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Aim: Estuarine vegetation routinely experiences natural tidal fluctuations and is highly vulnerable to extreme events such as heavy rainfall, leading to changes in plant population structure and adaptability. Genetic and epigenetic modifications are widely considered to be mechanisms of phenotypic variation, triggered in plants responding to extreme changing environments. However, understanding on correlations among genetic, epigenetic, and phenotypic variation of wild plant populations is still limited. Location: China. Methods: In this study, populations of the typical wetland clonal species Phragmites australis were selected from four estuaries along various latitudes in China. Genetic and epigenetic diversity and phenotypic variation of these populations were analysed. Results: Phenotypic variation of P. australis populations was the highest at Yellow River Estuary and the lowest at Min River Estuary. Across all estuaries, Genetic and epigenetic diversity was strongly linear‐correlated. Genetic diversity had significant correlations with variation in reproductive traits, whereas epigenetic diversity had significant correlations with variation in growth traits. Climatic factors of mean annual temperature and precipitation, as well as soil nitrogen and phosphorus, were negatively correlated with variation in genetic diversity, epigenetic diversity, and variation in reproductive traits of P. australis populations along latitudes. Variation in growth traits was negatively correlated with soil salinity, reflecting the limiting effect of salinity on plant growth. Main Conclusion: Our findings found that genetic and epigenetic variations may play different roles in phenotypic variation of P. australis populations along latitudes, the variation becomes greater when the climatic and edaphic conditions deteriorate. The findings shed new light on the adaptation and evolution of wetland plant populations along a large latitudinal scale, and may contribute to the revegetation of estuary wetlands. [ABSTRACT FROM AUTHOR]

Melting layer usually exists in precipitation where ice particles gradually melt into liquid particles. Utilizing the detection from the Dual-frequency Precipitation Radar onboard Global Precipitation Measurement Mission Core Observatory during 2018-2022, this paper investigates the quasi-global climatological features of Melting layer over 65°S ~65°N and analyzes the relationships with elevation in the golden case involving the section along 32.5°N across China. The distribution of Melting layer is latitude-dependent: Melting layer is higher in 30°S~30°N and decrease toward the mid-and high-latitude, which are generally lower in 30°S~65°S throughout the year. The height and thickness of Melting layer change more dramatically in mid-and high latitudes than in low latitudes for diurnal variations. The higher elevation terrain has the lower Melting layer top height than other terrains, yet the geometric thickness of Melting layer is also thinner. A golden case is selected to represent the analysis of Melting layer play role in rainfall. When the Melting layer grow thinner with steeply rising elevation due to the thermal change and orographic uplift, there is weak rain with a greater number of smaller raindrops in the golden case. However, Melting layer can get widen and raindrops can get sufficient growth as the elevation declines. [ABSTRACT FROM AUTHOR]

This paper presented an analysis of geomagnetic disturbance observed on the ground during geomagnetic storms with different intensities in 2015 using the meridian chain data at geomagnetic mid and low latitudes. Ground observation records superimpose varying types of space-current system and noise interference. Geomagnetic disturbance with variation of discontinuity and irregularities are difficult to identify and distinguish. We proposed a variational mode decomposition (VMD) algorithm for reconstructing geomagnetic horizontal (H ) disturbance signals. We decomposed the geomagnetic signals into geomagnetic disturbance signals, diurnal variation signals, and noise disturbance signals using the VMD algorithm. Intrinsic mode functions (IMFs) were selected to form the reconstructed signal, which represented a geomagnetic disturbance during a geomagnetic storm. We investigated the decreased amplitude of H component obtained from the reconstructed signals during main phase of geomagnetic storms with different geomagnetic storms intensities and seasons at mid and low latitudes. The maximum values of gradient variation of H component disturbance with geomagnetic latitude cosine are near magnetic latitude 30°N during geomagnetic storms with different intensities and seasons. Ionopheric structural changes in the low-to-mid latitude transition zone maybe the primary cause. The result provides a reference for the complex coupling relationship between the ionosphere and magnetosphere during geomagnetic storms. [ABSTRACT FROM AUTHOR]

The Black Skimmer (Rynchops niger) is a charismatic representative of coastal-nesting waterbird communities in North America and freshwater riverine and coastal systems in South America. Skimmers are at high risk of decline due to threats including habitat loss, human activity, and climate change throughout the annual cycle. To understand range-wide population connectivity, eight microsatellite loci were used to reveal genetic differentiation between North American Pacific and Atlantic Coasts, including the Gulf of Mexico, and very strong differentiation between the North American sites and a site in Peru, South America. A reduced dataset, incorporating previously published data from South America, documented strong inter-continental differentiation and moderate differentiation among sites within South America in a pattern inconsistent with current subspecies designations, and suggesting a more complex pattern of dispersal. We recommend combined use of telemetry and genomic tools to assist in future delineation of skimmer subspecies ranges and non-breeding habitat use in South America. Because genetic diversity was relatively low in North America and higher in South America, genetics could determine whether skimmers in South America represent the ancestral population now expanding along the Atlantic and Pacific Coasts of North America. Detailed knowledge of seasonal movement and non-breeding habitat use that can be obtained by telemetry and population-wide molecular analyses will be essential to informing effective management across the Americas. [ABSTRACT FROM AUTHOR]

The palaeobiogeographic distributions of the pleurotomariid gastropods (Family Pleurotomariidae) are investigated from Maastrichtian (Latest Cretaceous) to Holocene to understand the global distribution patterns of this gastropod group during the Cenozoic. Although the diversity of the pleurotomariids considerably declined during the Late Cretaceous, they survived the K-Pg mass extinction and thrived in the Cenozoic. The Tethyan group of localities hosted the greatest diversity and thus, can be considered the central hub for the pleurotomariid gastropods throughout the Paleogene. However, with the closure of the Tethyan seaway during the early Neogene, their abundance significantly dropped in the Mediterranean. In the present times, this group has entirely disappeared from the Mediterranean Sea. The distribution became bicentric from the Middle Miocene onwards with one cluster in the Caribbean group of localities and the other in the Western Pacific group of localities. Latitudinal distribution of the fossil pleurotomariids shows that during the end-Cretaceous and Paleocene these gastropods were mostly confined to the polar and temperate latitudinal zones. However, they become more abundant in the temperate latitudinal zone during the Eocene and gradually expanded their habitat towards the tropical latitudinal zone from the Pleistocene onwards. Thus, a typical unidirectional shift from higher to lower latitudes is observed during the Cenozoic revealing habitat tracking in pleurotomariid gastropods. [ABSTRACT FROM AUTHOR]

