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opencc-zeroDec 2014View details →

Data from: Plasma carotenoid concentrations of incubating American kestrels (Falco sparverius) show annual, seasonal, and individual variation and explain reproductive outcome

In wild birds, the proximate and ultimate factors that affect circulating carotenoid concentrations remain poorly understood. We studied variation in plasma carotenoid concentrations across several scales: annual, seasonal, pair, territory and individual, and evaluated whether plasma carotenoid concentrations explained reproductive outcome of wild American kestrels (Falco sparverius). We sampled plasma carotenoid concentrations of 99 female and 80 male incubating kestrels from April to June in 2008 to 2012. Plasma carotenoid concentrations were explained by an interaction between year and sex, date, and random effects for pair and individual identity. In general, plasma carotenoid concentrations of males were significantly higher than females, but this depended on year. Within a breeding season, earlier nesting kestrels had higher carotenoid concentrations than later nesting kestrels, a pattern that is coincident with seasonal trends in local fitness. Pair and individual identity explained variation in carotenoid concentrations suggesting that carotenoid concentrations of mated birds were correlated, and some individuals consistently maintained higher carotenoid levels than others. Male carotenoid concentrations were positively associated with number of young fledged per pair. These results are consistent with the hypothesis that higher quality individuals have higher carotenoid levels compared to lower quality individuals, despite annual variations in carotenoid availability.

opencc-zeroDec 2013View details →

Data from: Environmental filtering explains variation in plant diversity along resource gradients

The mechanisms that shape plant diversity along resource gradients remain unresolved because competing theories have been evaluated in isolation. By testing multiple theories simultaneously across a >2-million-year dune chronosequence in an Australian biodiversity hotspot, we show that variation in plant diversity is not explained by local resource heterogeneity, resource partitioning, nutrient stoichiometry, or soil fertility along this strong resource gradient. Rather, our results suggest that diversity is determined by environmental filtering from the regional flora, driven by soil acidification during long-term pedogenesis. This finding challenges the prevailing view that resource competition controls local plant diversity along resource gradients, and instead reflects processes shaping species pools over evolutionary time scales.

opencc-zeroDec 2015View details →

Data from: Asynchronous changes in abundance over large scales are explained by demographic variation rather than environmental stochasticity in an invasive flagellate

Environmental stochasticity is important in explaining the persistence and establishment of invasive species, but the simultaneous effects of environmental and demographic factors are difficult to separate. Understanding how demography and environmental factors affect invasive species abundance over large temporal and spatial scales is essential to anticipate populations at risk of becoming established and setting appropriate management measures. Using a hierarchical mixed modeling approach we analyzed the spatial and interannual dynamics of the invasive raphidophyte Gonyostomum semen, a noxious flagellate which is spreading in northern Europe, in response to demographic and environmental variation. We used data from 76 lakes distributed across two biogeographical regions in Sweden (Central Plains in the south and Fennoscandian region in the north) and sampled during 14 years. We found a strong asynchrony in the density dynamics of G. semen populations between the two regions. G. semen showed positive trends (i.e. increasing frequency of high density peaks) in most southern lakes, forming established populations with recurrent blooms in successive years in some of them. In contrast, G. semen populations were smaller and more stochastic in the north. G. semen previous year's abundance, a proxy for cyst production and recruitment, had a strong control on the dynamics, likely contributing to the stability of high density populations in southern lakes. Conversely, the effects of climate and habitat were weaker and their influence varied across regions. Temperature was the limiting factor in the north whereas local habitat was more important in the south. Synthesis: A full understanding of the mechanisms driving abundance changes across large scales can only be gained if endogenous and environmental factors are analyzed together. For phytoplankton species, and specially, noxious microalgae, this implies that proxies for cyst production and recruitment, which are the inoculum for next year population, should be included in e.g. distribution, bloom formation and climate models, as these may modify establishment and population response to environmental variation. Asynchronous changes in abundance across regions also indicate that management plans should be developed for small regions, as inference at a large scale may obscure the mechanisms driving local population changes.

opencc-zeroOct 2023View details →

Amata variation analysis for Eco-geographic hypotheses do not explain variation in warning signals in diurnal Amata nigriceps wasp moths

