scholarly journals The response of a metapopulation to a changing environment

2021 ◽  
Author(s):  
Nick H Barton ◽  
Oluwafunmilola Olusanya
Keyword(s):  
Migration Rate ◽  
Narrow Range ◽  
Heterogeneous Environments ◽  
Local Conditions ◽  
Frequency Distributions ◽  
State Approximation ◽  
Soft Selection ◽  
Model Finding ◽  
Fixed State ◽  
Capacity Selection

A species distributed across heterogeneous environments may adapt to local conditions. Szep et al. (2021, Evolution) modelled this process in the infinite island model, finding the stationary distribution of allele frequencies and deme sizes. We extend this to ask how a metapopulation responds to changes in carrying capacity, selection strength, or migration rate, restricting attention to fixed deme size ("soft selection"). We develop a "fixed-state" approximation (accurate when migration is rare) which assumes that the loci are near fixation. Under this approximation, polymorphism is only possible for a narrow range of habitat proportions when selection is weak compared to drift, but for a much wider range otherwise. When local conditions (Ns or Nm) change in a single deme, it takes a time of ~1/m to reach the new equilibrium. However, even withmany loci, there can be substantial fluctuations in net adaptation, due to the bimodal allele frequency distributions at each locus. Thus, in a finite metapopulation, variation may gradually be lost by chance, even if it would persist with infinitely many demes. When conditions change across the whole metapopulation, there can be rapid response, accurately predicted by the fixed-state approximation when Nm <<1.

A simulation–optimization algorithm for reservoir capacity calculation: the effect of inflow data set length

1989 ◽  
Vol 16 (4) ◽  
pp. 477-482 ◽  
Author(s):  
Kim D. Barlishen ◽  
Slobodan P. Simonovic ◽  
Donald H. Burn
Keyword(s):  
Water Supply ◽  
Optimization Algorithm ◽  
Simulation Optimization ◽  
Probability Level ◽  
Data Set ◽  
Frequency Distributions ◽  
Record Length ◽  
Key Factor ◽  
Capacity Selection ◽  
Final Probability

A simultion–optimization algorithm for sizing potential reservoirs on a river basin has been used to demonstrate the effects of the streamflow record length on capacity requirements. The sizing procedure involves the generation of synthetic streamflows and a reservoir reliability analysis. Two levels of reliability are present: the reliability in meeting water supply requirements, and the probability level associated with the final capacity selection. The procedure was applied to synthetic sequences generated from an 81-year inflow record and subsets of this sequence to produce frequency distributions of required capacities. The capacities with a 5% probability of exceedence were compared. Relying on short inflow sequences can lead to substantial overestimations or underestimations of capacity. A key factor is the presence of the critical period in the analysis. An open question remains regarding the effect of the final probability level selection on the range of capacities observed. Key words: design reservoirs, water supply, simulation, optimization, reliability, record length, synthetic streamflows.

scholarly journals Spatial resource heterogeneity creates local hotspots of evolutionary potential

2017 ◽  
Author(s):  
Emily Dolson ◽  
Charles Ofria
Keyword(s):  
Explanatory Power ◽  
Biological Evolution ◽  
Biological Data ◽  
Heterogeneous Environments ◽  
Digital Evolution ◽  
Resource Heterogeneity ◽  
Evolutionary Potential ◽  
Local Conditions ◽  
Local Diversity ◽  
Novel Traits

AbstractDo local conditions influence evolution’s ability to produce new traits? Biological data demonstrate that evolutionary processes can be profoundly influenced by local conditions. However, the evolution of novel traits has not been addressed in this context, owing in part to the challenges of performing the necessary experiments with natural organisms. We conduct in silico experiments with the Avida Digital Evolution Platform to address this question. We created eight different spatially heterogeneous environments and ran 100 replicates in each. Within each environment, we examined the distribution of locations where nine different focal traits first evolved. Using spatial statistics methods, we identified regions within each environment that had significantly elevated probabilities of containing the first organism with a given trait (i.e. hotspots of evolutionary potential). Having demonstrated the presence of many such hotspots, we explored three potential mechanisms that could drive the formation of these patterns: proximity of specific resources, variation in local diversity, and variation in the sequence of locations the members of an evolutionary lineage occupy. Resource proximity and local diversity appear to have minimal explanatory power. Lineage paths through space, however, show some promising preliminary trends. If we can understand the processes that create evolutionary hotspots, we will be able to craft environments that are more effective at evolving targeted traits. This capability would be useful both to evolutionary computation, and to efforts to guide biological evolution.

scholarly journals Assessing health status of corals at a tropical marginal reef site through bleaching and decadal change in population parameters

