Southernmost Limit Research Articles

Growth responses to climate and drought at the southernmost European limit of Mediterranean Pinus pinaster forests

Climate warming and increasing aridity may negatively impact forest productivity across southern Europe. A better understanding of growth responses to climate and drought in southernmost populations could provide insight on the vulnerability of those forests to aridification. Here we investigate growth responses to climate and drought in nine Pinus pinaster (maritime pine) stands situated in Andalusia, southern Europe. The effect of climatic variables (temperatures and precipitation) and drought on radial growth was studied using dendrochronology along biogeographic and ecological gradients. We analyzed old native stands with non-tapped and resin-tapped trees mixed, showing their usefulness in dendroclimatic studies. Our results indicate a high plasticity in the growth responses of maritime pine to climate and drought, suggesting that site aridity modulated these responses. The positive growth responses to spring precipitation and the negative responses to summer drought were stronger in the more xeric inland sites than in wet coastal ones, in particular from the 1980s onwards. The characterization of tree species’ responses to climate at the southern or dry limits in relation to site conditions allows improving conservation strategies in drought-prone forest ecosystems.

A new species of small-eared shrew of the genus Cryptotis (Mammalia, Eulipotyphla, Soricidae) from the northernmost Peruvian Andes.

The northernmost Peruvian Andes, a unique biogeographic region characterized by the confluence of multiple distinct ecosystems (i.e. Amazon basin, Pacific rainforest, the Sechura Desert, the northern and central Andes), is the southernmost geographic range limit of the South American shrews representing the genus Cryptotis. In the northernmost Peruvian Andes, two poorly known species have traditionally been reported (C. peruviensis and C. equatoris). Our study, based on molecular and morphologic traits, confirms the presence of C. peruviensis but also the occurrence of C. montivaga, based on specimens erroneously assigned to C. equatoris. Moreover, a new species of Cryptotis from the páramo and montane forests of the Tabaconas Namballe National Sanctuary near the Ecuadorian border is also described. It is a member of the thomasi group and is distinguished from other South American shrews by a unique set of morphological characters, including large body size, comparatively short tail, simple ectoloph of M3, and large PM4 post protocrista.

Sinopsis actualizada de Aristolochia (Aristolochiaceae, Piperales) en Panamá

Antecedentes y Objetivos: Se revisa la taxonomía de las especies panameñas de Aristolochia 57 años después del primer tratamiento del género para la Flora de Panamá. Se actualizan y discuten las novedades taxonómicas, nomenclaturales y corológicas de las especies que se encuentran en Panamá con respecto a la clasificación infragenérica actual.Métodos: Se revisaron los ejemplares de Aristolochia en 35 herbarios, incluidas colecciones efectuadas por el autor principal del trabajo. También se consultaron los ejemplares tipo disponibles en JSTOR Global Plants. Se presenta una clave de identificación y una diagnosis de los grupos infragenéricos y de las especies, 12 de las cuales son ilustradas con fotografías.Resultados clave: Cuatro de las 13 especies reportadas para el tratamiento de la Flora de Panamá (Aristolochia arborescens, A. costaricensis, A. sylvicola y A. veraguensis) se encuentran actualmente subordinadas como sinónimos. En total se reportan 16 especies, dos de ellas (A. cruenta y A. trilabiata) confirmadas como nuevos registros para Panamá. Aristolochia trilabiata, revalidado aquí en reemplazo de A. didyma, constituye el primer reporte de la especie en Mesoamérica. Se revalidan A. schippii, A. sprucei y A. surinamensis, recientemente subordinadas a las sinonimias de A. leuconeura, A. constricta y A. trilobata, respectivamente. Además, A. pfeiferi y A. translucida son confirmadas como sinónimos de A. tonduzii, y A. gorgona y A. securidata como sinónimos de A. grandiflora y A. sprucei, respectivamente. Un total de 13 lectotipos son aquí designados. Finalmente, se discute la presencia de A. constricta, A. gigantea y A. nummularifolia en Panamá.Conclusiones: Las especies de Panamá pertenecen a dos de los tres subgéneros de Aristolochia: A. panamensis, la única especie endémica de Panamá, marca el límite más austral del subgénero Siphisia en el Nuevo Mundo. Las 15 especies restantes pertenecen al subgénero Aristolochia, series Hexandrae (11 spp.) y Thyrsicae (4 spp.).