Ultralow frequency (ULF) waves in the Pc5 band are ubiquitous in the inner magnetosphere and can impact radiation belt dynamics by interacting with electrons through drift or drift‐bounce resonance. In this paper, based on ∼ 19 years of Cluster measurements, we perform a comprehensive study of the three‐dimensional distribution of poloidal, toroidal, and compressional ULF waves from L = 4 to 10, for magnetic latitudes (MLAT) up to Ultralow frequency ±50°, and in all magnetic local times (MLT). The distribution of the Pc5 ULF wave power is found to vary greatly as a function of L and MLT. For all L and MLT sectors, wave power of the poloidal and toroidal modes of the magnetic field increase with increasing |MLAT|, while the compressional mode decreases with increasing |MLAT|. The dawn–dusk asymmetries of wave power in poloidal and toroidal modes are more pronounced at higher |MLAT|. Furthermore, the wave power for Kp > 2 is approximately 2.93, 3.21, and 3.42 times greater than the wave power for Kp ≤ 2, respectively for compressional, poloidal and toroidal components. The information on the latitudinal distributions of ULF waves presented in this paper is important for future investigations on the radial diffusion process of radiation belt electrons with non‐90° pitch angles while they bounce away from the magnetic equator. Key Points: About 19 years of Cluster measurements are used to study the latitudinal distribution of magnetic Pc5 pulsationsWave power of the poloidal and toroidal modes increases with increasing |MLAT|, while compressional mode decreases with increasing |MLAT|The statistical results can be used for the study of radial diffusion of radiation belt electrons with non‐90° pitch angles [ABSTRACT FROM AUTHOR]

The upper Gulf of California is one of the most energetic regions owing to its tidal range and strong tidal currents, making the upper gulf and the archipelago zone highly turbulent regions; the abundance of zooplankton should be associated with mixing phenomena. We aimed to determine the latitudinal distribution of zooplanktonic organisms in this region and the influence of the islands on their distribution and abundance using historical data. Distribution of abundance followed the current patterns, the archipelago influences abundance favorably but does not affect diversity. Latitudinal zooplankton richness had a quasi-parabolic shape. A decrease in richness was observed at 27.5°N, in the archipelago region, with maximum richness at 26.5°N and 28.5°N. The distribution of latitudinal ranges is consistent with geometric constraints models; taxa with wide ranges are in the central area, while those with narrow ranges are near the boundaries and the Upper Gulf. Zooplankton responds in some way to the existence of the southern boundary as shown by the decrease of richness in this region. At the whole scale of the Gulf, the distribution of richness followed geometric constraints model, while at smaller scales, distribution and abundance are conditioned by the hydrodynamics of the Gulf. We compared zooplankton spatial distribution with Sea Level Anomaly, Sea Surface Temperature, and Chlorophyll-a concentrations from Copernicus to establish relationships between these factors. We performed Cluster and Redundancy Analysis to characterize similarities between stations in terms of biomass and taxon composition and to assess the importance of environmental variables on the distribution of zooplankton.

Body size is a fundamental trait determining individual fitness and ecological processes. Reduction in body size with increasing temperature has been widely observed in most ectotherms and endotherms, known as Bergmann's rule. However, we lack data to assess if ciliates, the major consumers of marine primary production, follow Bergmann's rule and what drives the distributions of their cell size. Here, we examined a data set (287 samples) collected across the global oceans to investigate biogeographic patterns in the mean cell‐size of ciliate communities. By measuring the sizes of every ciliate cell (< 10 to > 300 per sample), we found that community cell‐size increased with increasing latitude, conforming to Bergmann's rule. We then addressed the cause. Temperature was a main driver of the trend. Ciliate community mean cell‐size decreased 34% when temperature increased from 3.5 to 31°C, implying that temperature may be a direct physiological driver. In addition, prey (phytoplankton) size also influenced the trend, with ciliate size increasing by 35% across the gradient of phytoplankton size (0.6–15.5 μm). Generally, these findings emphasized the importance of how both biotic and abiotic factors affect size distribution of marine ciliates, a key component of pelagic ecosystems. Our novel, extensive dataset and the predictive trends arising from them contribute to understanding how climate change will influence pelagic ecosystem functions. [ABSTRACT FROM AUTHOR]

Simple Summary: Biodiversity is not evenly distributed on Earth. For phytophagous insects, we could expect increasing taxonomic richness from temperate to tropical latitudes, where plant diversity is high. In this paper, we explored the variation in the number of genera in one of the most widespread groups of phytophagous insects, flea beetles, from north to south on the African continent. We found that the number of genera depends on the number of vegetation types, the kind of vegetation, and some specific bioclimatic variables, leading to an up-and-down trend in taxonomic richness from north to south. The distribution of global biodiversity can be investigated based on comprehensive datasets and many methods to process them. The taxonomic diversity of phytophagous insects is typically linked to plant diversity, which increases from temperate to tropical latitudes. In this paper, we explored the latitudinal distribution of the flea beetle genera (Coleoptera, Chrysomelidae, Galerucinae, Alticini) on the African continent. We divided the area into latitudinal belts and looked for possible correlations with the number and types of vegetational divisions, the area of each belt, and the bioclimatic variables. The number of flea beetle genera is related to the number and types of vegetation divisions rather than the area of each belt. Some bioclimatic variables are highly related to the number of genera, which is higher within those belts where climate factors limit the oscillation of temperature over the year and favor high precipitations, especially in the warmest months. These biotic and abiotic factors lead to a two-peak trend in the taxonomic richness of flea beetle genera from north to south. Genera endemic to restricted areas are linked to the presence of high mountain systems and increase the taxonomic richness of the belt they belong to. [ABSTRACT FROM AUTHOR]

