scholarly journals Environmental disorder can tip the population genetics of range expansions

2018 ◽  
Author(s):  
Matti Gralka ◽  
Oskar Hallatschek
Keyword(s):  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Time Lapse ◽  
Small Scale ◽  
Spontaneous Mutations ◽  
Local Motion ◽  
Reproductive Process ◽  
Range Edge ◽  
Expanding Population ◽  
Number Of Individuals

Evolutionary dynamics is fundamentally shaped by stochastic processes: spontaneous mutations enter populations randomly, and the fate of a mutant lineage is determined by the competition between (random) genetic drift and (deterministic) selection. In populations undergoing range expansions, fluctuations in the reproductive process and the local motion of individuals are enhanced within a small subpopulation at the edge of the population. Range expansions are typically studied in homogeneous environments, but we argue here that the fluctuations at the range edge are susceptible to small-scale environmental heterogeneities that may have a strong effect on the evolutionary dynamics of the expanding population. To show this, we tracked the dynamics of the clones of spontaneous mutations with a tunable fitness effect in bacterial colonies grown on randomly disordered surfaces. We find that environmental heterogeneity on scales much larger than an individual, but much smaller than the total population, can dramatically reduce the efficacy of selection. Time lapse microscopy and computer simulations suggest that this effect is a general consequence of a local "pinning" of the expansion front, whereby stretches of the front are slowed down on a length scale that depends on the structure of the environmental heterogeneity. This pinning focuses the range expansion into a small number of individuals with access to expansion paths, increasing the importance of chance and thus limiting the efficacy of selection.

scholarly journals Environmental heterogeneity can tip the population genetics of range expansions

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Matti Gralka ◽  
Oskar Hallatschek
Keyword(s):  
Population Genetics ◽  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Time Lapse ◽  
Patterned Surfaces ◽  
Random Genetic Drift ◽  
Fitness Effect ◽  
Darwinian Selection ◽  
Time Lapse Microscopy ◽  
Highly Sensitive

The population genetics of most range expansions is thought to be shaped by the competition between Darwinian selection and random genetic drift at the range margins. Here, we show that the evolutionary dynamics during range expansions is highly sensitive to additional fluctuations induced by environmental heterogeneities. Tracking mutant clones with a tunable fitness effect in bacterial colonies grown on randomly patterned surfaces we found that environmental heterogeneity can dramatically reduce the efficacy of selection. Time-lapse microscopy and computer simulations suggest that this effect arises generically from a local 'pinning’ of the expansion front, whereby stretches of the front are slowed down on a length scale that depends on the structure of the environmental heterogeneity. This pinning focuses the range expansion into a small number of 'lucky’ individuals with access to expansion paths, altering the neutral evolutionary dynamics and increasing the importance of chance relative to selection.

scholarly journals Landscape resistance constrains hybridization across contact zones in a reproductively and morphologically polymorphic salamander

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillermo Velo-Antón ◽  
André Lourenço ◽  
Pedro Galán ◽  
Alfredo Nicieza ◽  
Pedro Tarroso
Keyword(s):  
Contact Zone ◽  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Morphological Differentiation ◽  
Phenotypic Traits ◽  
Hybrid Zones ◽  
Landscape Resistance ◽  
Phenotypic Differentiation ◽  
Contact Zones

AbstractExplicitly accounting for phenotypic differentiation together with environmental heterogeneity is crucial to understand the evolutionary dynamics in hybrid zones. Species showing intra-specific variation in phenotypic traits that meet across environmentally heterogeneous regions constitute excellent natural settings to study the role of phenotypic differentiation and environmental factors in shaping the spatial extent and patterns of admixture in hybrid zones. We studied three environmentally distinct contact zones where morphologically and reproductively divergent subspecies of Salamandra salamandra co-occur: the pueriparous S. s. bernardezi that is mostly parapatric to its three larviparous subspecies neighbours. We used a landscape genetics framework to: (i) characterise the spatial location and extent of each contact zone; (ii) assess patterns of introgression and hybridization between subspecies pairs; and (iii) examine the role of environmental heterogeneity in the evolutionary dynamics of hybrid zones. We found high levels of introgression between parity modes, and between distinct phenotypes, thus demonstrating the evolution to pueriparity alone or morphological differentiation do not lead to reproductive isolation between these highly divergent S. salamandra morphotypes. However, we detected substantial variation in patterns of hybridization across contact zones, being lower in the contact zone located on a topographically complex area. We highlight the importance of accounting for spatial environmental heterogeneity when studying evolutionary dynamics of hybrid zones.