Increased water-use efficiency translates into contrasting growth patterns of Scots pine and sessile oak at their southern distribution limits.

In forests, the increase in atmospheric CO2 concentrations (Ca ) has been related to enhanced tree growth and intrinsic water-use efficiency (iWUE). However, in drought-prone areas such as the Mediterranean Basin, it is not yet clear to what extent this "fertilizing" effect may compensate for drought-induced growth reduction. We investigated tree growth and physiological responses at five Scots pine (Pinus sylvestris L.) and five sessile oak (Quercus petraea (Matt.) Liebl.) sites located at their southernmost distribution limits in Europe for the period 1960-2012 using annually resolved tree-ring width and δ13 C data to track ecophysiological processes. Results indicated that all 10 natural stands significantly increased their leaf intercellular CO2 concentration (Ci ), and consequently iWUE. Different trends in the theoretical gas-exchange scenarios as a response to increasing Ca were found: generally, Ci tended to increase proportionally to Ca , except for trees at the driest sites in which Ci remained constant. Ci from the oak sites displaying higher water availability tended to increase at a comparable rate to Ca . Multiple linear models fitted at site level to predict basal area increment (BAI) using iWUE and climatic variables better explained tree growth in pines (31.9%-71.4%) than in oak stands (15.8%-46.8%). iWUE was negatively linked to pine growth, whereas its effect on growth of oak differed across sites. Tree growth in the western and central oak stands was negatively related to iWUE, whereas BAI from the easternmost stand was positively associated with iWUE. Thus, some Q.petraea stands might have partially benefited from the "fertilizing" effect of rising Ca , whereas P.sylvestris stands due to their strict closure of stomata did not profit from increased iWUE and consequently showed in general growth reductions across sites. Additionally, the inter-annual variability of BAI and iWUE displayed a geographical polarity in the Mediterranean.

Thermal responses of three native fishes from estuarine areas of the Beagle Channel, and their implications for climate change

The aim of this work was to analyze the thermal responses of Odontesthes nigricans, Eleginops maclovinus and diadromous Galaxias maculatus, key species in estuarine areas of the Beagle Channel (Tierra del Fuego, Argentina), under a climate change scenario. We hypothesized that in the southernmost limit of the species’ distribution, individuals are more likely to be affected by indirect consequences of climate change rather than direct temperature mortality. Their thermal tolerance limits were assessed using the Critical Thermal Methodology and their preferred temperatures, using a thermal gradient. Additionally, the Fulton’s condition factor and the energy density of individuals were analyzed as a proxy of the condition of fishes acclimated to different temperatures. Results showed that species analyzed have the ability to acclimate to the different temperatures, intermediate to large tolerance polygons and positive relationships between preferred and acclimation temperatures, indicating their eurythermic nature. Thus, O. nigricans, E. maclovinus and diadromous G. maculatus populations from Tierra del Fuego could experience enhanced performances because of moderate warming being and, as it was hypothesized, be influenced by indirect consequences of climate change (habitat degradation or changes in trophic structure) since they are living in environments that are widely cooler than their maximum tolerance.

Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species

Six extant species of non-human great apes are currently recognized: Sumatran and Bornean orangutans, eastern and western gorillas, and chimpanzees and bonobos [1]. However, large gaps remain in our knowledge of fine-scale variation in hominoid morphology, behavior, and genetics, and aspects of great ape taxonomy remain in flux. This is particularly true for orangutans (genus: Pongo), the only Asian great apes and phylogenetically our most distant relatives among extant hominids [1]. Designation of Bornean and Sumatran orangutans, P.pygmaeus (Linnaeus 1760) and P.abelii (Lesson 1827), as distinct species occurred in 2001 [1, 2]. Here, we show that an isolated population from Batang Toru, at the southernmost range limit of extant Sumatran orangutans south of Lake Toba, is distinct from other northern Sumatran and Bornean populations. By comparing cranio-mandibular and dental characters of an orangutan killed in a human-animal conflict to those of 33 adult male orangutans of a similar developmental stage, we found consistent differences between the Batang Toru individual andother extant Ponginae. Our analyses of 37 orangutan genomes provided a second line of evidence. Model-based approaches revealed that the deepestsplit in the evolutionary history of extant orangutans occurred ∼3.38 mya between the Batang Toru population and those to the north of Lake Toba,whereas both currently recognized species separated much later, about 674 kya. Our combinedanalyses support a new classification of orangutans into three extant species. The new species, Pongo tapanuliensis, encompasses the Batang Toru population, of which fewer than 800 individuals survive. VIDEO ABSTRACT.

Wood density of silver fir reflects drought and cold stress across climatic and biogeographic gradients

Climate influences wood density and this relationship affects the ability of conifer forests to uptake and store carbon. Some conifer species can show mixed responses to long-term climate variability in their within-ring width and density patterns. Here we analyze if tree-ring width and density differently respond to seasonal climate variability in silver fir (Abies alba) forests from the Spanish Pyrenees subjected to cold and Mediterranean influences. In these forests, early growing-season dry conditions increase minimum wood density, possibly by reducing lumen diameter and lowering growth rates. Cold conditions during the late growing season are associated to a decrease in maximum wood density, probably through a reduction in the lignification and thickening rates of latewood tracheids. We test if these associations follow climatic and biogeographic patterns since the Mediterranean influence, characterized by late-summer storms which alleviate drought stress, is prevalent eastwards in this region. Silver-fir intra-annual width and wood density data showed mixed responses to climate. Minimum wood density negatively responded to spring precipitation, particularly in dry sites forming the southernmost distribution limit of the species. Maximum wood density positively responded to mean maximum temperatures and sunshine duration during late summer and early autumn, mainly in eastern sites subjected to a dominant Mediterranean influence where late-summer drought stress is expected to be low. More extreme climate conditions including dry spells could shift minimum wood density and reduce hydraulic conductivity and growth in conifer species as silver fir which dominate mesic sites. Warmer conditions would lead to denser latewood in silver fir if accompanied by longer durations of sunshine.

First contribution to the study of the ants (Hymenoptera, Formicidae) of the Ζagοri region (Epirus, Greece): Αn annotated list of species

The paper contains records of 33 ant species collected in the Zagori region of Northwestern Greece in 1979 and 1981. These are the first records of ants from this region. Some notes on their morphology and ecology are included. An analysis of the general distribution of the species shows that the influence of the Mediterranean, South European, Asiatic and Pontic elements is approximately equal. For some species the region is the southernmost limit in the Balkans. Seven species were observed only over l000 m. while three of them were observed only over 1400m. Most species arc either insectivores or omnivores. Omnivores and species with Mediterranean or South European distribution predominate in or near human settlements.

The ectomycorrhizae of Lactarius rimosellus and Lactarius acatlanensis with the endangered Fagus grandifolia var. mexicana

In the mountains of Veracruz State (east of Mexico), the southernmost limit of Fagus in the Americas, two relict forests of F. grandifolia var. mexicana were visited between 2007 and 2009 and 2013–2014, in order to study the ectomycorrhizal (EcM) systems of these trees with Lactarius rimosellus (L. subg. Russularia) and with L. acatlanensis (L. subg. Lactarius). We confirmed their EcM association through comparison of the internal transcribed spacer (ITS) of nuclear ribosomal DNA sequences from the mycobiont in the ectomycorrhizal systems and basidiomes sampled in the forest stands. The phytobiont in the ectomycorrhizae was also identified through the comparison of ITS sequences from EcM root tips and leaves of F. grandifolia var. mexicana. Detailed descriptions on the morphology and anatomy of EcM systems and microscopical features of mantle layers and Hartig net are presented and illustrated.

