High Species Diversity Research Articles

Habitat characterization, anthropogenic impacts and conservation of rhodolith beds off southeastern Malta

Abstract Rhodolith beds, including maerl, are structurally complex perennial habitats that support a high species diversity but are threatened by numerous human activities, particularly in the Mediterranean Sea. Despite their global ecological importance, increased research efforts are needed to facilitate development of effective measures to conserve these habitats. Two areas hosting rhodolith beds are known to occur off the coast of Malta (central Mediterranean), but only one has been previously studied. Through analysis of video footage collected from 56 different stations coupled with a desk study on human activities, the present study characterized the rhodolith bed located off the southeastern coast of Malta, including its extent, rhodolith morphotype composition, associated megabiota and impacts of anthropogenic activities thereon. The bed occurred at depths of 60–95 m and covered an area of approximately 200 km2, making it the second most extensive rhodolith area reported for the Mediterranean to date. It was dominated by spherical and branched rhodoliths whose cover reached a maximum of 74% but was more often <50%, similar to other Mediterranean rhodolith beds. A total of 84 different megafaunal species were recorded, suggesting that the diversity of megafauna associated with rhodolith bed habitats has been previously underestimated. A number of human activities, including extensive vessel anchoring and officially designated areas for aquaculture, bunkering and trawling, overlap with the mapped rhodolith distribution, highlighting the risk of habitat degradation. A holistic approach to the management of all the competing activities and interests relative to the southeastern coast of Malta that gives due consideration to this newly characterized rhodolith bed and the threats it faces is therefore recommended. The legal framework and policy recommendations for better conservation of rhodolith bed habitats in the Mediterranean and European Seas are also discussed.

Moderate-severity silvicultural methods generate better forest reorganization than other silvicultural methods in temperate rainforests four decades after implementation

Silvicultural regeneration methods promote regeneration of new tree cohorts following the harvest of mature trees and include a gradient of options from cutting all (clearcuts) or some (selection cuts) trees resulting in even- or uneven-aged forests. For forest managers and landowners, it is essential to have the best possible information on how forests reorganize following these different methods. Forest development, composition and growth are dependent on site quality and harvest type. In this study we evaluated two even-aged (clearcut (CC), seed-tree cut (STC)), one two-aged cut (extended irregular shelterwood (ISC)), one uneven-aged (single-tree selection cut (SC)), and an unmanaged control (CON), four decades after harvest implementation in old-growth Evergreen temperate rainforests above 500 m a.s.l. in the Coastal Range of south-central Chile. These forests grow on poor-quality sites due to old and shallow soil conditions and were dominated by late-successional species and a thick understory with the bamboo Chusquea machrostachya at the time of harvest implementation. Compositional and structural conditions reflected the type of harvests, with even- and two-aged methods largely similar to one another and the SC and the OG having very similar characteristics, which is likely a consequence of the very light severity of the SC. Tree species composition in even-aged harvests was dominated by shade midtolerant species of high timber value, although short-lived pioneer species of the Proteaceae family were also abundant, especially in ISC. The ISC had the greatest homogeneity in all stand variables (tree density, basal area, volume, and quadratic stand diameter), and since it was a two-layered forest, had basal areas and volumes close to the SC and OG, and a rotated-sigmoid diameter distribution (different to all other treatments). Height of the new cohort in the ISC was significantly taller than in the CC and the STC for most species’ groups, suggesting that the cut plus the residual canopy of ISC diminished the initial cover of the bamboo C. macrostachya and competition for regeneration. Only diameter growth of trees of all shade tolerances was lower in ISC, but diameter growth patterns were similar to CC and STC, with increasing growth during the first two-three decades followed by a decline. Based on these findings, we conclude that silvicultural methods of intermediate harvesting severity, especially ISC, provide the best ecological and economic option in these poor-quality sites given rapid reorganization following their implementation, while maintaining a relatively complex vertical structure, high tree species diversity, and a growing stock dominated by tree species of high timber value.