Study of Thermal Activity in The Mixing Layer During First Generated Single Cloud by Using Combined Observation From Boundary Layer Radar, Doppler Lidar and Time Lapse Camera 

2021 ◽  
Author(s):  
Ginaldi Ari Nugroho ◽  
Kosei Yamaguchi ◽  
Eiichi Nakakita ◽  
Masayuki K. Yamamoto ◽  
Seiji Kawamura ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Atmospheric Boundary Layer ◽  
Vertical Velocity ◽  
Time Lapse ◽  
Small Scale ◽  
Thermal Activity ◽  
Doppler Lidar ◽  
Cumulus Cloud ◽  
Scale Perturbation

<p>Detailed observation of small scale perturbation in the atmospheric boundary layer during the first generated cumulus cloud are conducted. Our target is to study this small scale perturbation, especially related to the thermal activity at the first generated cumulus cloud. The observation is performed during the daytime on August 17, 2018, and September 03, 2018. Location is focused in the urban area of Kobe, Japan. High-resolution instruments such as Boundary Layer Radar, Doppler Lidar, and Time Lapse camera are used in this observation. Boundary Layer Radar, and Doppler Lidar are used for clear air observation. Meanwhile Time Lapse Camera are used for cloud existence observation. The atmospheric boundary layer structure is analyzed based on vertical velocity profile, variance, skewness, and estimated atmospheric boundary layer height. Wavelet are used to observe more of the period of the thermal activity. Furthermore, time correlation between vertical velocity time series from height 0.3 to 2 km and image pixel of generated cloud time series are also discussed in this study.</p>

scholarly journals Short-term post-mortality scavenging and longer term recovery after anoxia in the northern Adriatic Sea

2013 ◽  
Vol 10 (11) ◽  
pp. 7647-7659 ◽  
Author(s):  
M. Blasnig ◽  
B. Riedel ◽  
L. Schiemer ◽  
M. Zuschin ◽  
M. Stachowitsch
Keyword(s):  
Adriatic Sea ◽  
Time Lapse ◽  
Hermit Crabs ◽  
Small Scale ◽  
Short Term ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Hexaplex Trunculus ◽  
Distinct Sequence ◽  
And Function

Abstract. The northern Adriatic Sea is one of nearly 500 areas worldwide suffering widespread mortalities due to anoxia. The present study documents post-anoxia macrofauna dynamics after experimentally inducing small-scale anoxia in 24 m depth (2 plots, each 50 cm × 50 cm). Time-lapse camera deployments examined short-term scavenging of the moribund and dead organisms (multi-species clumps consisting of sponges and ascidians) over two 3-day periods (August 2009: 71.5 h, September 2009: 67.5 h). Longer term recovery (days to 2 yr) in the same two plots was examined with an independent photo series. Scavengers arrived quickly and in a distinct sequence: demersal (Gobius niger, Serranus hepatus) and benthopelagic fishes (Diplodus vulgaris, Pagellus erythrinus), followed by hermit crabs (Paguristes eremita, showing a clear day/night rhythm in presence) and gastropods (Hexaplex trunculus). This sequence is attributed to the relative speeds and densities of the organisms. The sessile fauna was largely removed or consumed within seven (August plot) and 13 (September plot) days after anoxia, confirming our first hypothesis that decaying organisms are quickly utilised. The scavengers remained in dense aggregations (e.g. up to 33 P. eremita individuals at one time) as long as dead organisms were available. No recovery of sessile macroepibenthos macroepibenthos occurred in the experimental plots one and two years after anoxia, undermining our second hypothesis that small denuded areas are more rapidly recolonised. This study underlines the sensitivity of this soft-bottom community and supports calls for reducing additional anthropogenic disturbances such as fishing practices that further impede recolonisation and threaten benthic community structure and function over the long term.