Contrasting Hydraulic Architectures of Scots Pine and Sessile Oak at Their Southernmost Distribution Limits.

Many temperate European tree species have their southernmost distribution limits in the Mediterranean Basin. The projected climatic conditions, particularly an increase in dryness, might induce an altitudinal and latitudinal retreat at their southernmost distribution limit. Therefore, characterizing the morphological and physiological variability of temperate tree species under dry conditions is essential to understand species’ responses to expected climate change. In this study, we compared branch-level hydraulic traits of four Scots pine and four sessile oak natural stands located at the western and central Mediterranean Basin to assess their adjustment to water limiting conditions. Hydraulic traits such as xylem- and leaf-specific maximum hydraulic conductivity (KS-MAX and KL-MAX), leaf-to-xylem area ratio (AL:AX) and functional xylem fraction (FX) were measured in July 2015 during a long and exceptionally dry summer. Additionally, xylem-specific native hydraulic conductivity (KS-N) and native percentage of loss of hydraulic conductivity (PLC) were measured for Scots pine. Interspecific differences in these hydraulic traits as well as intraspecific variability between sites were assessed. The influence of annual, summer and growing season site climatic aridity (P/PET) on intraspecific variability was investigated. Sessile oak displayed higher values of KS-MAX, KL-MAX, AL:AX but a smaller percentage of FX than Scots pines. Scots pine did not vary in any of the measured hydraulic traits across the sites, and PLC values were low for all sites, even during one of the warmest summers in the region. In contrast, sessile oak showed significant differences in KS-MAX, KL-MAX, and FX across sites, which were significantly related to site aridity. The striking similarity in the hydraulic traits across Scots pine sites suggests that no adjustment in hydraulic architecture was needed, likely as a consequence of a drought-avoidance strategy. In contrast, sessile oak displayed adjustments in the hydraulic architecture along an aridity gradient, pointing to a drought-tolerance strategy.

Do the arthropod communities on a parasitic plant and its hosts differ?

Parasitic plants growing on tree branches may be a novel niche and phytoresource for arthropods. The spatial continuity between hosts and their parasites in canopies might provide a homogeneous environment for arthropod communities, but differences in mistletoe leaves and host needles could be exploited by different species of arthropods. Therefore, it is important to determine insect-community assemblages in order to discover the role of parasitic plants as a different habitat for arthropods. Thus, we aim to evaluate the level of similarity between the arthropod community on mistletoe (Viscum album) and that on its two principal pine hosts, Black pine (Pinus nigra) and Scots pine (P. sylvestris), on a Mediterranean mountain. Our results reveal that, irrespective of the species of pine host, V. album has a stable, independent and simple arthropod trophic web, composed mainly of two specialist hemipteran herbivores, Cacopsylla visci (Psyllidae) and Pinalitus viscicola (Miridae), and a hemipteran predator, Anthocoris visci (Anthocoridae). Despite this, the composition of the arthropod communities differed significantly on both host species, with a greater richness and diversity on Scots than Black pine and these differences are not reflected in the community on mistletoe. Overall, we conclude that, although Viscum album is considered to be a pest of pine, its presence increases the heterogeneity of the forest canopy by providing a novel habitat for a new and specific community of arthropods. In addition, this is a new record for and most probably an extension of the southernmost limit of the known geographical distribution of the arthropod community inhabiting V. album.