Spider diversity (Arachnida: Araneae) at Saurashtra University Campus, Rajkot, Gujarat during the monsoon

The present work deals with the diversity of spiders during the monsoon within the Saurashtra University Campus, Rajkot, Gujarat. A total of 38 species of spiders belonging to 32 genera and 14 families were recorded. Araneidae (25.81%) was found to be the most dominant family, with nine species from five genera. Guild structure analysis revealed seven feeding guilds, among all 31% most dominant feeding guilds represented by orb-web builders and stalkers, followed by ground runners (13%), irregular webs (10%), ambushers (7%), foliage hunters (6%), and space-web builders (2%). Ecological indices reveal high species richness (Margalef’s d = 8.97) and diversity (Shannon Index H’ = 3.526, Fisher alpha diversity α = 41.73). It concludes that the abundance of spider species at this study site was high and the evenness index was also high (e >0, e = 0.8944). These findings suggest the absence of stress elements in the study area.

Fungal and Fungal-like Diseases of Halophytes in the Mediterranean Basin: A State-of-the-Art Review

Halophytes are salt-tolerant plants growing in saline ecosystems and are spread throughout the Mediterranean area. Recently, there has been a renewed interest in agricultural exploitation of halophytes, but poor attention has been given to pest and disease management of these species. The objective of this review is to assess the extent and distribution of pathogenic fungal and fungal-like (Oomycota) organisms on major Mediterranean halophytes. We retrieved 92 references spanning over 100 years, with more than half published since 2000. Ascomycota is the best-represented phylum, and the order Pleosporales has the highest species diversity. The order Pucciniales prevails in Basidiomycota, whereas Peronosporales is the richest order within Oomycota. Most of the pathogenic species have been isolated from aboveground organs, especially from leaves. Portulaca oleracea is the species with the most associated pathogens (16) and records (28). Leveillula powdery mildew, caused by Leveillula taurica, is the most common disease among the selected species. Cakile maritima was found to be vulnerable to different mycotoxigenic Alternaria species. Strengthening the research on diseases of halophytes is essential to successfully grow these species and to evaluate the risks related to the presence of mycotoxigenic species, which is crucial for the effective exploitation of halophytes as crops.

Ecological analyses of street trees of Indian cities to achieve United Nations sustainable development goals

The present study determined the community characteristics, structural composition, and regeneration status of street trees in two major Indian cities viz., Ranchi and Delhi. A total of 96 species of 86 genera belonging to 34 families were documented in the urban streets of Ranchi (of which 59 spp. were in the IUCN Red-list), while 64 species of 56 genera belonging to 28 families (of which 47 spp. were in the IUCN Red-list) were reported in Delhi. The study reported a very high species diversity index (H′) in both Ranchi (3.98) and Delhi (3.47), with similar species evenness (0.85). Fabaceae and Ficus were the predominant family and genus, respectively in both cities. The similarity of street trees of Ranchi and Delhi is quite low in terms of all the β-diversity indices (SI = 38.75% and dissimilarity = 61.25%; Cj = 0.24 and dissimilarity = 0.76; BCij = 0.61 and similarity = 0.39). The total street tree density in Ranchi (217 ind. ha−1) and Delhi (637 ind. ha−1) varied significantly, while the dominance (basal area) of both cities were quite similar (20.67 m2ha−1 and 21.70 m2ha−1) due to the predominance of young and adult individuals (GBH ≥30–90 cm) in the street tree community at Ranchi and pole and young individuals (GBH ≥ 10–60) in Delhi. The regeneration potential of street trees in both cities was quite concerning because the majority of street trees at Ranchi (62.5% of 96 spp.) and Delhi (57.38% of 64 spp.) had shown no regeneration. It is advised that re-greening, planting a variety of native tree tracts in urban niches, and tree planting in a ratio of one to three be implemented to counteract artificial urban land, maintain urban biodiversity and achieve UN SDGs.

Seasonally flooded Coquinal: typifying a particular plant association in the northern Yucatan peninsula, Mexico

Background: One of the most diverse and threatened plant associations in the Yucatan peninsula has not been characterized and therefore not included in any protection category in Mexico. We characterize and describe this plant association, which is rapidly disappearing or being irreversibly transformed as a result of anthropic activities. We propose a name and attempt a preliminary assessment of its taxonomic richness, and the identification of priority species to be preserved.
 Questions: What is the species richness and plant endemism associated within this plant association? What are the ecologically important and high-priority species for conservation? How is it different from associated or similar plant associations?
 Studied species: Vascular plants.
 Study site and dates: Northern Yucatan peninsula; 2021-2023.
 Methods: The plant association was characterized, and quantitative parameters were recorded. The Importance Value Index was estimated to assess its local ecological importance, and each species was assigned a conservation category in order to evaluate the conservation status in a global context.
 Results: We propose Seasonally flooded Coquinal (SFC) as a name for this plant association based on geomorphological, physiognomic, and structural attributes. A total of 206 species were recorded, which two are endemic to the SFC and 28 to the Yucatan Peninsula Biotic Province (YPBP). Twelve species are listed under a risk category.
 Conclusions: The SFC harbors a high plant diversity of endemic species to the YPBP, 12 of which are included in the IUCN red list, for which its typification and conservation should be a high priority in Mexico.