Aposematic prey use conspicuous warning signals to advertise a secondary defense. To be effective, warning signals should be reliable throughout a prey population. However, warning signals vary considerably across and within populations, often for unknown causes. Here, the Australian diurnal moth Amata nigriceps, which has orange wing spots on a black background, was used to explore four ecogeographic hypotheses explaining warning signal variability: the thermal melanism, the photo-protection, the desiccation resistance, and the predator-loss hypotheses. We collected live moths from 29 populations across 746 km of coastal New South Wales, Australia, and sampled relevant museum collections from 1896 to 1982. We quantified the proportion of orange wing spots (warning signal size) relative to site-specific abiotic (temperature, precipitation, solar radiation) and biotic factors (diversity of bird predators). In museum specimens, warning signal size varied within the decade of collection, without a discernible temporal trend. Recent collections also varied in signal size, but we found no support for the four hypotheses. Our results are in contrast with studies that have found significant relationships between warning colours and eco-geographic factors. Local phenotypic responses in Amata nigriceps together with relaxed predator selection and genetic effects may explain the persistence of warning signal variation.

opencc-zeroNov 2023View details →

Grass veins are leaky pipes: Vessel widening in grass leaves explain variation in stomatal conductance and vessel diameter among species

The widening of xylem vessels from tip-to-base of trees is an adaptation to minimize the hydraulic resistance of a long pathway. Given that parallel veins of monocot leaves do not branch hierarchically, vessels should also widen basipetally but, in addition to minimizing resistance, should also account for water volume lost to transpiration since they supply water to the lamina along their lengths, i.e. "leakiness". We measured photosynthesis, stomatal conductance, and vessel diameter at 5 locations along each leaf of 5 perennial grass species. We found that the rate of conduit widening in grass leaves was larger than the widening exponent required to minimize pathlength resistance (0.35 vs. ~0.22). Furthermore, variation in the widening exponent among species was positively correlated with maximal stomatal conductance (r2 = 0.20) and net CO2 assimilation (r2 = 0.45). These results suggest that faster rates of conduit widening (>0.22) were associated with higher rates of water loss. Taken together, our results show that the widening exponent is linked to plant function in grass leaves and that natural selection has favored parallel vein networks that are constructed to meet transpiration requirements while minimizing hydraulic resistance within grass blades.

opencc-by-4.0Apr 2024View details →

Small Variations in Ice Composition and Layer Thickness Explain Bright Reflections Below Martian Polar Cap Without Liquid Water

These files include the model results used in Lalich et al. 2024 as well as the code necessary to analyze and reprooduce those results. See README for more detail.

opencc-zeroNov 2021View details →

Nucleotide substitutions during speciation may explain substitution rate variation

Although molecular mechanisms associated with the generation of mutations are highly conserved across taxa, there is widespread variation in mutation rates between evolutionary lineages. When phylogenies are reconstructed based on nucleotide sequences, such variation is typically accounted for by the assumption of a relaxed molecular clock, which is just a statistical distribution of mutation rates without much underlying biological mechanism. Here, we propose that variation in accumulated mutations may be partly explained by an elevated mutation rate during speciation. Using simulations, we show how shifting mutations from branches to speciation events impacts inference of branching times in phylogenetic reconstruction. Furthermore, the resulting nucleotide alignments are better described by a relaxed than by a strict molecular clock. Thus, elevated mutation rates during speciation potentially explain part of the variation in substitution rates that is observed across the tree of life.

opencc-zeroMar 2022View details →

Data from: Transgenerational genetic effects help explain latitudinal variation in seed mass and germination timing in Plantago lanceolata

We know little about the underlying genetic control of phenotypic patterns of seed traits across large-scale geographic and environmental gradients. Such knowledge is important for understanding the evolution of populations within species and for improving species conservation. Therefore, to test for genetic variation in P. lanceolata, we made reciprocal crosses between northern and southern genotypes that span the species' range in Europe. Results provide evidence of transgenerational genetic effects on seed mass and germination timing. Northern mothers produced larger seeds with delayed germination, in contrast to southern mothers, which produced smaller seeds with accelerated germination. Maternal latitude affected both the seed coat, solely maternal tissue, and embryo/endosperm tissues. Thus, latitudinal variation in seed size and germination timing can be explained, in part, by the direct influence of maternal genotype, independent of zygotic genes that parents pass directly to the embryo and endosperm. Data suggest that researchers exploring the existence and evolution of large-scale geographic variation within species test for transgenerational genetic effects. Also, data suggest that transgenerational control of seed traits should be considered when developing procedures designed to facilitate species conservation and restoration.

