Biosonar,dive, and foraging activity of satellite tracked harbor porpoises (Phocoena phocoena)

This study presents bioacoustic recordings in combination with movements and diving behavior of three free‐ranging harbor porpoises (a female and two males) in Danish waters. Each porpoise was equipped with an acoustic data logger (A‐tag), a time‐depth‐recorder, a VHF radio transmitter, and a satellite transmitter. The units were programmed to release after 24 or 72 h. Possible foraging occurred mostly near the surface or at the bottom of a dive. The porpoises showed individual diversity in biosonar activity (<100 to >50,000 clicks per hour) and in dive frequency (6–179 dives per hour). We confirm that wild harbor porpoises use more intense clicks than captive animals. A positive tendency between number of dives and clicks per hour was found for a subadult male, which stayed near shore. It showed a distinct day‐night cycle with low echolocation rates during the day, but five times higher rates and higher dive activity at night. A female traveling in open waters showed no diel rhythm, but its sonar activity was three times higher compared to the males'. Considerable individual differences in dive and echolocation activity could have been influenced by biological and physical factors, but also show behavioral adaptability necessary for survival in a complex coastal environment.     

Conservation genetics of harbour porpoises, Phocoena phocoena, in eastern and central North Atlantic

We examined polymorphism at 12 microsatelliteloci in 807 harbour porpoises , Phocoenaphocoena, collected from throughout thecentral and eastern North Atlantic to theBaltic Sea. Multilocus tests for allelefrequency differences, assignment tests,population structure estimates (F_ST) andgenetic distance measures (D_LR andD_C) all indicate six geneticallydifferentiated populations/sub-populationsafter pooling sub-samples within regions.Harbour porpoises from West Greenland, theNorwegian Westcoast, Ireland, the British NorthSea, the Danish North Sea and the inland watersof Denmark (IDW) are all geneticallydistinguishable from each other. A sample ofharbour porpoises collected off the Dutch coast(mainly during winter) was geneticallyheterogeneous and likely comprised a mixture ofindividuals of diverse origin. A mixed stockanalysis indicated that most of the individualsin this sample (77%) were likely migrantsfrom the British and Danish North Sea.     

Group characteristics,site fidelity,and photo‐identification of harbor porpoises,Phocoena phocoena,in Burrows Pass,Fidalgo Island,Washington

Little is known about harbor porpoises at the individual level or local group structure. Group characteristics, site fidelity, and photo‐identification of harbor porpoises were investigated off Fidalgo Island, Washington State. Harbor porpoise presence was affected by season and rip tide strength (Wald χ² P < 0.04); calf presence was influenced by season and tide (Wald χ² P < 0.0075). Average group size (2.32 ± 1.38, n = 266) was influenced by season, behavior, and calf presence (F₇ = 9.71, P < 0.0001, R² = 0.294). Fifty‐three individuals were identified using a matrix of primary, secondary, and confirmation markings that were stable over months/years. Over 35% were resighted in more than 1 mo (range 1–7, = 1.83); 15.1% were seen in more than 1 yr, suggesting some level of residency. Despite having higher effort, presence and group size were significantly lower in Summer. Variations in the significance of rip tide strength and tides relate to calf presence and support other findings that harbor porpoise population structure is complex and varies at small spatiotemporal scales and may also vary between populations and habitats. This study identifies variables affecting group characteristics and emphasizes the importance of research on local populations of harbor porpoises.     

Contrasting responses to Pleistocene climate changes: a case study of two sister species Allium cyathophorum and A. spicata (Amaryllidaceae) distributed in the eastern and western Qinghai–Tibet Plateau

It has been hypothesized that species occurring in the eastern and the western Qinghai–Tibet Plateau (QTP) responded differently to climate changes during the Pleistocene. Here, we test this hypothesis by phylogeographic analysis of two sister species, Allium cyathophorum and A. spicata. We sequenced two chloroplast DNA (cpDNA) fragments (accD‐psaI and the rpl16 intron) of 150 individuals, and the nuclear (ITS) region of 114 individuals, from 19 populations throughout the distributional ranges of these species. The divergence between the two species was dated at 779 ‐ 714 thousand years before the present and was likely initiated by the most major glaciation in the QTP. Analysis of chlorotype diversity showed that A. spicata, the species occurring in the western QTP, contains much lower genetic diversity (0.25) than A. cyathophorum (0.93), which is distributed in the eastern QTP. Moreover, multiple independent tests suggested that the A. spicata population had expanded recently, while no such expansion was detected in A. cyathophorum, indicating a contrasting pattern of responses to Pleistocene climate changes. These findings highlight the importance of geographical topography in determining how species responded to the climate changes that took place in the QTP during the Pleistocene.     