2018 ◽  
Author(s):  
Lélis Carlos-Júnior ◽  
Carla Zilberberg ◽  
Amana Garrido ◽  
Fernanda Casares ◽  
Joel Christopher Creed ◽  
...  
Keyword(s):  
Health Status ◽  
Coral Cover ◽  
Anthropogenic Activities ◽  
Population Decline ◽  
Light Availability ◽  
Reef Site ◽  
Local Conditions ◽  
Frequency Distributions ◽  
Siderastrea Stellata ◽  
Marginal Reef

Scleractinian corals are key organisms in structuring reef habitats and coral cover is being lost due to local and global stressors caused and/or exacerbated by anthropogenic activities. Despite being hardly touched upon, studies of size-frequency distributions serve as snapshots of coral populations’ status and provide information on population decline or growth over time. In our study we have intermittently monitored two Brazilian scleractinians species, the endemic Mussismilia hispida and Siderastrea stellata, since 2000 in an important coral marginal reef site at Armação dos Búzios, Rio de Janeiro, Brazil. We measured length, width and arc of all colonies from both species found across transects at eleven sites. In total, over 5,000 colonies have been measured over the past 17 years. Although the frequency of small and medium colonies remained relatively constant, we observed a clear decline in the frequency of larger colonies (> 30 cm) for both species, particularly the most common S. stellata. Additionally, we have been monitoring colonies for bleaching in five of these sites throughout 2017 to assess health status. The relationship between observed bleaching prevalence/intensity and environmental variables (temperature, light availability and sedimentation) may elucidate how changes in local conditions influence coral health.

scholarly journals Assessing health status of corals at a tropical marginal reef site through bleaching and decadal change in population parameters

2018 ◽  
Author(s):  
Lélis Carlos-Júnior ◽  
Carla Zilberberg ◽  
Amana Garrido ◽  
Fernanda Casares ◽  
Joel Christopher Creed ◽  
...  
Keyword(s):  
Health Status ◽  
Coral Cover ◽  
Anthropogenic Activities ◽  
Population Decline ◽  
Light Availability ◽  
Reef Site ◽  
Local Conditions ◽  
Frequency Distributions ◽  
Siderastrea Stellata ◽  
Marginal Reef

Scleractinian corals are key organisms in structuring reef habitats and coral cover is being lost due to local and global stressors caused and/or exacerbated by anthropogenic activities. Despite being hardly touched upon, studies of size-frequency distributions serve as snapshots of coral populations’ status and provide information on population decline or growth over time. In our study we have intermittently monitored two Brazilian scleractinians species, the endemic Mussismilia hispida and Siderastrea stellata, since 2000 in an important coral marginal reef site at Armação dos Búzios, Rio de Janeiro, Brazil. We measured length, width and arc of all colonies from both species found across transects at eleven sites. In total, over 5,000 colonies have been measured over the past 17 years. Although the frequency of small and medium colonies remained relatively constant, we observed a clear decline in the frequency of larger colonies (> 30 cm) for both species, particularly the most common S. stellata. Additionally, we have been monitoring colonies for bleaching in five of these sites throughout 2017 to assess health status. The relationship between observed bleaching prevalence/intensity and environmental variables (temperature, light availability and sedimentation) may elucidate how changes in local conditions influence coral health.

Biological Theories of Race beyond the Millennium

2018 ◽  
Author(s):  
Joseph L. Graves
Keyword(s):  
Narrow Range ◽  
Purifying Selection ◽  
Eastern Africa ◽  
Human Populations ◽  
Local Conditions ◽  
Evolutionary Forces ◽  
The Social ◽  
Anatomically Modern Humans ◽  
Historical Contextualization

This chapter provides historical contextualization of the crisis faced by the social construction approach of race. It reveals that anatomically modern humans are a young species that spent the majority of their existence living in a narrow range of eastern Africa. Indeed the exit of our species has been pushed forward in time from previous estimates. Evolutionary forces of natural selection and genetic drift have differentiated human populations, but this differentiation has been small. Most of the signal of human differentiation occurs in noncoding loci that do not face the force of purifying selection. Within the coding loci, some adaptation to local conditions has occurred. This adaptation does not allow the unambiguous classification of human populations into biological races.

scholarly journals Colony size-frequency distributions among different populations of the scleractinan coral Siderastrea stellata in Southwestern Atlantic: implications for life history patterns

2006 ◽  
Vol 54 (4) ◽  
pp. 213-223 ◽  
Author(s):  
Monica Moraes Lins de Barros ◽  
Débora de Oliveira Pires
Keyword(s):  
Life History ◽  
Colony Size ◽  
Large Scale ◽  
Environmental Changes ◽  
Size Structure ◽  
Growth Potential ◽  
Local Conditions ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Siderastrea Stellata

