Reid's Paradox of Rapid Plant Migration

Clark, James S.; Fastie, Chris; Hurtt, George C.; Jackson, Stephen T.; Johnson, Carter; King, George A.; Lewis, Mark A.; Lynch, Jason; Pacala, Stephen W.; Prentice, Colin; Schupp, Eugene W.; Webb, Thompson; Wyckoff, P.

doi:10.2307/1313224

Cited by 656 publications

(308 citation statements)

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“…Glacial refugia in Beringia and Haida Gwaii may also explain very high calculated post-glacial migration rates, a phenomenon known as 'Reid's Paradox' [41]. For example, the expansion of Picea glauca into northern Canada and Alaska evident from the fossil record requires migration rates of 1.5-2.0 km yr 21 , necessitating mechanisms such as repeated long-distance dispersal events [14].…”

Section: (C) Refugia West and North Of The Icementioning

confidence: 99%

Glacial refugia and modern genetic diversity of 22 western North American tree species

2015

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North American tree species, subspecies and genetic varieties have primarily evolved in a landscape of extensive continental ice and restricted temperate climate environments. Here, we reconstruct the refugial history of western North American trees since the last glacial maximum using species distribution models, validated against 3571 palaeoecological records. We investigate how modern subspecies structure and genetic diversity corresponds to modelled glacial refugia, based on a meta-analysis of allelic richness and expected heterozygosity for 473 populations of 22 tree species. We find that species with strong genetic differentiation into subspecies had widespread and large glacial refugia, whereas species with restricted refugia show no differentiation among populations and little genetic diversity, despite being common over a wide range of environments today. In addition, a strong relationship between allelic richness and the size of modelled glacial refugia (r 2 ¼ 0.55) suggest that population bottlenecks during glacial periods had a pronounced effect on the presence of rare alleles.

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Section: (C) Refugia West and North Of The Icementioning

confidence: 99%

Glacial refugia and modern genetic diversity of 22 western North American tree species

2015

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“…Dispersal processes are key to understanding community dynamics and functioning in a variety of ecological conditions ranging from pathogen dispersal and plant diseases [Brown and Hovmoller, 2002] to seed dispersal [Nathan, 2001] and the spreading rates of tree species [Clark et al, 1998]. Traditionally, ecologists assumed that organismic dispersal mimics diffusion; hence follow a normal distribution of individuals displacement step [Hapca et al, 2009].…”

Section: Bacterial Dispersal In Unsaturated Pore Spacesmentioning

confidence: 99%

Microbial dispersal in unsaturated porous media: Characteristics of motile bacterial cell motions in unsaturated angular pore networks

Ebrahimi

2014

Water Resources Research

110

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The dispersal rates of self-propelled microorganisms affect their spatial interactions and the ecological functioning of microbial communities. Microbial dispersal rates affect risk of contamination of water resources by soil-borne pathogens, the inoculation of plant roots, or the rates of spoilage of food products. In contrast with the wealth of information on microbial dispersal in water replete systems, very little is known about their dispersal rates in unsaturated porous media. The fragmented aqueous phase occupying complex soil pore spaces suppress motility and limits dispersal ranges in unsaturated soil. The primary objective of this study was to systematically evaluate key factors that shape microbial dispersal in model unsaturated porous media to quantify effects of saturation, pore space geometry, and chemotaxis on characteristics of principles that govern motile microbial dispersion in unsaturated soil. We constructed a novel 3-D angular pore network model (PNM) to mimic aqueous pathways in soil for different hydration conditions; within the PNM, we employed an individual-based model that considers physiological and biophysical properties of motile and chemotactic bacteria. The effects of hydration conditions on first passage times in different pore networks were studied showing that fragmentation of aquatic habitats under dry conditions sharply suppresses nutrient transport and microbial dispersal rates in good agreement with limited experimental data. Chemotactically biased mean travel speed of microbial cells across 9 mm saturated PNM was $3 mm/h decreasing exponentially to 0.45 mm/h for the PNM at matric potential of 215 kPa (for 235 kPa, dispersal practically ceases and the mean travel time to traverse the 9 mm PNM exceeds 1 year). Results indicate that chemotaxis enhances dispersal rates by orders of magnitude relative to random (diffusive) motions. Model predictions considering microbial cell sizes relative to available liquid pathways sizes were in good agreement with experimental results for unsaturated soils. The new modeling platform enables quantitative consideration of key biophysical factors (e.g., pore space heterogeneities and hydration conditions) governing microbial interactions in 3-D soil pore spaces.

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“…In some studies, however, the next item sampled might greatly increase the whole sample's variance, no matter how many were sampled before, in which case the sample may be best fit by a distribution with infinite variance. Biologists have long realized that exponentially bounded dispersal kernels cannot account for the speed with which trees reoccupied regions vacated by retreating glaciers at the end of the Pleistocene as measured by the pollen record (Skellam, 1951;Davis, 1963;Clark et al, 1998). Clark (1998), using the formalism developed by Kot et al (1996), showed that ''fat-tailed'' dispersal kernels, where some seeds disperse quite long distances, can explain the speed with which trees spread in the Pleistocene.…”

Section: Power-law Dispersal Kernelsmentioning

confidence: 99%