General Species Diversity Research Articles

Влияние навозных стоков на почвенные фототрофные микроорганизмы

Soil phototrophic microorganisms (algae, cyanobacteria) play a very important role in functioning of anthropogenic systems. They take an active part in soil self-purification by directly absorbing biogenic elements, as well as by stimulating the activity of mineralizing microorganisms at the expense of disengaged oxygen. The research was carried out at a plough field with sod-podzol soil situated near a large pig-breeding farm. Neutralization took place due to natural microbiological processes during the time of disgorging the liquid fraction in the lagoons. Long-term application of manure runoff from pig-breeding farms into plough soil had an impact on species diversity of phototrophic microorganisms, which was considered in the research. Groups of species tolerant to the impact formed in the soil in course of long-term application of liquid manure fraction. The influence of long-term runoff of manure from pig breeding farms on specious diversity of soil phototrophic microorganisms was assessed. In plough soils affected by liquid manure runoff a group of species tolerant to this impact has formed. Their basis is represented by green algae: Klebsormidium flaccidum, K. nitens, Chlorococcum infusionum, Chlorella vulgaris, as well as by the heterocyst-free cyanobacteria Phormidium autumnale and the diatom alga Hantzschia amphioxys. On the surface of plough soil these species make microscopically marked films, i. e. soil “blooming” takes place. General species diversity of microphototrophs in soil of the experimental site is lower than that of the control site. Jaccard coefficient of the experimental and control sites of the field is 47.8%. Nitrogen-fixing cyanobacteria are not represented in the microphototrophic community; it indicates that the natural microcoenosis is damaged in the plough soils and nitrogen content is high.

Evidence of prezygotic isolation, but not assortative mating, between locally adapted populations of Fundulus heteroclitus across a salinity gradient.

Selection along environmental gradients can drive reproductive isolation and speciation. Among fishes, salinity is a major factor limiting species distributions, and despite its importance in generating species diversity, speciation events between marine and freshwater are rare. Here, we tested for mechanisms of reproductive isolation between locally adapted freshwater and brackish water-native populations of killifish, Fundulus heteroclitus, from either side of a hybrid zone along a salinity gradient. There was evidence for pre-zygotic endogenous reproductive isolation with reduced fertilization success between crosses of freshwater-native males and brackish water-native females. Exogenous pre-zygotic isolation was also present where females had highest fertilization in their native salinity. We used a replicated mass spawning design to test for mate choice in both brackish and fresh water. After genotyping 187 parents and 2523 offspring at 2347 SNPs across the genome, 85% of offspring were successfully assign to their parents. However, no reinforcing mate choice was observed. These results therefore demonstrate emerging, yet limited, reproductive isolation and incipient speciation across a marine to freshwater salinity gradient and suggest that both endogenous and exogenous mechanisms, but not assortative mating, contribute to divergence.

Современное состояние природных условий и экосистем Памиро-Алая

Research relevance in this article given analyzes the current state of the natural conditions of the Pamir-Alai ecosystem in Kyrgyzstan, where live over 2500 plant species, 20 mammal species and 288 bird species. Research objectives: Studying and preserving the general species diversity are the main conservation tasks. Research materials and methods: This article provides analysis of the current state of the natural conditions of the Pamir-Alai within Kyrgyzstan, where over 2500 species of plants, 20 species of mammals, 288 species of birds live. Research results: It is highlighted that the following species included in the Red Book of Kyrgyzstan are present in the Alai fauna: Eurasian otter (Lutra lutra), snow leopard (Uncia uncia), mountain sheep (Ovis ammon), stone marten (Martes foina). Conclusions: Considering the economic, scientific, natural value of flora and fauna, we must find an approach to the conservation, restoration and protection of wildlife.

