A genetic assessment of a successful seagrass meadow (Posidonia australis) restoration trial

Seagrass meadows are in decline globally. Although numerous experimental methods have been implemented to restore meadows, few have been successful in the long term. Poor decisions on the sourcing of transplants from donor sites, including poor genetic integration and/or low genetic diversity, may impact on restoration success. However, despite evidence to suggest a positive association between genetic diversity and ecological resilience, there is usually little or no input from genetic data to inform on the genetic management of ecological restoration. Cockburn Sound has seen a 77% decline in seagrass cover since 1967. A transplant trial was conducted between 2004 and 2008 with sprigs of Posidonia australis being planted into a bare sand area. Survival was monitored annually, and in 2012, we compared genetic diversity in this transplant area with the original donor site. Genetic diversity in the restored meadow was very high and comparable to the donor site, with no genetic differentiation detected. The high level of genetic diversity and choice of site may have played an important role in the success of this restoration trial. The observed natural recruits around the site after establishment of transplants suggest that local restoration efforts may improve seafloor habitat and facilitate natural expansion of the meadow.     

On‐ground habitat restoration: Interview with Nancy Pallin

Nancy Pallin has been involved in bush regeneration practice for over 25 years as well as being involved in conservation advocacy. Her main work, helping to establish the Ku‐ring‐gai Flying‐Fox Reserve and coordinating its ecological restoration, draws on an ability to interpret nature to others and inspire collective action     

p53 restoration kills primitive leukemia cells in vivo and increases survival of leukemic mice

Loss of p53 function is a common feature of human cancers and it is required for differentiated tumor cell maintenance; however, it is not known whether sustained inactivation of the p53 pathway is needed for cancer stem cell persistence. Chronic myeloid leukemia (CML) is caused by a chromosome translocation that generates the BCRABL oncogene encoding a constitutively active protein tyrosine kinase. The disease originates in a hematopoietic stem cell and is maintained by leukemic stem cells (LSCs). Treatment with specific tyrosine kinase inhibitors does not eliminate LSCs because they do not depend on the oncogene for survival. We have combined a switchable p53 knock-in mouse model, p53^KI/KI, with the well-characterized Sca1-BCRABLp210 CML transgenic model, to show that transient restoration of p53 slows disease progression and significantly extends the survival of leukemic animals, being the mechanism responsible for this effect, apoptotic death of primitive leukemia cells. In agreement with these in vivo findings, in vitro assays show that restoring p53 reduces hematopoietic colony formation by cells of leukemic animals. These results suggest that reestablishing p53 function may be a therapeutic strategy for the eradication of leukemic stem cells and to prevent disease progression.     

The effects of different vegetation restoration patterns on soil bacterial diversity for sandy land in Hulunbeier

Grassland desertification seriously threatens sustainable economic and social development. Much attention has been paid to the control of grassland desertification, and even to the restoration and reconstruction of the grassland. Vegetation restoration is considered to be a very effective solution. Soil sustains an immense diversity of microbes, and the characteristics of soil microbial communities are sensitive indicators of soil. It is important to understand the relationship between vegetation and soil microbial diversity during the restoration process. Soil microbial, which is the main index to evaluate soil quality, plays a significant role in ecosystem and soil microbial diversity is the important one of global diversity. Exploring the effects of different vegetation patterns on soil microbial diversity can provide scientific bases and technical support for systemic and impersonal assessment of the best vegetation restoration patterns, as well as the vegetation restoration and reconstruction of Hulunbeier sandy land. Based on PCR–DGGE technology, a case study was carried out to investigate the effects of five different vegetation restoration patterns on soil microbial functional diversity after 4 years in sandy land in Hulunbeier, China. The five vegetation restoration patterns included mono-cultivar planting of Agropyron cristatum (UA), mono-cultivar planting of Hedysarum fruticosum (UH), mono-cultivar planting of Caragana korshinskii (UC), mixed-cultivar planting of Agropyron cristatum and Hedysarum fruticosum (AC) and mixed-cultivar planting of Agropyron cristatum, Hedysarum fruticosum, Caragana korshinskii and Elymus nutans (ACHE). Completely degraded sandy land was used as control.The results indicated that the vegetation restoration increased the genetic diversity of soil bacterial community obviously, and the structure of soil bacterial community was changed. The results of phylogenetic analysis suggested that the bacterial community in Hulunbeier sandy land mainly attributed to Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, and Acidobacteria. The dominant groups were Proteobacteria and Bacteroidetes. The effects of different vegetation type on soil bacterial community structures were different.     

