Source population characteristics affect heterosis following genetic rescue of fragmented plant populations

Understanding the relative importance of heterosis and outbreeding depression over multiple generations is a key question in evolutionary biology and is essential for identifying appropriate genetic sources for population and ecosystem restoration. Here we use 2455 experimental crosses between 12 population pairs of the rare perennial plant Rutidosis leptorrhynchoides (Asteraceae) to investigate the multi-generational (F 1 , F 2 , F 3 ) fitness outcomes of inter-population hybridization. We detected no evidence of outbreeding depression, with inter-population hybrids and backcrosses showing either similar fitness or significant heterosis for fitness components across the three generations. Variation in heterosis among population pairs was best explained by characteristics of the foreign source or home population, and was greatest when the source population was large, with high genetic diversity and low inbreeding, and the home population was small and inbred. Our results indicate that the primary consideration for maximizing progeny fitness following population augmentation or restoration is the use of seed from large, genetically diverse populations.

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Genetic Management of Fragmented Animal and Plant Populations

10.1093/oso/9780198783398.001.0001 ◽

2017 ◽

Cited By ~ 103

Author(s):

Richard Frankham ◽

Jonathan D. Ballou ◽

Katherine Ralls ◽

Mark Eldridge ◽

Michele R. Dudash ◽

...

Keyword(s):

Genetic Diversity ◽

Gene Flow ◽

Biological Diversity ◽

Extinction Risk ◽

Outbreeding Depression ◽

Genetic Rescue ◽

Isolated Populations ◽

Genetic Management ◽

Plant Populations ◽

Loss Of Genetic Diversity

The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation increases, loss of genetic diversity reduces their ability to adapt to changes in the environment, with inbreeding and reduced fitness inevitable consequences for many species. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow into them from another population within the species, but this is very rarely done. This novel and authoritative book addresses the issues involved in genetic management of fragmented animal and plant populations, including inbreeding depression, loss of genetic diversity and elevated extinction risk in small isolated populations, augmentation of gene flow, genetic rescue, causes of outbreeding depression and predicting its occurrence, desirability and implementation of genetic translocations to cope with climate change, and defining and diagnosing species for conservation purposes.

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Modified rescue and risk expectations for species with diverse mating systems and modes of inheritance

10.1093/oso/9780198783398.003.0008 ◽

2017 ◽

Author(s):

Richard Frankham ◽

Jonathan D. Ballou ◽

Katherine Ralls ◽

Mark D. B. Eldridge ◽

Michele R. Dudash ◽

...

Keyword(s):

Mating Systems ◽

Outbreeding Depression ◽

Mixed Mating ◽

Genetic Rescue ◽

Mode Of Inheritance

The risks of inbreeding and outbreeding depression, and the prospects for genetic rescue are often different in species with alternative mating systems and mode of inheritance (compared to outbreeding diploids), such as self-incompatible, self-fertilizing, mixed mating, non-diploid (haploid, haplodiploid and polyploid) and asexual.

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Genetic rescue by augmenting gene flow

10.1093/oso/9780198783398.003.0006 ◽

2017 ◽

Author(s):

Richard Frankham ◽

Jonathan D. Ballou ◽

Katherine Ralls ◽

Mark D. B. Eldridge ◽

Michele R. Dudash ◽

...

Keyword(s):

Genetic Diversity ◽

Gene Flow ◽

Inbreeding Coefficient ◽

Outbreeding Depression ◽

Genetic Rescue ◽

Evolutionary Potential ◽

Beneficial Effects ◽

The Difference ◽

Inbred Populations ◽

Harmful Effects

Inbreeding is reduced and genetic diversity enhanced when a small isolated inbred population is crossed to another unrelated population. Crossing can have beneficial or harmful effects on fitness, but beneficial effects predominate, and the risks of harmful ones (outbreeding depression) can be predicted and avoided. For crosses with a low risk of outbreeding depression, there are large and consistent benefits on fitness that persist across generations in outbreeding species. Benefits are greater in species that naturally outbreed than those that inbreed, and increase with the difference in inbreeding coefficient between crossed and inbred populations in mothers and zygotes. However, benefits are similar across invertebrates, vertebrates and plants. There are also important benefits for evolutionary potential of crossing between populations.