Applying predictive models to study the ecological properties of urban ecosystems: A case study in Zürich, Switzerland

Cities are human dominated ecosystems providing novel conditions for organisms. Research on urban biodiversity is rapidly increasing, yet it is still hampered by the partial spatial coverage of cities and because of existing taxonomic biases. Predictive models have proved to be a key tool to solve this shortfall. However, predictive models have rarely been used in urban ecosystems due to either the lack of sufficient species records or high-quality predictors (e.g. meaningful ecological maps). Here, we assemble a large cross-taxa inventory of 1446 species from 12 taxonomic groups, including several understudied invertebrate groups, sampled in 251 sites in Zürich, Switzerland. We investigate the species diversity distributions and the structure of species assemblages along artificial urban ecological gradients by applying predictive models. We find that the general species diversity distribution law, where assemblages are dominated by a few very abundant and frequent species, applied consistently across all taxonomic groups (3% of the species accounting for approximately 50% of abundance). Furthermore, only species of intermediate abundance and frequency are spatially structured along urban intensity gradients, with rare species numbers keeping constant even in the most urbanised parts of the city. In addition, we show that green areas with low mowing regimes are associated with higher species diversity in the majority of taxonomic groups. Hence, this suggests management relaxation as a low-cost solution to promote species richness. Our study demonstrates the potential of predictive modelling for addressing ecological questions in urban environments and to inform management and planning.

Инфузории пресных вод и почв Большого Кавказа (в пределах Азербайджана)

Based on the collected long-term material from 6 permanent sample points, in the vicinity of which samples were taken from water bodies and forest soils of the Greater Caucasus (within Azerbaijan), 163 species of free-living ciliates belonging to 4 classes, 18 orders, and 44 families have been found. In 2012–2015, 450 samples were collected from freshwater bodies and more than 570 soil samples. The cluster analysis of similarity (Bray, Curtis 1957) was used to assess the general species diversity of various sample points. The greatest species diversity (111 species) was noted in Ismayilli; 93 species were found in Pirguli sample points, 77 species in Altiagach and Shemakha each, 76 in Zakatala and 73 in Cuba, which is the minimum number of species observed. The greatest similarity in species composition was observed between Zagatala and Pirguli (68.5%), then Cuba (66,65%) and Altyagach sample point (62,23%). These sample points compose the first cluster. The second cluster consisted of Shamakha and Ismayilli, with a 56,37% similarity. The similarity of the first and second clusters was 55,65%. The analysis of the ratio (by occurrence in samples) of the main groups of free-living ciliates of aquatic and soil biotopes at six studied sample points was carried out. It has been established that depending on environmental factors, first of all temperature, humidity and food resources, the affiliation of various ciliates species to a particular group can vary, i.e. dominant species after changing environmental conditions can become subdominant and even secondary. Thus, the data obtained may undergo certain changes during the course of seasonal succession.

Unravelling the mechanisms of spatial correlation between species and size diversity in forest ecosystems

With ongoing climate change at global scale we are currently losing biodiversity at an unprecedented rate. The insurance hypothesis and associated research, however, suggest that biodiversity has a major stabilising effect in ecosystems. In this situation, it is crucial to develop a better understanding of natural processes of maintaining biodiversity for employing them in conservation practice. In forest ecosystems, spatial species and size diversity are important aspects of α-diversity at woodland community and species population level. Both aspects of spatial diversity stem from complex relationships between tree interaction, disturbances and subsequent waves of colonisation by tree seedlings of various species. Using point process statistics, particularly the mark mingling function and the mark variogram, we studied the processes causing spatial correlations of species and size diversity. We found that spatial species dispersal and conspecific size distributions are key drivers of spatial species-size correlations and that a combination of simple random size-labelling techniques applied to mark variograms is instrumental in efficiently diagnosing them. If size ranges differ between species, spatial size diversity is largely a function of spatial species mingling. The existence of these correlations is crucial to conservation because they imply that conservation efforts can be rationalised: It is possible to focus on only one of the two tree diversity aspects. Interestingly, in multi-species forest ecosystems, although general species diversity is high, spatial species-size correlations can be diluted, because some of the many species populations may have similar size distributions.