One of the most important factors regulating the distribution and abundance of seaweeds is desiccation, triggered mainly by tidal changes and climatic variation. Porphyra and Pyropia species have evolved multiple strategies to tolerate desiccation stress; however, how these tolerance strategies differ in these species inhabiting different latitudes is still unknown. In this context, we analyzed, in situ, the physiological responses of these species (collected from 18° S to 41° S along the Chilean coast) to desiccation stress using biochemical and molecular analyses. The hyper-arid terrestrial climate of northern Chile, with high evaporation and lack of constant rain determines a very steep increase in desiccation stress in the upper intertidal during low tide for these species. Accordingly, the results showed that, in comparison with the southernmost populations, the Porphyra/Pyropia species from the north zone of Chile (18°–30° S) exhibited higher contents of lipoperoxide and carbonyls (1.6–1.9 fold) together with higher enzymatic activities, including ascorbate peroxidase, catalase, peroxiredoxin, and thioredoxin (2–3-fold). In addition, a substantial expression of cat, prx, and trx transcripts during desiccation was demonstrated, mainly in the northernmost populations. These results provide evidence of (i) significant activation of antioxidant enzymes and transcripts (principally cat and prx); (ii) participation of phenolic antioxidant compounds as a highly plastic physiological strategy to cope with desiccation; and (iii) the activation of the tolerance responses was affected by species latitudinal distribution. Thus, for the first time, this study integrated the biochemical and genetic responses of diverse Porphyra/Pyropia species to better understand their physiological dynamics of tolerance over a wide latitudinal range. [ABSTRACT FROM AUTHOR]

Based on original data, the most complete and updated species list of the water fleas (Crustacea: Cladocera) of both the southern part of the Russian Far East and Korea is represented. In total, 122 taxa are identified to the species level. The list includes 92 valid species recorded in the Far East of Russia and 71 in South Korea. Each taxon is attributed to one of the six zoogeographical groups: one among four faunistic complexes (widespread Eurasian, East Asian–American, endemic East Asian, and southern tropical), a group of widely distributed unrevised taxa, and a group of invasive species. With a decrease in latitude (i.e., in the north–south direction), (1) the species richness is decreased, (2) the dominance structure (based on species occurrence frequencies) is changed from two–three dominant species to a lack of clear dominants; (3) the rate of representatives of the widespread Eurasian complex is decreased, while that of the southern tropical taxa is increased, and (4) the taxocoenoses of the boreal type are changed to those of subtropical type. In addition to boreal and subtropical type taxocoenoses, three more taxocoenosis types are found in the Khanka Lake basin (the largest water body in the region). The relative abundance and occurrence of taxa from the endemic East Asian complex are similar within the entire region and do not vary with latitude. [ABSTRACT FROM AUTHOR]

One of the most important factors regulating the distribution and abundance of seaweeds is desiccation, triggered mainly by tidal changes and climatic variation. Porphyra and Pyropia species have evolved multiple strategies to tolerate desiccation stress; however, how these tolerance strategies differ in these species inhabiting different latitudes is still unknown. In this context, we analyzed, in situ, the physiological responses of these species (collected from 18° S to 41° S along the Chilean coast) to desiccation stress using biochemical and molecular analyses. The hyper-arid terrestrial climate of northern Chile, with high evaporation and lack of constant rain determines a very steep increase in desiccation stress in the upper intertidal during low tide for these species. Accordingly, the results showed that, in comparison with the southernmost populations, the Porphyra/Pyropia species from the north zone of Chile (18°–30° S) exhibited higher contents of lipoperoxide and carbonyls (1.6–1.9 fold) together with higher enzymatic activities, including ascorbate peroxidase, catalase, peroxiredoxin, and thioredoxin (2–3-fold). In addition, a substantial expression of cat, prx, and trx transcripts during desiccation was demonstrated, mainly in the northernmost populations. These results provide evidence of (i) significant activation of antioxidant enzymes and transcripts (principally cat and prx); (ii) participation of phenolic antioxidant compounds as a highly plastic physiological strategy to cope with desiccation; and (iii) the activation of the tolerance responses was affected by species latitudinal distribution. Thus, for the first time, this study integrated the biochemical and genetic responses of diverse Porphyra/Pyropia species to better understand their physiological dynamics of tolerance over a wide latitudinal range.

Abstract Wetland methane (CH4) emissions comprise about one‐third of the global CH4 source. The latitudinal distribution and climate sensitivity of wetland CH4 fluxes are the key determinants of the global CH4‐climate feedback. However, large differences exist between bottom‐up estimates, informed by ground‐based flux measurements, and top‐down estimates derived from spaceborne total column CH4. Despite the extensive coverage of satellite CH4 concentration observations, challenges remain with using top‐down estimates to test bottom‐up models, mainly because of the uncertainties in the satellite retrievals, the model representation errors, the variable prior emissions, and the confounding role of the posterior error covariance structures. Here, we use satellite‐based top‐down CH4 flux estimates (2010–2012) to test and refine 42 bottom‐up estimates of wetland emissions that use a range of hypothesized wetland extents and process controls. Our comparison between bottom‐up models and satellite‐based fluxes innovatively accounts for cross‐correlations and spatial uncertainties typically found in top‐down inverse estimates, such that only the information from satellite observations and the atmospheric transport model is kept as a constraint. We present a satellite‐constrained wetland CH4 ensemble product derived from assembling the highest‐performance bottom‐up models, which estimates global wetland CH4 emissions of 148 (117–189, 5th–95th percentile) Tg CH4 yr−1. We find that tropical wetland emissions contribute 72% (63%–85%) to the global wetland total. We also find that a lower‐than‐expected temperature sensitivity agrees better with atmospheric CH4 measurements. Overall, our approach demonstrates the potential for using satellites to quantitatively refine bottom‐up wetland CH4 emission estimates, their latitudinal distributions, and their sensitivity to climate.

Equinoctial asymmetry of the range of the solar quiet day variation (Sq) of the horizontal geomagnetic field (H) has been found in some low latitude geomagnetic observatories. This study conducted an investigation of its latitude distribution and the relationship with the solar cycle by using the H field measurements from six observatories along the 120° E meridian chain in the years 1957–2013. Results illustrate a significant equinoctial asymmetry of the SqH range at all observatories. Three main features were identified. First, the signature of the equinoctial asymmetry of the SqH range is opposite for observatories located at the northern and southern sides of the Northern Hemisphere Sq current focus. It shows larger values around spring than autumn equinox at southern observatories, and the converse is seen at northern observatories. Second, the asymmetry increases with the distance from the Sq current focus, suggesting the stronger sensitivity of the distant observatories than observatories around the focus. The result of linear fitting presents a positive dependence of the asymmetry coefficient on geographic latitude, with a reversal of the asymmetry occurring at 28.1° N near the focus of the average Sq current. Third, there is no obvious dependence of the equinoctial asymmetry of the SqH range on solar activity, suggesting a possible cause from some regional factors related to the ionospheric dynamo process. [ABSTRACT FROM AUTHOR]