Rediscovery of Sporophila frontalis (Verreaux, 1869) (Aves, Thraupidae) in the state of Rio Grande do Sul, southern Brazil

The Buffy-fronted Seedeater, Sporophila frontalis (Verreaux, 1869) (Aves, Thraupidae), is a threatened passerine endemic to the Atlantic Forest of southeastern South America. Habitat loss and illegal capture for the pet trade has reduced the geographical distribution of this species. The Brazilian state of Rio Grande do Sul represents the southernmost limit of this species’ range. There, S. frontalis was last recorded in 1883, and currently this species is thought to be as extirpated in this state. After 133 years, we report photographic and audiotape records of S. frontalis, made in the municipalities of Maquiné and Mampituba, Rio Grande do Sul.

Assessing forest vulnerability to climate warming using a process-based model of tree growth: bad prospects for rear-edges.

Growth models can be used to assess forest vulnerability to climate warming. If global warming amplifies water deficit in drought-prone areas, tree populations located at the driest and southernmost distribution limits (rear-edges) should be particularly threatened. Here, we address these statements by analyzing and projecting growth responses to climate of three major tree species (silver fir, Abies alba; Scots pine, Pinus sylvestris; and mountain pine, Pinus uncinata) in mountainous areas of NE Spain. This region is subjected to Mediterranean continental conditions, it encompasses wide climatic, topographic and environmental gradients, and, more importantly, it includes rear-edges of the continuous distributions of these tree species. We used tree-ring width data from a network of 110 forests in combination with the process-based Vaganov-Shashkin-Lite growth model and climate-growth analyses to forecast changes in tree growth during the 21st century. Climatic projections were based on four ensembles CO2 emission scenarios. Warm and dry conditions during the growing season constrain silver fir and Scots pine growth, particularly at the species rear-edge. By contrast, growth of high-elevation mountain pine forests is enhanced by climate warming. The emission scenario (RCP 8.5) corresponding to the most pronounced warming (+1.4 to 4.8°C) forecasted mean growth reductions of -10.7% and -16.4% in silver fir and Scots pine, respectively, after 2050. This indicates that rising temperatures could amplify drought stress and thus constrain the growth of silver fir and Scots pine rear-edge populations growing at xeric sites. Contrastingly, mountain pine growth is expected to increase by +12.5% due to a longer and warmer growing season. The projections of growth reduction in silver fir and Scots pine portend dieback and a contraction of their species distribution areas through potential local extinctions of the most vulnerable driest rear-edge stands. Our modeling approach provides accessible tools to evaluate forest vulnerability to warmer conditions.

Population genetic structure and demographic history of the spadefish, Chaetodipterus faber (Ephippidae) from Southwestern Atlantic

Genetic diversity, population structure and demographic history of Chaetodipterus faber in SW Atlantic were investigated using mitochondrial DNA cytochrome c oxidase subunit I (620 bp) and D-loop (817 bp) sequences. Individuals were collected in five sampling units (SUs) located in latitudes between 2 °S and 27 °S, southernmost limit of species distribution. The COI sequences from Brazilian sampling units were compared with eight sequences from the Gulf of Mexico and Caribbean, resulting in no significant genetic differences (K2P<0.32%). On the contrary, pairwise FST analysis based on D-loop datasets from the five SUs indicated divergence between Tropical and Subtropical clades of SW Atlantic C. faber. The SAMOVA approach was consistent with this divergence and revealed maximal variance among groups (63.59%) when two clades are simulated (k=2), setting apart Tropical and Subtropical SUs. Demographic analyses support the hypothesis of population expansion, both for Tropical and Subtropical clades. Moreover, Subtropical population size increase was dated after the Tropical clade reached the demographic stability, around 10kyr ago, during the beginning of interglacial Pleistocene–Holocene transition. The historical demographic results, along with the lower genetic diversity and the star-shaped haplotype network of the Subtropical clade corroborate an ancient scenario of the species' adaptive radiation southward.

Histology and gametogenesis in Heleobia piscium (Cochliopidae) from the Multiple Use Reserve "Isla Martín García," Buenos Aires, Argentina.