The Use of Wood Chips for Revitalization of Degraded Forest Soil on Young Scots Pine Plantation

The aim of the study was to assess the impact of several methods of mulching degraded forest soil with wood chips on the development of mite (Acari) community, with particular emphasis to oribatid mites (Oribatida), and on the growth of young plantings of Scots pine (Pinus sylvestris L.). Mulching with wood chips should contribute to revitalize soil fauna and restore natural forests on degraded soils. Scots pine seedlings were planted at the post-military training ground. Four experimental treatments were tested: control—uncovered soil (C), mulching with wood chips (W), W + mycorrhiza preparation (WM), and W + forest litter (WL). At the end of the growing season in 2012, 2013 and 2014, the following plant measurements were carried out: length of annual increment of the main stem, stem base diameter, number and lengths of lateral shoots in the annual whorl. The mite calculations included average mite density, dominance index, species richness, oribatid mite diversity, average number of species, and Shannon general species diversity index. The use of mulching with wood chips did not significantly affect the growth characteristics of Scots pine plants, but strongly increased the mite community. After mulching, the total number and species diversity of Acari increased many times, and Oribatida began to dominate among micro-arthropods. The number of Oribatida increased most in W. The largest species diversity was observed in WL. 24 species of Oribatida were found that were used as the bio-indicators of soil succession changes. Tectocepheus velatus clearly dominated in all mulching treatments. Oppiella nova and Scutovertex sculptus were also numerous populations of Oribatida. The study shows that mulching with Scots pine wood chips, especially with the addition of forest litter, significantly enriches soil fauna and is therefore useful in the regeneration process of degenerated forest soils.

Synergetic use of in situ and hyperspectral data for mapping species diversity and above ground biomass in Shoolpaneshwar Wildlife Sanctuary, Gujarat

Biodiversity loss in tropical forests is rapidly increasing, which directly influence the biomass and productivity of an ecosystem. In situ methods for species diversity assessment and biomass in synergy with hyperspectral data can adeptly serve this purpose and hence adopted in this study. Quadrat sampling was carried out in Shoolpaneshwar Wildlife Sanctuary (SWS), Gujarat, which was used to compute Shannon–Weiner Diversity Index (H′). Above ground biomass (AGB) was calculated measuring the Height and Diameter at Breast Height (DBH) of different trees in the sampling plots. Four spectral indices, namely Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Photochemical Reflectance Index (PRI), and Structure Insensitive Pigment Index (SIPI) were derived from the EO-1 Hyperion Data. Spearman and Pearson’s correlation analysis was performed to examine the relationship between H′, AGB and spectral indices. The best fit model was developed by establishing a relationship between H′ and AGB. Fifteen models were developed by performing multiple linear regression analysis using all possible combinations of spectral indices and H′ and their validation was performed by relating observed H′ with model predicted H′. Pearson’s correlation relation showed that SIPI has the best relationship with the H′. Model 15 with a combination of NDVI, PRI and SIPI was determined as the best model for retrieving H′ based on its statistics performance and hence was used for generating species diversity map of the study area. Power model showed the best relationship between AGB and H′, which was used for the development of AGB map.

Mitotic Recombination and Adaptive Genomic Changes in Human Pathogenic Fungi.