The biological cropping hypothesis over evolutionary time: an experimental test

Ecological disturbance has been proposed to have a variety of effects on biodiversity. These mechanisms are well studied over shorter timescales through experimental manipulation of ecosystems, but the effect of disturbance on longer timescales, where evolutionary processes operate, is less well understood. This is at least in part because evolutionary processes are too slow to observe in experimental manipulations of ecosystems. Here, we use the Rapid Evolutionary Simulator system (REvoSim) to solve this problem. REvoSim is a spatially explicit, agent-based simulation tool that models both ecological and evolutionary processes and is capable of simulating many thousands of generations of evolution per hour in a population of up to 1 million organisms. We use REvoSim to evaluate the biological cropping hypothesis, which predicts that the non-selective culling of organisms from populations (“cropping”) can enhance diversity in those populations over long timescales by reducing the homogenising effects of competitive exclusion. Our experiments demonstrate that cropping alone can increase diversity within populations under certain circumstances: those where it has the net effect of reducing the selection pressure acting on those populations. However, intense cropping pressure may increase the selection pressure on organisms to reproduce rapidly, potentially offsetting the effects of reduced competitive exclusion on diversity. We also show that cropping alone is not sufficient to result in reproductive isolation within populations. This implies that, while cropping can maintain a high species diversity within an ecosystem, additional mechanisms must be invoked to generate that high diversity in the first instance.

Evolutionary causes of global patterns of species richness in regional fern floras across the world

AbstractAimGlobally, biodiversity is unevenly distributed, as a result of varying environmental conditions and regionally different historical processes. The influence of the latter on current diversity patterns is poorly understood. We explore geographic patterns of matches and mismatches between phylogenetic relatedness metrics measuring different depths of evolutionary history and investigate the effects of evolutionary legacy at different evolutionary depths on species density of ferns.MethodsWe divided the globe into 392 geographic regions on land, and collated species lists of ferns for each geographic region. We related species richness to phylogenetic metrics reflecting different depths of evolutionary history (standardized effect sizes of mean nearest taxon distance and mean pairwise distance, MNTDses and MPDses, respectively) for ferns in regional floras across the world.LocationGlobal.Time PeriodCurrent.TaxonFerns.ResultsWe show that different centers of fern diversity have strikingly different phylogenetic composition. We find that overall fern species diversity is negatively correlated with both MNTDses and MPDses, so that regions with high species diversity tend to have clustered species assemblages, whereas species‐poor regions tend to have overdispersed species assemblages. At the global extent, MNTDses and MPDses together explained 62.2%, 19.3%, and 65.7% of the variation in species diversity for all ferns as a whole, non‐polypod ferns, and polypods, respectively.Main ConclusionsOur study suggests that current geographic patterns of fern species richness are driven, at least in part, by evolutionary history of ferns, which varies among biogeographic regions.

Woody semi‐natural habitats modulate the effects of field size and functional crop diversity on farmland birds

Abstract Agricultural intensification has simplified landscape composition and configuration, which has led to biodiversity declines. Increasing landscape‐wide crop heterogeneity can promote farmland biodiversity. However, knowledge is still lacking on how the effects of configurational and compositional crop heterogeneity (i.e. field size and crop diversity) are modulated by the amount of semi‐natural habitats in the landscape, especially across large scales. We tested how mean field size and functional crop diversity affect farmland bird diversity and abundance over three consecutive years, and how these effects are modulated by the amount of small woody features (SWF) in the landscape. We related data from a national bird monitoring scheme to field‐level information from a novel, high‐resolution remote sensing‐based crop type map. Smaller field sizes and higher functional crop diversity were not generally associated with a higher diversity or abundance of farmland birds. Associations varied with species' breeding habitat preferences and were modulated by the amount of SWF. In landscapes with a low SWF amount, species diversity and the abundance of species breeding in field edges or shrubs were negatively associated with increasing field size. However, where the amount of SWF was high, larger field size was associated with higher species diversity and abundance of field and shrub breeders. Diversity increased with higher functional crop diversity, as did the abundance of non‐field breeders in landscapes with a medium to high SWF amount. Field size tended to have a stronger effect on bird diversity and abundance than functional crop diversity. Policy implications: National and EU agricultural policies should adopt a landscape perspective by considering the amount of semi‐natural habitats when designing biodiversity‐enhancing measures that target field size and functional crop diversity. In landscapes with low SWF amount, decreasing field sizes may be particularly effective to promote farmland bird diversity and the abundance of non‐field breeders. In landscapes with a medium to high SWF amount, increasing functional crop diversity is likely more effective than reducing field sizes. Field and shrub breeders may be promoted by maintaining landscapes with large fields, only if these offer a high SWF amount, low agronomic yield potential and low productivity.