The observations from the Juno spacecraft in polar orbit of Jupiter provide for the first time a complete view of Jupiter's radio emissions from all latitudes. Characterizing the latitudinal distribution of radio emissions' occurrence and intensity is a useful step for elucidating their origin. Here, we analyze for that purpose the first 3 years of observations from the Waves experiment on the Juno spacecraft (mid‐2016 to mid‐2019). Two prerequisites for the construction of the latitudinal distribution of intensities for each Jovian radio component are (a) to work with absolute flux densities and (b) to be able to associate each radio measurement with a specific radio component. Accordingly, we develop a method to convert the Juno/Waves data in flux densities and then we build a catalog of all Jovian radio components over the first 3 years of Juno's orbital mission. From these, we derive occurrence and intensity distributions versus observer's latitude and frequency for each component; these will be the basis for future detailed studies and interpretations of each component's characteristics and origin. Key Points: We build a processing pipeline of Juno/Waves data that include conversion to absolute flux densitiesWe build a catalog of all Jovian radio components over the first 3 years of Juno's orbital missionWe derive occurrence and intensity distributions versus observer's latitude and frequency for each component [ABSTRACT FROM AUTHOR]

Abstract Climate warming may affect reproductive isolation between sympatric sister species by modifying reproductive phenology or mate choice. This is expected to result in a latitudinal progression of hybridization in response to the shifting of environmental conditions. The fish species northern redbelly dace (Chrosomus eos) and finescale dace (C. neogaeus) display a wide sympatric distribution in North America. The asexual reproduction of their hybrids allows determining where and when hybridization occurred. The aim of this study was twofold: first, to assess whether temperature affected reproductive isolation, and second, whether the effects of climate warming resulted in a latitudinal progression of hybridization. We performed a 500 km latitudinal survey (51 sites) in southeastern Quebec (Canada) and determined the distribution of clonal hybrid lineages. Results revealed a total of 78 hybrid lineages, including 70 which originated locally. We detected a significant difference between the southern and northern range of the survey in terms of the proportion of sites harboring local hybrids (20/23 vs. 8/28 sites, respectively) and hybrid diversity (57 vs. 13 lineages, respectively). This confirmed that there was more frequent interspecific mating in the warmest sites. In the southern range, diversity of lineages and simulations suggest that hybridization first took place (>7,000 years) in sites characterized by a longer growing season, followed by northerly adjacent sites (ca. 3,500–5,000 years). Moreover, evidence of hybridization occurring in present‐day time was detected. This suggests that the current warming episode is going beyond the limits of the previous warmest period of the Holocene.

This paper presents an analysis of the literature data on the Subantarctic fauna of the benthic Myodocopida, including 97 species. The studied fauna is characterized by a high degree but a low level of endemism. The fauna is based on the species of common genera. Ostracods of the families Cylindroleberididae and Cypridinidae lead in the number of species and genera. With depth increase, species richness of ostracods, and the number of their genera decrease; taxonomic and bathymetric characteristics markedly change. Similarities between the Antarctic and Subantarctic faunas of Myodocopida are evident in the low diversity of species, in the high degree and low rank of endemism, and in the proportion of the number of species and genera in families. Differences between the faunas are defined by significant isolation, by the pattern of vertical distribution, and by the taxonomic structure of myodocopids. The Subantarctic fauna of Myodocopida is completely isolated from the boreal fauna and exceeds it in the number of species and genera but is comparable to the boreal fauna in the number of endemic species. Both faunas are characterized by a high degree but a low level of endemism. Species richness of these faunas depends on different families. With a depth increase the number of myodocopid species decreases in both faunas; myodocopids do not penetrate deeper than 5500 m. [ABSTRACT FROM AUTHOR]

The impact of global warming on the metabolic state of a species may be examined by either measuring physiological rates across a latitudinal gradient or by assessing short‐term responses under experimentally controlled temperature regimes. The combination of the two approaches is seldom used but it provides valuable information on an organism's responses to temperature at broader temporal and spatial scales while allowing the isolation of temperature effects from other environmental variables.Here we used both approaches to assess the warming effects on the total acquisition of dissolved inorganic nitrogen (DIN; nitrate, ammonium) and organic N (DON; amino acids, peptides) by the globally widespread seagrass Zostera marina. DIN and DON uptake rates were measured in plants from three sites covering the species latitudinal distribution in Europe (Iceland, UK and Portugal). The responses of DIN and DON uptake rates of plants from the middle latitude (UK) to a latitudinal range of temperatures (8, 12 and 17°C) were also measured. We further examined the microbial uptake of DON along the latitudinal distribution and whether temperature is the main driver of that uptake.Our results showed that warming greatly increased the total N uptake by Z. marina and also the relative contribution of DON to total N acquisition. The microbial uptake of DON increased towards warmer latitudes, and temperature was the main driver of these observations.Ocean warming will increase the nitrogen demand of Z. marina and this demand may be met by an increasing uptake of organic nitrogen forms. This indicates that Z. marina, and probably other seagrass species, can be winners under global change as nitrogen uptake capacity will not limit growth driven by increased photosynthetic assimilation of CO2. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

The scale Physokermes hellenicus (Kozár & Gounari) (Hemiptera: Coccidae) has been recently included in the Greek entomofauna as a beneficial honeydew species. However, there are no adequate data about its geographical distribution and degree of infestation. Therefore, a study was conducted to examine these parameters in fifteen mountains of Greece. Furthermore, the monitoring of P. hellenicus infestation was carried out over a six-year period with regard to natural enemies and honeydew presence at three mountains (i.e., Menalon, Parnis and Tymfristos) that are traditional honeybee foraging areas. An extensive geographical distribution of the scale was negatively correlated with the latitude. Over the period of the study, P. hellenicus infestation exhibited a decreasing trend in the three mountains, which was more obvious at Menalon. The abundance of natural enemies of P. hellenicus, their effectiveness on honeydew excretion and the fecundity of P. hellenicus are discussed. The reduction in the honey produced at the Menalon mountain (a protected designation of origin product) could be attributed to the reduced presence of P. hellenicus in the fir forest. Among the other identified arthropods, Dreyfusia nordmannianae Eckstein (Hemiptera: Adelgidae) is reported for the first time infesting Abies cephalonica (Pinales: Pinaceae) in Greece. Furthermore, this species is reported for the first time as a co-parasite with P. hellenicus on A. cephalonica in Greece. Since D. nordmannianae is a serious pest, additional research is needed to determine its status in Greek fir forest ecosystems.

