The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
George N Somero - One of the best experts on this subject based on the ideXlab platform.
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heat shock protein 70 hsp70 expression in four limpets of the genus lottia interspecific variation in constitutive and inducible synthesis correlates with in situ exposure to heat stress
The Biological Bulletin, 2008Co-Authors: Yunwei Dong, Luke P Miller, Jon G Sanders, George N SomeroAbstract:Limpets of the genus Lottia occupy a broad vertical distribution on wave-exposed rocky shores, a range that encompasses gradients in the frequency and severity of thermal and desiccation stress brought on by aerial emer- sion. Using western blot analysis of levels of heat-shock protein 70 (Hsp70), we examined the heat-shock responses of four Lottia congeners: Lottia scabra and L. austrodigi- talis, which occur in the high-Intertidal zone, and L. pelta and L. scutum, which are restricted to the low- and mid- Intertidal zones. Our results suggest distinct strategies of Hsp70 expression in limpets occupying different heights and orientations in the rocky Intertidal zone. In freshly field-collected animals and in specimens acclimated at am- bient temperature (14 °C) for 14 days, the two high- Intertidal Species had higher constitutive levels of Hsp70 than the low- and mid-Intertidal Species. During aerial ex- posure to high temperatures, the two low-shore Species and L. austrodigitalis exhibited an onset of Hsp70 expression at 28 °C; no induction of Hsp70 occurred in L. scabra. Our findings suggest that high-Intertidal congeners of Lottia employ a "preparative defense" strategy involving mainte- nance of high constitutive levels of Hsp70 in their cells as a mechanism for protection against periods of extreme and unpredictable heat stress.
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a comparative analysis of the upper thermal tolerance limits of eastern pacific porcelain crabs genus petrolisthes influences of latitude vertical zonation acclimation and phylogeny
Physiological and Biochemical Zoology, 2000Co-Authors: Jonathon H Stillman, George N SomeroAbstract:Abstract Marine Intertidal organisms are subjected to a variety of abiotic stresses, including aerial exposure and wide ranges of temperature. Intertidal Species generally have higher thermal tolerance limits than do subtidal Species, and tropical Species have higher thermal tolerance limits than do temperate Species. The adaptive significance of upper thermal tolerance limits of Intertidal organisms, however, has not been examined within a comparative context. Here, we present a comparative analysis of the adaptive significance of upper thermal tolerance limits in 20 congeneric Species of porcelain crabs, genus Petrolisthes, from Intertidal and subtidal habitats throughout the eastern Pacific. Upper thermal tolerance limits are positively correlated with surface water temperatures and with maximal microhabitat temperatures. Analysis of phylogenetically independent contrasts (from a phylogenetic tree on the basis of the 16s rDNA gene sequence) suggests that upper thermal tolerance limits have evolved in r...
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evolutionary and acclimation induced variation in the heat shock responses of congeneric marine snails genus tegula from different thermal habitats implications for limits of thermotolerance and biogeography
The Journal of Experimental Biology, 1999Co-Authors: Lars Tomanek, George N SomeroAbstract:Heat stress sufficient to cause cellular damage triggers the heat-shock response, the enhanced expression of a group of molecular chaperones called heat-shock proteins (hsps). We compared the heat-shock responses of four Species of marine snails of the genus Tegula that occupy thermal niches differing in absolute temperature and range of temperature. We examined the effects of short-term heat stress and thermal acclimation on the synthesis of hsps of size classes 90, 77, 70 and 38 kDa by measuring incorporation of (35)S-labeled methionine and cysteine into newly synthesized proteins in gill tissue. Temperatures at which enhanced synthesis of hsps first occurred (T(on)), temperatures of maximal induction of hsp synthesis (T(peak)) and temperatures at which hsp synthesis was heat-inactivated (T(off)) were lowest in two low-Intertidal to subtidal Species from the temperate zone, T. brunnea and T. montereyi, intermediate in a mid- to low-Intertidal Species of the temperate zone, T. funebralis, and highest in a subtropical Intertidal Species from the Gulf of California, T. rugosa. Synthesis of hsps and other classes of protein by T. brunnea and T. montereyi was heat-inactivated at temperatures commonly encountered by T. funebralis during low tides on warm days. In turn, protein synthesis by T. funebralis was blocked at the upper temperatures of the habitat of T. rugosa. Acclimation of snails to 13 degrees C, 18 degrees C and 23 degrees C shifted T(on) and T(peak) for certain hsps, but did not affect T(off). The heat-shock responses of field-acclimatized snails were generally reduced in comparison with those of laboratory-acclimated snails. Overall, despite the occurrence of acclimatory plasticity in their heat-shock responses, genetically fixed differences in T(on), T(peak) and T(off) appear to exist that reflect the separate evolutionary histories of these Species and may play important roles in setting their thermal tolerance limits and, thereby, their biogeographic distribution patterns.