Release from sheep-grazing appears to put some heart back into upland vegetation: A comparison of nutritional properties of plant species in long-term grazing experiments

Rewilding or wilding is a popularised means for enhancing the conservation value of marginal land. In the British uplands, it will involve a reduction, or complete removal, of livestock grazing (sheep), based on the belief that grazing has reduced plant species diversity, the ‘Wet Desert’ hypothesis. The hope is that if livestock is removed, diversity will recover. If true, we hypothesise that the species extirpated/reduced by grazing and then recover on its removal would more nutritious compared to those that persisted. We test this hypothesis at Moor House National Nature Reserve (North-Pennines), where seven sets of paired plots were established between 1953 and 1967 to compare ungrazed/sheep-grazed vegetation. Within these plot-pairs, we compared leaf properties of seven focal species that occurred only, or were present in much greater abundance, in the absence of grazing to those of 10 common species that were common in both grazed and ungrazed vegetation. Each sample was analysed for macro-nutrients, micro-nutrients, digestibility, palatability and decomposability. We ranked the species with respect to 22 variables based on effect size derived from Generalised Linear Modelling (GLM) and compared species using a Principal Components Analysis. We also assessed changes in abundance of the focal species through time using GLMs. Our results support the ‘Wet Desert’ hypothesis, that is, that long-term sheep grazing has selectively removed/reduced species like our focal ones and on recovery, they were more nutritious (macro-nutrients, some micro-nutrients) palatable, digestible and decomposable than common species. Measured changes in abundance of the focal species suggest that their recovery will take 10–20 years in blanket bog and 60 years in high-altitude grasslands. Collectively, these results suggest that sheep grazing has brought about biotic homogenization, and its removal in (re)wilding schemes will reverse this process eventually! The ‘white woolly maggots’ have eaten at least part of the heart out of the highlands/uplands, and it will take some time for recovery.     

Agouti reintroduction recovers seed dispersal of a large-seeded tropical tree

The aim of animal reintroductions has mainly been species recovery; only few reintroduction initiatives focus on ecosystem restoration. Therefore, reintroduction consequences on ecological interactions are seldom assessed. We used the interaction between a reintroduced population of agoutis (Dasyprocta leporina) and a vulnerable tropical endemic tree (Joannesia princeps) to examine reintroduction effects on seed dispersal and seedling establishment. To test the outcomes of this interaction, we tracked seeds of J. princeps in two adjacent forest areas with and without reintroduced agoutis. We also assessed if dispersal distances affected seedling survival. To determine seed fate and dispersal distance, we used spool-and-line tracking, together with camera traps to identify dispersers. Agoutis were the only species removing J. princeps seeds, thus dispersal only occurred where agoutis had been reintroduced; in the area without agoutis, all seeds remained intact on the soil, even one year after the experiment's beginning. At the reintroduction area, most seeds were preyed upon by agoutis but 7% remained dispersed and 2% germinated after ten months. Only seeds buried by agoutis were able to germinate. Most dispersed seeds were dispersed 15 m or farther and longer dispersal distances benefited J. princeps, since seedlings farther from a conspecific adult tree had greater survival probability. Agoutis were also seen burying seeds of two other plant species; these mammals have the potential to benefit dozens of large-seeded species in our study system. Agouti reintroduction thus exemplifies the value of trophic rewilding programs to re-establish ecological interactions and restore ecosystem functioning.     