Equinoctial asymmetry of the range of the solar quiet day variation (Sq) of the horizontal geomagnetic field (H) has been found in some low latitude geomagnetic observatories. This study conducted an investigation of its latitude distribution and the relationship with the solar cycle by using the H field measurements from six observatories along the 120° E meridian chain in the years 1957–2013. Results illustrate a significant equinoctial asymmetry of the SqH range at all observatories. Three main features were identified. First, the signature of the equinoctial asymmetry of the SqH range is opposite for observatories located at the northern and southern sides of the Northern Hemisphere Sq current focus. It shows larger values around spring than autumn equinox at southern observatories, and the converse is seen at northern observatories. Second, the asymmetry increases with the distance from the Sq current focus, suggesting the stronger sensitivity of the distant observatories than observatories around the focus. The result of linear fitting presents a positive dependence of the asymmetry coefficient on geographic latitude, with a reversal of the asymmetry occurring at 28.1° N near the focus of the average Sq current. Third, there is no obvious dependence of the equinoctial asymmetry of the SqH range on solar activity, suggesting a possible cause from some regional factors related to the ionospheric dynamo process.

Climate warming may affect reproductive isolation between sympatric sister species by modifying reproductive phenology or mate choice. This is expected to result in a latitudinal progression of hybridization in response to the shifting of environmental conditions. The fish species northern redbelly dace (Chrosomus eos) and finescale dace (C. neogaeus) display a wide sympatric distribution in North America. The asexual reproduction of their hybrids allows determining where and when hybridization occurred. The aim of this study was twofold: first, to assess whether temperature affected reproductive isolation, and second, whether the effects of climate warming resulted in a latitudinal progression of hybridization. We performed a 500 km latitudinal survey (51 sites) in southeastern Quebec (Canada) and determined the distribution of clonal hybrid lineages. Results revealed a total of 78 hybrid lineages, including 70 which originated locally. We detected a significant difference between the southern and northern range of the survey in terms of the proportion of sites harboring local hybrids (20/23 vs. 8/28 sites, respectively) and hybrid diversity (57 vs. 13 lineages, respectively). This confirmed that there was more frequent interspecific mating in the warmest sites. In the southern range, diversity of lineages and simulations suggest that hybridization first took place (>7,000 years) in sites characterized by a longer growing season, followed by northerly adjacent sites (ca. 3,500–5,000 years). Moreover, evidence of hybridization occurring in present‐day time was detected. This suggests that the current warming episode is going beyond the limits of the previous warmest period of the Holocene. [ABSTRACT FROM AUTHOR]

Boccardia proboscidea is an exotic polychaete that was introduced to a Southwestern Atlantic Ocean coastal area of Argentina (Mar del Plata; Province of Buenos Aires). This polychaete proved to be a threat to local diversity as it displaced native species and modified the natural intertidal community structure. However, nothing is known about its latitudinal distribution in the country and the degree of its invasion. It is possible that due to deficiencies in taxonomy and lack of ecological studies, other localities of the Argentine coast were also invaded by this polychaete but have not yet been registered. The goal of the present study was to survey the latitudinal distribution of B. proboscidea in the coastal area of Argentina from 37°S to 54°S. In addition, this study aimed to evaluate the type of substrate colonized, investigate the presence of sewage effluence as a conditional factor for B. proboscidea establishment, and evaluate differences in the composition of species assemblages associated with the intertidal community invaded by the polychaete. Boccardia proboscidea was found latitudinally from 37°S to 47°S. The highest abundance was found on hard substrates and with intertidal sewage effluent. The opportunistic nature (r strategy) of B. proboscidea coupled with a continuous supply of organic matter (sewage effluent) may indicate the mechanism that has led to the success of its introduction into new localities. [ABSTRACT FROM AUTHOR]

To study the photosynthetic associations of modern radiolarians, we analyzed plankton samples from waters shallower than 200 m at 30 stations in the western North Pacific. A total of 328 taxa, including morphotypes, were identified from 2091 specimens. The fluorescence patterns under an epifluorescence microscope were mainly classified into five groups: 1) R&D; 2) R-G; 3) Y-B; 4) Periph-R; and 5) Pale-R. There were 37 species/morphotypes with the R&D pattern in the orders Collodaria, Entactinaria, Nassellaria, and Spumellaria. The R-G and Y-B patterns were confirmed in only four species ( Dictyocoryne profunda , D. truncata , Spongaster tetras tetras , S. tetras irregularis ) of our identified 328 taxa, suggesting a strong species-specific effect on the presence of PE-containing Synechococcus -type cyanobacteria. In the Periph-R pattern, red fluorescence is emitted from the peripheral part inside flat spumellarians, suggesting that the source of this pale red fluorescence is photosynthetic organisms digested by radiolarians. In particular, taxa with the R&D pattern can be classified into three groups: 1) obligate associations; 2) facultative associations; and 3) non-associations. Many taxa belonging to Acanthodesmiidae and Lophospyris have a great number of symbiotic dinoflagellates outside the central capsule. However, the Acanthodesmiidae includes non-photosynthetic holobionts ( Amphispyris and Ceratobotrys borealis ), suggesting different environmental adaptability in some acanthodesmiid species. In contrast with the obligate symbiosis tendency in Acanthodesmiidae, the Lophophaenidae tends to have non-photosynthetic holobionts. In Spumellaria, one significant tendency was recognized in Tetrapyle and Phorticium as obligate dinoflagellate holobionts. Thus, Tetrapyle and Phorticium are useful for tracing oceanographic conditions in the euphotic zone. Dictyocoryne truncata and D. profunda are classified into the R-G pattern, whereas D. muelleri was grouped into the R&D pattern, indicating that the difference in the photosynthetic association may be closely related to the dwelling depth. The Q-mode cluster analysis showed that the 30 stations were classified into four clusters: A1, A2, B, and C. The geographical distributions of the four cluster groups are consistent with the climate zone and water masses, suggesting that the species composition of these shallow taxa is influenced by the distribution of water masses. In particular, the Kuroshio Current may play an important role in the migration of shallow living radiolarian species from the subtropical climatic zone to the subarctic climatic zone. [ABSTRACT FROM AUTHOR]

The latitudinal distributions in Devonian–Cretaceous ammonoids were analyzed at the genus level, and were compared with the hatchling sizes (i.e., ammonitella diameters) and the geological durations. The results show that (1) length of temporal ranges of ammonoids effected broader ranges of fossil distribution and paleobiogeography of ammonoids, and (2) the hatchling size was not related to the geographical range of fossil distribution of ammonoids. Reducing the influence of geological duration in this analysis implies that hatchling size was one of the controlling factors that determined the distribution of ammonoid habitats at any given period in time: ammonoids with smaller hatchling sizes tended to have broader ammonoid habitat ranges. These relationships were somewhat blurred in the Devonian, Carboniferous, Triassic, and Jurassic, which is possibly due to (1) the course of development of a reproductive strategy with smaller hatchling sizes in the Devonian and (2) the high origination rates after the mass extinction events.

