Conference Paper

Title: A Thorny Issue: Adaptive Divergence In The Thornback Ray Raja Clavata

September 2013

Conference: American Fisheries Society 143rd Annual Meeting

Authors:

Catherine S Jones

University of Aberdeen

University of Aberdeen

The thornback ray Raja clavata is common to the varying environments in European waters. Although its dispersal is limited, it occupies a range of habitats along a considerable latitudinal gradient, factors which may contribute to genetic differentiation and local adaptation. Studies employing solely neutral molecular markers, whilst usefully determining population history and connectivity, may overlook important functional traits under strong environmental selectionsuch as body shape, colouration and armour. We have contrasted the variation in these distinct morphological characteristics with neutral genetic divergence in a number of populations to assess the extent of evolutionary adaptation at both local and broader geographic scales.

ResearchGate has not been able to resolve any citations for this publication.

ResearchGate has not been able to resolve any references for this publication.

Article

Full-text available

Mutation accumulation and the formation of range limits

January 2015 · Biology Letters

The dynamics of range formation are important for understanding and predicting species distributions. Here, we focus on a process that has thus far been overlooked in the context of range formation; the accumulation of mutation load. We find that mutation accumulation severely reduces the extent of a range across an environmental gradient, especially when dispersal is limited, growth rate is low ... [Show full abstract] and mutations are of intermediate deleterious effect. Our results illustrate the important role deleterious mutations can play in range formation. We highlight this as a necessary focus for further work, noting particularly the potentially conflicting effects dispersal may have in reducing mutation load and simultaneously increasing migration load in marginal populations.

Article

Full-text available

Evolutionary rescue by beneficial mutations in environments that change in space and time

January 2013 · Philosophical Transactions B

A factor that may limit the ability of many populations to adapt to changing conditions is the rate at which beneficial mutations can become established. We study the probability that mutations become established in changing environments by extending the classic theory for branching processes. When environments change in time, under quite general conditions, the establishment probability is ... [Show full abstract] approximately twice the 'effective selection coefficient', whose value is an average that gives most weight to a mutant's fitness in the generations immediately after it appears. When fitness varies along a gradient in a continuous habitat, increased dispersal generally decreases the chance a mutation establishes because mutations move out of areas where they are most adapted. When there is a patch of favourable habitat that moves in time, there is a maximum speed of movement above which mutations cannot become established, regardless of when and where they first appear. This critical speed limit, which is proportional to the mutation's maximum selective advantage, represents an absolute constraint on the potential of locally adapted mutations to contribute to evolutionary rescue.

Article

Effet of asymetric dispersal and environmental gradients on the stability of host-parasitoid systems

March 2005 · Oikos

We consider host–parasitoid systems spatially distributed on a row of patches connected by dispersal. We analyze the effects of dispersal frequency, dispersal asymmetry, number of patches and environmental gradients on the stability of the host–parasitoid interactions. To take into account dispersal frequency, the hosts and parasitoids are allowed to move from one patch to a neighboring patch a ... [Show full abstract] certain number of times within a generation. When this number is high, aggregation methods can be used to simplify the proposed initial model into an aggregated model describing the dynamics of both the total host and parasitoid populations. We show that as the number of patches increases less asymmetric parasitoid dispersal rates are required for stability. We found that the ‘CV2>1 rule’ is a valid approximation for stability if host growth rate is low, otherwise the general condition of stability we establish should be preferred. Environmental variability along the row of patches is introduced as gradients on host growth rate and parasitoid searching efficiency. We show that stability is more likely when parasitoids move preferentially towards patches where they have high searching efficiency or when hosts go mainly to patches where they have a low growth rate.

