Non-stationary problem optimization using the primal-dual genetic algorithm

This article is posted here with permission from IEEE - Copyright @ 2003 IEEEGenetic algorithms (GAs) have been widely used for stationary optimization problems where the fitness landscape does not change during the computation. However, the environments of real world problems may change over time, which puts forward serious challenge to traditional GAs. In this paper, we introduce the application of a new variation of GA called the primal-dual genetic algorithm (PDGA) for problem optimization in nonstationary environments. Inspired by the complementarity and dominance mechanisms in nature, PDGA operates on a pair of chromosomes that are primal-dual to each other in the sense of maximum distance in genotype in a given distance space. This paper investigates an important aspect of PDGA, its adaptability to dynamic environments. A set of dynamic problems are generated from a set of stationary benchmark problems using a dynamic problem generating technique proposed in this paper. Experimental study over these dynamic problems suggests that PDGA can solve complex dynamic problems more efficiently than traditional GA and a peer GA, the dual genetic algorithm. The experimental results show that PDGA has strong viability and robustness in dynamic environments

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 274)

This bibliography lists 128 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1985

Scotland’s biodiversity progress to 2020 Aichi Targets:Conserving genetic diversity- development of a national approach for addressing Aichi Biodiversity Target 13 that includes wild species

Aichi Target 13 (T13) focuses on the conservation of genetic diversity. •Major challenges in implementing T13 are that the type of genetic diversity to conserve is not clearly defined, and that key issues in genetic conservation vary across different sectors (e.g., forestry vs agriculture vs other species of socio-economic importance). •In Scotland and the UK more widely, baseline mechanisms are well established for assessing and reporting on genetic diversity in species of agricultural importance (e.g., rare livestock breeds, crop wild relatives), and a methodology has been established for ornamental plants. •A new UK Strategy for Forest Genetics Resources was launched in 2019, creating a framework for linking forest trees into T13 reporting. •However, there is no clear strategy to deal with ‘other species of socio-economic importance’ in Scotland, the UK or indeed elsewhere, and addressing this gap is the major focus of this report. •There is a lack of guidance for identifying focal species of socio-economic importance, and no clear mechanism for addressing T13 for these species once they have been identified. •To address this, we have identified a set of criteria for defining terrestrial and freshwater species of socio-economic importance in Scotland, and selected an initial list of 26 species. •The criteria applied were: -National conservation priority wild species. -Species of national cultural importance. -Species providing key ecosystem services. -Species of importance for wild harvesting (food and medicine). -Economically important game species. •We then developed a simple, readily applicable scorecard method for assessing risks to the conservation of genetic diversity in these species. •The scorecard approach is not dependent on prior genetic knowledge, and instead uses structured expert opinion assessments of whether: -Demographic declines are likely to lead to loss of genetic diversity (genetic erosion). -Hybridisation is likely to lead to undesirable replacement of genetic diversity. -Restrictions to regeneration/turnover are likely to impede evolutionary change. •For plant species where seed-banking is a viable mechanism for holding genetic resources ex situ,we also report on the representativeness of these ex situ collections. •Overall, this scorecard provides a mechanism for incorporating ‘other species of socio-economic importance’ into T13 actions and reporting. •Furthermore, its application is not restricted to Aichi T13 as the approach is designed as a generic scorecard for genetic diversity. It is thus relevant to post-2020 CBD targets focusing on genetic diversity. •Future priorities include: -Extension to other species of socio-economic, commercial and cultural importance (with the inclusion of marine species being a particularly high priority). -Harmonising genetic conservation strategies between sectors (drawing on commonalities), whilst minimising disruption of existing well-established methodologies within sectors. -Greater incorporation of genomic data into monitoring genetic diversity (particularly in the agricultural and forestry sectors where data availability is potentially high)

GENETIC MONITORING AND RESCUE IN MID-ATLANTIC BROOK TROUT (SALVELINUS FONTINALIS) POULATIONS

Brook trout (Salvelinus fontinalis) populations have experienced dramatic declines throughout their native range, in part, due to anthropogenic land use and habitat fragmentation. In the mid-Atlantic region, brook trout populations often occupy small, headwater habitat fragments in demographic and genetic isolation, making them vulnerable to inbreeding and genetic drift. My dissertation evaluates different methods for genetic assessment, monitoring, and management of small, isolated brook trout populations. First, I examined the potential value of effective number of breeders (Nb) estimates for genetic monitoring by determining whether Nb estimates were sensitive to habitat characteristics known to affect brook trout populations. Using genetic data from 71 brook trout habitat patches, I found significant evidence that Nb estimates were positively related to habitat size and base flow index, and negatively related to temperature. These results provide further support for the use of Nb in genetic assessments and monitoring of isolated salmonid populations. Human-mediated gene flow is a promising approach to reduce extinction risk and alleviate negative fitness effects associated with small effective population size (i.e., genetic rescue). However, there had not been an assessment of the statistical power of commonly used approaches to determine fitness effects of gene flow, despite calls for more widespread use of human-mediated gene flow. I addressed this need by using individual-based simulations of gene flow and found that these monitoring approaches frequently suffered from low statistical power but also identified strategies to improve inference. Finally, I examined the multigenerational effects of genetic rescue in a small, isolated population of brook trout and found consistent evidence of elevated fitness in F1 hybrids as compared to resident individuals. In contrast, I found a negative relationship between proportion migrant ancestry and lifetime reproductive success in backcrosses (F2 and later generations). Still, backcrosses with less than 0.48 migrant ancestry had lifetime reproductive success greater than residents, on average. These results highlight that gene flow often introduces beneficial and deleterious variation with the net-effect depending on the efficacy of natural selection, which suggests that ecological conditions affecting demography can play an outsized role in determining the outcome of genetic rescue attempts

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 349)

This bibliography lists 149 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during April, 1991. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance