scholarly journals Gene flow between introduced and native Eucalyptus species: exotic hybrids are establishing in the wild

2003 ◽  
Vol 51 (4) ◽  
pp. 429 ◽  
Author(s):  
R. C. Barbour ◽  
B. M. Potts ◽  
R. E. Vaillancourt
Keyword(s):  
Gene Flow ◽  
Native Species ◽  
Parental Species ◽  
F1 Hybrids ◽  
Eucalyptus Species ◽  
Eucalyptus Nitens ◽  
Natural Hybrids ◽  
In The Wild ◽  
Long Term Impact

F1 hybrids between exotic Eucalyptus nitens plantations and native E. ovata have previously been reported among seedlings grown from open-pollinated seed collected from E. ovata, on the island of Tasmania. Such exotic hybrid seedlings have now been found in the wild adjacent to plantations at three locations. The proportion of exotic hybrids in open-pollinated seed collected from nearby mature E. ovata was 5.5%. This level compares with only 0.4% for natural hybrids between native species at these sites (E. ovata, E. viminalis and E.�rodwayi). Detection of hybrids was initially based on their deviant morphology, which was generally intermediate between parental species. This subjective classification was then successfully verified by morphometric and allozyme analyses. Pure E. nitens seedlings (wildlings) were restricted to within 30 m of these plantations, whereas established hybrids were found up to 310 m from the plantations. This pattern of establishment reflects dispersal of exotic seed and pollen respectively. It is likely that the recent expansion of the eucalypt plantation estate in Australia will cause an increase in the frequency of exotic hybrids. However, the long-term impact of such hybridisation is yet to be assessed.

scholarly journals Gene Flow Between Introduced and Native Eucalyptus Species: Morphological Analysis of Tri-Species and Backcross Hybrids Involving E. nitens

2007 ◽  
Vol 56 (1-6) ◽  
pp. 127-133 ◽  
Author(s):  
C. Barbour ◽  
B. M. Potts ◽  
R. E. Vaillancourt
Keyword(s):  
Gene Flow ◽  
Second Generation ◽  
Current Work ◽  
F1 Hybrids ◽  
Morphological Identification ◽  
Eucalyptus Species ◽  
Pure Species ◽  
Backcross Hybrids ◽  
In The Wild ◽  
Species Hybrids

Summary Morphometric analyses were conducted on second-generation tri-species and backcross hybrids in Eucalyptus. These hybrids were all produced using pollen from two E. nitens x cordata F1 hybrids and controlled pollination techniques. Tri-species hybrids were created with E. gunnii, E. ovata and E. viminalis as females, while backcrosses were produced with E. cordata. Multivariate analysis of seedling characteristics indicated that eighty percent of the backcross hybrids fell within the morphological range of E. cordata. All three cross combinations of the tri-species hybrids were biased away from E. nitens and towards their maternal parent and E. cordata. The inclusion of data for first-generation (F1) hybrids between the pure parental species in the current work showed the F1’s to be easily distinguishable from pure species, compared to second-generation hybrids. The use of morphology for detecting second-generation hybridisation involving exotic plantation species and native eucalypt populations will therefore be unreliable, and identifies a need for preventing second-generation hybrids from establish in the wild. The current work, nevertheless, provides further demonstration of the effectiveness of morphological identification of F1 hybrids. The easy recognition of F1 hybrids will be useful in identifying sites and species at risk of exotic gene flow and enable the development of weeding programs that focus on removing exotic hybrids in the wild.

Gene flow between introduced and native Eucalyptus species: crossability of native Tasmanian species with exotic E. nitens

2005 ◽  
Vol 53 (5) ◽  
pp. 465 ◽  
Author(s):  
R. C. Barbour ◽  
B. M. Potts ◽  
R. E. Vaillancourt
Keyword(s):  
Gene Flow ◽  
Native Species ◽  
Seed Set ◽  
Pollen Competition ◽  
F1 Hybrids ◽  
Eucalyptus Species ◽  
F1 Hybrid ◽  
Genetic Pollution ◽  
Morphometric Analyses ◽  
Natural Hybridisation

Eucalyptus nitens (Deane & Maiden) Maiden has been extensively introduced to the island of Tasmania for plantation purposes. Natural hybridisation with two native species has already been confirmed and this study aimed to determine which other Tasmanian native species could potentially hybridise with E. nitens. Controlled and supplementary pollinations with E. nitens pollen were undertaken on all Tasmanian native species that are potentially at risk of exotic gene flow and hence genetic pollution. Across the seven species tested by using controlled pollinations, seed set per flower, following E. nitens pollinations, was significantly less than for intraspecific outcross pollinations. No significant differences were evident in the percentage of seed that germinated or the percentage of germinants that grew into healthy seedlings in the glasshouse. Hybridity was verified by morphometric analyses and F1 hybrid seedlings were clearly differentiated from parental species and generally intermediate in morphology. Supplementary E. nitens pollination of open-pollinated native flowers was conducted to simulate natural pollination where pollen competition would occur. Seven of the fifteen species tested produced F1 hybrids in this case; however, further crossing is required to verify failed cross combinations. Although E. nitens can potentially hybridise with many native species, the results from both supplementary and controlled pollinations suggest the presence of post-pollination barriers of varying strength that need to be considered in assessing the risk of exotic gene flow from plantations.

scholarly journals Long-Term Effects of Forest Plantation Species on Chemical Soil Properties in Southern Rwanda

Soil Systems ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 59
Author(s):  
Peter Rwibasira ◽  
Francois Xavier Naramabuye ◽  
Donat Nsabimana ◽  
Monique Carnol
Keyword(s):  
Soil Properties ◽  
Tree Species ◽  
Native Species ◽  
Water Soluble ◽  
Hot Water ◽  
Eucalyptus Species ◽  
Long Term Effects ◽  
Soil Functioning ◽  
C And N

Understanding the long-term effects of tree species on soil properties is crucial for the development of forest restoration policies in relation to the choice of species that meet both environmental and local livelihood needs. This study was performed in the Arboretum of Ruhande, Southern Rwanda, where monocultures of 148 deciduous and 56 conifer species have been established in 0.25 ha replicated plots from 1933 onwards. We investigated the effects of six exotic and two native tree species planted in monoculture plots and native species mixed within one self-regenerated plot on soil properties in two layers (0–5 cm and 5–10 cm depth). We measured general soil properties (pH, SOM, exchangeable base cations) and water-soluble C and N as a proxy for soil functioning. Changes in soil properties were observed in the upper soil layer for all tree species. Planting Eucalyptus species caused soil acidification, whereas soil exchangeable cations and pH were higher under native species (Entandrophragma excelsum and Polyschias fulva) and mixed native species. The effects of tree species were more pronounced for hot water-extractable C and N than for other soil properties. Their analyses could be used for detecting changes in soil functioning linked to vegetation types.

scholarly journals Pure species discriminate against hybrids in the Drosophila melanogaster species subgroup

2020 ◽  
Author(s):  
Antonio Serrato-Capuchina ◽  
Timothy D. Schwochert ◽  
Stephania Zhang ◽  
Baylee Roy ◽  
David Peede ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Flow ◽  
Parental Species ◽  
Cuticular Hydrocarbon ◽  
F1 Hybrids ◽  
Sexual Attractiveness ◽  
Pure Species ◽  
Species Pairs ◽  
Fertile Hybrids ◽  
Drosophila Melanogaster Species Subgroup

ABSTRACTIntrogression, the exchange of alleles between species, is a common event in nature. This transfer of alleles between species must happen through fertile hybrids. Characterizing the traits that cause defects in hybrids illuminate how and when gene flow is expected to occur. Inviability and sterility are extreme examples of fitness reductions but are not the only type of defects in hybrids. Some traits specific to hybrids are more subtle but are important to determine their fitness. In this report, we study whether F1 hybrids between two species pairs of Drosophila are as attractive as the parental species. We find that in both species pairs, the sexual attractiveness of the F1 hybrids is reduced and that pure species discriminate strongly against them. We also find that the cuticular hydrocarbon (CHC) profile of the hybrids is intermediate between the parental species. Perfuming experiments show that modifying the CHC profile of the hybrids to resemble pure species improves their chances of mating. Our results show that behavioral discrimination against hybrids might be an important component of the persistence of species that can hybridize.

RESTRICTION FRAGMENT LENGTH POLYMORPHISM IN WILD AND CULTIVATED TETRAPLOID WHEAT

1999 ◽  
Vol 47 (4) ◽  
pp. 213-224 ◽  
Author(s):  
Li Huang ◽  
Eitan Millet ◽  
Junkang Rong ◽  
Jonathan F. Wendel ◽  
Yehoshua Anikster ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Triticum Turgidum ◽  
Large Population ◽  
Tetraploid Wheat ◽  
Nuclear Genome ◽  
Wild Emmer ◽  
Long Term Study ◽  
In The Wild

RFLP diversity in the nuclear genome was estimated within and among Israeli populations of wild emmer wheat (Triticum turgidumvar.dicoccoides) from a long-term study site at Ammiad (NE Israel), and from several other geographical locations. Using 55 enzyme-probe combinations, high levels of genetic diversity were revealed in wild emmer in general and within the Ammiad site. In spite of high diversity, observed heterozygosity was low and populations consisted of a patchwork of alternate multilocus homozygotes, consistent with the reproductive biology of a predominant self-fertilizing species. Retention of genetic diversity in wild emmer may be promoted by large population sizes, microhabitat diversity, and occasional gene flow through both pollen and seed. Population genetic structure in wild emmer appears to have been influenced by historical founder events as well as selective factors. Multivariate analyses indicated that individuals tend to cluster together according to their population of origin, and that there is little geographical differentiation among populations. Sampling of 12 domesticated land-races and both primitive and modern cultivars ofT. turgidumrevealed high levels of diversity and a large number of alleles that were not detected in the wild emmer populations. This may reflect a long-term domestication process in which wild, semi-domesticated, and domesticated types grew sympatrically, continuing introgression from wild populations, and perhaps also gene flow from trans-specific sources.

scholarly journals Impact of interspecific relations between native red deer (Cervus elaphus) and introduced sika deer (Cervus nippon) on their rutting season in the Doupovské hory Mts.

2014 ◽  
Vol 60 (No. 7) ◽  
pp. 272-280 ◽  
Author(s):  
Z. Macháček ◽  
S. Dvořák ◽  
M. Ježek ◽  
D. Zahradník
Keyword(s):  
Cervus Elaphus ◽  
Native Species ◽  
Red Deer ◽  
Sika Deer ◽  
Military Training ◽  
Cervus Nippon ◽  
Data Set ◽  
In The Wild ◽  
The Military

The behaviour of sika and red deer during the rutting season is highly variable in relation to vocalization, habitat preference during the rut, and onset and termination of rutting. The red deer is a native species in Central Europe, but the areas where it lives in sympatry with the introduced sika deer have been increasing in the last three decades. Such situation can be found in the Doupovské hory Mts., where sika deer has been intensively spreading. Hybridization between the two species and changes in behaviour are the most important problems. In this study we prove the shift in the rutting period shown by both species. To evaluate the shift in the rutting season, we used a very extensive long-term data set on deer shot within the Military Training Area. These changes occur very slowly, however, and are very difficult to monitor and evaluate in the wild. Based on our results, the timing of the rutting season has converged at the mean rate of 0.62 day per year (rutting season starts later in the red deer and earlier in the sika deer).  

scholarly journals Landscape and taxon age are associated with differing patterns of hybridization in two Eucalyptus (Myrtaceae) subgenera

2020 ◽  
Vol 127 (1) ◽  
pp. 49-62
Author(s):  
T P Robins ◽  
R M Binks ◽  
M Byrne ◽  
S D Hopper
Keyword(s):  
Evolutionary Process ◽  
F1 Hybrids ◽  
Divergence Times ◽  
Eucalyptus Species ◽  
Reproductive Barriers ◽  
Nucleotide Polymorphism ◽  
Plant Populations ◽  
Single Nucleotide ◽  
Clonal Spread

Abstract Background and Aims Hybridization is an important evolutionary process that can have a significant impact on natural plant populations. Eucalyptus species are well known for weak reproductive barriers and extensive hybridization within subgenera, but there is little knowledge of whether patterns of hybridization differ among subgenera. Here, we examine eucalypts of Western Australia’s Stirling Range to investigate how patterns of hybridization are associated with landscape and taxon age between the two largest Eucalyptus subgenera: Eucalyptus and Symphyomyrtus. In doing so, we tested a hypothesis of OCBIL (old, climatically buffered, infertile landscape) theory that predicts reduced hybridization on older landscapes. Methods Single nucleotide polymorphism markers were applied to confirm the hybrid status, parentage and genetic structure of five suspected hybrid combinations for subg. Eucalyptus and three combinations for subg. Symphyomyrtus. Key Results Evidence of hybridization was found in all combinations, and parental taxa were identified for most combinations. The older parental taxa assessed within subg. Eucalyptus, which are widespread on old landscapes, were identified as well-defined genetic entities and all hybrids were exclusively F1 hybrids. In addition, many combinations showed evidence of clonality, suggesting that the large number of hybrids recorded from some combinations is the result of long-term clonal spread following a few hybridization events rather than frequent hybridization. In contrast, the species in subg. Symphyomyrtus, which typically occur on younger landscapes and are more recently evolved, showed less distinction among parental taxa, and where hybridization was detected, there were high levels of introgression. Conclusions Reduced hybridization in subg. Eucalyptus relative to extensive hybridization in subg. Symphyomyrtus affirmed the hypothesis of reduced hybridization on OCBILs and demonstrate that clade divergence times, landscape age and clonality are important drivers of differing patterns of speciation and hybridization in Eucalyptus.

scholarly journals Telomere shortening as a mechanism of long-term cost of infectious diseases in natural animal populations

2019 ◽  
Vol 15 (5) ◽  
pp. 20190190 ◽  
Author(s):  
Mathieu Giraudeau ◽  
Britt Heidinger ◽  
Camille Bonneaud ◽  
Tuul Sepp
Keyword(s):  
Telomere Maintenance ◽  
Laboratory Animals ◽  
Experimental Investigations ◽  
Telomere Shortening ◽  
Animal Populations ◽  
In The Wild ◽  
Selective Forces ◽  
Long Term Impact ◽  
Telomere Erosion

Pathogens are potent selective forces that can reduce the fitness of their hosts. While studies of the short-term energetic costs of infections are accumulating, the long-term costs have only just started to be investigated. Such delayed costs may, at least in part, be mediated by telomere erosion. This hypothesis is supported by experimental investigations conducted on laboratory animals which show that infection accelerates telomere erosion in immune cells. However, the generalizability of such findings to natural animal populations and to humans remains debatable. First, laboratory animals typically display long telomeres relative to their wild counterparts. Second, unlike humans and most wild animals, laboratory small-bodied mammals are capable of telomerase-based telomere maintenance throughout life. Third, the effect of infections on telomere shortening and ageing has only been studied using single pathogen infections, yet hosts are often simultaneously confronted with a range of pathogens in the wild. Thus, the cost of an infection in terms of telomere-shortening-related ageing in natural animal populations is likely to be strongly underestimated. Here, we discuss how investigations into the links between infection, immune response and tissue ageing are now required to improve our understanding of the long-term impact of disease.

Gene flow between introduced and native Eucalyptus species: Early-age selection limits invasive capacity of exotic E. ovata×nitens F1 hybrids

2006 ◽  
Vol 228 (1-3) ◽  
pp. 206-214 ◽  
Author(s):  
R.C. Barbour ◽  
B.M. Potts ◽  
R.E. Vaillancourt
Keyword(s):  
Gene Flow ◽  
F1 Hybrids ◽  
Early Age ◽  
Eucalyptus Species ◽  
Invasive Capacity

Crisis Phones - Suicide Prevention Versus Suggestion/Contagion Effects

Crisis ◽  
2015 ◽  
Vol 36 (3) ◽  
pp. 220-224 ◽  
Author(s):  
Steven Stack
Keyword(s):  
Suicide Prevention ◽  
Contagion Effects ◽  
Long Term Impact

Abstract. Background: There has been no systematic work on the short- or long-term impact of the installation of crisis phones on suicides from bridges. The present study addresses this issue. Method: Data refer to 219 suicides from 1954 through 2013 on the Skyway Bridge in St. Petersburg, Florida. Six crisis phones with signs were installed in July 1999. Results: In the first decade after installation, the phones were used by 27 suicidal persons and credited with preventing 26 or 2.6 suicides a year. However, the net suicide count increased from 48 in the 13 years before installation of phones to 106 the following 13 years or by 4.5 additional suicides/year (t =3.512, p < .001). Conclusion: Although the phones prevented some suicides, there was a net increase after installation. The findings are interpreted with reference to suggestion/contagion effects including the emergence of a controversial bridge suicide blog.

Sign in / Sign up

Export Citation Format

Share Document