Conservation implications of small population size and habitat fragmentation in an endangered lupine

Conservation measures to preserve critically endangered species aim to maintain healthy and self-sustaining populations and often involve reintroductions. Effective introductions must take into account the genetic structure and diversity remaining in the species to inform choices of germplasm for introduction strategies. Lupinus aridorum (McFarlin ex Beckner; Fabaceae) is an endangered plant found on two disjunct ridge systems in central Florida. All plants are found in areas that are favored for human development and agriculture. Few options exist for introduction locations, so the most informed strategies must be used to preserve this species. We used ten microsatellite loci, developed for this species, to determine genetic diversity and genetic differentiation among populations, and to compare L. aridorum with two closely related congeners. Our results show a low level of diversity remaining in the species in comparison with a more abundant congener and similar levels of variability among each L. aridorum population. At least three L. aridorum populations exhibit a genetic signal of partial selfing. Hybridization with a closely-related congener was not apparent; however, additional crossing trials are needed to fully assess the possibility of hybridization. Although some sources list the taxonomy of L. aridorum as a variety of a Florida panhandle species, L. westianus (Small), the genetic differences revealed by our data support listing these two species as separate entities. Our findings can be used to guide sampling strategies for ex situ conservation such as providing a mixture of source populations to improve the probability of successful introductions.     

Population structure in an endangered songbird: maintenance of genetic differentiation despite high vagility and significant population recovery

Black-capped vireos ( Vireo atricapilla ), an endangered, migratory species dependent upon early successional habitat, have experienced significant recovery since its protection. In light of its vagility and known increase in population size and range, limited genetic differentiation would be expected in the species. Using 15 microsatellite loci and an extensive sampling regime, we detected significant overall genetic differentiation ( F _ST = 0.021) and high interpopulation differentiation compared to other migratory birds. Although proximate sites (separated by < 20 km) tended to be genetically similar, there was no apparent association of either geographical distance or landscape attributes with differentiation between sites. Evidence of a population bottleneck was also detected in a site located near other large concentrations of birds. Although black-capped vireos are capable of large-scale movements and the population has experienced a recent expansion, dispersal appears too insufficient to eliminate the genetic differentiation resulting from restricted colonization of ephemeral habitats.     

An endangered seahorse selectively chooses an artificial structure

The development of a residential marina estate within the Knysna estuary, South Africa, introduced Reno mattresses (horizontal wire cages filled with rocks) as a novel habitat for the endangered Knysna seahorse Hippocampus capensis. Consistently high seahorse densities on these artificial structures, despite the availability of seagrass habitat, begged the question of whether this habitat was chosen by the seahorse in preference to natural vegetation. An in situ habitat choice experiment was conducted which focused on the choice made by adult H. capensis between natural vegetation (Zostera capensis) and artificial (Reno mattress) habitat within a choice chamber. Seahorses were significantly more likely to move away from Z. capensis onto a Reno mattress structure or remain on this structure. This study concludes that higher H. capensis densities on Reno mattresses within Thesen Islands Marina are owing to some positive feature of this habitat and the underlying processes responsible for the choice made by this species (additional food, holdfasts, protection) can now be investigated.     

Life history and population dynamics of an endangered seahorse (Hippocampus capensis) within an artificial habitat

Species-specific life-history information is critical for successful conservation, particularly in establishing an accurate baseline status. Obtaining such information is challenging for most species, but in particular for rare and threatened marine species. To facilitate future conservation of the endangered Knysna seahorse (Hippocampus capensis) this study aimed to determine important life-history information for this species. Visible implant fluorescent elastomer (VIFE) tags were used to mark 78 seahorses within a residential marina estate in the Knysna estuary, South Africa, in February 2018. Using a mark-resight approach, the size and movement patterns of the population and growth rate of seahorses were determined over a 14-month period. The closed population estimate for H. capensis, within Thesen Islands Marina, was estimated to be 134 (118–152 95% C.I. ) in February 2018 compared to only 72 (48–108 95% C.I. ) in February 2019. The species showed rapid initial growth with males and females having similar rates of growth based on the specialised von Bertalanffy growth function model. The importance of Reno mattresses as a habitat for H. capensis was confirmed based on the high abundance and site fidelity of the population, which emphasises the conservation potential of heavily modified environments for threatened seahorse species. The use of VIFE tags was deemed effective in studying this endangered seahorse and allowed the collection of important information for this species which can be used in future Red List assessments and conservation actions.     