A meta-analysis of physicochemical changes in the rhizosphere and bulk soil under woodlands

Monoculture for timber production has been replacing natural environments as the demand for renewable energy sources increases. The lack of nutrient compensation may increase the risk of soil depletion, thus changing soil properties. To summarize the impact of forestry activities in edaphic environments, we present a meta-analysis on the rhizosphere effects of coniferous and broadleaved trees established as monoculture and natural regeneration on soil physicochemical properties. Records of soil attributes published in peer-reviewed journals from eight countries were collected. Clay content changed only in monoculture sites, decreasing 55.51% in the rhizosphere, while silt and sand presented significant variations in both monoculture and naturally regenerated areas. Conifers affected the soil more than broadleaved trees, evidenced by higher pH reduction (-2.96% vs. -1.98%) and higher increase of Al3+ (197.43% vs. 50.68%), K+ (80.40% vs. 69.90%), CEC (24.61% vs. 17.35%), and total organic carbon (82.21% vs. 69.89%). Also, the rhizosphere affected regeneration soils more than monoculture, indicated by higher Al3+ (50.68% vs. ns) and available P (32.31% vs. ns), K+ (203.44% vs. ns), CEC (34.90% vs. 20.93), and total organic carbon (91.55% vs. 63.23%). These results indicate higher nutrient availability in naturally regenerated than monoculture sites, as higher species diversity and better plant litter quality are expected. This meta-analysis shows that coniferous and naturally regenerated trees had a higher influence on the rhizosphere and soil properties than broadleaved and monocultures. Management practices must be revisited to ensure the long-term sustainability of forestry activity, and studies in tropical zones must be intensified.

Soil physical properties in a oxisol under a syntropic agroforestry system: row versus inter-row

Synthropic agroforestry systems are agricultural systems designed to reconcile agricultural production with environmental conservation. However, the benefits related to soil physical properties of these systems have only been documented for the planting rows. Thus, the physical behavior of the soil in the inter-rows remains unknown. The objective of this paper was to characterize the physical properties of the soil in the rows and inter-rows of a syntropical agroforestry system - SAS. For this, infiltration capacity (mini-disk infiltrometer) and soil resistance to penetration (STOLF Penetrometer) were measured in five ramdomly located blocks involving the rows and inter-rows. The results showed that there were no significant differences between row and inter-rows for both variables. The high species diversity, continuous addition of organic matter to the soil via pruning, the absence of heavy machinery use, and the vigorous growth of exotic grasses in the inter-row are the likely factors that explain the absence of differences reported here. We conclude that the rows and inter-rows of a SAS behave similarly in relation to the attributes evaluated. This demonstrates that such systems are highly beneficial for food production as well as maintaining soil physical properties.

Insect diversity and abundance in three forest areas of Lagos State

Mangrove forest ecosystem preserves diversity of species, which includes insects. Insects serve as bioindicators, pollinators and nutrient recyclers in the forest. However, the number of insects decline as the forest fades. We conducted this field survey to assess the diversity and abundance of insect species in three selected mangrove swamp forests located in Lagos State, Nigeria. Samples were collected fortnightly using different techniques, for a period of three months. Insects collected were preserved in 70% alcohol, but butterflies and moths were preserved dry. Representative samples were identified with picture insect mobile application V1.0.8 and confirmed using standard identification keys. Vegetation cover was quite similar in all the areas sampled comprising of Alchornea cordifolia, Eragrosis racemose, Paspalum dilatatum and Avicennia germania. A total of 182 insects were collected belonging to seven Orders, 18 Families and 38 species. The most dominant Order was Coleoptera with relative abundance of 66.48% and the least was Hemiptera (0.59%). The Order Odonata was the most diverse (HꞋ=1.09), and the most dominant species were Pantala flavescens and Sympetrum fonscolombii, having relative abundance of 8.24% each, followed by Palpopleura lucia (7.69%), Ceriagrion glabrum (7.14%) and Lestinogomphus africanus (6.04%). Psedagrion kersteni was rare with relative abundance < 0.5%. Iba site had the highest species diversity (HꞋ=1.24) but lowest number of individuals. This study documents the diversity and abundance of insects in the fast-disappearing mangrove forest of Lagos State, Nigeria.

