Browsing by Subject "population dynamics"

Sort by: Order: Results:

Now showing items 1-10 of 10
  • Scridel, Davide; Brambilla, Mattia; Martin, Kathy; Lehikoinen, Aleksi; Iemma, Aaron; Matteo, Anderle; Jahnig, Susanne; Caprio, Enrico; Bogliani, Giuseppe; Pedrini, Paolo; Rolando, Antonio; Arlettaz, Raphael; Chamberlain, Dan (2018)
    Mountain regions are globally important areas for biodiversity but are subject to multiple human-induced threats, including climate change, which has been more severe at higher elevations. We reviewed evidence for impacts of climate change on Holarctic mountain bird populations in terms of physiology, phenology, trophic interactions, demography and observed and projected distribution shifts, including effects of other factors that interact with climate change. We developed an objective classification of high-elevation, mountain specialist and generalist species, based on the proportion oftheir breeding range occurring in mountain regions. Our review found evidence of responses of mountain bird populations to climate (extreme weather events, temperature, rainfall and snow) and environmental (i.e. land use) change, but we know little about either the underlying mechanisms or the synergistic effects of climate and land use. Long-term studies assessing reproductive success or survival of mountain birds in relation to climate change were rare. Few studies have considered shifts in elevational distribution over time and a meta-analysis did not find a consistent direction in elevation change. A meta-analysis carried out on future projections of distribution shifts suggested that birds whose breeding distributions are largely restricted to mountains are likely to be more negatively impacted than other species. Adaptation responses to climate change rely mostly on managing and extending current protected areas for both species already present, and for expected colonizing species that are losing habitat and climate space at lower elevation. However, developing effective management actions requires an improvement in the current knowledge of mountain species ecology, in the quality of climate data and in understanding the role of interacting factors. Furthermore, the evidence was mostly based on widespread species rather than mountain specialists. Scientists should provide valuable tools to assess the status of mountain birds, for example through the development of a mountain bird population index, and policy-makers should influence legislation to develop efficient agri-environment schemes and forestry practices for mountain birds, as well as to regulate leisure activities at higher elevations.
  • Tonnang, Henri E. Z.; Herve, Bisseleua D. B.; Biber-Freudenberger, Lisa; Salifu, Daisy; Subramanian, Sevgan; Ngowi, Valentine B.; Guimapi, Ritter Y. A.; Anani, Bruce; Kakmeni, Francois M. M.; Affognon, Hippolyte; Niassy, Saliou; Landmann, Tobias; Ndjomatchoua, Frank T.; Pedro, Sansao A.; Johansson, Tino Petri; Tanga, Chrysantus M.; Nana, Paulin; Fiaboe, Komi M.; Mohamed, Samira F.; Maniania, Nguya K.; Nedorezov, Lev V.; Ekesi, Sunday; Borgemeister, Christian (2017)
    A wide range of insects affect crop production and cause considerable yield losses. Difficulties reside on the development and adaptation of adequate strategies to predict insect pests for their timely management to ensure enhanced agricultural production. Several conceptual modelling frameworks have been proposed, and the choice of an approach depends largely on the objective of the model and the availability of data. This paper presents a summary of decades of advances in insect population dynamics, phenology models, distribution and risk mapping. Existing challenges on the modelling of insects are listed; followed by innovations in the field. New approaches include artificial neural networks, cellular automata (CA) coupled with fuzzy logic (FL), fractal, multi-fractal, percolation, synchronization and individual/agent based approaches. A concept for assessing climate change impacts and providing adaptation options for agricultural pest management independently of the United Nations Intergovernmental Panel on Climate Change (IPCC) emission scenarios is suggested. A framework for estimating losses and optimizing yields within crop production system is proposed and a summary on modelling the economic impact of pests control is presented. The assessment shows that the majority of known insect modelling approaches are not holistic; they only concentrate on a single component of the system, i.e. the pest, rather than the whole crop production system. We suggest system thinking as a possible approach for linking crop, pest, and environmental conditions to provide a more comprehensive assessment of agricultural crop production.