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Sperm motility and offspring pre- and post-hatching survival in hybridization crosses among a landlocked and two anadromous Atlantic salmon populations: implications for conservation

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2020-0158 ◽

2020 ◽

Author(s):

Aslak Tiuna Eronen ◽

Jukka Kekäläinen ◽

Jorma Piironen ◽

Pekka Hyvärinen ◽

Hannu Huuskonen ◽

...

Keyword(s):

Genetic Diversity ◽

Sperm Motility ◽

First Generation ◽

Hybrid Vigor ◽

Outbreeding Depression ◽

Genetic Rescue ◽

Low Genetic Diversity ◽

Salmon Eggs ◽

Salmon Population ◽

Lake Saimaa

The landlocked salmon (Salmo salar m. sebago) endemic to Lake Saimaa, Finland, is critically endangered and severely threatened by low genetic diversity and inbreeding. To explore the possibility of increasing the genetic diversity of threatened salmon populations by controlled hybridization (genetic rescue), we studied sperm motility and offspring pre- and post-hatching survival in hybridization crosses of landlocked salmon with two geographically close anadromous salmon populations (Rivers Neva and Tornio) relative to the pure-bred populations. While some degree of gametic incompatibility between landlocked and Tornio salmon cannot be ruled out, there were no indications of outbreeding depression in survival traits in these first-generation hybridizations. Instead, pre-hatching survival of landlocked salmon eggs fertilized with Neva salmon sperm and post-hatching survival of anadromous salmon eggs fertilized with landlocked salmon sperm were higher than in pure-bred landlocked salmon. These differences might imply genetic rescue effects (hybrid vigor), although there were also strong maternal effects involved. Our results on early viability point to the possibility of applying genetic rescue to the landlocked salmon population by hybridization with an anadromous population.

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An Evaluation of the AFLP Fingerprinting Technique for the Analysis of Paternity in Natural Populations of Persoonia mollis (Proteaceae)

Australian Journal of Botany ◽

10.1071/bt97043 ◽

1998 ◽

Vol 46 (4) ◽

pp. 533 ◽

Cited By ~ 21

Author(s):

Siegfried L. Krauss ◽

Rod Peakall

Keyword(s):

Evolutionary Biology ◽

Fragment Length Polymorphism ◽

Natural Populations ◽

Molecular Fingerprinting ◽

Ecological Studies ◽

Aflp Fingerprinting ◽

Single Population ◽

Plant Populations ◽

Fingerprinting Technique ◽

The Mean

The accurate assignment of paternity in natural plant populations is required to address important issues in evolutionary biology, such as the factors that affect reproductive success. Newly developed molecular fingerprinting techniques offer the potential to address these aims. Here, we evaluate the utility of a new PCR-based multi-locus fingerprinting technique called Amplified Fragment Length Polymorphism (AFLP) for paternity studies in Persoonia mollis (Proteaceae). AFLPs were initially scored for five individuals from three taxonomic levels for 64 primer pairs: between species (P. mollis and P. levis), between subspecies (P. mollis subsp. nectens and subsp. livens), between individuals within a single population of P. mollis, as well as for a naturally pollinated seed from a single P. mollis subsp. nectens plant. Overall, 1164 fragments (24.6% of all fragments) were polymorphic between species, 743 (16.5%) between subspecies, 371 (8.6%) between individuals within a single population, and 265 (6.2%) between a plant and its seed. Within a single P. mollis population of 14 plants, 42 polymorphic fragments were scored from profiles generated by a single AFLP primer pair. The mean frequency of the recessive allele (q) over these 42 loci was 0.773. Based on these observations, it will be feasible to generate well over 100 polymorphic AFLP loci with as few as three AFLP primer pairs. This level of polymorphism is sufficient to assign paternity unambiguously to more than 99% of all seed in experiments involving small, known paternity pools. More generally, the AFLP procedure is well suited to molecular ecological studies, because it produces more polymorphism than allozymes or RAPDs but, unlike conventionally developed microsatellite loci, it requires no prior sequence knowledge and minimal development time.

