ArticlePublisher preview available
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

We applied a step-down factor analysis (SDFA) and multi-site generalised dissimilarity modelling (MS-GDM) to local flea communities harboured by small mammals (i.e., collected at small sampling sites over a short time period) in two South American regions (Patagonia and the Northwestern Argentina) with the aim of understanding whether these communities were assembled via niche-based or dispersal-based processes. The SDFA allows us to determine whether clusters of flea assemblages across different types of climates, vegetation and soils can be distinguished (suggesting niche-based assembly). MS-GDM allows us to determine whether a substantial proportion of the variation in flea species turnover is explained by specific climate-associated, vegetation-associated and soil-associated variables (indicating niche-based assembly) or host turnover (indicating dispersal-based assembly). Mapping of assemblages on climate, vegetation and soil maps, according to their loadings on axis 1 or axis 2 of the SDFA, did not provide clear-cut results. Clusters of similar loadings could be recognized within some, but not other, climate, vegetation and soil types. However, MS-GDM demonstrated that the effect of environmental variables (especially air temperature) on flea compositional turnover was much stronger than that of host turnover, indicating the predominance of niche-based processes in local community assembly. A comparison of our results with those on the mechanisms that drive species assembly in regional communities allows us to conclude that local and regional communities result from the joint action of niche-based and dispersal-based processes, with the former more important at a smaller spatial scale and the latter at a larger spatial scale.
This content is subject to copyright. Terms and conditions apply.
Vol.:(0123456789)
1 3
https://doi.org/10.1007/s00436-022-07759-2
RESEARCH
The species composition oflocal flea assemblages atasmall
scale intwo South American regions ispredominantly driven
byniche‑based mechanisms
BorisR.Krasnov1· M.FernandaLópezBerrizbeitia2· JulianaP.Sanchez3· M.MónicaDíaz2· MarcelaLareschi4·
IrinaS.Khokhlova5· VasilyI.Grabovsky5
Received: 15 November 2022 / Accepted: 8 December 2022
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2022
Abstract
We applied a step-down factor analysis (SDFA) and multi-site generalised dissimilarity modelling (MS-GDM) to local flea
communities harboured by small mammals (i.e., collected at small sampling sites over a short time period) in two South
American regions (Patagonia and the Northwestern Argentina) with the aim of understanding whether these communities
were assembled via niche-based or dispersal-based processes. The SDFA allows us to determine whether clusters of flea
assemblages across different types of climates, vegetation and soils can be distinguished (suggesting niche-based assembly).
MS-GDM allows us to determine whether a substantial proportion of the variation in flea species turnover is explained by
specific climate-associated, vegetation-associated and soil-associated variables (indicating niche-based assembly) or host
turnover (indicating dispersal-based assembly). Mapping of assemblages on climate, vegetation and soil maps, accord-
ing to their loadings on axis 1 or axis 2 of the SDFA, did not provide clear-cut results. Clusters of similar loadings could
be recognized within some, but not other, climate, vegetation and soil types. However, MS-GDM demonstrated that the
effect of environmental variables (especially air temperature) on flea compositional turnover was much stronger than that
of host turnover, indicating the predominance of niche-based processes in local community assembly. A comparison of our
results with those on the mechanisms that drive species assembly in regional communities allows us to conclude that local
and regional communities result from the joint action of niche-based and dispersal-based processes, with the former more
important at a smaller spatial scale and the latter at a larger spatial scale.
Keywords Dispersal-based mechanisms· Fleas· Local assemblages· Niche-based mechanisms· South America
Handling Editor: Una Ryan
* Boris R. Krasnov
krasnov@bgu.ac.il
1 Mitrani Department ofDesert Ecology, Swiss Institute
forDryland Environmental andEnergy Research,
Jacob Blaustein Institutes forDesert Research, Ben-
Gurion University oftheNegev, Sede Boqer Campus,
MidreshetBen-Gurion, Israel
2 Programa de Conservación de los Murciélagos de
Argentina (PCMA) andInstituto de Investigaciones de
Biodiversidad Argentina (PIDBA)-CCT CONICET Noa
Sur (Consejo Nacional de Investigaciones Científicas
Y Técnicas), Facultad de Ciencias Naturales E IML,
UNT, andFundación Miguel Lillo, Miguel Lillo 251,
CP4000SanMigueldeTucumán, Argentina
3 Centro de Investigaciones y Transferencia del
Noroeste de La Provincia de Buenos Aires-CITNOBA
(UNNOBA-UNSAdA-CONICET), Pergamino, Argentina
4 Laboratorio de Ectoparásitos, Centro de Estudios
Parasitológicos Y de Vectores (CEPAVE)
(CONICET-UNLP), 45–53 Bv. 120 s/n e/ Av. 60 y Calle 64,
1900, LaPlata, Argentina
5 French Associates Institute forAgriculture
andBiotechnology ofDrylands, Ben-Gurion University
oftheNegev, Sede Boqer Campus, MidreshetBen-Gurion,
Israel
/ Published online: 14 December 2022
Parasitology Research (2023) 122:571–583
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
ResearchGate has not been able to resolve any citations for this publication.