  • Siren, Jukka; Lens, Luc; Cousseau, Laurence; Ovaskainen, Otso (2018)
    1. Individual-based models (IBMs) allow realistic and flexible modelling of ecological systems, but their parameterization with empirical data is statistically and computationally challenging. Approximate Bayesian computation (ABC) has been proposed as an efficient approach for inference with IBMs, but its applicability to data on natural populations has not been yet fully explored. 2. We construct an IBM for the metapopulation dynamics of a species inhabiting a fragmented patch network, and develop an ABC method for parameterization of the model. We consider several scenarios of data availability from count data to combination of mark-recapture and genetic data. We analyse both simulated and real data on white-starred robin (Pogonocichla stellata), a passerine bird living in montane forest environment in Kenya, and assess how the amount and type of data affect the estimates of model parameters and indicators of population state. 3. The indicators of the population state could be reliably estimated using the ABC method, but full parameterization was not achieved due to strong posterior correlations between model parameters. While the combination of the data types did not provide more accurate estimates for most of the indicators of population state or model parameters than the most informative data type (ringing data or genetic data) alone, the combined data allowed robust simultaneous estimation of all unknown quantities. 4. Our results show that ABC methods provide a powerful and flexible technique forparameterizing complex IBMs with multiple data sources, and assessing the dynamics of the population in a robust manner.
  • Mutanen, Marko; Ovaskainen, Otso; Várkonyi, Gergely; Itämies, Juhani; Prosser, Sean W. J.; Hebert, Paul D. N.; Hanski, Ilkka (2020)
    Abstract It has been hypothesised that the 2-year oscillations in abundance of Xestia moths are mediated by interactions with 1-year Ophion parasitoid wasps. We tested this hypothesis by modelling a 35-year time series of Xestia and Ophion from Northern Finland. Additionally, we used DNA barcoding to ascertain the species diversity of Ophion and targeted amplicon sequencing of their gut contents to confirm their larval hosts. Modelling of the time-series data strongly supported the hypothesised host?parasitoid dynamics and that periodic occurrence of Xestia moths is mediated by Ophion. DNA barcodes revealed that Ophion included five species rather than just one while targeted amplicon sequencing verified that Ophion does parasitise Xestia. At least one Ophion species employs 1-year Syngrapha interrogationis as an alternate host, but it did not detectably affect Xestia?Ophion dynamics. We also demonstrate the previously unrecognised complexity of this system due to cryptic parasitoid diversity.
  • Wikström, Mikael (Helsingfors universitet, 2013)
    Managing a population of white-tailed deer requires knowledge about the dynamics of the population. Population dynamics include nativity, mortality and movements, which all depend on the density, sex ratio and age distribution of the population. Until now, there has not been any knowledge about the movements of the white-tailed deer in Finland. Because of this, the possibilities of managing the populations of white-tailed deer have been small. This study was conducted by following the movements of some 30 whitetails during 2008 – 2012, by using GPS-transmitters. The size of the home range, site fidelity and dispersal turned out to be depending on the density, sex ratio and age distribution of the population. The higher density, the smaller is the size of the home range and the higher is the site fidelity. The larger share of females, the smaller is the average home range size. The larger share of adult whitetails, the smaller is the average home range size. Established females had a home range of 394 – 5 619 hectares and established males had a home range of 847 – 5 248 hectares. Established whitetails were very site-faithful and the shortest distance between the centers of two home ranges used during two following years, was only 22 meters. The whitetails have turned out to use very large areas, compared to the size of the hunting grounds used by hunting clubs. For being able to manage a whitetail population, many hunting clubs have to co-operate regarding goals and management strategies. In general, an area of 100 000 hectares where the same strategies are applied, is required for managing a whitetail population.
  • Forsblom, Louise; Lindén, Andreas; Engström‐Öst, Jonna; Lehtiniemi, Maiju; Bonsdorff, Erik (Blackwell Publishing Ltd, 2021)
    Ecology and Evolution 11:9
    Benthic species and communities are linked to pelagic zooplankton through life-stages encompassing both benthic and pelagic habitats and through a mutual dependency on primary producers as a food source. Many zooplankton taxa contribute to the sedimentary system as benthic eggs. Our main aim was to investigate the nature of the population level biotic interactions between and within these two seemingly independent communities, both dependent on the pelagic primary production, while simultaneously accounting for environmental drivers (salinity, temperature, and oxygen conditions). To this end, we applied multivariate autoregressive state-space models to long (1966–2007) time series of annual abundance data, comparing models with and without interspecific interactions, and models with and without environmental variables included. We were not able to detect any direct coupling between sediment-dwelling benthic taxa and pelagic copepods and cladocerans on the annual scale, but the most parsimonious model indicated that interactions within the benthic community are important. There were also positive residual correlations between the copepods and cladocerans potentially reflecting the availability of a shared resource or similar seasonal dependence, whereas both groups tended to correlate negatively with the zoobenthic taxa. The most notable single interaction within the benthic community was a tendency for a negative effect of Limecola balthica on the amphipods Monoporeia affinis and Pontoporeia femorata which can help explain the observed decrease in amphipods due to increased competitive interference.