Conservation value of Codium tenue habitat for the endangered Knysna seahorse Hippocampus capensis

We investigated the density and size structure of the endangered Knysna seahorse Hippocampus capensis in the macroalga Codium tenue at three sites in a residential marina estate in the Knysna Estuary, South Africa, over an 18 month period from March 2017 to August 2018. Seahorses were present in C. tenue throughout the year. Average (± SE) densities of 0.33 (± 0.03) and 0.23 (± 0.03) seahorses per kg of C. tenue were found for 2017 and 2018 respectively. Density did not vary across sites but varied significantly across months with a decreasing trend from summer to spring. The average (± SE) adult seahorse height was 75.16 mm (± 0.63 mm) and 69.09 mm (± 0.64 mm) and mass was 2.05 g (± 0.04 g) and 1.65 g (± 0.04 g) for males and females, respectively, and an even sex ratio was observed throughout the sampling period. Height varied across months, with significantly smaller seahorses found in June and August of 2017. Tail length was highly correlated with height and therefore can serve as a potential proxy for determining the height of H. capensis. This study showed that C. tenue is consistently utilised by Knysna seahorse and should therefore be considered an important habitat to protect and facilitate the ongoing conservation of this endangered seahorse species.     

Conservation implications of midden selection and use in an endangered gazelle (Gazella gazella)

This study examines midden selection and use by mountain gazelles Gazella gazella in central Saudia Arabia and the implications of middens (dung piles) for the conservation of this species. Specifically, we tested poachers' claims that mountain gazelles are easy to kill because midden use was predictable and conspicuous. We found that midden selection in mountain gazelles is non-random, with middens typically located at the base of the most conspicuous and largest trees, although the choice of midden sites is also influenced by tree species. Middens clearly have olfactory importance; the majority of mountain gazelles that visited middens were observed sniffing the ground. Mountain gazelles visit middens at night, which corroborates poachers' claims that the animals are easily hunted at night through spotlighting. Although the use of open habitats that are accessible to automobiles makes gazelles vulnerable to hunting and being run down, our data suggest that midden use is also an attribute that makes gazelles susceptible to hunting. Poachers can locate gazelles because of middens' predictable locations, as they are placed at prominent landmarks, are visually conspicuous as large dung piles, and are visited at night, which allows the animals to be found through spotlighting. Other taxa that use predictable and prominent landmarks, or communicate through visually conspicuous methods could also be susceptible to poaching.     

Monthly population density and structure patterns of an endangered seahorse Hippocampus capensis: a comparison between natural and artificial habitats

This study investigated aspects of the population ecology of the endangered Knysna seahorse Hippocampus capensis within different habitat types. High densities of H. capensis were found within artificial Reno mattress habitat, within the Knysna Estuary, South Africa. Monthly surveys at three sites were conducted from October 2015 to August 2016 to compare population densities of H. capensis in this artificial habitat with natural eel grass Zostera capensis habitat. Hippocampus capensis densities varied significantly across all sites and highest population densities were consistently observed within the Reno mattress habitat. Hippocampus capensis were also found to be significantly larger within the Reno mattress habitat and pooled data showed that males were significantly larger than females. The overall sex ratio for all three sites was female biased, although this varied across seasons at two sites. The findings suggest that artificial Reno mattresses provide novel habitat for this endangered species and consideration should be given to the usefulness of these structures in future conservation actions.     

Conservation genetics of an endangered orchid in eastern Canada

Platanthera leucophaea, the Eastern Prairie Fringed-orchid, is a globally imperilled species native to the USA and Canada, with its Canadian distribution limited to the Province of Ontario. In Canada, where P. leucophaea is listed as endangered, approximately 40 % of populations have been extirpated in recent years, and many remaining populations have experienced substantial declines. In this study, we investigated whether reduced population sizes have led to low genetic diversity and inbreeding. We also investigated the extent to which hybridization with Platanthera psycodes may be threatening the genetic integrity of P. leucophaea populations. We found that overall, genetic diversity is low, and inbreeding is high. This is despite evidence of regular gene flow between proximate populations, although more distant populations show high levels of genetic differentiation. At sites where P. leucophaea is sympatric with P. psycodes, interspecific hybridization occurs in a bidirectional manner, i.e. with both parental species acting as either pollen donor or pollen recipient. Inbreeding and low genetic diversity in all populations, and hybridization in some populations, may pose future threats to P. leucophaea, and should be considered in the future by biodiversity managers.     