Genome rearrangements and ploidy alterations are important for adaptive change in the pathogenic fungal species Candida and Cryptococcus, which propagate primarily through clonal, asexual reproduction. These changes can occur during mitotic growth and lead to enhanced virulence, drug resistance, and persistence in chronic infections. Examples of microevolution during the course of infection were described in both human infections and mouse models. Recent discoveries defining the role of sexual, parasexual, and unisexual cycles in the evolution of these pathogenic fungi further expanded our understanding of the diversity found in and between species. During mitotic growth, damage to DNA in the form of double-strand breaks (DSBs) is repaired, and genome integrity is restored by the homologous recombination and non-homologous end-joining pathways. In addition to faithful repair, these pathways can introduce minor sequence alterations at the break site or lead to more extensive genetic alterations that include loss of heterozygosity, inversions, duplications, deletions, and translocations. In particular, the prevalence of repetitive sequences in fungal genomes provides opportunities for structural rearrangements to be generated by non-allelic (ectopic) recombination. In this review, we describe DSB repair mechanisms and the types of resulting genome alterations that were documented in the model yeast Saccharomyces cerevisiae. The relevance of similar recombination events to stress- and drug-related adaptations and in generating species diversity are discussed for the human fungal pathogens Candida albicans and Cryptococcus neoformans.

Different-Scale Variations in the Abundance and Species Diversity of Metazoan Microzooplankton in the Coastal Zone of the Black Sea

The short-term, seasonal, and interannual variations in the abundance and species composition of the Black Sea metazoan microzooplankton have been analyzed at the open coastal area and the mouth of Sevastopol Bay in 2009–2015. Whatever the time scale, the temperature factor played the main role in abundance variations. In particular, the coincidence of two-year periodicities in the sum of active temperatures and the abundance of copepod-invader Oithona davisae at the year-to-year scale have been demonstrated. Variations of wind speed and direction have been shown to be significant factors in the short-term variations of microzooplankton abundance. The general species diversity of the community was found to depend significantly on the abundance of the invader species.

Overlooked and undervalued: the neglected role of fauna and a global bias in ecological restoration assessments

Globally increasing rates of mine site discontinuations are resulting in the need for immediate implementation of effective conservation and management strategies. Surveying vegetation structure is a common method of assessing restoration success; however, responses of fauna to mine site restoration remain largely overlooked and understudied despite their importance within ecosystems as ecological engineers, pollinators, and restoration facilitators. Here we review the current state of the use of fauna in assessments of mine site restoration success globally, and address biases or shortcomings that indicate the assessment approach may undershoot closure and restoration success. We identified just 101 peer-reviewed publications or book chapters over a 49-year period that assess responses of fauna to mine site restoration globally. Most studies originate in Australia, with an emphasis on just one company. Assessments favour general species diversity and richness, with a particular focus on invertebrate responses to mine site restoration. Noteworthy issues included biases towards origin of study, study type, and target taxa. Further searches of the grey literature relating to fauna monitoring in mine site restoration, which was far more difficult to access, yielded six monitoring/guidance documents, three conference proceedings, two book chapters without empirical data, and a bulletin. As with peer-reviewed publications, grey literature focussed on invertebrate responses to restoration, or mentioned fauna only at the most basic level. We emphasise the need for global re-evaluation of regulatory standards to address these major limitations in assessing the capacity of the mining industry to comprehensively and representatively restore faunal communities after mining.

The dual role of Amazonian rivers in the generation and maintenance of avian diversity.

The Amazon River and its major tributaries delimit the distributions of hundreds of terrestrial taxa. It remains unclear whether river-bounded distributions and taxon replacements reflect the historical role of rivers in generating species diversity as vicariant forces, or are the result of their role as secondary barriers, maintaining current levels of species diversity by inhibiting gene flow and population introgression. We use a community-wide comparative phylogeographic and phylogenetic approach to address the roles that the Rio Negro and the Rio Branco play in the avian speciation process in the Guiana Shield. Examining 74 pairs of ecologically similar geographic replacements that turn over across the lower Negro, we found substantial variation in the levels of genetic divergence and the inferred timing of diversification among pairs, ranging from ~0.24 to over 8 million years (Ma ago). The breadth of this variation is inconsistent with a single, shared speciation event. Coalescent simulations also rejected a simultaneous divergence scenario for pairs divided by the Rio Branco but could not reject a single diversification pulse for a subset of 12 pairs of taxa divided by the upper Negro. These results are consistent with recent geomorphological hypotheses regarding the origins of these rivers. Phylogenetically, taxon pairs represent a blend of sister (~40%) and nonsister taxa (~60%), consistent with river-associated allopatric or peripatric speciation and secondary contact, respectively. Our data provide compelling evidence that species turnover across the Rio Negro basin encompasses a mixture of histories, supporting a dual role for Amazonian rivers in the generation and maintenance of biological diversity.