Preprint
Full-text available
A multitude of physical and biological processes on which ecosystems and human societies depend are governed by climatic conditions. Understanding how these processes are altered by climate change is central to mitigation efforts. Based on mechanistically downscaled climate data, we developed a set of climate-related variables at yet unprecedented spatiotemporal detail as a basis for environmental and ecological analyses. We created gridded data for near-surface relative humidity (hurs), cloud area fraction (clt), near-surface wind speed (sfcWind), vapour pressure deficit (vpd), surface 15 downwelling shortwave radiation (rsds), potential evapotranspiration (pet), climate moisture index (cmi), and site water balance (swb), at a monthly temporal and 30 arcsec spatial resolution globally, from 1980 until 2018 (time-series variables). At the same spatial resolution, we further estimated climatological normals of frost change frequency (fcf), snow cover days (scd), potential net primary productivity (npp), growing degree days (gdd), and growing season characteristics for the periods three shared socioeconomic pathways (SSP126, SSP370, 20 SSP585) and five Earth system models (projected variables). Time-series variables showed high accuracy when validated against observations from meteorological stations. Projected variables were also highly correlated to observations, although some variables showed notable biases, e.g., snow cover days (scd). Together, the CHELSA-BIOCLIM+ data set presented here (https://doi.org/10.16904/envidat.332, Brun et al., 2022) allows improving our understanding of patterns and processes that are governed by climate, including the impact of recent and future climate changes on the world's ecosystems and 25 associated services to societies.
Article
Full-text available
Biological communities may be assembled by both niche-based and dispersal-based (= historic) processes with the relative importance of these processes in community assembly being scale- and context-dependent. To infer whether (a) niche‐based or dispersal‐based processes play the main role in the assembly of flea communities parasitic on small mammals and whether (b) the main processes of flea community assembly are scale-dependent, we applied a novel permutation-based algorithm (PER-SIMPER) and the dispersal–niche continuum index (DNCI), to data on the species incidence of fleas and their hosts at two spatial scales. At the larger (continental) scale, we analysed flea communities in four biogeographic realms across adjacent continental sections. At the smaller (local) scale, we considered flea communities across two main regions (lowlands and mountains) and seven habitat types within Slovakia. Our analyses demonstrated that species composition of fleas and their small mammalian hosts depended predominantly on historical processes (dispersal) at both scale. This was true for the majority of biogeographic realms at continental scale (except the Nearctic) and both regions at local scale. Nevertheless, strong niche-based assembly mechanism was found in the Nearctic assemblages. At local scale, the intensity of dispersal processes was weaker and niche-driven processes were stronger between habitats within a region than between mountain and lowland regions. We provide historical and ecological explanations for these patterns. We conclude that the assembly of compound flea communities is governed, to a great extent, by the dispersal processes acting on their hosts and, to a lesser extent, by the niche-based processes.
Article
Full-text available
Patterns in community composition are scale-dependent and generally difficult to distinguish. Therefore, quantifying the main assembly processes in various systems and across different datasets has remained challenging. Building on the PER-SIMPER method, we propose a new metric, the dispersal-niche continuum index (DNCI), which estimates whether dispersal or niche processes dominate community assembly and facilitates the comparisons of processes among datasets. The DNCI was tested for robustness using simulations and applied to observational datasets comprising organismal groups with different trophic level and dispersal potential. Based on the robustness tests, the DNCI discriminated the respective contribution of niche and dispersal processes in pairwise comparisons of site groups with less than 40% and 30% differences in their taxa and site numbers, respectively. In the observational datasets, the DNCI suggested that dispersal rather than niche assembly was the dominant assembly process which, however, varied in intensity among organismal groups and study contexts, including spatial scale and ecosystem types. The proposed DNCI measures the relative strength of community assembly processes in a way that is simple, easily quantifiable and comparable across datasets. We discuss the strengths and weaknesses of the DNCI and provide perspectives for future research.