Conserved growth rate and age structure of Xenopus laevis in the edge and core of an expanding population

2019 ◽  
Vol 128 (1) ◽  
pp. 122-129 ◽  
Author(s):  
Julien Courant ◽  
Layla Adil ◽  
Barbara De Kegel ◽  
Dominique Adriaens ◽  
Anthony Herrel
Keyword(s):  
Growth Rate ◽  
Xenopus Laevis ◽  
Age Structure ◽  
Reproductive Investment ◽  
Individual Growth ◽  
Evolutionary Mechanisms ◽  
Range Edge ◽  
Investment In Reproduction ◽  
Range Core ◽  
Expanding Population

Abstract Invasive species represent a unique opportunity to study the evolutionary mechanisms driving range expansions. Although range expansion is expected to be associated with increased reproduction and dispersal at the range edge, Xenopus laevis seems to decrease its reproductive investment and to enhance dispersal at the range edge. Evidence of increased dispersal at the edge of expanding populations occurring simultaneously with a faster growth rate has been reported for other organisms. Here, we focused on the growth rate and age structure at the range edge vs. the range core in an expanding population of X. laevis. We used skeletochronology to characterize the age of 250 individuals captured at the range core and edge of this expanding population. Using the Von Bertalanffy equation, we then compared individual growth rates between locations. We found no significant changes in growth rate or age structure between edge and core samples. This result suggests that the reduced investment in reproduction recorded in another study at the range edge might compensate for the increased dispersal without impacting growth in this population. This implies that the resource allocation in an expanding population might thus be more diverse than commonly assumed.

Small-scale Environmental Heterogeneity and Spatiotemporal Dynamics of Seedling Establishment in a Semiarid Degraded Ecosystem

Ecosystems ◽  
2003 ◽  
Vol 6 (7) ◽  
pp. 630-643 ◽  
Author(s):  
Fernando T. Maestre ◽  
Jordi Cortina ◽  
Susana Bautista ◽  
Juan Bellot ◽  
Ramon Vallejo
Keyword(s):  
Seedling Establishment ◽  
Environmental Heterogeneity ◽  
Spatiotemporal Dynamics ◽  
Small Scale ◽  
Degraded Ecosystem

scholarly journals Evolution of populations expanding on curved surfaces

2018 ◽  
Author(s):  
Daniel A. Beller ◽  
Kim M. J. Alards ◽  
Francesca Tesser ◽  
Ricardo A. Mosna ◽  
Federico Toschi ◽  
...  
Keyword(s):  
Range Expansion ◽  
Evolutionary Dynamics ◽  
Flat Surface ◽  
Analytical Description ◽  
Relative Increase ◽  
Curved Surfaces ◽  
Complex Environments ◽  
Neutral Genetic Diversity ◽  
Expanding Population ◽  
Dynamics Of Populations

AbstractThe expansion of a population into new habitat is a transient process that leaves its footprints in the genetic composition of the expanding population. How the structure: of the environment shapes the population front and the evolutionary dynamics during such a range expansion is little understood. Here, we investigate the evolutionary dynamics of populations consisting of many selectively neutral genotypes expanding on curved surfaces. Using a combination of individual-based off-lattice simulations, geometrical arguments, and lattice-based stepping-stone simulations, we characterise the effect of individual bumps on an otherwise flat surface. Compared to the case of a range expansion on a flat surface:, we observe a transient relative increase, followed by a decrease, in neutral genetic diversity at the population front. Ill addition, we find that individuals at the sides of the bump have a dramatically increased expected number of descendants, while their neighbours closer to the bump’s centre are far less lucky. Both observations can be explained using an analytical description of straight paths (geodesics) on the curved surface, Complementing previous studies of heterogeneous flat environments, the findings here build our understanding of how complex environments shape the evolutionary dynamics of expanding populations.