Colony size-frequency distributions of reef corals may be used to infer growth potential and population responses upon environmental changes. The present paper compares the size structure of colonies of Siderastrea stellata Verrill, 1868,among 11 sites, six of them distributed along a gradient of sediment deposition in Abrolhos, Bahia, Brazil (18º S). Results indicated that the population structure is likely to be influenced by local conditions, rather than large scale factors, such as latitude. The 11 distributions, however, showed higher frequencies of small size classes. Class 1 (up to 2.5 cm diameter) was always present and the frequency of colonies from size class 3 (10 cm diameter) tended to decrease in all sites. Comparison among the six Abrolhos sites showed that S. stellata has advantages at sites with intermediate sedimentation, where colonies attain larger sizes, probably, reflecting a higher survivorship over time. The present study showed that, despite the influence of environmental conditions on parameters of the populations such as size of colony, the life history strategy of S. stellata reflects a local adaptation that allows its development and survivorship in shallow waters and horizontal substrates, sites characterized by high mortality rates.

scholarly journals Kleptothermy: an additional category of thermoregulation, and a possible example in sea kraits ( Laticauda laticaudata , Serpentes)

2009 ◽  
Vol 5 (6) ◽  
pp. 729-731 ◽  
Author(s):  
François Brischoux ◽  
Xavier Bonnet ◽  
Richard Shine
Keyword(s):  
Narrow Range ◽  
Large Body ◽  
Local Area ◽  
Spatial And Temporal Variation ◽  
Heterogeneous Environments ◽  
Body Temperatures ◽  
Ambient Conditions ◽  
Thermal Monitoring ◽  
Cool Environment ◽  
Thermal Heterogeneity

Lacking the capacity for thermogenesis, most ectotherms inhabiting thermally heterogeneous environments rely instead upon exploiting that ambient heterogeneity. In many cases they maintain body temperatures within a narrow range despite massive spatial and temporal variation in ambient conditions. Reliance on diverse thermal opportunities is reflected in specific terms for organisms that bask in sunlight to regulate their temperature (heliotherms), or that press their bodies against warm substrates to facilitate heat flow (thigmotherms), or that rely on large body mass to maintain thermal constancy (gigantothermy). We propose an additional category of thermoregulators: kleptotherms , which regulate their own temperature by ‘stealing’ heat from other organisms. This concept involves two major conditions: the thermal heterogeneity created by the presence of a warm organism in a cool environment and the selective use of that heterogeneity by another animal to maintain body temperatures at higher (and more stable) levels than would be possible elsewhere in the local area. Kleptothermy occurs in endotherms also, but is usually reciprocal (rather than unilateral as in ectotherms). Thermal monitoring on a small tropical island documents a possible example of kleptothermy, based on high stable temperatures of a sea snake ( Laticauda laticaudata ) inside a burrow occupied by seabirds.

Adaptive Dynamics in a 2-Patch Environment: A Toy Model for Allopatric and Parapatric Speciation

1997 ◽  
Vol 05 (02) ◽  
pp. 265-284 ◽  
Author(s):  
Géza Meszéna ◽  
István Czibula ◽  
Stefan Geritz
Keyword(s):  
Migration Rate ◽  
Adaptive Dynamics ◽  
Density Regulation ◽  
Stable Coalition ◽  
Soft Selection ◽  
The Difference ◽  
Monomorphic Population ◽  
And Migration ◽  
Parapatric Speciation ◽  
Evolutionarily Stable

Adaptation to an environment consisting of two patches (each with different optimal strategy) is investigated. The patches have independent density regulation ('soft selection'). If the patches are similar enough and migration between them is strong, then evolution ends up with a generalist ESS. If either the difference between the patches increases or migration weakens, then the generalist strategy represents a branching singularity: The initially monomorphic population first evolves towards the generalist strategy, there it undergoes branching, and finally two specialist strategies form an evolutionarily stable coalition. Further increasing the between-patch difference or decreasing migration causes the generalist to lose its convergence stability as well, and an initially monomorphic population evolves towards one of the specialists optimally adapted to one of the two patches. Bifurcation pattern of the singularities is presented as a function of patch difference and migration rate. Connection to speciation theory is discussed. The transition from the generalist ESS to the coexisting pair of specialist strategies is regarded as a clonal prototype of parapatric (if the between-patch difference increases) or allopatric (if the migration decreases) speciation. We conclude that the geographic and the competitive speciation modes are not distinct classes.

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