Article
Full-text available
Aim: Determine the relative influence of geographical distance, environmental differences, and host species composition on the similarity of bat fly species composition. Location: Neotropics. Taxon: Bats (Chiroptera: Phyllostomidae) and bat flies (Diptera: Streblidae). Methods: Abundance data on bats and ectoparasites were obtained from published studies. The relative influences of environmental variation (annual precipitation, temperature seasonality, elevation, and NDVI), host species composition, and geographic distance on parasite community composition were analysed with Generalized Dissimilarity Modelling and variance partitioning. Additionally, we evaluated the influence of these environmental variables and geographic distance on host species composition. Results: Our model explains 45.3% of the variance in the dissimilarity of bat fly species. Host species composition had the most significant influence on bat fly species composition across communities, followed by environmental effects. Variance partitioning showed that host species composition explained 14.9% and environmental characteristics explained 10.3% of the variance in bat fly species dissimilarity. Geographical distance alone had a negligible effect as it accounted for only 0.007% of the variance in bat fly species composition. Host species composition was mainly influenced by geographic distance (18.0%) and secondarily by environmental variables (9.8%). The most important environmental variables influencing parasite and host species composition were annual precipitation and temperature seasonality, respectively. Main Conclusions: The lack of relationship between geographical distance and bat fly species composition may reflect either the high mobility or the high dispersal capacity of bat flies, or a combination of these. Alternatively, it could reflect a taxonomic artefact. Environmental differences seem to directly affect bat flies, as opposed to affecting them indirectly through their impact on the hosts. Our results support the fundamental role that host species composition plays in determining the species composition of highly host‐specific parasites. However, we argue that host specificity is not the only trait impacting ectoparasite species composition.
Article
Full-text available
Northwestern Argentina (NOA) is one of the least studied areas in Argentina with respect to ectoparasites of the order Siphonaptera; previous investigations, until this study, were scarce and specific. The objective of this study was to contribute to the knowledge of the diversity of siphonaptera that parasitize small mammals from the NOA, emphasizing in their systematics and distribution. Specimens of fleas collected in several localities of NOA, and stored in the “Annexes” of the Colección Mamíferos Lillo, Universidad Nacional de Tucuman, Argentina, were studied. Fleas were manually removed from the host pelage, fixed in alcohol 70% and prepared following conventional techniques for later observation under microscope. For specimen identification, the original descriptions of species and subspecies were reviewed and compared with specimens stored in systematic collections. Nine families, 22 genera, 53 species, and eight subspecies were recorded. A new family, a new genus, and three new species are recorded for the first time in Argentina; five species are new for NOA and nine are new to science. The distribution of 11 species and two subspecies are extended in the NOA, new records are added to different provinces and new flea-hosts associations are reported. The greatest diversity of fleas in the Yungas is the reflection of one of the areas with the highest biodiversity in the Neotropical region, such as the Yungas forests, which also includes mammals, as sigmodontine rodents and bats among them. The similarity analysis among eco-regions showed a major faunistic congruence between the Yungas and the Dry Chaco. The greatest differentiation was given by the High Andes and Puna compared with the other eco-regions, probably because these areas are the least surveyed and with the lowest richness and abundance of small mammal species. From the total of 82 new flea-host associations, 81 belong to sigmodontine rodent hosts and one to a marsupial.
Article
Full-text available
Incidence, or compositional, matrices are generated for a broad range of research applications in biology. Zeta diversity provides a common currency and conceptual framework that links incidence‐based metrics with multiple patterns of interest in biology, ecology and biodiversity science. It quantifies the variation in species (or OTU) composition of multiple assemblages (or cases) in space or time, to capture the contribution of the full suite of narrow, intermediate and wide‐ranging species to biotic heterogeneity. Here we provide a conceptual framework for the application and interpretation of patterns of continuous change in compositional diversity using zeta diversity. This includes consideration of the survey design context, and the multiple ways in which zeta diversity decline and decay can be used to examine and test turnover in the identity of elements across space and time. We introduce the zeta ratio‐based retention rate curve to quantify rates of compositional change. We illustrate these applications using 11 empirical datasets from a broad range of taxa, scales and levels of biological organisation – from DNA molecules and microbes to communities and interaction networks – including one of the original data sets used to express compositional change and distance decay in ecology. We show (i) how different sample selection schemes used during the calculation of compositional change are appropriate for different data types and questions, (ii) how higher orders of zeta may in some cases better detect shifts and transitions, and (iii) the relative roles of rare versus common species in driving patterns of compositional change. By exploring the application of zeta diversity decline and decay, including the retention rate, across this broad range of contexts, we demonstrate its application for understanding continuous turnover in biological systems. This article is protected by copyright. All rights reserved.