  • Blomqvist, Minna; Lyytikäinen-Saarenmaa, Päivi; Kantola, Tuula; Kosunen, Maiju; Talvitie, Mervi; Holopainen, Markus (2016)
  • Gauthier, Jérémy; Pajkovic, Mila; Neuenschwander, Samuel; Kaila, Lauri; Schmid, Sarah; Orlando, Ludovic; Alvarez, Nadir (2020)
    Erosion of biodiversity generated by anthropogenic activities has been studied for decades in many areas at species level, using taxa monitoring. In contrast, genetic erosion within species has rarely been tracked, and is often studied by inferring past population dynamics from contemporaneous estimators. An alternative to such inferences is the direct examination of past genes, by analysing museum collection specimens. While providing direct access to genetic variation over time, historical DNA is usually not optimally preserved, and it is necessary to apply genotyping methods based on hybridization-capture to unravel past genetic variation. In this study, we apply such a method (i.e., HyRAD), to large time series of two butterfly species in Finland, and present a new bioinformatic pipeline, namely PopHyRAD, that standardizes and optimizes the analysis of HyRAD data at the within-species level. In the localities for which the data retrieved have sufficient power to accurately examine genetic dynamics through time, we show that genetic erosion has increased across the last 100 years, as revealed by signatures of allele extinctions and heterozygosity decreases, despite local variations. In one of the two butterflies (Erebia embla), isolation by distance also increased through time, revealing the effect of greater habitat fragmentation over time.
  • Lahtinen, Maria; Oinonen, Markku; Tallavaara, Miikka; Walker, James; Rowley-Conwy, Peter (2017)
    Dates for early cultivation in Finland obtained from pollen analysis and from remains from archaeological sites are compared to changes in population size derived from the summed calendar year probability distributions published by Tallavaara et al. (2010). The results from these two independent proxies correlate strongly with one another, indicating that population size and the advance of farming were closely linked with each other. Moreover, the results show that the adaptation and development of farming in this area was a complex process comprising several stages and with major differences between regions. The most intensive expansion occurred in and after the Iron Age. It is therefore more accurate describe the introduction of farming into the area as a long-lasting process rather than an event.
  • Uusi-Heikkilä, Silva; Whiteley, Andrew R.; Kuparinen, Anna; Matsumura, Shuichi; Venturelli, Paul A.; Wolter, Christian; Slate, Jon; Primmer, Craig R.; Meinelt, Thomas; Killen, Shaun S.; Bierbach, David; Polverino, Giovanni; Ludwig, Arne; Arlinghaus, Robert (2015)
    Size-selective harvesting is assumed to alter life histories of exploited fish populations, thereby negatively affecting population productivity, recovery, and yield. However, demonstrating that fisheries-induced phenotypic changes in the wild are at least partly genetically determined has proved notoriously difficult. Moreover, the population-level consequences of fisheries-induced evolution are still being controversially discussed. Using an experimental approach, we found that five generations of size-selective harvesting altered the life histories and behavior, but not the metabolic rate, of wild-origin zebrafish (Danio rerio). Fish adapted to high positively size selective fishing pressure invested more in reproduction, reached a smaller adult body size, and were less explorative and bold. Phenotypic changes seemed subtle but were accompanied by genetic changes in functional loci. Thus, our results provided unambiguous evidence for rapid, harvest-induced phenotypic and evolutionary change when harvesting is intensive and size selective. According to a life-history model, the observed life-history changes elevated population growth rate in harvested conditions, but slowed population recovery under a simulated moratorium. Hence, the evolutionary legacy of size-selective harvesting includes populations that are productive under exploited conditions, but selectively disadvantaged to cope with natural selection pressures that often favor large body size.