Otterly diverse - A high diversity of Dracunculus species (Spirurida: Dracunculoidea) in North American river otters (Lontra canadensis)

The genus Dracunculus contains numerous species of subcutaneous parasites of mammals and reptiles. In North America, there are at least three mammal-infecting species of Dracunculus. Reports of Dracunculus infections have been reported from river otters (Lontra canadensis) since the early 1900s; however, little is known about the species infecting otters or their ecology. Most reports of Dracunculus do not have a definitive species identified because females, the most common sex found due to their larger size and location in the extremities of the host, lack distinguishing morphological characteristics, and few studies have used molecular methods to confirm identifications. Thus, outside of Ontario, Canada, where both D. insignis and D. lutrae have been confirmed in otters, the species of Dracunculus in river otters is unknown. In the current study, molecular characterization of nematodes from river otters revealed a high diversity of Dracunculus species. In addition to confirming D. insignis infections, two new clades were detected. One clade was a novel species in any host and the other was a clade previously detected in Virginia opossums (Didelphis virginiana) from the USA and a domestic dog from Spain. No infections with D. lutrae were detected and neither new lineage was genetically similar to D. jaguape, which was recently described from a neotropical otter (Lontra longicaudis) from Argentina. These data also indicate that Dracunculus spp. infections in otters are widespread throughout Eastern North America. Currently the life cycles for most of the Dracunculus spp. infecting otters are unknown. Studies on the diversity, life cycle, and natural history of Dracunculidae parasites in wildlife are important because the related parasite, D. medinensis (human Guinea worm) is the subject of an international eradication campaign and there are increasing reports of these parasites in new geographic locations and new hosts, including new species in humans and domestic dogs.

Torque Teno Virus (TTV) in Renal Transplant Recipients: Species Diversity and Variability.

Torque Teno Virus (TTV) is a nonpathogenic and ubiquitous ssDNA virus, a member of the Anelloviridae family. TTV has been postulated as a biomarker in transplant patients. This study aimed to determine the TTV species diversity and variability in renal transplant recipients and to associate species diversity with the corresponding TTV viral load. From 27 recipients, 30 plasma samples were selected. Viral load was determined using two real-time PCR assays, followed by RCA-NGS and ORF1 phylogenetic analysis. The TTV diversity was determined in all samples. Variability was determined in three patients with two sequential samples (pre- and post-transplantation). Most of the samples presented multiple TTV species, up to 15 different species were detected. In the pre-transplant samples (n = 12), the most prevalent species were TTV3 (75%) and TTV13 (75%), and the median number of species per sample was 5 (IQR: 4-7.5). TTV3 was also the most prevalent (56%) in the post-transplant samples (n = 18), and the median number of species was 2 (IQR: 1.8-5.5). No significant correlation between the number of species and viral load was found. The number and type of TTV species showed total variability over time. We report high TTV species diversity in Argentinian recipients, especially in pre-transplant period, with total intra-host variability. However, we found no significant correlation between this high diversity and TTV viral load.

Phylometagenomics of cycad coralloid roots reveals shared symbiotic signals.