Phylogenomics of montane frogs of the Brazilian Atlantic Forest is consistent with isolation in sky islands followed by climatic stability

Abstract Despite encompassing a relatively small geographical area, montane regions harbor disproportionately high levels of species diversity and endemism. Yet, relatively little is known about the evolutionary mechanisms ultimately leading to montane diversity. In this study, we use target capture of ultraconserved elements to investigate the phylogenetic relationships and diversification patterns of Melanophryniscus (Bufonidae) and Brachycephalus (Brachycephalidae), two frog genera that occur in sky islands of the southern Atlantic Forest of Brazil. Specifically, we test whether diversification of montane species in these genera can be explained by a single climatic shift leading to isolation in sky islands, followed by relative climatic stability that maintained populations in allopatry. In both genera, the topologies inferred using concatenation and coalescent-based methods were concordant and had strong nodal support, except for a few recent splits. These recent splits tended to be supported by more informative loci (those with higher average bootstrap support), suggesting that, while individual trees may be well resolved, the relationships they recover are being obscured by non-informative data. Divergence dating of a combined dataset using both genera is consistent with concordant timing of their diversification. These results support the scenario of diversification-by-isolation in sky islands, and suggest that allopatry due to climatic gradients in montane regions are an important mechanism for generating species diversity and endemism in these regions.

Symbioses with nitrogen-fixing bacteria: nodulation and phylogenetic data across legume genera.

How species interactions shape global biodiversity and influence diversification is a central - but also data-hungry - question in evolutionary ecology. Microbially based mutualisms are widespread and could cause diversification by ameliorating stress and thus allowing organisms to colonize and adapt to otherwise unsuitable habitats. Yet the role of these interactions in generating species diversity has received limited attention, especially across large taxonomic groups. In the massive angiosperm family Leguminosae, plants often associate with root-nodulating bacteria that ameliorate nutrient stress by fixing atmospheric nitrogen. These symbioses are ecologically-important interactions, influencing community assembly, diversity, and succession, contributing ~100-290 million tons of N annually to natural ecosystems, and enhancing growth of agronomically-important forage and crop plants worldwide. In recent work attempting to determine whether mutualism with N-fixing bacteria led to increased diversification across legumes, we were unable to definitively resolve the relationship between diversification and nodulation. We did, however, succeed in compiling a very large searchable, analysis-ready database of nodulation data for 749 legume genera (98% of Leguminosae genera; LPWG 2017), which, along with associated phylogenetic information, will provide a valuable resource for future work addressing this question and others. For each legume genus, we provide information about the species richness, frequency of nodulation, subfamily association, and topological correspondence with an additional data set of 100 phylogenetic trees curated for database compatibility. We found 386 legume genera were confirmed nodulators (i.e., all species examined for nodulation nodulated), 116 were non-nodulating, four were variable (i.e., containing both confirmed nodulators and confirmed non-nodulators), and 243 had not been examined for nodulation in published studies. Interestingly, data exploration revealed that nodulating legume genera are ~3×more species-rich than non-nodulating genera, but we did not find evidence that this difference in diversity was due to differences in net diversification rate. Our metadata file describes in more detail the structure of these data that provide a foundational resource for future work as more nodulation data become available, and as greater phylogenetic resolution of this ca. 19,500-species family comes into focus. We release this data set under the Creative Commons 4.0 Attribution-ShareAlike License (https://creativecommons.org/licenses/by-sa/4.0/). The data may be used, distributed, and reproduced with proper citation of this article.

The origin and evolution of coral species richness in a marine biodiversity hotspot.