Stephen J Hawkins - One of the best experts on this subject based on the ideXlab platform.
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spatial scales of variance in abundance of Intertidal Species effects of region dispersal mode and trophic level
Ecology, 2009Co-Authors: Michael T Burrows, Robin Harvey, Linda Robb, Elvira S Poloczanska, Nova Mieszkowska, Pippa J Moore, R Leaper, Stephen J HawkinsAbstract:Determination of the pattern of variation in population abundance among spatial scales offers much insight into the potential regulating factors. Here we offer a method of quantifying spatial variance on a range of scales derived by sampling of irregularly spaced sites along complex coastlines. We use it to determine whether the nature of spatial variance depends on the trophic level or the mode of dispersal of the Species involved and the role of the complexity of the underlying habitat. A least-cost distance model was used to determine distances by sea between all pairs of sites. Ordination of this distance matrix using multidimensional scaling allowed estimation of variance components with hierarchical ANOVA at nested spatial scales using spatial windows. By repeatedly moving these spatial windows and using a second set of spatial scales, average variance scale functions were derived for 50+ Species in the UK rocky Intertidal. Variance spectra for most Species were well described by the inverse power l...
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spatial scales of variance in abundance of Intertidal Species effects of region dispersal mode and trophic level
Ecology, 2009Co-Authors: Michael T Burrows, Robin Harvey, Linda Robb, Elvira S Poloczanska, Nova Mieszkowska, Pippa J Moore, R Leaper, Stephen J HawkinsAbstract:Determination of the pattern of variation in population abundance among spatial scales offers much insight into the potential regulating factors. Here we offer a method of quantifying spatial variance on a range of scales derived by sampling of irregularly spaced sites along complex coastlines. We use it to determine whether the nature of spatial variance depends on the trophic level or the mode of dispersal of the Species involved and the role of the complexity of the underlying habitat. A least-cost distance model was used to determine distances by sea between all pairs of sites. Ordination of this distance matrix using multidimensional scaling allowed estimation of variance components with hierarchical ANOVA at nested spatial scales using spatial windows. By repeatedly moving these spatial windows and using a second set of spatial scales, average variance scale functions were derived for 50+ Species in the UK rocky Intertidal. Variance spectra for most Species were well described by the inverse power law (1/fbeta) for noise spectra, with values for the exponent ranging from 0 to 1.1. At higher trophic levels (herbivores and carnivores), those Species with planktonic dispersal had significantly higher beta values, indicating greater large- than small-scale variability, as did those on simpler coastlines (southwestern England and Wales vs. western Scotland). Average abundance and proportional incidence of Species had the strongest influence on p values, with those of intermediate abundance and incidence having much greater large-scale variance (beta approximately 0.5) than rare or ubiquitous Species (beta approximately 0).
