Inconsistent interspecific and intraspecific differentiation of climate envelopes in a subtropical tree

AimsComparisons of climate envelopes among species have shown that niche conservatism tends to break down over time. Here, we use the Asian tree genusPlatycarya(Juglandaceae) as a case study to test this tendency at relatively short timescales in a single lineage. This, together with a reanalysis of the extant literature, should help evaluate prospects of using correlations between climate and species occurrence data to infer evolutionary processes.     

Phylogeography and genetic structure of the red-legged partridge (Alectoris rufa): more evidence for refugia within the Iberian glacial refugium

The Pleistocene climatic oscillations promoted the diversification in avian species during the last glacial period. The red‐legged partridge (Alectoris rufa, Family Phasianidae) has a large natural distribution extending from the Mediterranean to humid temperate zones. However, the genetic structure for this species is unknown. The present study investigates the phylogeography, genetic structure and demographic history of A. rufa across its distribution, employing both mitochondrial DNA control region sequences and nuclear microsatellite loci. Our results propose that this species was greatly affected by Pleistocene glaciations. The mismatch analyses suggest that the current populations resulted from post‐glacial expansion and subsequent differentiation resulting in five diagnosable genetic clusters: Southwestern, Central‐eastern, Northwestern, Balearic and French and Italian. Further, we found evidence of three glacial refugia within the currently recognized Iberian glacial refugium. The intraspecific structure revealed by both maternal and biparental phylogeographic analyses was not resolved in the phylogenetic analyses. Based on all considerations, we recommended that five management units be recognized.     

The role of glacial cycles in promoting genetic diversity in the Neotropics: the case of cloud forests during the Last Glacial Maximum

The increasing aridity during the Last Glacial Maximum (LGM) has been proposed as a major factor affecting Neotropical species. The character and intensity of this change, however, remains the subject of ongoing debate. This review proposes an approach to test contrasting paleoecological hypotheses by way of their expected demographic and genetic effects on Neotropical cloud forest species. We reviewed 48 paleoecological records encompassing the LGM in the Neotropics. The records show contrasting evidence regarding the changes in precipitation during this period. Some regions remained fairly moist and others had a significantly reduced precipitation. Many paleoecological records within the same region show apparently conflicting evidence on precipitation and forest stability. From these data, we propose and outline two demographic/genetic scenarios for cloud forests species based on opposite precipitation regimes: the dry refugia and the moist forests hypotheses. We searched for studies dealing with the population genetic structure of cloud forest and other montane taxa and compared their results with the proposed models. To date, the few available molecular studies show insufficient genetic evidence on the predominance of glacial aridity in the Neotropics. In order to disentangle the climatic history of the Neotropics, the present study calls for a general multi‐disciplinary approach to conduct future phylogeographic studies. Given the contradictory paleoecological information, population genetic data on Neotropical cloud forest species should be used to explicitly test the genetic consequences of competing paleoecological models.     

Global patterns of species richness of the holarctic alpine herb Saxifraga: the role of temperature and habitat heterogeneity

北半球高山和极地虎耳草属物种丰富度的地理格局：温度和生境异质性的作用 现代气候、生境异质性和长期气候变化对森林生态系统中分布的木本植物的物种丰富度格局的影响在以往研究中受到广泛关注,但对高寒-极地生态系统中的草本植物物种丰富度格局及其影响因素的研究仍较少。本研究旨在检验以往研究中基于物种丰富度和环境因子关系提出的假说是否能够解释高寒-极地地区典型草本植物-虎耳草属(Saxifraga)的物种丰富度格局。本研究利用全球437种虎耳草属物种分布数据,探讨了全部物种、广域和狭域物种丰富度格局的影响因素。采用广义线性模型和空间自回归模型,评估了现代气候、生境异质性和历史气候对虎耳草属物种丰富度格局的影响。采用偏回归分析了不同变量对物种丰富度的独立解释率和共同解释率,并检验了4种广泛使用的物种丰富度与环境关系模型对物种丰富度格局的解释能力。研究结果表明,温度与虎耳草属所有物种和广域物种的物种丰富度格局呈显著负相关关系,是影响物种丰富度格局最重要的环境因子,这可能反映了虎耳草属对其祖先温带生态位的保守性。生境异质性和末次冰期以来的气候变化是虎耳草属狭域物种丰富度空间变异的最佳预测因子。总体而言,包含5个预测变量的组合模型可以解释大约40%–50%的虎耳草属物种丰富度的空间变异。此外,进化和生物地理过程在虎耳草属物种丰富度格局形成方面可能发挥了重要作用,这有待进一步研究。     