Thesis

Full-text available

AConstructive method for Estimating Liapunov Function of Large scale Non-Linear Systems

August 2001

Kawther Abbood Neamah

The main theme of this thesis is oriented toward two objectives. The first one is to study the stability of large-scale system and how to decompose such systems into lower interconnected subsystems. As it is known, the main difficulty in studying stability of differential equation by the second direct method of liapunov, is the construction of Liapunov fuctions. Therefore, the second objective is ... [Show full abstract] oriented towards introducing a new approach for constructing Liapunov function, uses the optimization techniques in connection with the method of variable gradient method. Then improving this approach to study the stability of large-scale systems using two approaches.

Article

Evolution of C 3 and C 4 Plants Along an Environmental Moisture Gradient: Patterns of Photosynthetic...

January 1984 · American Journal of Botany

Light-saturated photosynthetic capacities range from 12.0n24.7 mu mol CO2 m⁻² s⁻¹ in the Scaevola species and from 18.2-51.4 mu mol CO2 m⁻²s⁻¹ in the Euphorbia species. Within each genus, differences in light-saturated photosynthetic capacity are paralleled by differences in mesophyll and leaf conductances to CO2. Within each habitat, the C4 Euphorbia species exhibits a significantly higher ... [Show full abstract] photosynthetic capacity and a significantly higher mesophyll conductance than the corresponding C3, Scaevola species, differences greatest in the dry scrub habitat and least in the wet forest habitat. One photosynthetic characteristic that exhibits little variation among the species within each genus, yet that exhibits a consistently large difference between the species within each habitat, is photosynthetic water-use efficiency. The C4 Euphorbia species possess water-use efficiencies that are 2-3.5 times as high as those of the C3 Scaevola species. -from Authors

Article

Separability of Local and Regional Dynamics in Metapopulations

February 1997 · Theoretical Population Biology

Many models of metapopulations describe the regional dynamics of local extinction and recolonization separately from the local dynamics within the habitat patches. A strict justification of this approach has not been given yet. In this work we systematically derive the processes of extinction and colonization from the local dynamics and the dispersal of the individuals. We show that local and ... [Show full abstract] regional dynamics can be described separately only if the variances of environmental fluctuations and the rates of dispersal (emigration and immigration) are below particular bounds. If environmental fluctuations and dispersal satisfy these conditions the local dynamics have a much faster time scale than the regional dynamics and extinction and recolonization can each be described by a single rate which depends on the parameters of the local dynamics and dispersal.

Article

Are Species' Range Limits Simply Niche Limits Writ Large? A Review of Transplant Experiments beyond...

February 2014 · The American Naturalist

Abstract Many species' range limits (RL) occur across continuous environmental gradients without obvious barriers imposing them. Such RL are expected to reflect niche limits (NL) and thus to occur where populations cease to be self-sustaining. Transplant experiments comparing fitness within and beyond species' ranges can test this hypothesis, but interpretive power depends strongly on ... [Show full abstract] experimental design. We first identify often overlooked aspects of transplant design that are critical to establishing the causes of RL, especially incorporating transplant sites at, and source populations from, the range edge. We then conduct a meta-analysis of published beyond-range transplant experiments ([Formula: see text] tests). Most tests (75%) found that performance declined beyond the range, with the strongest declines detected when the measure of performance was lifetime fitness (83%), suggesting that RL commonly involve niche constraints (declining habitat quality). However, only 46% supported range limits occurring at NL; 26% (mostly geographic RL) fell short of NL with self-sustaining transplants beyond the range, and 23% (all elevational RL) exceeded NL with range-edge populations acting as demographic sinks. These data suggest an important but divergent role for dispersal, which may commonly constrain geographic distributions while extending elevational limits. Meta-analysis results also supported the importance of biotic interactions at RL, particularly the long-held assertion of their role in causing low-elevation and equatorial limits.

Article

Fitness declines toward range limits and local adaptation to climate affect dispersal evolution duri...