The Coral Triangle (CT) region of the Indo-Pacific realm harbors an extraordinary number of species, with richness decreasing away from this biodiversity hotspot. Despite multiple competing hypotheses, the dynamics underlying this regional diversity pattern remain poorly understood. Here, we use a time-calibrated evolutionary tree of living reef coral species, their current geographic ranges, and model-based estimates of regional rates of speciation, extinction, and geographic range shifts to show that origination rates within the CT are lower than in surrounding regions, a result inconsistent with the long-standing center of origin hypothesis. Furthermore, endemism of coral species in the CT is low, and the CT endemics are older than relatives found outside this region. Overall, our model results suggest that the high diversity of reef corals in the CT is largely due to range expansions into this region of species that evolved elsewhere. These findings strongly support the notion that geographic range shifts play a critical role in generating species diversity gradients. They also show that preserving the processes that gave rise to the striking diversity of corals in the CT requires protecting not just reefs within the hotspot, but also those in the surrounding areas.

Taxonomy and climatic zonation of the Late Quaternary bathyal ostracods from the Campos Basin, Brazil

This work represents a new contribution to the knowledge on deep-sea ostracods from the western South Atlantic Ocean based on the core GL77 drilled in the Campos Basin (40°02′50″W; 21°12′22″S), 1287m water depth. Radiocarbon dating and oxygen isotopic analyses in planktonic foraminifera indicate that the 275cm interval studied of this core comprises the marine isotope stages 1, 2 and 3 (approximately 45kyr). Forty ostracode species were identified, yet 19 of them are kept in open nomenclature due to either the absence of adult individuals or poor preservation. Thirteen of those species have been recorded previously in the Brazilian continental margin: Bythocypris kyamos, B. affinis, Cytheropteron inornatum, C. perlaria, K. coimbrai, K. morkhoveni, K. sinuosa, K. trinidadensis, Macrocypris adrecta, Microcythere dubia, M. cronini, Poseidonamicus pintoi and Saida ionia. A new Trachyleberididae species, Ambocythere circumporus nov. sp. is proposed, and Cobanocythere? dubia is reassigned to the genus Microcythere. The stratigraphic distribution of the species in the core GL77 was compared to other studies on deep-sea assemblages carried out in the western Atlantic Ocean. The general species diversity pattern is a significant reduction during the Last Glacial Maximum (LGM) followed by conspicuous changes in Holocene assemblages caused by the appearance of species absent in the Pleistocene. The species Bythocypris kyamos, Cytheropteron perlaria and Saida ionia are restricted to the Marine Isotope Stage (MIS) 1. Poseidonamicus pintoi and Australoecia sp. are predominant and almost exclusive to the MIS 2 and 3. These data indicate the possibility of elaboration of an ostracod-based paleoclimatic zonation for the Quaternary of the south/southeast Brazilian margin.

A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system

A new species of tyrannosaurid from the upper Two Medicine Formation of Montana supports the presence of a Laramidian anagenetic (ancestor-descendant) lineage of Late Cretaceous tyrannosaurids. In concert with other anagenetic lineages of dinosaurs from the same time and place, this suggests that anagenesis could have been a widespread mechanism generating species diversity amongst dinosaurs, and perhaps beyond. We studied the excellent fossil record of the tyrannosaurid to test that hypothesis. Phylogenetic analysis places this new taxon as the sister species to Daspletosaurus torosus. However, given their close phylogenetic relationship, geographic proximity, and temporal succession, where D. torosus (~76.7–75.2 Ma) precedes the younger new species (~75.1–74.4 Ma), we argue that the two forms most likely represent a single anagenetic lineage. Daspletosaurus was an important apex predator in the late Campanian dinosaur faunas of Laramidia; its absence from later units indicates it was extinct before Tyrannosaurus rex dispersed into Laramidia from Asia. In addition to its evolutionary implications, the texture of the facial bones of the new taxon, and other derived tyrannosauroids, indicates a scaly integument with high tactile sensitivity. Most significantly, the lower jaw shows evidence for neurovasculature that is also seen in birds.