Heleobia piscium (d’Orbigny, 1835), a member of the Cochliopidae family found only in South America, is distributed from Entre Ríos, Delta del Paraná, and the littoral of the Río de la Plata down as far as to Punta Indio (Buenos Aires), the southernmost limit of the snail’s geographical distribution. To date, little information is available regarding the reproductive cycle of species within this family either in Argentina or throughout South America. The present work analyzed the histology of the reproductive system of the gonochoric species H. piscium and determined the stages oogenesis and spermatogenesis under natural conditions. Specimens of H. piscium were collected in the Multiple-Use Natural Reserve Isla Martín García, located in the Upper Río de la Plata estuary to the south of the mouth of the Uruguay River. The gametogenic cycle in both sexes was found to consist of the following stages: early maturation, maturation, and evacuation. The maturation period was found to extend from January to October and evacuation of the gametes to start in November and end in February (summer in the Southern Hemisphere). The results indicated the H. piscium exhibit a reproductive cycle without a resting period.

A naturally-occurring 'cold earth' spot in Northern China.

Permafrost is determined to a large extent by the Earth’s surface temperature, therefore it distributes mainly in high altitude and latitude regions. However, stable, warm (about −1 °C) permafrost occurs within a scree slope in northern China that is more than 600 km south of the southernmost limit of latitudinal permafrost on the Eurasian Continent. It is at an elevation of only 900 m above sea level (ASL). The area has a mean annual air temperature (MAAT) of 6 to 8 °C. Thermal processes of the scree slope, investigated through field monitoring and numerical simulation, showed that the permafrost is caused by winter air convection within the porous rock deposits and is stable as air convection does not occur in summer time. The deposit is covered by a 30-cm-thick peaty soil layer dated (carbon C-14) to between 1,000 to 1,600 years ago. The layer also contributes to the permafrost’s existence due to the peat’s thermal conductivity offset when frozen and thawed. The existence of permafrost under such warm climatic conditions confirms the effectiveness of using crushed rock layer as basement or slope cover to protect the warm permafrost subgrade of the recently-constructed Qinghai-Tibet Railway (QTR), even under the predicted climate warming conditions.

Purifying Selection, Density Blocking and Unnoticed Mitochondrial DNA Diversity in the Red Deer, Cervus elaphus.

The trajectories of postglacial range expansions, the occurrence of lineage patches and the formation and maintenance of secondary contact between lineages may mostly reflect neutral demographic processes, including density blocking, that may leave long-lasting genetic signatures. However, a few studies have recently shown that climate may also play a role. We used red deer, a large, mobile herbivore that is assumed to be sensitive to climate change, to test hypotheses of possible selection on the mitochondrial DNA cytochrome b gene (mtDNA cytb) and competitive and/or density-blocking (using mtDNA control region). We searched for a possible link between the phylogeographic structure and abiotic climatic variables. Finally, we tested for isolation by distance and isolation by environment and assessed the impact of human-mediated translocations on the genetic structure of red deer. Our analysis of 30 red deer populations in Poland using the mtDNA control region (N = 357) and cytochrome b (N = 50) markers not only confirmed the presence of the Western and South-Eastern lineages of the species but also indicated the presence of a previously unnoticed, rare relic haplotype that grouped together C. e. italicus from Italy (the Mesola deer). No significant signs of positive selection were detected for the mtDNA cytb gene in the studied red deer. However, a significant signal for purifying selection was found in our study that may explain the narrowness of the contact zone because gene flow between the Western and South-Eastern lineages should drive relatively strong mito-nuclear incompatibilities. MtDNA control region differentiation among red deer populations in Poland correlated with different abiotic climatic variables. Strikingly, the southernmost ice sheet limits during the Elsterian was the most important factor, and it explained the largest amount of variation. However, neither isolation by distance (IBD) nor isolation by environment (IBE) were recorded, and a very limited impact of human translocations was evident. The above-mentioned results suggest that in contemporary red deer populations in Poland, the phylogeographic pattern is well preserved, and long-term processes (density and/or competitive blocking) still play a major role.