Genetic differentiation of the tephritid fly Urophora cardui in Europe as evidence for its biogeographical history

Gaps in the large-scale distribution of the tephritid fly Urophora cardui in Europe have been explained as the results of an ongoing re-immigration from Pleistocene refugia due to a very low dispersal capacity. Following evidence of a much greater dispersal capacity of U. cardui than previously assumed, the pattern of genetic differentiation of 41 populations from 16 European regions was studied using allozyme electrophoresis. In these analyses 18 enzyme systems were scored consistently providing 27 alleles. Allozyme variation indicated high gene flow and low levels of genetic differentiation within and between sampling regions as well as in recently colonized areas. No geographical pattern of heterozygosity or allozyme differentiation could be found matching the previously suggested recent immigration pattern. An observed south-north gradient in allozyme frequencies was interpreted as a geographical cline due to environmental factors. The results corroborate evidence from more recent studies that U. cardui is a highly mobile species which is likely to have repeatedly colonized some suboptimal European regions since the Pleistocene after retreats during 'little ice ages'. Patterns resulting from postglacial immigration processes are likely to have been long wiped out through high exchange rates.     

Climate change at the landscape scale: predicting fine-grained spatial heterogeneity in warming and potential refugia for vegetation

Current predictions of how species will respond to climate change are based on coarse‐grained climate surfaces or idealized scenarios of uniform warming. These predictions may erroneously estimate the risk of extinction because they neglect to consider spatially heterogenous warming at the landscape scale or identify refugia where species can persist despite unfavourable regional climate. To address this issue, we investigated the heterogeneity in warming that has occurred in a 10 km × 10 km area from 1972 to 2007. We developed estimates by combining long‐term daily observations from a limited number of weather stations with a more spatially comprehensive dataset (40 sites) obtained during 2005–2006. We found that the spatial distribution of warming was greater inland, at lower elevations, away from streams, and at sites exposed to the northwest (NW). These differences corresponded with changes in weather patterns, such as an increasing frequency of hot, dry NW winds. As plant species were biased in the topographic and geographic locations they occupied, these differences meant that some species experienced more warming than others, and are at greater risk from climate change. This species bias could not be detected at coarser scales. The uneven seasonal nature of warming (e.g. more warming in winter, minimums increased more than maximums) means that climate change predictions will vary according to which predictors are selected in species distribution models. Models based on a limited set of predictors will produce erroneous predictions when the correct limiting factor is not selected, and this is difficult to avoid when temperature predictors are correlated because they are produced using elevation‐sensitive interpolations. The results reinforce the importance of downscaling coarse‐grained (∼50 km) temperature surfaces, and suggest that the accuracy of this process could be improved by considering regional weather patterns (wind speed, direction, humidity) and topographic exposure to key wind directions.     

Eelgrass meadows in the California Channel Islands and adjacent coast reveal a mosaic of two species, evidence for introgression and variable clonality

BACKGROUND AND AIMS: Seagrasses are important facilitator species in shallow, soft-bottom marine environments worldwide and, in many places, are threatened by coastal development and eutrophication. One narrow-leaved species (Zostera marina) and one wide-leaved species, variously designated as Z. marina, Z. pacifica or Z. asiatica, are found off the California Channel Islands and adjacent California-Mexico coast. The aim of the present study was to confirm species identification genetically and to link patterns of genetic diversity, connectivity and hybridization among and within the populations with historical sea levels (Ice Age) or the contemporary environment. METHODS: Samples (n = 11-100) were collected from 28 sites off five California Channel Islands and six sites off the adjacent coast of southern California and Baja California, Mexico. DNA polymorphisms of the rDNA-ITS (internal transcribed spacer) cistron (nuclear), the matK intron (chloroplast) and nine microsatellite loci (nuclear) were examined in a population genetic and phylogeographic context. KEY RESULTS: All wide-leaved individuals were Z. pacifica, whereas narrow-leaved forms were Z. marina. Microsatellite genotypes were consistent with hybridization between the two species in three populations. The present distribution of Z. pacifica follows a glacial age land mass rather than present oceanographic regimes, but no link was observed between the present distribution of Z. marina and past or present environments. Island populations of Z. marina often were clonal and characterized by low genotypic diversity compared with populations along the Baja California coast. The high level of clonal connectivity around Santa Catalina Island indicated the importance of dispersal and subsequent re-establishment of vegetative fragments. CONCLUSIONS: The pristine environmental conditions of offshore islands do not guarantee maximum genetic diversity. Future restoration and transplantation efforts of seagrasses must recognize cryptic species and consider the degree of both genetic and genotypic variation in candidate donor populations.     