Population genetics of the endangered Knysna seahorse,Hippocampus capensis

The evolutionary history of the endangered Knysna seahorse, Hippocampus capensis, and the extent of gene flow among its three known populations, were investigated using 138 mitochondrial DNA control region sequences. Similarly high levels of genetic diversity were found in two of the populations (Knysna and Keurbooms Estuaries), whereas diversity in the third population (Swartvlei Estuary) was lower. Although most haplotypes are shared between at least two populations, based on the haplotype frequency distributions the three assemblages constitute distinct management units. The extant population structure of H. capensis suggests that the Knysna seahorse originated in the large Knysna Estuary. The presence of seahorses in the two smaller estuaries is either the result of a vicariance event at the beginning of the present interglacial period, colonization of the estuaries via the sea, or a combination of the two.     

Conservation implications of past and present nesting habitat selection of the endangered Osprey Pandion haliaetus population of the Canary Islands

We studied nesting habitat selection of the endangered non‐migratory Osprey Pandion haliaetus population of the Canary Islands and evaluated the effect of human expansion in recent decades. Compared with randomly selected potential nest‐sites, Osprey nests were more frequently found on taller, southwest‐facing cliffs, characterized by lower human pressure and closer to Yellow‐legged Gull Larus michahellis colonies and Barbary Falcon Falco pelegrinoides breeding sites. Furthermore, changes in some breeding habitat features have been detected in recent decades. According to our predictive models, large areas of suitable habitat are available but unoccupied in the Canaries, and human activities are probably limiting the settlement and dispersion of new pairs.     

High regional genetic differentiation of an endangered relict plant Craigia yunnanensis and implications for its conservation

Of the genus Craigia, widespread in the Tertiary, only two relict species survived to modern times. One species is now possibly extinct and the other one, Craigia yunnanensis, is severely endangered. Extensive surveys have located six C. yunnanensis populations in Yunnan province, southwest China. Using fluorescent amplified fragment length polymorphism (AFLP), the genetic diversity and population structure of these populations were examined. It was found that genetic diversity of C. yunnanensis was moderate at the species level, but low at regional and population levels. Analysis of population structure showed significant genetic differentiation between Wenshan and Dehong regions, apparently representing two geographically isolated for long time refuges. There are also clear indications of isolation between populations, which, together with anthropogenically caused decline of population size, will lead to general loss of the species genetic variation with subsequent loss of adaptive potential. To conserve the genetic integrity of C. yunnanensis, we recommend that ex-situ conservation should include representative samples from every population of the two differentiated regions (e.g. Wenshan and Dehong). The crosses between individuals originated from different regions should be avoided because of a high risk of outbreeding depression. As all the extant populations of C. yunnanensis are in unprotected areas with strong anthropogenic impact, there is no alternative to reintroduction of C. yunnanensis into suitable protected locations.     

Seed germination traits of Trapella sinensis (Trapellaceae), an endangered aquatic plant in Japan: Conservation implications

We investigated the effects of cold stratification, temperature, light, and oxygen conditions on seed germination of Trapella sinensis Oliver, an endangered aquatic plant in Japan. Seeds had physiological dormancy, and final germination rate increased with an increasing period of cold stratification. Seeds of T. sinensis had an almost absolute requirement for aerobic conditions to germinate. Also, alternating temperatures significantly promoted germination regardless of light conditions, although final germination percentage was twice to four times higher in light under constant temperature conditions. Suitable sites for germination of T. sinensis appear to be shallow water with alternating temperatures and sufficient oxygen and sediment anoxia, caused by eutrophication of water bodies, may have prevented recruitment of T. sinensis from seed.     

Inbreeding and strong population subdivision in an endangered salamander

Studies of genetic population structure and genetic diversity are often critical components of endangered species conservation and management plans. Genetic studies are thus particularly important for amphibians, which are in global decline. We studied genetic variation and population structure among 276 individuals from approximately half of the known localities of the endangered Sonora tiger salamander, Ambystoma mavortium stebbinsi, using ten microsatellite loci. Allelic diversity was generally low (2.7 alleles per locus per population) and overall observed heterozygosity (0.191) was significantly lower than expected (0.332). Most populations showed significant departures from Hardy–Weinberg equilibrium, which are likely due to inbreeding. In addition, evidence of recent bottlenecks was suggested by shifted allele frequency distributions in 5 of 16 populations, and ratios of allele number to allele size range (M) values lower than critical values in all populations. A high degree of genetic subdivision (θ = 0.133) was found over all populations, and nearly all pairwise population combinations were genetically subdivided. Thus, gene flow is limited even over small distances, perhaps because high desert grassland throughout the study area limits the efficacy of inter-pond movement of salamanders. Further, population sizes and gene flow of Sonora tiger salamanders are likely compromised by several contemporary ecological threats, including: frequent die-offs due to an infectious virus, introductions of non-native species, and continuing cattle grazing. Overall, these genetic data support the endangered status of the Sonora tiger salamander and suggest the subspecies exists in small, inbred populations.     