Background. Abiotic constraints, historical effects of the last glaciation, and differential dispersal, have been proposed as potential explanations to account for the latitudinal decrease in acorn size of wide-ranging oak species distributed in the U.S. and Canada. Hypothesis. We specifically tested the abiotic constraints hypothesis on oak acorn size in a geographical area without the counfounding influence of glaciation and related dispersal history. Data description. Acorns from seven populations of the white oak Quercus rugosa were collected, encompassing the distribution of the species in Mexico. Study site and years of study. Mexico, 2009-2010. Results. Acorn length, width, mass and volume differed significantly among populations and indicated a marked clinal latitudinal reduction in acorn size. A multiple regression model revealed that this reduction in size (measured as acorn volume) can be explained by two important bioclimatic variables (growing season precipitation and growing season degree-days above 5 °C), while spatial variables (latitude and longitude) are not significant. Furthermore, germination percentage was significantly correlated to acorn mass and volume. Conclusions. The main determinants of the latitudinal decline in acorn size are climate factors constraining seed development. This decline is maladaptive for seedling establishment, with important implications for the delination of northern limits of species ranges.

PREMISE OF THE STUDY:: For many plant species, historical climatic conditions may have left lasting imprints that are detectable in contemporary populations. Additionally, if these historical conditions also prevented gene flow among populations, these populations may be differentiated with respect to one another and their contemporary environmental conditions. For the fern, Vittaria appalachiana, one theory is that historical conditions during the Pleistocene largely shaped both the distribution and lack of sporophyte production. Our goals—based on this theory—were to examine physiological differences among and within populations spanning the species’ geographic range, and the contribution of historical climatic conditions to this differentiation. METHODS:: We exposed explants from five populations to four drying treatments and examined differences in physiological response. Additionally, we examined the role of historical and current climatic conditions in driving the observed population differentiation. KEY RESULTS:: Populations differ in their ability to tolerate varying levels of dehydration, displaying a pattern of countergradient selection. Exposure to historical and contemporary climatic conditions, specifically variation in temperature and precipitation regimes, resulted in population divergence observed among contemporary populations. CONCLUSIONS:: Historical conditions have shaped not only the distribution of V. appalachiana, but also its current physiological limitations. Results from this study support the hypothesis that climatic conditions during the Pleistocene are responsible for the distribution of this species, and may be responsible for the observed differences in dehydration tolerance. Additionally, dehydration tolerance may be the driving factor for previously reported patterns of countergradient selection in this species. [ABSTRACT FROM AUTHOR]

Changes in abundance and distribution of anchovy and other species of pelagic fish of the Northern Humboldt Current System (NHCS) are driven by environmental forcing variations in different time and spatial scales between the coastal 'cold' ecosystem and the 'warm' oceanic one. Data to study these fluctuations have come mostly from the fishery to show how anchovy (Engraulis ringens) increases when sardine (Sardinops sagax) declines and vice versa. However, using acoustic data on latitudinal biomass we show that other species as mackerel (Scomber japonicus) and jack mackerel (Trachurus murphyi) also follow the same opposed trend, then the fishery data hides the true dimension of the balance of abundance among species. Based on Hovmoller diagrams we scrutinized the changes in interannual latitudinal acoustic biomass, landings and influence of El Nino events from 1966 to 2009 in order to describe: 1) how the anchovy decadal distribution pattern moved from south to north since the 1960's; 2) how there have been produced concomitant changes in the latitudinal abundance and distribution of other species such as sardine, jack mackerel and mackerel before, during and after El Nino events; and 3) what was the overall effect of the succession of El Nino events on all these pelagic species. We concluded that: a) every El Nino event has had an effect on the expansion or contraction of pelagic species distribution and abundance, with different latitudinal effects; and b) the El Nino 1997-98 did not trigger but accelerated a decline phase on the abundance of sardine, jack mackerel and mackerel by a reduction of their ideal habitat due to an expansion of the coastal ecosystem caused by a shallower location of the upper limit of the Oxygen Minimum Zone (OMZ) These findings observed using past data might be taken into consideration for fishery management purposes when considering future scenarios.Los cambios en la abundancia y distribución de anchoveta y de otras especies de pequenos peces pelágicos de la región norte del Sistema de la Corriente de Humboldt (NHCS) son el producto de la variación de forzantes ambientales en diferentes escalas de tiempo y espacio que influyen entre el ecosistema 'frío' costero y el oceánico 'cálido'. La información para estudiar estas fluctuaciones provienen mayormente de las pesquerías, y muestran que la anchoveta (Engraulis ringens) incrementa su abundancia cuando la de sardina (Sardinops sagax) declina y viceversa. Sin embargo, utilizando datos acústicos de biomasa latitudinal se muestra que otras especies como la caballa (Scomber japonicus) y el jurel (Trachurus murphyi) también siguen la misma tendencia opuesta a anchoveta, lo que en principio indica que los datos pesqueros disponibles no indican la verdadera dimensión del balance de abundancia entre especies. Utilizando diagramas de Hovmoller se analizan los cambios en la biomasa acústica latitudinal, capturas e influencia de eventos El Nino ocurridos entre 1966 y 2009 con el objetivo de describir: 1) cómo el patrón de distribución decadal de anchoveta se movió de sur a norte desde la década de 1960, 2) cómo se han producido cambios concomitantes en la abundancia latitudinal de otras especies tales como sardina, caballa y jurel antes, durante y después de eventos El Nino, y 3) cuál fue el efecto general de la sucesión de eventos El Nino sobre todas estas especies. Se concluye que: a) cada evento El Nino ha tenido un efecto en la expansión o contracción de la distribución de especies pelágicas, con diferente gradiente latitudinal, y b) El Nino 1997-98 no disparó sino aceleró la fase declinante de la abundancia de sardina, caballa y jurel al reducirse el tamano de su hábitat ideal debido a una expansión del hábitat costero que presentó además un acercamiento a la superficie del límite superior de la Zona Mínima de Oxígeno (MOZ). Las observaciones logradas con datos acústicos podrían ser tomadas en consideración para el manejo pesquero al considerar escenarios futuros.