Diet composition and food consumption rate of harbor porpoises (Phocoena phocoena) in the western Baltic Sea

Stomach content composition and prey‐specific consumption rates of juvenile and adult harbor porpoises (Phocoena phocoena) were estimated from a data set including 339 stomachs collected over a 32 yr period (1980–2011) in the western Baltic Sea. The stomach contents were mainly hard parts of fish prey and in particular otoliths. The bias originating from differential residence time of otoliths in the stomachs was addressed by use of a recently developed approach. Atlantic cod and herring were the main prey of adults, constituting on average 70% of the diet mass. Juvenile porpoises also frequently consumed gobies. Here, the mass contribution by gobies was on average 25%, which was as much as cod. Other species such as whiting, sprat, eelpout, and sandeels were of minor importance for both juveniles and adults. The diet composition differed between years, quarters, and porpoise acquisition method. Yearly consumption rates for porpoises in the western Baltic Sea were obtained in three scenarios on the daily energy requirements of a porpoise in combination with an estimate including the 95% CLs of the porpoise population size. Cod of age groups 1 and 2 and intermediate‐sized herring suffered the highest predation from porpoises.     

A recovery of harbour porpoises (Phocoena phocoena) in the southern North Sea? A case study off Eastern Frisia, Germany

Detailed information on year-round distribution, seasonal abundance and inter-annual trends of a given species is essential for any conservation effort. However, for most odontocetes this knowledge is rather limited. Therefore, area-specific management or conservation plans are often difficult to argue for. This is also true for the harbour porpoise (Phocoena phocoena), although it is the most common cetacean species in the North Sea. Knowledge of the current status of local stocks as well as fine scale information on the temporal use of certain areas by the species is incomplete. One area of concern is the southern North Sea where the abundance of harbour porpoises has declined in the twentieth century. Recent studies using stranding data and observations from seabird surveys indicate a comeback of the species along the Dutch and Belgian coast. However, data on other regions of the southern North Sea is sparse. Between 2002 and 2004, we undertook 25 aerial line transect surveys (11,000 km on effort; altitude = 250 and 600 ft) in a 2,500 km² coastal area off Eastern Frisia, Germany including a small portion of Dutch coastal waters. The data were g(0) corrected using a double platform approach and analysed with distance sampling software. A total of 426 harbour porpoises were sighted, including eight calves. Densities ranged between <0.1 and 1.62 individuals/km² with peaks in February and July 2003 as well as February and May 2004. The results of our study show that harbour porpoises are present in the coastal part of the southern North Sea even during their reproductive period. However, they seem to appear in lower numbers and much more irregular than in other areas, for example off Northern Frisia. The results of this study support the recent findings that despite a decline in the mid-twentieth century, harbour porpoises are now at times quite abundant in the southern North Sea. The underlying factors of this ‘return’ should be investigated using a combination of surveys and satellite telemetry.     

Taxonomy of the long‐tailed mouse Oligoryzomys destructor (Sigmodontinae: Oryzomyini) with the designation of neotypes for Hesperomys destructor Tschudi, 1844 and Hesperomys melanostoma Tschudi, 1844

The genus Oligoryzomys, distributed from southern South America to southern North America, is the most diverse of the tribe Oryzomyini of sigmodontine rodents. Even when 22 species are currently recognized, species boundaries are unclear for several forms. The species Oligoryzomys destructor is one of the least studied species of the genus and is the one with the largest distribution along the Andes (from southern Colombia to northern Bolivia). The species was described without the selection of a holotype and indication of its type locality. In addition, several taxa are regarded as synonyms of O. destructor. These facts are relevant because previous analysis of DNA sequences has shown that O. destructor represents a species complex. Herein, in addition to test the phylogenetic position of O. destructor within the genus Oligoryzomys, we assess patterns of morphological and molecular variation of O. destructor and its associated nominal forms aimed to assess the boundaries of the species. As part of the study, we selected neotypes for Hesperomys destructor and H. melanostoma. At the light of our results, we recognized O. destructor as a species with two subspecies, O. d. destructor and O. d. spodiurus. Also, we discuss the role of Andean rivers, and their different permeability, as allopatric barriers molding the structure of O. destructor.     

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise,Phocoena phocoena

During the evolution of odontocetes, the nasal complex was modified into a complicated system of passages and diverticulae. It is generally accepted that these are essential structures for nasal sound production. However, the mechanism of sound generation and the functional significance of the epicranial nasal complex are not fully understood. We have studied the epicranial structures of harbor porpoises (Phocoena phocoena) using light and electron microscopy with special consideration of the nasal diverticulae, the phonic lips and dorsal bursae, the proposed center of nasal sound generation. The lining of the epicranial respiratory tract with associated diverticulae is consistently composed of a stratified squamous epithelium with incomplete keratinization and irregular pigmentation. It consists of a stratum basale and a stratum spinosum that transforms apically into a stratum externum. The epithelium of the phonic lips comprises 70–80 layers of extremely flattened cells, i.e., four times more layers than in the remaining epicranial air spaces. This alignment and the increased number of desmosomes surrounding each cell indicate a conspicuous rigid quality of the epithelium. The area surrounding the phonic lips and adjacent fat bodies exhibits a high density of mechanoreceptors, possibly perceiving pressure differentials and vibrations. Mechanoreceptors with few layers and with perineural capsules directly subepithelial of the phonic lips can be distinguished from larger, multi‐layered mechanoreceptors without perineural capsules in the periphery of the dorsal bursae. A blade‐like elastin body at the caudal wall of the epicranial respiratory tract may act as antagonist of the musculature that moves the blowhole ligament. Bursal cartilages exist in the developmental stages from fetus through juvenile and could not be verified in adults. These histological results support the hypothesis of nasal sound generation for the harbor porpoise and display specific adaptations of the echolocating system in this species. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