Social organization influences the exchange and species richness of medicinal plants in Amazonian homegardens.

Medicinal plants provide indigenous and peasant communities worldwide with means to meet their healthcare needs. Homegardens often act as medicine cabinets, providing easily accessible medicinal plants for household needs. Social structure and social exchanges have been proposed as factors influencing the species diversity that people maintain in their homegardens. Here, we assess the association between the exchange of medicinal knowledge and plant material and medicinal plant richness in homegardens. Using Tsimane' Amazonian homegardens as a case study, we explore whether social organization shapes exchanges of medicinal plant knowledge and medicinal plant material. We also use network centrality measures to evaluate people's location and performance in medicinal plant knowledge and plant material exchange networks. Our results suggest that social organization, specifically kinship and gender relations, influences medicinal plant exchange patterns significantly. Homegardens total and medicinal plant species richness are related to gardeners' centrality in the networks, whereby people with greater centrality maintain greater plant richness. Thus, together with agroecological conditions, social relations among gardeners and the culturally specific social structure seem to be important determinants of plant richness in homegardens. Understanding which factors pattern general species diversity in tropical homegardens, and medicinal plant diversity in particular, can help policy makers, health providers, and local communities to understand better how to promote and preserve medicinal plants in situ. Biocultural approaches that are also gender sensitive offer a culturally appropriate means to reduce the global and local loss of both biological and cultural diversity.

Cryptic diversity hides host and habitat specialization in a gorgonian-algal symbiosis.

Shallow water anthozoans, the major builders of modern coral reefs, enhance their metabolic and calcification rates with algal symbionts. Controversy exists over whether these anthozoan-algae associations are flexible over the lifetimes of individual hosts, promoting acclimative plasticity, or are closely linked, such that hosts and symbionts co-evolve across generations. Given the diversity of algal symbionts and the morphological plasticity of many host species, cryptic variation within either partner could potentially confound studies of anthozoan-algal associations. Here, we used ribosomal, organelle and nuclear sequences, along with microsatellite variation, to study the relationship between lineages of a common Caribbean gorgonian and its algal symbionts. The gorgonian Eunicea flexuosa is a broadcast spawner, composed of two recently diverged, genetically distinct lineages largely segregated by depth. We sampled colonies of the two lineages across depth gradients at three Caribbean locations. We find that each host lineage is associated with a unique Symbiodinium B1/184 phylotype. This relationship between host and symbiont is maintained when host colonies are reciprocally transplanted, although cases of within phylotype switching were also observed. Even when the phylotypes of both partners are present at intermediate depths, the specificity between host and symbiont lineages remained absolute. Unrecognized cryptic diversity may mask host-symbiont specificity and change the inference of evolutionary processes in mutualistic associations. Symbiotic specificity thus likely contributes to the ecological divergence of the two partners, generating species diversity within coral reefs.

Morphological disparity opposes latitudinal diversity gradient in lacertid lizards.

While global variation in taxonomic diversity is strongly linked to latitude, the extent to which morphological disparity follows geographical gradients is less well known. We estimated patterns of lineage diversification, morphological disparity and rates of phenotypic evolution in the Old World lizard family Lacertidae, which displays a nearly inverse latitudinal diversity gradient with decreasing species richness towards the tropics. We found that lacertids exhibit relatively constant rates of lineage accumulation over time, although the majority of morphological variation appears to have originated during recent divergence events, resulting in increased partitioning of disparity within subclades. Among subclades, tropical arboreal taxa exhibited the fastest rates of shape change while temperate European taxa were the slowest, resulting in an inverse relationship between latitudinal diversity and rates of phenotypic evolution. This pattern demonstrates a compelling counterexample to the ecological opportunity theory of diversification, suggesting an uncoupling of the processes generating species diversity and morphological differentiation across spatial scales.