Genetic diversity and population history of the Killarney fern,Vandenboschia speciosa(Hymenophyllaceae), at its southern distribution limit in continental Europe

The improvement of the conservation and management strategies of endangered species requires an understanding of the history and current state of their populations and thus population genetic studies become essential. This situation is especially critical for the relict populations at the low-latitude limit of the species range, which have persisted at suitable sites across Tertiary and Quaternary climatic changes and are expected to have retained a high proportion of the genetic diversity of the species. Here we investigate the genetic diversity and structure of Vandenboschia speciosa, a vulnerable endemic European-Macaronesian species with a disjunct distribution, at its southernmost distribution limit in continental Europe (S Iberian Peninsula: Andalusia, Spain). We analysed six sporophyte populations from the eight known populations using ten microsatellite loci. The results indicated moderate genetic diversity at the regional scale but low diversity at the population level and a significant genetic differentiation between populations. Coalescent analyses revealed a population history in Andalusia characterized by a migration-drift equilibrium with historical dispersals as the main factors influencing population structure, but now predominately influenced by genetic drift, according to the genetic differentiation detected. Spatial autocorrelation and genetic-structure analyses (multivariate and STRUCTURE analyses) suggest that historic gene flow was mainly over short distances, since significant genetic relationships were detected between pairs of nearby populations (< 7 km). Only one population, the most diverse, shows evidence of long-distance dispersal. This study provides a baseline for designing appropriate conservation strategies for V. speciosa in Andalusia, where the regional government has recently approved a recovery and conservation plan.

New Record ofSchmitzia hiscockianaMaggs &amp; Guiry (Rhodophyta, Florideophyceae) in the Bay of Morlaix, Brittany, France

Abstract The red alga Schmitzia hiscockiana Maggs & Guiry is reported for Brittany for the first time. Our finding point to the southernmost limit of geographic distribution of this species. Molecular sequences (COI-5P, psbA, rbcL and LSU) are provided for the species and molecular phylogeny resolved Schmitzia hiscockiana along with two unidentified australian species of Schmitzia as sister to the lineage encompassing the Acrosymphytales and the Ceramiales.

Ground beetles (Coleoptera: Carabidae) inhabiting anthropogenic habitats in the lower delta of the Paraná river, Argentina: geographic distribution and ecological characteristics

AbstractThe primary aims of this paper were to provide the first inventory of carabid beetles collected in five different anthropogenic habitat types of the Lower Delta of the Paraná River, to describe their main ecological characteristics and to provide information on their distribution range in ecoregions, subregions and ecosystem complexes of Argentina and across the Neotropical region. Species were grouped according to six classes of distributions in relation to their presence in the Delta of the Paraná River. In addition, rarefaction curves were built in order to compare the seasonal species richness. We collected 1486 individuals belonging to 48 species. The southernmost distribution limit of 50% of the species is located south of the Delta region. Moreover, 21% of the species are confined to the Delta and Islands of the Parana and Uruguay Rivers ecoregion and to localities within the neighbouring ecoregions of Espinal and Pampa. Most (63%) of the species were zoophagous and 25% were either omnivorous or seed eaters; 52% were hydrophilous, 44% mesophilous and one was xerophilous. The high number of species found in this ecoregion emphasising its importance as a biodiversity hotspot of South American carabids. Human activities have led to changes in the landscape of the Delta Islands which could favour the establishment of mesophilous and xerophilous species from other ecoregions. Seasonal carabid richness is higher in the warm seasons (spring and summer) compared with the cold seasons (autumn and winter). Although, the highest absolute richness was found in the most anthropised habitat types, secondary forests had exclusive species, showing the importance of preserving the ecological mosaic of the landscape.