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Persistent border: an analysis of the geographic boundary of an Intertidal Species
Marine Ecology Progress Series, 2009Co-Authors: Roger Jh Herbert, Alan J. Southward, R. T. Clarke, Martin Sheader, Stephen J HawkinsAbstract:The biological performance of Species close to their biogeographic boundaries is of critical interest in a period of rapid climate change and can inform predictions of future patterns of distribution. The classic view is that performance attributes (reproduction, growth, survival) will gradually decline from the centre towards the edge of a Species range. A persistent discontinuity in the distribution of the Intertidal barnacle Chthamalus montagui on the central south coast of England has enabled us to test hypotheses about its performance and recruitment as the range edge is approached. Although adult density was reduced by over 5 orders of magnitude along a 200 km dis- tance, there was little evidence of impaired performance at the range edge. There have been fluctu- ations in abundance over the last 50 yr at shores approaching the border, which are associated with changes in temperature and suggest thermal sensitivities. A study of recruitment in C. montagui and in other Intertidal barnacles revealed a region of very low recruitment for all Species close to the bor- der of C. montagui. We propose that reductions in larval supply caused by complex regional hydrog- raphy and suboptimal habitat quality, not adult performance, is most likely responsible for a steep gradient in recruitment as the border is approached, although possible reductions in larval perfor- mance cannot be totally discounted. The location of 'low recruitment cells' caused by oceanographic processes that obstruct the dispersal of propagules needs to be identified when modelling the rate of change of biological assemblages and the location and spacing of reserves.
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living on the edge of two changing worlds forecasting the responses of rocky Intertidal ecosystems to climate change
Annual Review of Ecology Evolution and Systematics, 2006Co-Authors: Brain Helmuth, Nova Mieszkowska, Philippa Moore, Stephen J HawkinsAbstract:Long-term monitoring shows that the poleward range edges of Intertidal biota have shifted by as much as 50 km per decade, faster than most recorded shifts of terrestrial Species. Although most studies have concentrated on Species-range edges, recent work emphasizes how modifying factors such as regional differences in the timing of low tide can overwhelm large-scale climatic gradients, leading to a mosaic of environmental stress. We discuss how changes in the mean and variability in climatic regimes, as modified by local and regional factors, can lead to complex patterns of Species distribution rather than simple range shifts. We describe how ecological forecasting may be used to generate explicit hypotheses regarding the likely impacts of different climatic change scenarios on the distribution of Intertidal Species and how related hindcasting methods can be used to evaluate changes that have already been detected. These hypotheses can then be tested over a hierarchy of temporal and spatial scales using coupled field and laboratory-based approaches.
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changes in the range of some common rocky shore Species in britain a response to climate change
Hydrobiologia, 2006Co-Authors: Nova Mieszkowska, R Leaper, Stephen J Hawkins, Mark A F Kendall, Phillip Williamson, Nick J Hardmanmountford, A J SouthwardAbstract:Since the 1990s there has been a period of rapid climate warming in Europe. Long-term broad scale datasets coupled with time series at specific locations for rocky Intertidal Species dating back to the 1950s have been collected in Britain and Ireland. Resurveys of the original locations in 2001–2003 have been undertaken to identify changes in the biogeographical range and abundance of these Species. The results show that some ‘southern’ Species including Osilinus lineatus da Costa and Gibbula umbilicalis da Costa have undergone north and north-eastern range extensions. Populations have increased in abundance and adult size has decreased since the previous surveys were conducted. These changes have been synchronous throughout Britain, strongly suggesting that climate is responsible. The use of Intertidal Species as indicators of climate change is proposed.
Yunwei Dong - One of the best experts on this subject based on the ideXlab platform.