Evolutionary history of Caenorhabditis elegans inferred from microsatellites: evidence for spatial and temporal genetic differentiation and the occurrence of outbreeding

Although diverse biological disciplines employ the nematode Caenorhabditis elegans as a highly efficient laboratory model system, little is known about its natural history. We investigated its evolutionary past using 10 polymorphic trinucleotide and tetranucleotide microsatellites, derived from across the whole genome. These microsatellites were analyzed from the 35 previously available natural isolates from different parts of the world and also 23 new strains isolated from northwest Germany. Our results highlight that C. elegans lineages differentiate genetically with respect to geographic distance and, to a lesser extent, differences in the time of strain isolation. The latter indicates some turnover of strain genotypes at specific locations. Our data also demonstrate the coexistence of highly diverse genotypes in the population from northwest Germany, which is best explained by recent migration events. Furthermore, selfing is confirmed as the primary mode of reproduction for this hermaphroditic nematode in nature. Importantly, we also find evidence for the occurrence of occasional outbreeding. Taken together, these results support the previous notion that C. elegans is a colonizer, whereby selfing may permit rapid dispersal within new habitats even in the absence of potential mates, whereas occasional outcrossing may serve to compensate for the disadvantages of inbreeding. Such information about the natural history of C. elegans should be of great value for an in-depth understanding of the complexity of this organism, including its multifaceted developmental, neurological, or molecular genetic pathways.     

Genetic and palaeo-climatic evidence for widespread persistence of the coastal tree species Eucalyptus gomphocephala (Myrtaceae) during the Last Glacial Maximum

Background and Aims

Few phylogeographic studies have been undertaken of species confined to narrow, linear coastal systems where past sea level and geomorphological changes may have had a profound effect on species population sizes and distributions. In this study, a phylogeographic analysis was conducted of Eucalyptus gomphocephala (tuart), a tree species restricted to a 400 × 10 km band of coastal sand-plain in south west Australia. Here, there is little known about the response of coastal vegetation to glacial/interglacial climate change, and a test was made as to whether this species was likely to have persisted widely through the Last Glacial Maximum (LGM), or conforms to a post-LGM dispersal model of recovery from few refugia.

Methods

The genetic structure over the entire range of tuart was assessed using seven nuclear (21 populations; n = 595) and four chloroplast (24 populations; n = 238) microsatellite markers designed for eucalypt species. Correlative palaeodistribution modelling was also conducted based on five climatic variables, within two LGM models.

Key Results

The chloroplast markers generated six haplotypes, which were strongly geographically structured (G_ST = 0·86 and R_ST = 0·75). Nuclear microsatellite diversity was high (overall mean H_E 0·75) and uniformly distributed (F_ST = 0·05), with a strong pattern of isolation by distance (r² = 0·362, P = 0·001). Distribution models of E. gomphocephala during the LGM showed a wide distribution that extended at least 30 km westward from the current distribution to the palaeo-coastline.

Conclusions

The chloroplast and nuclear data suggest wide persistence of E. gomphocephala during the LGM. Palaeodistribution modelling supports the conclusions drawn from genetic data and indicates a widespread westward shift of E. gomphocephala onto the exposed continental shelf during the LGM. This study highlights the importance of the inclusion of complementary, non-genetic data (information on geomorphology and palaeoclimate) to interpret phylogeographic patterns.     

Evolution and Conservation of Central African Biodiversity: Priorities for Future Research and Education in the Congo Basin and Gulf of Guinea

The tropical forests of the Congo Basin and Gulf of Guinea harbor some of the greatest terrestrial and aquatic biological diversity in the world. However, our knowledge of the rich biological diversity of this region and the evolutionary processes that have shaped it remains limited, as is our understanding of the capacity for species to adapt or otherwise respond to current and projected environmental change. In this regard, research efforts are needed to increase current scientific knowledge of this region's biodiversity, identify the drivers of past diversification, evaluate the potential for species to adapt to environmental change and identify key populations for future conservation. Moreover, when evolutionary research is combined with ongoing environmental monitoring efforts, it can also provide an important set of tools for assessing and mitigating the impacts of development activities. Building on a set of recommendations developed at an international workshop held in Gabon in 2011, we highlight major areas for future evolutionary research that could be directly tied to conservation priorities for the region. These research priorities are centered around five disciplinary themes: (1) documenting and discovering biodiversity; (2) identifying drivers of evolutionary diversification; (3) monitoring environmental change; (4) understanding community and ecosystem level processes; (5) investigating the ecology and epidemiology of disease from an evolutionary perspective (evolutionary epidemiology). Furthermore, we also provide an overview of the needs and priorities for biodiversity education and training in Central Africa.     