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Environmental uncertainty, autocorrelation and the evolution of survival

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2007.0561 ◽

2007 ◽

Vol 274 (1622) ◽

pp. 2153-2160 ◽

Cited By ~ 24

Author(s):

C.J.E Metcalf ◽

D.N Koons

Keyword(s):

Evolutionary Biology ◽

Environmental Variability ◽

Variable Density ◽

Allocation Of Resources ◽

Fitness Component ◽

Fitness Components ◽

Temporal Autocorrelation ◽

Variable Environments ◽

Survival Patterns ◽

Evolutionarily Stable

Survival is a key fitness component and the evolution of age- and stage-specific patterns in survival is a central question in evolutionary biology. In variable environments, favouring chances of survival at the expense of other fitness components could increase fitness by spreading risk across uncertain conditions, especially if environmental conditions improve in the future. Both the magnitude of environmental variation and temporal autocorrelation in the environment might therefore affect the evolution of survival patterns. Despite this, the influence of temporal autocorrelation on the evolution of survival patterns has not been addressed. Here, we use a trade-off structure which reflects the empirically inspired paradigm of acquisition and allocation of resources to investigate how the evolutionarily stable survival probability is shaped in variable, density-dependent environments. We show that temporal autocorrelation is likely to be an important aspect of environmental variability that contributes to shaping age- and stage-specific patterns of survival probabilities in nature.

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Outbreeding depression and breeding system evolution in small, remnant populations of Primula vulgaris: consequences for genetic rescue

Conservation Genetics ◽

10.1007/s10592-017-1031-x ◽

2017 ◽

Vol 19 (3) ◽

pp. 545-554 ◽

Cited By ~ 9

Author(s):

S. Henrik Barmentlo ◽

Patrick G. Meirmans ◽

Sheila H. Luijten ◽

Ludwig Triest ◽

J. Gerard B. Oostermeijer

Keyword(s):

Breeding System ◽

Outbreeding Depression ◽

Genetic Rescue ◽

System Evolution ◽

Primula Vulgaris ◽

Breeding System Evolution

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Genetic monitoring in natural perennial plant populations

Botany ◽

10.1139/b10-087 ◽

2011 ◽

Vol 89 (2) ◽

pp. 75-81 ◽

Cited By ~ 26

Author(s):

F. A. Aravanopoulos

Keyword(s):

Allelic Richness ◽

Keystone Species ◽

Genetic Monitoring ◽

Gene Conservation ◽

Effective Population ◽

Conservation Units ◽

Plant Populations ◽

Perennial Plant ◽

Genetic Potential ◽

Inbreeding Rate

Genetic monitoring, the quantification of temporal changes in population genetics and dynamics metrics generated by using appropriate parameters, constitutes a method with a prognostic value. Genetic monitoring has been recognized in several international agreements and documents, and can be an important tool for the protection of biodiversity. However, approaches developed so far for perennial plant species are rather cumbersome for practical use. It is proposed that perennial plant genetic monitoring should focus on keystone species of biological and economical importance, as well as rare or endangered species. In addition, genetic monitoring should concentrate on gene conservation units of such species, to be advanced in a dynamic gene conservation scheme. Three indicators are proposed for genetic monitoring based on a gene-ecological approach: natural selection, genetic drift, and a gene flow-mating system. These are evaluated based on three demographic (age and size class distribution, reproductive fitness, regeneration abundance) and four genetic (effective population size, allelic richness, latent genetic potential, outcrossing/actual inbreeding rate) parameters. Minimum sample sizes, critical levels of differences among parameters, and costs for temporal evaluation are proposed. The benefits of the immediate application of genetic monitoring are highlighted.