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causations of phylogeographic barrier of some rocky shore Species along the chinese coastline
BMC Evolutionary Biology, 2015Co-Authors: Jie Wang, Ling Ming Tsang, Yunwei DongAbstract:Substrate, ocean current and freshwater discharge are recognized as important factors that control the larval dispersal and recruitment of Intertidal Species. Life history traits of individual Species will determine the differential responses to these physical factors, and hence resulting in contrasting phylogeography across the same biogeographic barrier. To determine how these factors affect genetic structure of rocky shore Species along the China coast, a comparative phylogeographic study of four Intertidal and subtidal Species was conducted using mitochondrial and nuclear DNA by combining new sequences from Siphonaria japonica with previously published sequences from three Species (Cellana toreuma, Sargassum horneri and Atrina pectinata). Analysis of molecular variance and pairwise ΦST revealed significant genetic differences between the Yellow Sea (YS) and the other two marginal seas (East China Sea, ECS and South China Sea, SCS) for rocky-shore Species (S. japonica, C. toreuma, S. horneri), but not for muddy-shore Species Atrina pectinata. Demographic history analysis proved that the population size of all these four Species were persistent though the Last Glacial Maximum (LGM, ~20 ka BP). Migration analysis revealed that gene flow differentiated northward and southward migration for these four Species. However, the inferred direction of gene flow using alternatively mitochondrial or nuclear markers was contradictory in S. japonica. It is concluded that there is a phylogeographical break at the Yangtze River estuary for the rocky shore Species and the causation of the barrier is mainly due to the unsuitable substratum and freshwater discharge. All four Intertidal and subtidal Species appear to have persisted through the LGM in China, indicating the lower impact of LGM on Intertidal and subtidal Species than generally anticipated. The imbalanced gene flow between YS and ESCS groups for these four Species could be explained by historical refugia. The discordance between mitochondrial and nuclear markers in the MIGRATE analysis of S. japonica prove the importance of employing multi-locus data in biogeographic study. Climate change, land reclamation and dam construction, which are changing substrate and hydrological conditions around Yangtze River estuary, will consequently affect the biogeographic pattern of Intertidal Species.
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variations in cardiac performance and heat shock protein expression to thermal stress in two differently zoned limpets on a tropical rocky shore
Marine Biology, 2011Co-Authors: Yunwei Dong, Gray A WilliamsAbstract:Understanding variation in physiological adaptations to thermal stress is vital when investigating Intertidal Species’ distribution patterns. The thermal sensitivities of two limpets, Cellana grata and C. toreuma, differed in accordance with their vertical distributions. Cardiac performance was maintained at higher temperatures (~47°C) for the high-zone C. grata than the mid-zone C. toreuma (~42°C). At 40°C, C. grata maintained regular heart function for ~4 h, while heart function of C. toreuma decreased rapidly. Heat shock protein expression revealed that C. toreuma had two constitutive isoforms, Hsp77 and Hsp72, and C. grata one inducible form, Hsp75, which was upregulated at 40°C, suggesting C. grata has a more effective heat shock response than C. toreuma. The temperature-adaptive differences in cardiac thermal tolerance and Hsp expression match observed differences in thermally induced mortalities with the onset of summer and may help predict differential effects of climate change on the two congeners.
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heat shock protein 70 hsp70 expression in four limpets of the genus lottia interspecific variation in constitutive and inducible synthesis correlates with in situ exposure to heat stress
The Biological Bulletin, 2008Co-Authors: Yunwei Dong, Luke P Miller, Jon G Sanders, George N SomeroAbstract:Limpets of the genus Lottia occupy a broad vertical distribution on wave-exposed rocky shores, a range that encompasses gradients in the frequency and severity of thermal and desiccation stress brought on by aerial emer- sion. Using western blot analysis of levels of heat-shock protein 70 (Hsp70), we examined the heat-shock responses of four Lottia congeners: Lottia scabra and L. austrodigi- talis, which occur in the high-Intertidal zone, and L. pelta and L. scutum, which are restricted to the low- and mid- Intertidal zones. Our results suggest distinct strategies of Hsp70 expression in limpets occupying different heights and orientations in the rocky Intertidal zone. In freshly field-collected animals and in specimens acclimated at am- bient temperature (14 °C) for 14 days, the two high- Intertidal Species had higher constitutive levels of Hsp70 than the low- and mid-Intertidal Species. During aerial ex- posure to high temperatures, the two low-shore Species and L. austrodigitalis exhibited an onset of Hsp70 expression at 28 °C; no induction of Hsp70 occurred in L. scabra. Our findings suggest that high-Intertidal congeners of Lottia employ a "preparative defense" strategy involving mainte- nance of high constitutive levels of Hsp70 in their cells as a mechanism for protection against periods of extreme and unpredictable heat stress.
Nova Mieszkowska - One of the best experts on this subject based on the ideXlab platform.