Conservation genetics of an endangered rainforest tree (Fontainea oraria – Euphorbiaceae) and implications for closely related species

Four new eastern Australian Fontainea species have beenrecently described and all have a limited distribution. F.oraria is the rarest, being restricted to 10 adult individualswithin a single site in regrowth littoral rainforest. In order todevelop adequate management strategies, this study was aimed atsurveying the genetic variability remaining within the species by usingRAPD analysis. To assist with the correct interpretation of the results,a matching study was conducted on four populations of the closelyrelated F. australis. Similar amounts of within-populationgenetic diversity were recorded for both species. The RAPD-based studysuggested that adult plants are contributing unevenly to successivegenerations. RAPD analysis also recognised a close evolutionaryrelationship between F. oraria and F. australis.Sequencing of cpDNA (trnL-F) and nrDNA (ITS2) regions,confirmed recent divergence and possibly some historical reticulationbetween these two species and two other members of the genus. Ofparticular interest was the recognition that one of the F.australis populations (Limpinwood) represented a novel genotypiccombination in need of conservation attention. The implications of theRAPD and sequencing results are discussed in reference to theirinfluence upon the development of adequate conservation strategies forall important conservation units.     

典型极小种群野生植物保护与恢复技术研究

极小种群野生植物是急需优先抢救的国家重点保护濒危植物。目前,有关极小种群野生植物濒危原因及相应解濒技术的研究还非常缺乏,已有的植物种群生态学和保护生物学理论对极小种群植物并不完全适用,迫切需要研发有针对性的科学理论和保育技术。介绍了国家重点研发计划项目"典型极小种群野生植物保护与恢复技术研究(2016YFC0503100)"的研究意义、内容、目标及展望。项目拟针对典型极小种群野生植物开展保护与恢复技术的研究,拟构建极小种群野生植物的种群生态学和保护生物学理论体系,研发极小种群野生植物保护和更新复壮的技术体系,并建立相应的应用技术标准和示范基地,为极小种群野生植物的保护与可持续利用奠定坚实的理论基础和技术支撑。     

Historical and contemporary population genetic connectivity of the European short-snouted seahorse Hippocampus hippocampus and implications for management

This first genetic study of Hippocampus hippocampus covers the species' entire geographic range and employs two mtDNA markers (control region and cytochrome b) to establish patterns of population structuring. A total of 255 specimens from 21 locations were used to obtain 89 concatenated haplotypes. The common haplotype was present in all but one population, however, most haplotypes were unique. The haplotype network had a star-like construction, suggesting expansion from a bottleneck event. F(ST) and AMOVA revealed population subdivision into three geographic regions (English Channel + Bay of Biscay, Mediterranean Sea + Atlantic Ocean Iberian coast + Macaronesian Islands, and West Africa) with barriers to gene flow indentified at Cape Finisterre and the Cape Verde frontal zone. Neutrality tests and nested clade analysis suggest a complex demographic history, with both historic events and contemporary processes shaping patterns of genetic differentiation. The genetic population subdivision detected in this study indicates that H. hippocampus should be managed as three separate units. This is especially pertinent as H. hippocampus populations within the West African region are the only ones known to be specifically targeted for exploitation.     

Conservation genetics of the Common Tern (Sterna hirundo) in the North Atlantic region; implications for the critically endangered population at Bermuda

Common Terns nesting at Bermuda are isolated by 1,000–4,000?km from other populations of the species around the North Atlantic Ocean. This population experienced a severe demographic bottleneck as a result of a hurricane in 2003 and was subsequently re-established by four males and four females. Using seven microsatellite loci, we compared the genetic diversity of the pre- and post-bottleneck populations, compared the genetic profile of the Bermuda population with those of other populations around the North Atlantic Ocean and mainland Europe, and assessed the potential contribution of immigration to genetic diversity. We found a loss of genetic diversity (number of alleles and heterozygosity) in the post-bottleneck Bermudian population (4.6–2.9 and 0.56–0.52, respectively). We also report significant differentiation among all sampled locations (global F_ST?=?0.16) with no evidence for immigration into Bermuda. Common Terns from the Azores were genetically more similar to those from mainland North America than to those from Bermuda or mainland Europe. Our results suggest that the critically endangered population in Bermuda is genetically distinct and requires continued and enhanced conservation priority.