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Experimental crosses within European Silene latifolia (Caryophyllaceae): intraspecific differentiation, distance effects, and sex ratio

Botany ◽

10.1139/b08-137 ◽

2009 ◽

Vol 87 (3) ◽

pp. 231-240 ◽

Cited By ~ 8

Author(s):

Louise Hathaway ◽

Stefan Andersson ◽

Honor C. Prentice

Keyword(s):

Sex Ratio ◽

Seed Morphology ◽

Silene Latifolia ◽

Outbreeding Depression ◽

Incipient Speciation ◽

Crossing Experiments ◽

Source Populations ◽

Negative Relationships ◽

East West ◽

Experimental Crosses

The dioecious weed Silene latifolia Poiret is thought to have spread northwards through Europe from separate southern source populations and shows a pronounced east–west pattern of differentiation in seed morphology. We used crossing experiments to investigate whether patterns of interfertility in S. latifolia are consistent with a scenario of ongoing speciation (reflected by outbreeding depression in crosses between the seed races), a scenario involving local inbreeding (reflected by heterosis in interpopulations crosses), or a combination of both scenarios. The experiments involved three western and three eastern populations, which were crossed reciprocally in all possible inter- and intra-population combinations. Inter-race cross-progenies did not have lower fitness than those from intra-racial crosses, and the results are not consistent with a scenario of incipient speciation. A pattern of overall heterosis was found in three variables, indicating the expression of inbreeding depression in progeny from intrapopulation crosses. For two fitness variables, negative relationships between interpopulation distance and heterosis, together with signs of outbreeding depression in the longest-distance crosses, suggest that there may be significant levels of genetic differentiation between geographically distant populations. The sex ratio was female-biased in most progenies, especially in those from the longest-distance crosses.

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Population characteristics, habitat, and conservation status of Rhododendron ferrugineum L. (Ericaceae), a glacial relict new to Poland

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.3634 ◽

2019 ◽

Vol 88 (3) ◽

Author(s):

Marek Malicki ◽

Wojciech Pusz ◽

Michał Ronikier ◽

Tomasz Suchan

Keyword(s):

Plant Community ◽

Conservation Status ◽

Population Characteristics ◽

High Genetic Diversity ◽

Rhododendron Ferrugineum ◽

The Status ◽

Long Time ◽

High Conservation ◽

The Alps ◽

Glacial Relict

The first reliable information on the occurrence of Rhododendron ferrugineum in the Karkonosze Mts (excluding spots of directly acknowledged anthropogenic origin) was provided by A. Boratyński in 1983, but the status and origin of the plants were unknown. A recent phylogeographical study proved the natural character and relict status of the aforementioned population, which makes it the northernmost and most isolated site within the whole distribution of the species. In this study, we characterized the basic aspects of the ecology and conservation status of the population and, more specifically, focused on assessing the size of the population, general health of individuals, generative propagation ability, habitat conditions, and potential threats for the species. The population persists in the Sowia Dolina (east part of the Karkonosze Mts), in a microtopographically controlled, treeless microrefugium. Shrubs of R. ferrugineum are part of an acidophilous dwarf-heath plant community, similar to those occurring in the Alps and the Pyrenees, although less species-diverse. The plant community in the Karkonosze Mts has been preliminarily classified into the Genisto pilosae-Vaccinion alliance. The R. ferrugineum population consists of 68 individuals: 57 fully grown and juvenile and 11 seedlings. In 2017, 10 individuals flowered, seven of which developed fruits, while in 2018, 15 individuals produced flowers and eight developed mature fruits. Seeds collected in 2017 germinated in high numbers. Plants in the Karkonosze population hosted some fungal parasites typically found in Rhododendron species, but no intense disease symptoms strongly influencing plant fitness were observed. A combination of significant isolation, genetic distinctness, and high genetic diversity implies a high conservation priority for the R. ferrugineum population in Karkonosze. Despite the theoretical threats, including stochastic risks, the R. ferrugineum population seems to have been stable for a long time and, importantly, it is composed of individuals of different ages, from large flowering plants to seedlings.

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