Cycads are known to host symbiotic cyanobacteria, including Nostocales species, as well as other sympatric bacterial taxa within their specialized coralloid roots. Yet, it is unknown if these bacteria share a phylogenetic origin and/or common genomic functions that allow them to engage in facultative symbiosis with cycad roots. To address this, we obtained metagenomic sequences from 39 coralloid roots sampled from diverse cycad species and origins in Australia and Mexico. Culture-independent shotgun metagenomic sequencing was used to validate sub-community co-cultures as an efficient approach for functional and taxonomic analysis. Our metanalysis shows a host-independent microbiome core consisting of seven bacterial orders with high species diversity within the identified taxa. Moreover, we recovered 43 cyanobacterial metagenome-assembled genomes, and in addition to Nostoc spp., symbiotic cyanobacteria of the genus Aulosira were identified for the first time. Using this robust dataset, we used phylometagenomic analysis to reveal three monophyletic cyanobiont clades, two host-generalist and one cycad-specific that includes Aulosira spp. Although the symbiotic clades have independently arisen, they are enriched in certain functional genes, such as those related to secondary metabolism. Furthermore, the taxonomic composition of associated sympatric bacterial taxa remained constant. Our research quadruples the number of cycad cyanobiont genomes and provides a robust framework to decipher cyanobacterial symbioses, with the potential of improving our understanding of symbiotic communities. This study lays a solid foundation to harness cyanobionts for agriculture and bioprospection, and assist in conservation of critically endangered cycads.

Climate change vulnerability of tribe managing Piper agroforestry systems in the Indian sub-Himalayan region

CONTEXTThe agrarian society of the Himalayan landscape is experiencing the continuous growing ill impact of climate change. The impacts are compounding due to shifting agriculture, which has jeopardized the ecological balance mainly by reducing the cultivation fallow cycles. Pnar, a hill tribe of the Assam state, Indian sub-Himalayan region, has transitioned shifting agriculture to Piper agroforestry (Piper betle L.), providing them numerous tangible and non-tangible benefits. Over the past three decades, there has been a notable transition from shifting agriculture to Piper agroforestry, driven by the rising demand in the market. OBJECTIVEUnderstanding climate change impact on agroforestry is crucial to addressing the climate crisis and to provision the adaptation of the tribe for the successful promotion of Piper agroforestry. METHODSTo assess the cause and nature of vulnerability in the study region, we surveyed 171 randomly selected households across 15 randomly selected tribe villages using the household-level questionnaire. RESULTS AND CONCLUSIONThe present study showed that the villages with lower land holdings, higher loss of crop productivity due to extreme events, disease infestation and lower livelihood diversification were more vulnerable to climate change. The prominent diseases “leaf spot” and “root rot” were identified as a serious concern among the Piper farmers responsible for a decline in crop yield; the severity of losses in productivity leads to economic instability among households. Villages with prominent farm management strategies and greater decision-making abilities contributed explicitly to lower vulnerability. In contrast, villages with lower adaptive strategies were found specifically due to poor social networking and inadequate household infrastructure besides poor literacy levels. Additionally, the lack of multi-cropping farming and livestock management was a major cause of high climate sensitivity. Therefore, appropriate state government support is required to invest in crop diversification, better decision-making capability of tribes through education, and improved infrastructure besides diversifying the rural economy to enhance the adaptive capacity of the farmers to reduce their climate vulnerability and achieve agriculture-livestock-forestry nexus. SIGNIFICANCEThe sustainable Piper agroforestry farm management practices represent climate-smart agriculture, favouring high tree species diversity while reducing the farmers' vulnerability to climate change.

Richness of yeast community associated with apple fruits in Estonia

Yeasts are single-celled fungi that are widespread around the globe. They are part of a community of microorganisms that use a wide variety of habitats, including fruit surfaces. This study aimed to characterise the culturable epiphytic yeasts associated with apple fruits. The isolated yeast strains were identified by sequencing the 5.8S-ITS region and D1/D2 region of the large subunit ribosomal RNA gene and maintained for long-term storage. A total of 230 yeast isolates belonging to 33 species were recovered. Most of the collected isolates belonged to the phylum Basidiomycota. Members of genera Vishniacozyma, Filobasidium, and Rhodotorula were most frequently isolated. Over half of the species were isolated on only one to three occasions. In seven of the species obtained, the isolates were considerably divergent from their closest relatives and may therefore represent new distinct species. The results of this study demonstrate a high diversity of yeast species associated with apple fruits.

Testing alternative hypotheses for the decline of cichlid fish in Lake Victoria using fish tooth time series from sediment cores.