Ant–scale mutualism increases scale infestation,decreases folivory,and disrupts biological control in restored tropical forests

Ant–hemipteran mutualisms can have positive and negative effects on host plants depending on the level of hemipteran infestation and plant protection conferred by ants against folivory. Differential effects of such mutualisms on plant survival are well documented in undisturbed and ant-invaded systems, but few have explored how anthropogenic disturbance affects interactions between hemipterans and native ant species and what the consequences may be for recovering ecosystems. Within a fragmented landscape in Costa Rica, restored tropical forests harbor a mutualism between the native ant Wasmannia auropunctata and the scale insect Alecanochiton marquesi on the abundant, early-successional tree Conostegia xalapensis. I added A. marquesi scales to C. xalapensis seedlings and either allowed or excluded W. auropunctata to investigate if this mutualism leads to increased scale infestation, decreased scale mortality, and decreased folivory. I also examined whether these effects are mediated by the percentage of remnant forest cover in the landscape. I found that seedlings with ants excluded had fewer scale insects and higher herbivory than plants with ants present. I also found evidence that scale mortality due to fungal attack and parasitism was higher on ant-excluded versus ant-allowed seedlings but only at sites with high surrounding landscape forest cover. Together, these results suggest that mutualisms between scale insects and native ants can promote scale infestation, reduce folivory on native plant species, and potentially disrupt biological control of scale insects in recovering tropical forests. Further, my experiment underscores the importance of remnant tropical forests as sources of biological control in anthropogenically disturbed landscapes. Abstract in Spanish is available with online material.     

The acceptability of meadow plants to the slug Deroceras reticulatum and implications for grassland restoration

Background and Aims

Despite the selective pressure slugs may exert on seedling recruitment there is a lack of information in this context within grassland restoration studies. Selective grazing is influenced by interspecific differences in acceptability. As part of a larger study of how slug–seedling interactions may influence upland hay meadow restoration, an assessment of relative acceptability is made for seedlings of meadow plants to the slug, Deroceras reticulatum.

Methods

Slug feeding damage to seedling monocultures of 23 meadow species and Brassica napus was assessed in microcosms over 14 d. The severity and rate of damage incurred by each plant species was analysed with a generalized additive mixed model. Plant species were then ranked for their relative acceptability.

Key Results

Interspecific variation in relative acceptability suggested seedlings of meadow species form a hierarchy of acceptability to D. reticulatum. The four most acceptable species were Achillea millefolium and the grasses Holcus lanatus, Poa trivialis and Festuca rubra. Trifolium pratense was acceptable to D. reticulatum and was the second highest ranking forb species. The most unacceptable species were mainly forbs associated with the target grassland, and included Geranium sylvaticum, Rumex acetosa, Leontodon hispidus and the grass Anthoxanthum odoratum. A strong positive correlation was found for mean cumulative feeding damage and cumulative seedling mortality at day 14.

Conclusions

Highly unacceptable species to D. reticulatum are unlikely to be selectively grazed by slugs during the seedling recruitment phase, and were predominantly target restoration species. Seedlings of highly acceptable species may be less likely to survive slug herbivory and contribute to seedling recruitment at restoration sites. Selective slug herbivory, influenced by acceptability, may influence community-level processes if seedling recruitment and establishment of key functional species, such as T. pratense is reduced.     

Behavioral and Morphological Studies of Fetal Neural Transplants into SCN-Lesioned Rats

We have studied the effects of fetal neuronal grafts on the temporal pattern of drinking behavior of suprachiasmatic nuclei (SCN)-lesioned adult rats. Additionally, in an independent set of animals, the immunohistochemical staining for vasopressin, vasoactive intestinal polypeptide, and neuropeptide Y and the retinal connections to the hypothalamus were studied. The behavioral experiments indicate that anterior hypothalamic transplants induced reorganization of the temporal pattern of drinking behavior when placed in the third ventricle of adult hosts bearing complete SCN lesions, but not when placed in a cavity in the occipital cortex. Such rhythmicity persists only when the animals were recorded under constant darkness but not under constant light, indicating that the restored rhythmicity was generated endogenously but that the oscillator was extremely sensitive to light. Fetal occipital cortex induced reorganization of the temporal pattern of previously arrhythmic hosts, but it disappeared when the animals were recorded under constant light or constant darkness. It is clear that this rhythmicity was exogenous. In contrast to the cortical transplants, the hypothalamic transplants showed a morphological organization similar to that found in the normal hypothalamus regardless of their placement in the host brain. From these observations it is concluded that development of neocortex is more affected by environmental factors than that of the hypothalamus. Both hypothalamic and cortical transplants induced sprouting of retinal fibers into the anterior hypothalamus and the grafted tissue. It is possible that such fibers could be the neuroanatomical substrate by which rhythmicity is induced by cortical tissue.