June 2015 · Journal of Evolutionary Biology

Dispersal ability will largely determine whether species track their climatic niches during climate change, a process especially important for populations at contracting (low-latitude/low-elevation) range limits that otherwise risk extinction. We investigate whether dispersal evolution at contracting range limits is facilitated by two processes that potentially enable edge populations to ... [Show full abstract] experience and adjust to the effects of climate deterioration before they cause extinction: a) climate-induced fitness declines toward range limits, and b) local adaptation to a shifting climate gradient. We simulate a species distributed continuously along a temperature gradient using a spatially explicit, individual-based model. We compare range-wide dispersal evolution during climate stability vs. directional climate change, with uniform fitness vs. fitness that declines toward range limits (RLs), and for a single climate genotype vs. multiple genotypes locally adapted to temperature. Dispersal decreased toward stable RLs when range-wide fitness was uniform, but increased when fitness declined toward RLs, due to highly dispersive genotypes maintaining sink populations at RLs, increased kin selection in smaller populations, and an emergent fitness asymmetry that favoured dispersal in low-quality habitat. However, this initial dispersal advantage at low-fitness RLs did not facilitate climate tracking, as it was outweighed by an increased probability of extinction. Locally-adapted genotypes benefited from staying close to their climate optima; this selected against dispersal under stable climates but for increased dispersal throughout shifting ranges, compared to cases without local adaptation. Dispersal increased at expanding RLs in most scenarios, but only increased at the range centre and contracting RLs given local adaptation to climate. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Data

Appendix - Wind dispersal results in a gradient of dispersal limitation and environmental match amon...

August 2016

Chapter

Logistic Models with Diffusions

May 2014

Population dispersal plays an important role in the population dynamics which arises from environmental and ecological gradients in the habitat. We assume that the systems under consideration are allowed to diffuse spatially besides evolving in time. The spatial diffusion arises from the tendency of species to migrate towards regions of lower population density where the life is better. The most ... [Show full abstract] familiar model systems incorporating these features are reaction diffusion equations.

Article

Evolution of dispersal in a spatially periodic integrodifference model

April 2016 · Nonlinear Analysis Real World Applications

An integrodifference model describing the reproduction and dispersal of a population is introduced to investigate the evolution of dispersal in a spatially periodic habitat. The dispersal is determined by a kernel function, and the dispersal strategy is defined as the probability of population individuals' moving to a different habitat. Both conditional and unconditional dispersal strategies are ... [Show full abstract] investigated, the distinction being whether dispersal depends on local environmental conditions. For competing unconditional dispersers, we prove that the population with the smaller dispersal probability always prevails. Alternatively, for conditional dispersers, it is shown that the strategy known as ideal free dispersal is both sufficient and necessary for evolutionary stability. These results extend those in the literature for discrete diffusion models in finite patchy landscapes and from reaction-diffusion models.

Article

Full-text available

The effects of the number, size and isolation of patches along a gradient of native vegetation cover...

March 2014 · Landscape Ecology

Habitat availability—or how much habitat species can reach at the landscape scale—depends primarily on the percentage of native cover. However, attributes of landscape configuration such as the number, size and isolation of habitat patches may have complementary effects on habitat availability, with implications for the management of landscapes. Here, we determined whether, and at which ... [Show full abstract] percentages of native cover, the number, size and isolation of patches contribute for habitat availability. We quantified habitat availability in 325 landscapes spread across the state of Rio de Janeiro, in the Atlantic Forest hotspot, with either high ([50 %), intermediate (50–30 %), low (30–10 %) or very low (\10 %) percentage of native cover, and for six hypothetical species differing in inter-patch dispersal ability. Above 50 % of native cover, the percentage of cover per se was the only determinant of habitat availability, but below 50 % the attributes of landscape configuration also contributed for habitat availability. The number of patches had a negative effect on habitat availability in landscapes with 50–10 % of native cover, whereas patch size had a positive effect in landscapes with\10 % of native cover. The different species generally responded to the same set of landscape attributes, although to different extents, potentially facilitating decision making for conservation. In landscapes with[50 % of native cover, conservation actions are probably sufficient to guarantee habitat availability, whereas in the remaining landscapes additional restoration efforts are needed, especially to reconnect and/or enlarge remaining habitat patches.