Lake Victoria is well known for its high diversity of endemic fish species and provides livelihoods for millions of people. The lake garnered widespread attention during the twentieth century as major environmental and ecological changes modified the fish community with the extinction of approximately 40% of endemic cichlid species by the 1980s. Suggested causal factors include anthropogenic eutrophication, fishing, and introduced non-native species but their relative importance remains unresolved, partly because monitoring data started in the 1970s when changes were already underway. Here, for the first time, we reconstruct two time series, covering the last approximately 200 years, of fish assemblage using fish teeth preserved in lake sediments. Two sediment cores from the Mwanza Gulf of Lake Victoria, were subsampled continuously at an intra-decadal resolution, and teeth were identified to major taxa: Cyprinoidea, Haplochromini, Mochokidae and Oreochromini. None of the fossils could be confidently assigned to non-native Nile perch. Our data show significant decreases in haplochromine and oreochromine cichlid fish abundances that began long before the arrival of Nile perch. Cyprinoids, on the other hand, have generally been increasing. Our study is the first to reconstruct a time series of any fish assemblage in Lake Victoria extending deeper back in time than the past 50 years, helping shed light on the processes underlying Lake Victoria's biodiversity loss.

Unraveling the diversity of Trypanosoma species from Central Mexico: molecular confirmation on the presence of Trypanosoma dionisii and novel Neobat linages

Bats are one of the groups of mammals with the highest number of associated Trypanosoma taxa. There are 50 Trypanosoma species and genotypes infecting more than 75 species of bats across five continents. However, in Mexico, the inventory of species of the genus Trypanosoma associated with bats is limited to only two species (Trypanosoma vespertilionis and Trypanosoma cruzi) even though 140 species of bats inhabit this country. Specifically, 91 bat species have been recorded in the state of Veracruz, but records of trypanosomatids associated with this mammalian group are absent. Due to the complex Trypanosoma–bat relationship, the high diversity of bat species in Veracruz, as well as the lack of records of trypanosomatids associated with bats for this state, the aim of this work was to analyze the diversity of species of the genus Trypanosoma and their presence from a bat community in the central area of the state of Veracruz, Mexico. During the period of January to August 2022 in the Tequecholapa Environmental Management Unit where bats were collected using mist nets and blood samples were obtained from their thumbs. We extracted genetic material and amplified a fragment of 800 bp of the 18S ribosomal gene of the genus Trypanosoma by conventional PCR. The positive amplicons were sequenced, and phylogenetic reconstruction was performed to identify the parasite species. A total of 285 bats (149♀, 136♂) belonging to 13 species from 10 genera and a single family (Phyllostomidae) were collected. Twenty-three specimens from six species tested positive for the presence of Trypanosoma dionisii, Trypanosoma sp. Neobat 4, and a potential novelty species provisionally named as Trypanosoma sp. Neobat 6. The results of the present work increase the number of species of the genus Trypanosoma infecting bats in Mexico and in the Neotropical region.

Success in restoring native plant communities on kimberlite mining dumps in the Afro-alpine Drakensberg region of Lesotho.

Rehabilitation strategies for degraded mine dumps have generally seen limited success due to different complications associated with mining biophysical disturbance. In this study, we tested a combination of two methods to expedite revegetation of kimberlite tailings at Letseng Diamond Mine (i.e., in the Afro-alpine areas of Lesotho). We ran trials on different growth media located on fine and coarse kimberlite tailings (i.e. sites) mixed with different substrate combinations and topsoil and sowing a seed mix comprised of native plant species. Overall, as predicted, fine kimberlite tailings displayed significantly higher plant abundance than coarse kimberlite tailings, and sown seeds performed significantly better than spontaneous colonisation by emerging species. Kimberlite tailings mixed with topsoil (100 mm) showed significantly greater plant abundance, and similarly, when coarse kimberlite tailings were introduced to fine tailings. Physicochemical analyses of growth media components suggested that topsoil provided additional nutrients and that plants could readily access available nutrients in the fine kimberlite tailings. We noted a gradual significant increase in plant abundance over 5 years, enhanced by new plant species emerging from the topsoil seed bank or by natural seed dispersal. Although plant abundance differed significantly, both fine and coarse kimberlite tailings displayed high plant species diversity (H = 3.4 and D = 0.95 and H = 3.5 and D = 0.95, respectively). Out of 36 emerging plant species, 15 species spontaneously colonised both growth media. The significant variation in abundance among plant species between treatments was mostly attributed to dominant forb species, namely Chrysocoma ciliata, Glumicalyx montanus, Oxalis obliquifolia, Senecio inaequidens and Trifolium burchellianum. We have identified suitable growth media for plant community restoration on kimberlite tailings in the Drakensberg alpine area using a seed mix of native plant species in combination with natural seed dispersal from the surrounding pristine environment. We provide evidence for using two complementary approaches to optimise native plant community development during restoration in the Drakensberg alpine area.