Article
We used data on the species composition of regional assemblages of fleas and their small mammalian hosts from 6 biogeographic realms and applied a novel method of step-down factor analyses (SDFA) and cluster analyses to identify biogeographic (across the entire globe) and ecological (within a realm across the main terrestrial biomes) clusters of these assemblages. We found that, at the global scale, the clusters of regional assemblage loadings on SDFA axes reflected well the assemblage distribution, according to the biogeographic realms to which they belong. At the global scale, the cluster topology, corresponding to the biogeographic realms, was similar between flea and host assemblages, but the topology of subtrees within realm-specific clusters substantially differed between fleas and hosts. At the scale of biogeographic realms, the distribution of regional flea and host assemblages did not correspond to the predominant biome types. Assemblages with similar loadings on SDFA axes were often situated in different biomes and vice versa. The across-biome, within-realm distributions of flea vs host assemblages suggested weak congruence between these distributions. Our results indicate that dispersal is a predominant mechanism of flea and host community assembly across large regions.
Article
Aim We studied compositional turnover in two ectoparasite taxa asking whether (a) the main driver of turnover (environmental factors, host composition, or distance) is the same in both taxa; (b) the turnover of rare and widespread fleas and mites is driven by different factors; and (c) the turnover of either fleas or mites or both respond to the same environmental gradients as the turnover of their hosts. Location Northern and central Palaearctic. Time period 1959–2004. Main taxa studied Fleas, gamasid mites, mammals. Methods We used data on fleas and mites collected from 30 and 20 regions, respectively, and applied a novel metric, zeta diversity, and a novel approach, multi‐site generalized dissimilarity modelling (MS‐GDM). Results In fleas, variance explained by the models with host turnover as a predictor was higher than that of models with environment and distance or environment only. In mites, similar proportions of variance were explained by models with and without a host‐associated predictor. Host turnover strongly affected the compositional turnover of fleas, whereas mite turnover was equally influenced by host turnover and dissimilarity in air temperature. When host turnover was removed from the models, temperature became the most important predictor of turnover, followed by precipitation (for both taxa) and distance (for fleas). The effects of host turnover and environment were stronger for turnover of rare than widespread species. Temperature was the most important predictor of the host turnover independently of whether distance was included in the model. Main conclusions We conclude that the strength and manifestation of the effects of host compositional turnover as compared to environmental dissimilarity differ between ectoparasite taxa. Moreover, the application of MS‐GDM allowed us to reveal patterns that were obscured or distorted in earlier studies.
Article
1. Generalised dissimilarity modelling (GDM) applies pairwise beta diversity as a measure of species turnover with the purpose of explaining changes in species composition under changing environments or along environmental gradients. Beta diversity only captures turnover across pairs of sites and, therefore, disproportionately represents turnover in rare species across communities. By contrast, zeta diversity, the average number of shared species across multiple sites, captures the full spectrum of rare, intermediate and widespread species as they contribute differently to compositional turnover. 2. We show how integrating zeta diversity into GDMs (which we term multi-site generalised dissimilarity modelling , MS-GDM), provides a more information rich approach to modelling how communities respond to environmental variation and change. We demonstrate the value of including zeta diversity in biodiversity assessment and modelling using BirdLife Australia Atlas data. Zeta diversity values for different numbers of sites (the order of zeta) are regressed against environmental differences and distance using two kinds of regressions: shape constrained additive models and a combination of I-splines and generalised linear models. 3. Applying MS-GDM to different orders of zeta revealed shifts in the importance of environmental variables in explaining species turnover, varying with the order of zeta and thus with the level of co-occurrence of the species and, by extension, their commonness and rarity. In particular, precipitation gradients emerged as drivers in the turnover of rare species, whereas temperature gradients were more important drivers of turnover in widespread species. 4. Appreciation of the factors that drive compositional turnover across multiple sites is necessary for accommodating the full spectrum of compositional turnover across rare to common species. This extends beyond understanding drivers for pairwise beta diversity only. MS-GDM provides a valuable addition to the toolkit of GDM, with further potential for survey gap analysis and prediction of species composition in unsampled sites.