Los cangrejos ermitaños son un grupo representativo de la fauna marina del Caribe colombiano, además, son importantes en el mantenimiento del equilibrio dinámico, en los ecosistemas por sus interacciones ecológicas y también por el impacto en la estabilidad de las redes tróficas. Sus patrones de distribución se identificaron mediante análisis multivariados de clasificación y ordenación espacial, se usaron registros históricos desde 1916 hasta el 2006. Los resultados indican diferencias por profundidad entre la fauna costera y la del talud continental y diferencias en la distribución latitudinal, en donde se encontraron tres grupos: Noreste, Centro y Suroeste, sustentados por diferencias en la composición faunística. Con base en los mapas de ecosistemas marinos de Colombia, se determinó que los principales factores que afectan su distribución son la influencia del talud Caribaná (profundidad), la temperatura de las masas de agua, las praderas de pastos marinos de la Guajira y las condiciones particulares de las ecorregiones Archipiélagos coralinos y Darién. Se identificó la distribución mundial de las especies colombianas y su afinidad geográfica, y se encontró mayor afinidad con el Atlántico norte y las Antillas que con el Atlántico sur y el Golfo de México, asimismo, las subprovincias geográficas que incluyen a Colombia son zonas de transición dentro de la subprovincias septentrionales y australes del Gran CaribeHermit crabs (Anomura: Paguroidea) distribution patterns in the Colombian Caribbean Sea. Hermit crabs represent the marine life in the Colombian Caribbean, and are important for the dynamic equilibrium maintenance in ecosystems, the ecological interactions and their impact on food web stability. Generally, in order to come up with some conservation strategies, strong bio-geographical information is needed for policies definition. With this aim, this study analyzed the distribution patterns of hermit crabs in the Colombian Caribbean Sea, through classification and spatial ordination multivariate analyses, using historical records from years 1916 to 2006. Besides, the world distribution of Colombian species and their geographic affinity in the Caribbean and Western Atlantic were identified. The results show deep differences between coastal and continental slope faunas, and latitudinal differences in the assemblages, with the identification of three groups: Northeast, Center and Southwest. The differences in faunal composition that support these three groups were determined. Based on maps of the Colombian marine ecosystems, it was found that the main factors affecting the distribution of hermit crabs were the Caribaná slope (depth), water-mass temperature, Guajira sea-grass beds, and particular conditions of “Coralline Archipelagos” and “Darién” eco-regions. Colombian hermit crab fauna is more related to the North Atlantic and the Antilles, than to the South Atlantic and the Gulf of Mexico. Additionally, geographical sub-provinces in which Colombia is included, these were found as transition zones among Northern and Austral subprovinces of the Greater Caribbean.

Oceanographic conditions can affect spatial variability in fish community structures by influencing the temperature-dependent latitudinal distribution of adult fishes and transport during their young stages. In order to examine latitudinal variability in the fish community structure within a single coastal ecosystem, quantitative sampling was conducted in the sub-tidal zone of seagrass Zostera marina beds over a broad latitudinal scale (31.31-43.0°N: from subtropical to sub-boreal zones, covering 80% of the latitudinal range of seagrass distribution in Japan) in the western North Pacific based on a uniform methodology. Cluster analysis with the similarity of fish communities showed that 13 sampling sites were divided into two clusters. The border between the two clusters corresponded with the area of mixing of two dominant currents, Oyashio and Kuroshio, which form a border between the warm temperate zone and the cool temperate zone off the Pacific coast of Japan. Oceanographic properties, such as major currents off the coast, are suggested to affect the latitudinal variability in the fish communities in the coastal ecosystem in the western North Pacific. [ABSTRACT FROM AUTHOR]

The study tested the hypothesis that measurement, using multivariate Principal Components Analysis (PCA), of the niche-breadth of river macrophyte species in southern tropical Africa, may predict their larger-scale biogeographical range. Two measures of niche-breadth were calculated for 44 riverine macrophyte species, from 20 families commonly occurring in Zambia, using an approach based on PCA ordination with 16 bio-physico-chemical input variables. These included altitude, stream order, stream flow, pH, conductivity and soluble reactive phosphate concentration (SRP). In the absence of additional chemical water quality data for Zambian rivers, invertebrate-based measures of general water quality were also used. These were benthic macroinvertebrate Average Score per Taxon (ASPT), and individual abundance of nine macroinvertebrate families with differing water quality tolerance, indicated by their Sensitivity Weightings within the Zambian Invertebrate Scoring System (ZISS). Macrophyte large-scale latitudinal range was derived from world geopositional records held by online databases, and additional records held by the authors. The two niche-breadth metrics divided the species into narrow-niche and intermediate/broad-niche categories, showing significant variation (from one or both of correlation and ANOVA test outcomes) in altitude, stream flow, conductivity, SRP, pH and ASPT, but not stream order. Macrophyte alpha-diversity (as a measure of number of individual niches co-existing per habitat) showed no significant relationship with individual species niche-breadth. Narrow-niche species included a higher proportion of Afrotropical endemics than did species with broader niche size. There were significant predictive relationships between macrophyte niche-breadth and latitudinal range of the target species at global and Afrotropical scales, but not for the Neotropics. [ABSTRACT FROM AUTHOR]