scholarly journals Remote Sensing Reveals Lasting Legacies of Land-Use by Small-Scale Foraging Communities in the Southwestern Indian Ocean

2021 ◽  
Vol 9 ◽  
Author(s):  
Dylan S. Davis ◽  
Kristina Douglass
Keyword(s):  
Remote Sensing ◽  
Land Use ◽  
Evolutionary Dynamics ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Small Scale ◽  
Environment Interaction ◽  
Human Environment ◽  
Landscape Modification ◽  
Geochemical Properties

Archaeologists interested in the evolution of anthropogenic landscapes have productively adopted Niche Construction Theory (NCT), in order to assess long-term legacies of human-environment interactions. Applications of NCT have especially been used to elucidate co-evolutionary dynamics in agricultural and pastoral systems. Meanwhile, foraging and/or highly mobile small-scale communities, often thought of as less intensive in terms of land-use than agropastoral economies, have received less theoretical and analytical attention from a landscape perspective. Here we address this lacuna by contributing a novel remote sensing approach for investigating legacies of human-environment interaction on landscapes that have a long history of co-evolution with highly mobile foraging communities. Our study is centered on coastal southwest Madagascar, a region inhabited by foraging and fishing communities for close to two millennia. Despite significant environmental changes in southwest Madagascar’s environment following human settlement, including a wave of faunal extinctions, little is known about the scale, pace and nature of anthropogenic landscape modification. Archaeological deposits in this area generally bear ephemeral traces of past human activity and do not exhibit readily visible signatures of intensive land-use and landscape modification (e.g., agricultural modifications, monumental architecture, etc.). In this paper we use high-resolution satellite imagery and vegetative indices to reveal a legacy of human-landscape co-evolution by comparing the characteristics – vegetative productivity and geochemical properties – of archaeological sites to those of locations with no documented archaeological materials. Then, we use a random forest (RF) algorithm and spatial statistics to quantify the extent of archaeological activity and use this analysis to contextualize modern-day human-environment dynamics. Our results demonstrate that coastal foraging communities in southwest Madagascar over the past 1,000 years have extensively altered the landscape. Our study thus expands the temporal and spatial scales at which we can evaluate human-environment dynamics on Madagascar, providing new opportunities to study early periods of the island’s human history when mobile foraging communities were the dominant drivers of landscape change.

scholarly journals Open-source personal pipetting robots with live-cell incubation and microscopy compatibility

2021 ◽  
Author(s):  
Philip Dettinger ◽  
Tobias Kull ◽  
Geethika Arekatla ◽  
Nouraiz Ahmed ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Open Source ◽  
Time Lapse ◽  
Small Scale ◽  
Liquid Handling ◽  
Academic Settings ◽  
Stem And Progenitor Cells ◽  
Cell Incubation ◽  
Self Production ◽  
Liquid Handling Robot ◽  
Laboratory Member

Liquid handling robots have the potential to automate many procedures in life sciences. However, they are not in widespread use in academic settings, where funding, space and maintenance specialists are usually limiting. In addition, current robots require lengthy programming by specialists and are incompatible with most academic laboratories with constantly changing small-scale projects. Here, we present the Pipetting Helper Imaging Lid (PHIL), an inexpensive, small, open-source personal liquid handling robot. It is designed for inexperienced users, with self-production from cheap commercial and 3D-printable components and custom control software. PHIL successfully automated pipetting for e.g. tissue immunostainings and stimulations of live stem and progenitor cells during time-lapse microscopy. PHIL is cheap enough for any laboratory member to have their own personal pipetting robot(s), and enables users without programming skills to easily automate a large range of experiments.

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