opencc-by-4.0May 2022View details →

Life-history genotype explains variation in migration activity in Atlantic salmon (Salmo salar)

Data and R-script used in the paper titled in the title.

opencc-zeroMay 2022View details →

Individual variation explains aging patterns in a cooperatively breeding bird, the long-tailed tit (Aegithalos caudatus)

1. Alloparental care in cooperatively-breeding species may alter breeder age-specific survival and reproduction, and subsequently senescence. The helping behaviour itself might also undergo age-related change, and decisions to help in facultative cooperative breeders are likely to be affected by the individual condition. 2. Helpers in long-tailed tits (Aegithalos caudatus) assist relatives after failing to raise their own brood, with offspring from helped nests being more likely to recruit into the breeding population. 3. Using data collected over 25 years, we examined the age-trajectories of survival and reproduction in adult long-tailed tits to determine how these were affected by the presence or absence of helpers, and how helper behaviour changed with age. 4. There was evidence for increased reproductive performance with breeder age, but no effect of age on the probability of survival. We found no evidence of significant senescent decline in survival or reproductive performance, although individuals accrued less inclusive fitness in their last year of life. Lifetime reproductive success was positively related to both reproductive lifespan and body mass. Within a season, breeders that were assisted by helpers enjoyed greater reproductive success through enhanced offspring recruitment in the following year. We found no evidence that age affected an individual's propensity to help, or the amount of indirect fitness accrued through helping. 5. We found a positive correlation between lifespan and multiple components of reproductive success, suggesting that individual variation in quality underpins age-related variation in fitness in this species. Helping decisions are driven by condition, and the lifetime inclusive fitness of immigrants was predicted by body mass. These findings further support individual heterogeneity in quality being a major driver for fitness gains across the life course of long-tailed tits.

Supplementary material 2 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Supplementary material 2 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Supplementary material 4 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Supplementary material 4 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Supplementary material 3 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Supplementary material 3 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Supplementary material 1 from: Martín-Forés I, Casado MA, Castro I, del Pozo A, Molina-Montenegro MA, de Miguel JM, Acosta-Gallo B (2018) Variation in phenology and overall performance traits can help to explain the plant invasion process amongst Mediterranean ecosystems. NeoBiota 41: 67-89. https://doi.org/10.3897/neobiota.41.29965

Figure S1 : Explanation note: Distribution of Leontodonsaxatilis, Hypochaerisglabra and Trifoliumglomeratum in both the native (Spain) and the introduced (Chile) ranges.

opencc-zeroDec 2017View details →

Data from: Primary productivity explains size variation across the Pallid bat's (Antrozous pallidus) western geographic range

1. Body size is associated with many aspects of the life history, ecology, and physiology of animals. Within a species, body size can vary substantially across space and time, and the mechanisms generating these patterns have been the focus of evolutionary and ecology research. 2. Bergmann's Rule predicts a negative relationship between body size and temperature across the geographic range of endothermic animals; larger animals have a lower surface to volume ratio, which would allow for greater heat conservation. Despite the broad support for this pattern, its underlying mechanisms are heavily debated. Numerous alternative explanations have been proposed to explain why larger animals are found in colder climates, and vice versa, including heat dissipation, environmental seasonality, and resource availability. 3. We used the Pallid bat, Antrozous pallidus, as a model to evaluate Bergmannian size patterns and the relative support for major explanatory hypotheses of geographic body size variation. We tested the hypothesis that geographic size variation is predicted by productivity, as opposed to seasonality, heat conservation or dissipation, or some combination of these processes. Additionally, we investigated the potential ecomorphological consequences of size variation in Pallid bats by determining if skull shape (an indicator of bite performance) varies with size. 4. Whereas we did find that Pallid bat populations in northern latitudes are composed of larger individuals, our results suggest that net primary productivity and, to a lesser extent heat conservation, best explains size variation throughout the western range of this species. We also found that skull shape in Pallid bats changes in tandem with skull size, with larger bats having cranial traits associated with greater bite force production. 5. The results of our study indicate that variation in resource availability may be a key factor underlying spatial patterns in size, morphology and, possibly, feeding performance within wide-ranging bat species.