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global scale Species distributions predict temperature related changes in Species composition of rocky shore communities in britain
Global Change Biology, 2020Co-Authors: Michael T Burrows, Jon Moore, Leoni Adams, H Sugden, Louise B Firth, Nova MieszkowskaAbstract:Changes in rocky shore community composition as responses to climatic fluctuations and anthropogenic warming can be shown by changes in average Species thermal affinities. In this study, we derived thermal affinities for European Atlantic rocky Intertidal Species by matching their known distributions to patterns in average annual sea surface temperature. Average thermal affinities (the Community Temperature Index, CTI) tracked patterns in sea surface temperature from Portugal to Norway, but CTI for communities of macroalgae and plant Species changed less than those composed of animal Species. This reduced response was in line with the expectation that communities with a smaller range of thermal affinities among Species would change less in composition along thermal gradients and over time. Local-scale patterns in CTI over wave exposure gradients suggested that canopy macroalgae allow Species with ranges centred in cooler than local temperatures ('cold-affinity') to persist in otherwise too-warm conditions. In annual surveys of rocky shores, communities of animal Species in Shetland showed a shift in dominance towards warm-affinity Species ('thermophilization') with local warming from 1980 to 2018 but the community of plant and macroalgal Species did not. From 2002 to 2018, communities in southwest Britain showed the reverse trend in CTI: declining average thermal affinities over a period of modest temperature decline. Despite the cooling, trends in Species abundance were in line with the general mechanism of direction and magnitude of long-term trends depending on the difference between Species thermal affinities and local temperatures. Cold-affinity Species increased during cooling and warm-affinity ones decreased. The consistency of responses across different communities and with general expectations based on Species thermal characteristics suggests strong predictive accuracy of responses of community composition to anthropogenic warming.
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spatial scales of variance in abundance of Intertidal Species effects of region dispersal mode and trophic level
Ecology, 2009Co-Authors: Michael T Burrows, Robin Harvey, Linda Robb, Elvira S Poloczanska, Nova Mieszkowska, Pippa J Moore, R Leaper, Stephen J HawkinsAbstract:Determination of the pattern of variation in population abundance among spatial scales offers much insight into the potential regulating factors. Here we offer a method of quantifying spatial variance on a range of scales derived by sampling of irregularly spaced sites along complex coastlines. We use it to determine whether the nature of spatial variance depends on the trophic level or the mode of dispersal of the Species involved and the role of the complexity of the underlying habitat. A least-cost distance model was used to determine distances by sea between all pairs of sites. Ordination of this distance matrix using multidimensional scaling allowed estimation of variance components with hierarchical ANOVA at nested spatial scales using spatial windows. By repeatedly moving these spatial windows and using a second set of spatial scales, average variance scale functions were derived for 50+ Species in the UK rocky Intertidal. Variance spectra for most Species were well described by the inverse power l...
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spatial scales of variance in abundance of Intertidal Species effects of region dispersal mode and trophic level
Ecology, 2009Co-Authors: Michael T Burrows, Robin Harvey, Linda Robb, Elvira S Poloczanska, Nova Mieszkowska, Pippa J Moore, R Leaper, Stephen J HawkinsAbstract:Determination of the pattern of variation in population abundance among spatial scales offers much insight into the potential regulating factors. Here we offer a method of quantifying spatial variance on a range of scales derived by sampling of irregularly spaced sites along complex coastlines. We use it to determine whether the nature of spatial variance depends on the trophic level or the mode of dispersal of the Species involved and the role of the complexity of the underlying habitat. A least-cost distance model was used to determine distances by sea between all pairs of sites. Ordination of this distance matrix using multidimensional scaling allowed estimation of variance components with hierarchical ANOVA at nested spatial scales using spatial windows. By repeatedly moving these spatial windows and using a second set of spatial scales, average variance scale functions were derived for 50+ Species in the UK rocky Intertidal. Variance spectra for most Species were well described by the inverse power law (1/fbeta) for noise spectra, with values for the exponent ranging from 0 to 1.1. At higher trophic levels (herbivores and carnivores), those Species with planktonic dispersal had significantly higher beta values, indicating greater large- than small-scale variability, as did those on simpler coastlines (southwestern England and Wales vs. western Scotland). Average abundance and proportional incidence of Species had the strongest influence on p values, with those of intermediate abundance and incidence having much greater large-scale variance (beta approximately 0.5) than rare or ubiquitous Species (beta approximately 0).
