baltensperger, R. ; Gabriel, J.P. ; Merz, Y. ; Ulanowicz, R.E. ; Tavares, A.F. ; Williams, D.D. ; Ruiter, P.C. de; Winemiller, K.O. ; Naisbit, R.E. - \ 2009
Ecology 90 (2009)6. - ISSN 0012-9658 - p. 1470 - 1477.
trophic interactions - community stability - sampling effort - scale - networks - descriptors - connectance - adaptation - ecosystems - patterns
Food webs depict who eats whom in communities. Ecologists have examined statistical metrics and other properties of food webs, but mainly due to the uneven quality of the data, the results have proved controversial. The qualitative data on which those efforts rested treat trophic interactions as present or absent and disregard potentially huge variation in their magnitude, an approach similar to analyzing traffic without differentiating between highways and side roads. More appropriate data are now available and were used here to analyze the relationship between trophic complexity and diversity in 59 quantitative food webs from seven studies (14-202 species) based on recently developed quantitative descriptors. Our results shed new light on food-web structure. First, webs are much simpler when considered quantitatively, and link density exhibits scale invariance or weak dependence on food-web size. Second, the "constant connectance'' hypothesis is not supported: connectance decreases with web size in both qualitative and quantitative data. Complexity has occupied a central role in the discussion of food-web stability, and we explore the implications for this debate. Our findings indicate that larger webs are more richly endowed with the weak trophic interactions that recent theories show to be responsible for food-web stability.
Empirical and theoretical challenges in aboveground-belowground ecology
Putten, W.H. van der; Bardgett, R.D. ; Ruiter, P.C. de; Hol, W.H.G. ; Meyer, K.M. ; Bezemer, T.M. ; Bradford, M.A. ; Christensen, S. ; Eppinga, M.B. ; Fukami, T. ; Hemerik, L. ; Molofsky, J. ; Schädler, M. ; Scherber, C. ; Strauss, S.Y. ; Vos, M. ; Wardle, D.A. - \ 2009
Oecologia 161 (2009)1. - ISSN 0029-8549 - p. 1 - 14.
plant-soil feedback - increased competitive ability - climate-change - community composition - trophic interactions - insect herbivory - enemy release - food-web - terrestrial ecosystems - grassland ecosystems
A growing body of evidence shows that aboveground and belowground communities and processes are intrinsically linked, and that feedbacks between these subsystems have important implications for community structure and ecosystem functioning. Almost all studies on this topic have been carried out from an empirical perspective and in specific ecological settings or contexts. Belowground interactions operate at different spatial and temporal scales. Due to the relatively low mobility and high survival of organisms in the soil, plants have longer lasting legacy effects belowground than aboveground. Our current challenge is to understand how aboveground¿belowground biotic interactions operate across spatial and temporal scales, and how they depend on, as well as influence, the abiotic environment. Because empirical capacities are too limited to explore all possible combinations of interactions and environmental settings, we explore where and how they can be supported by theoretical approaches to develop testable predictions and to generalise empirical results. We review four key areas where a combined aboveground¿belowground approach offers perspectives for enhancing ecological understanding, namely succession, agro-ecosystems, biological invasions and global change impacts on ecosystems. In plant succession, differences in scales between aboveground and belowground biota, as well as between species interactions and ecosystem processes, have important implications for the rate and direction of community change. Aboveground as well as belowground interactions either enhance or reduce rates of plant species replacement. Moreover, the outcomes of the interactions depend on abiotic conditions and plant life history characteristics, which may vary with successional position. We exemplify where translation of the current conceptual succession models into more predictive models can help targeting empirical studies and generalising their results. Then, we discuss how understanding succession may help to enhance managing arable crops, grasslands and invasive plants, as well as provide insights into the effects of global change on community re-organisation and ecosystem processes