Molecular phylogeography of the nose-horned viper (Vipera ammodytes, Linnaeus (1758)): evidence for high genetic diversity and multiple refugia in the Balkan peninsula

The nose-horned viper (Vipera ammodytes) occurs in a large part of the south-eastern Europe and Asia Minor. Phylogenetic relationships were reconstructed for a total of 59 specimens using sequences from three mitochondrial regions (16S and cytochrome b genes, and control region, totalling 2308 bp). A considerable number of clades were observed within this species, showing a large genetic diversity within the Balkan peninsula. Splitting of the basal clades was evaluated to about 4 million years ago. Genetic results are in contradiction with presently accepted taxonomy based on morphological characters: V. a. gregorwallneri and V. a. ruffoi do not display any genetic difference compared with the nominotypic subspecies (V. a. ammodytes), involving that these subspecies can be regarded as synonyms. High genetic divergence in the central part of the Balkan peninsula is not concordant with low morphological differentiation. Finally, the extensive genetic diversity within the Balkan peninsula and the colonisation routes are discussed.     

Insights into wolf presence in human‐dominated landscapes: the relative role of food availability,humans and landscape attributes

Aim Understanding which human or environmental factors interact to enable or to limit the occurrence and persistence of large carnivores in human‐dominated landscapes is an important issue for their effective conservation, especially under the current scenario of global change where most of their former habitat is being transformed by humans. Location NW Iberian Peninsula. Methods We combine data on the distribution of Iberian wolves (Canis lupus signatus) living in a human‐dominated landscape in NW Spain and variation and partitioning methods to investigate the relative importance of three groups of predictors: food availability, humans and landscape attributes – each group expected to have unequal effects on wolf reproduction and survival – and their interactions on the occurrence of this species. Results We found that the group of predictors related with landscape attributes (altitude, roughness and refuge) strongly determined wolf occurrence, followed by humans and food availability. Variance partitioning analysis revealed that the three most important components determining wolf occurrence were related with landscape attributes: (1) the joint effects of the three predictor groups, (2) the joint effect of humans and landscape attributes and (3) the pure effect of landscape attributes. Altitude had the main independent contribution to explain the probability of wolf occurrence. Main conclusions In human‐dominated landscapes, the occurrence of wolves is the result of a complex interaction among several environmental and human factors. Our results suggest that the characteristics of the landscape (spatial context) – factors associated with the security of wolves facilitating that animals go unnoticed by humans, wolf movements, dispersal events and short‐time colonization – become more important in human‐dominated landscapes and may have played a key role in the occurrence and persistence of this species throughout decades modulating the relationship between humans and wolf distribution.     

Global warming potentials of stemwood used for energy and materials in Southern Finland: differentiation of impacts based on type of harvest and product lifetime

Wood harvesting in boreal forests typically consists of sequential harvesting operations within a rotation: a few thinnings and a final felling. The aim of this paper is to model differentiated relative global warming potential (GWP) coefficients for stemwood use from different thinnings and final fellings, and correction factors for long‐lived wood products, potentially applicable in life cycle assessment studies. All thinnings and final fellings influence the development of forest carbon stocks. The climate impact of a single harvesting operation is generated in comparison with no harvesting, thus encountering a methodological problem on how to handle the subsequent operations. The dynamic forest stand simulator MOTTI was applied in the modelling of evolution of forest carbon stocks at landscape level in Southern Finland. The landscape‐level approach for climate impact assessment gave results similar to some stand‐level approaches presented in previous literature that included the same forest C pools and also studied the impacts relative to the no‐harvest situation. The climate impacts of stemwood use decreased over time. For energy use, the impacts were higher or similar in the short term and 0–50% lower in the midterm in comparison with an identical amount of fossil CO₂. The impacts were to some extent (approximately 20–40%) lower for wood from intermediate thinnings than for wood from final fellings or first thinnings. However, the study reveals that product lifetime has higher relative influence on the climate impacts of wood‐based value chains than whether the stemwood originates from thinnings or final fellings. Although the evolution of future C stocks in unmanaged boreal forests is uncertain, a sensitivity analysis suggests that landscape‐level model results for climate impacts would not be sensitive to the assumptions made on the future evolution of C stocks in unmanaged forest. Energy use of boreal stemwood seems to be far from climate neutral.