opencc-zeroDec 2021View details →

Isolation by geographical distance after release from Pleistocene refugia explains genetic and phenotypic variation in Xylotrupes siamensis (Coleoptera: Scarabaeidae)

Consistent and objective species delimitation is crucial to biodiversity studies, but challenges remain when conflicting taxonomic decisions have been made because different data sets and analytical methods were used to delineate species. In the rhinoceros beetle, Xylotrupes siamensis, the use of different morphological characters has resulted in taxonomic disagreement between studies. We used three molecular loci (mitochondrial CO1 and nuclear ITS2 and H3) to investigate the genetic divergence between populations exhibiting different male horn phenotypes. We also applied an approximate Bayesian computation approach to test alternative historical hypotheses that might explain the present genetic diversity among geographical populations. Furthermore, we used species distribution models to estimate the temporal variation in the geographical distribution of suitable habitats. The results show that the two phenotypic taxa within X. siamensis are not genetically structured and that their genetic structure can be explained using isolation by geographical distance. The emergence of the two phenotypic taxa might have been associated with historical isolation in separate refugia. However, spatial expansion and genetic interchange between populations might have gradually eroded the spatial genetic structure. We demonstrate that understanding the historical processes responsible for phenotypic divergence and genetic diversity among current populations could help with making evolutionarily coherent taxonomic decisions.

Figure 3 in Isolation by geographical distance after release from Pleistocene refugia explains genetic and phenotypic variation in Xylotrupes siamensis (Coleoptera: Scarabaeidae)

Figure 3. Phylogenetic networks of the three analysed loci and three historical scenarios explaining the origin of the CLAOS population tested using the DIYABC program. The colour of each individual shown in the network corresponds to the taxonomic assignment colour in the DIYABC analysis. Scenario 2 was the most likely model selected by the program (~60% posterior support), and scenario 1 also received moderate support (~30% posterior support). Results of posterior support among scenarios and model checking, in addition to the estimated parameter values (population sizes and divergence times), can be found in the Supporting Information (Figs S3–S8).

Figure 1 in Isolation by geographical distance after release from Pleistocene refugia explains genetic and phenotypic variation in Xylotrupes siamensis (Coleoptera: Scarabaeidae)

Figure 1. Different male horn phenotypes in Xylotrupes siamensis. Left panels show exemplars of males of the Tonkinensis (short horn) phenotypes and right panels the Siamensis (long horn with a cephalic horn denticle) phenotype. Samples from the CLAOS population (for details, see Table 1; Fig. 2) exhibit intermediate horn length, and the major males have the cephalic horn denticle.

Figure 4 in Isolation by geographical distance after release from Pleistocene refugia explains genetic and phenotypic variation in Xylotrupes siamensis (Coleoptera: Scarabaeidae)

Figure 4. Associations between three biogeographical distance measures and genetic differentiation (FST), measured at three loci (CO1, ITS2 and H3), for populations of Xylotrupes siamensis. Mantel test statistics (r) indicate the strength and significance of correlations between the genetic distance and biogeographical distance. Distance calculations are detailed in the Material and Methods section. Least cost distances were subject to rescaling and are thus unitless.

Figure 2. A in Isolation by geographical distance after release from Pleistocene refugia explains genetic and phenotypic variation in Xylotrupes siamensis (Coleoptera: Scarabaeidae)

Figure 2. A, the sampling sites of Xylotrupes siamensis populations in this study. White circles indicate samples of the Tonkinensis form and grey circles the Siamensis form. The Mekong River is indicated using a thick grey line; elevational differences are shown via a coloured scale, where a lighter colour depicts higher elevation (maximum = 4000 m a.s.l.). B, location of the study area within the Asia–Pacific region. C–E, species distribution model predictions based on the Last Interglacial (C), the Last Glacial Maximum (D) and current climatic conditions (E) are shown, where darker blue indicates higher predicted climatic suitability.