Este estudio describe la diversidad, y la distribución latitudinal y batimétrica de los caracoles de la Familia Trochidae en el norte de Chile, mediante muestreos intermareales y submareales someros, realizados entre 1996 y 1999 entre Arica (18º S) y Los Vilos (31º S), y de muestras de profundidad provenientes de la pesca de arrastre del camarón nylon, Heterocarpus reedi. En el norte de Chile, la Familia Trochidae está representada por cuatro géneros: Tegula y Diloma de distribución intermareal y submareal somero hasta los 20 m de profundidad, y Bathybembix y Calliostoma presentes en profundidades superiores a los 200 m. El género Tegula tiene seis especies (T. quadricostata, T. luctuosa, T. ignota, T. atra, T. tridentata y T. euryomphala) distribuídas en sustratos rocosos intermareales y submarales someros. El género Diloma está representado por una especie, D. nigerrima, de distribución intermareal hasta pocos metros de profundidad. El género Calliostoma tiene dos especies C. chilena y C. delli, las que se distribuyen entre 200 y 750 m de profundidad. Finalmente, el género Bathybembix está representado por B. humboldti y B. macdonaldi distribuídas entre 200 y 1480 m de profundidad. Esta segregación batimétrica parece estar relacionada a las estrategias alimentarias de cada uno de los géneros de la familia Trochidae. Diloma y Tegula son herbívoros, las especies del género Bathybembix son alimentadoras de depósito y las de Calliostoma son carnívorasThis study reveals the diversity, and the bathimetric and latitudinal distribution of the snails of the Trochidae family members in northern Chile, throughout the analysis of all Trochidae gastropods entailed in intertidal and subtidal (from the `camarón naylon' fishery) samples collected during 1996 and 1999 between Arica (ca 18º S) and Los Vilos (ca 31º S). The Trochidae family in northern Chile have four genus: Tegula and Diloma that are distributed on intertidal and shallow subtidal habitats, and Calliostoma and Bathybembix which occurr at dephts greather than 200 m. Tegula have 6 species: T. quadricostata, T. luctuosa, T. ignota, T. atra, T. tridentata, and T. euryomphala are distributed on intertidal and shallow subtidal habitats. Diloma is a monospecific genus, whereas D. nigerrima is an intertidal species. The genus Calliostoma have two species C. chilena and C. delli occurring between 200 and 750 m depth and the Bathybembix with two species, B. Humboldti and B. macdonaldi, distributed between 200 and 1480 m depth. The bathimetric distribution of Trochidae shows a strong correlation with food strategy: Diloma and Tegula are herbivores, while Bathybembix species are deposit feeders and Calliostoma are carnivores

Spatial and temporal variation in copepod community structure, abundance, distribution and biodiversity were examined in the western subarctic North Pacific (40-53°N, 144-173°E) during 2001-2013. Continuous Plankton Recorder ( CPR) observational data during the summer season (June and July) were analyzed. The latitudinal distribution of warm-water species in June shifted northward after 2011 while no apparent latitudinal shift of cold-water and other species was observed. Species number and the Shannon-Wiener biodiversity index ( H′) in June tended to increase in the northern area after 2011. The warm-water species abundance and center latitude of warm-water distribution were positively correlated with sea surface temperature ( SST) across sampling locations, whereas no significant correlations with SST were observed for cold-water species or other species. Warm SSTs in June after 2011 appeared to cause the northward shift of warm-water species distribution, which in turn contributed to the higher biodiversity in the northern area. This study demonstrated the rapid response of warm-water species to warm SST variation, whereas cold-water and other species did not exhibit such clear responses. These findings indicate that the response of copepods to environmental changes differs among copepod species, highlighting the importance of investigating lower trophic levels to the species level to evaluate individual species' responses to climate change. [ABSTRACT FROM AUTHOR]

Latitudinal distributions of pelagic chaetognaths from 3-34°N along the 137°E meridian in the Philippine Sea in winter from 1967 to 1995 were studied using the data of oceanographic observations by the Japan Meteorological Agency. Zooplankton was collected at almost every latitudinal degree in every winter (mid-January to early-February) by vertical hauls of a 0.33-mm mesh NORPAC net from 150-m depth. Twenty-six chaetognath species, including four mesopelagic species, were recorded. Flaccisagitta enflata was most abundant, comprising 25%, on average, of the chaetognath community, followed by Serratosagitta pacifica and Pterosagitta draco. The community structure was analyzed according to the following five areas along the survey line: Japan coast area (JC), Kuroshio Current area (KC), subtropical area (ST), North Pacific Equatorial Current area (NEC), and North Pacific Equatorial Counter Current area (NECC). The dominant species were S. pacifica and Mesosagitta minima in JC, Pseudosagitta lyra and Pt. draco in KC and ST, and F. enflata in NEC and NECC. The cluster analysis revealed that the community was generally more similar among the samples from the same area than those from different areas except for KC and ST, which were not separated into different cluster groups. This suggests that the chaetognath communities are location-specific. Multiple comparisons of the mean densities of 17 common species among these areas revealed six distribution types, i.e. JC type, JC-KC type, KC-ST type, NEC-NECC type, NECC types, and bimodal type. Possible mechanisms determining the distribution types, especially the bimodal distribution, are discussed in terms of environmental factors. [ABSTRACT FROM AUTHOR]

Data collected by the International Monitoring System (IMS) during 2009–2012 were used to study influence of precipitation and relative humidity on changes in 7 Be concentrations in atmosphere. The significant decrease in 7 Be concentrations, corresponding to measurements collected by stations located within Intertropical Convergence Zone (ITCZ) is demonstrated. This effect can be attributed to the process of enhanced wet deposition within the ITCZ. To quantify this effect data collected by IMS stations within ITCZ were thoroughly analyzed. It was found that the atmospheric content of 7 Be strongly decreases under the rain conditions. The rain mediated depletion of 7 Be to half of its before rain value, needs about 62 h in case of light precipitation, while in the case of moderate precipitation about 38 h is needed. In addition the evaluated impact of humidity showed that increase in relative humidity by 20%, for example from 70% ± 5% to 90% ± 5% causes almost a double decrease in beryllium concentration in surface air. [ABSTRACT FROM AUTHOR]

Aim Gymnosperms are often described as a marginal and threatened group, members of which tend to be out-competed by angiosperms and which therefore preferentially persist at higher latitudes and elevations. The aim of our synthesis was to test these statements by investigating the global latitudinal and elevational distribution of gymnosperms, as well as their conservation status, using all extant gymnosperm groups (cycads, gnetophytes, ginkgophytes and conifers). Location Worldwide. Methods We developed a database of 1014 species of gymnosperms containing latitudinal and elevational distribution data, as well as their global conservation status, as described in the literature. The 1014 species comprised 305 cycads, 101 gnetophytes, the only living representative of ginkgophytes, and 607 conifers. Generalized additive models, frequency histograms, kernel density estimations and distribution maps based on Takhtajan's floristic regions were used. Results Although the diversity of gymnosperms decreases at equatorial latitudes, approximately 50% of the extant species occur primarily between the tropics. More than 43% of gymnosperms can occur at very low elevations (≤ 200 m a.s.l.). Gymnosperms, considering all species together as well as their main taxonomic groups separately, do not exhibit a latitudinal diversity gradient as commonly observed for many other taxa. Gymnosperms, and especially conifers, are on average less threatened at higher and equatorial latitudes. Main conclusions Gymnosperms display an unusual latitudinal diversity gradient, which we suggest cannot fully be accounted for by angiosperm dominance and competitive superiority. We hypothesize that other factors explain their present distribution, such as the development of centres of endemism in several regions and the adaptation of certain taxa to cold and arid climates. [ABSTRACT FROM AUTHOR]