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living on the edge of two changing worlds forecasting the responses of rocky Intertidal ecosystems to climate change
Annual Review of Ecology Evolution and Systematics, 2006Co-Authors: Brain Helmuth, Nova Mieszkowska, Philippa Moore, Stephen J HawkinsAbstract:Long-term monitoring shows that the poleward range edges of Intertidal biota have shifted by as much as 50 km per decade, faster than most recorded shifts of terrestrial Species. Although most studies have concentrated on Species-range edges, recent work emphasizes how modifying factors such as regional differences in the timing of low tide can overwhelm large-scale climatic gradients, leading to a mosaic of environmental stress. We discuss how changes in the mean and variability in climatic regimes, as modified by local and regional factors, can lead to complex patterns of Species distribution rather than simple range shifts. We describe how ecological forecasting may be used to generate explicit hypotheses regarding the likely impacts of different climatic change scenarios on the distribution of Intertidal Species and how related hindcasting methods can be used to evaluate changes that have already been detected. These hypotheses can then be tested over a hierarchy of temporal and spatial scales using coupled field and laboratory-based approaches.
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changes in the range of some common rocky shore Species in britain a response to climate change
Hydrobiologia, 2006Co-Authors: Nova Mieszkowska, R Leaper, Stephen J Hawkins, Mark A F Kendall, Phillip Williamson, Nick J Hardmanmountford, A J SouthwardAbstract:Since the 1990s there has been a period of rapid climate warming in Europe. Long-term broad scale datasets coupled with time series at specific locations for rocky Intertidal Species dating back to the 1950s have been collected in Britain and Ireland. Resurveys of the original locations in 2001–2003 have been undertaken to identify changes in the biogeographical range and abundance of these Species. The results show that some ‘southern’ Species including Osilinus lineatus da Costa and Gibbula umbilicalis da Costa have undergone north and north-eastern range extensions. Populations have increased in abundance and adult size has decreased since the previous surveys were conducted. These changes have been synchronous throughout Britain, strongly suggesting that climate is responsible. The use of Intertidal Species as indicators of climate change is proposed.
Michael J Hickerson - One of the best experts on this subject based on the ideXlab platform.
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late pleistocene Species distribution modelling of north atlantic Intertidal invertebrates
Journal of Biogeography, 2013Co-Authors: Eric Waltari, Michael J HickersonAbstract:Aim In this study we test molecular-based biogeographical hypotheses of Pleistocene persistence and recolonization in a North Atlantic rocky Intertidal invertebrate assemblage using Species distribution modelling. Location North Atlantic coastlines. Methods We develop a novel application of Species distribution models for Intertidal taxa by using both oceanographic and terrestrial environmental variables recently made available at biologically relevant pixel resolutions. We use these model-based distribution estimates to test alternative hypotheses of late Pleistocene history across six amphi-Atlantic taxa whose hypothesized Pleistocene distributions are constructed from previous population genetic inferences. Results Species distribution models correctly estimate all six current amphi-Atlantic distributions on both sides of the Atlantic. Models hindcasted to the Last Glacial Maximum estimate trans-Atlantic distributional persistence in three of six taxa, and conversely indicate no suitable habitat on the North American coastline in the other three taxa. These results are consistent with the histories inferred from population genetic data for five of six of the taxa, the exception being Nucella lapillus, whose hindcasted trans-Atlantic persistence at the Last Glacial Maximum contrasts with the mitochondrial DNA-based estimates of post-glacial expansion from Europe to North America. Main conclusions Marine and terrestrial distribution models are broadly concordant with known contemporary distributions and fail to reject five of six historical distributional hypotheses based on population genetic inferences. This demonstrated utility suggests that this technique could be expanded to examine how Pleistocene and contemporary climate change might play a role in Intertidal Species distributions across the entire community. Future application and development of these marine and terrestrial distribution models will strengthen inferences regarding the processes generating Intertidal community assembly and population divergence, and may assist in conservation planning and the design of marine reserves.