Northward displacement of optimal climate conditions for ecotypes of Eriophorum vaginatum L. across a latitudinal gradient in Alaska

Plants are often genetically specialized as ecotypes attuned to local environmental conditions. When conditions change, the optimal environment may be physically displaced from the local population, unless dispersal or in situ evolution keep pace, resulting in a phenomenon called adaptational lag. Using a 30‐year‐old reciprocal transplant study across a 475 km latitudinal gradient, we tested the adaptational lag hypothesis by measuring both short‐term (tiller population growth rates) and long‐term (17‐year survival) fitness components of Eriophorum vaginatum ecotypes in Alaska, where climate change may have already displaced the optimum. Analyzing the transplant study as a climate transfer experiment, we showed that the climate optimum for plant performance was displaced ca. 140 km north of home sites, although plants were not generally declining in size at home sites. Adaptational lag is expected to be widespread globally for long‐lived, ecotypically specialized plants, with disruptive consequences for communities and ecosystems.     

Robust geographical determinants of infection prevalence and a contrasting latitudinal diversity gradient for haemosporidian parasites in Western Palearctic birds

Identifying robust environmental predictors of infection probability is central to forecasting and mitigating the ongoing impacts of climate change on vector‐borne disease threats. We applied phylogenetic hierarchical models to a data set of 2,171 Western Palearctic individual birds from 47 species to determine how climate and landscape variation influence infection probability for three genera of haemosporidian blood parasites (Haemoproteus, Leucocytozoon, and Plasmodium). Our comparative models found compelling evidence that birds in areas with higher vegetation density (captured by the normalized difference vegetation index [NDVI]) had higher likelihoods of carrying parasite infection. Magnitudes of this relationship were remarkably similar across parasite genera considering that these parasites use different arthropod vectors and are widely presumed to be epidemiologically distinct. However, we also uncovered key differences among genera that highlighted complexities in their climate responses. In particular, prevalences of Haemoproteus and Plasmodium showed strong but contrasting relationships with winter temperatures, supporting mounting evidence that winter warming is a key environmental filter impacting the dynamics of host‐parasite interactions. Parasite phylogenetic community diversities demonstrated a clear but contrasting latitudinal gradient, with Haemoproteus diversity increasing towards the equator and Leucocytozoon diversity increasing towards the poles. Haemoproteus diversity also increased in regions with higher vegetation density, supporting our evidence that summer vegetation density is important for structuring the distributions of these parasites. Ongoing variation in winter temperatures and vegetation characteristics will probably have far‐reaching consequences for the transmission and spread of vector‐borne diseases.     

Risk of genetic maladaptation due to climate change in three major European tree species

Tree populations usually show adaptations to their local environments as a result of natural selection. As climates change, populations can become locally maladapted and decline in fitness. Evaluating the expected degree of genetic maladaptation due to climate change will allow forest managers to assess forest vulnerability, and develop strategies to preserve forest health and productivity. We studied potential genetic maladaptation to future climates in three major European tree species, Norway spruce (Picea abies), silver fir (Abies alba), and European beech (Fagus sylvatica). A common garden experiment was conducted to evaluate the quantitative genetic variation in growth and phenology of seedlings from 77 to 92 native populations of each species from across Switzerland. We used multivariate genecological models to associate population variation with past seed source climates, and to estimate relative risk of maladaptation to current and future climates based on key phenotypic traits and three regional climate projections within the A1B scenario. Current risks from climate change were similar to average risks from current seed transfer practices. For all three climate models, future risks increased in spruce and beech until the end of the century, but remained low in fir. Largest average risks associated with climate projections for the period 2061–2090 were found for spruce seedling height (0.64), and for beech bud break and leaf senescence (0.52 and 0.46). Future risks for spruce were high across Switzerland. However, areas of high risk were also found in drought‐prone regions for beech and in the southern Alps for fir. Genetic maladaptation to future climates is likely to become a problem for spruce and beech by the end of this century, but probably not for fir. Consequently, forest management strategies should be adjusted in the study area for spruce and beech to maintain productive and healthy forests in the future.     

Diversification and biogeographic history of the Western Palearctic freshwater flatworm genus Schmidtea (Tricladida: Dugesiidae), with a redescription of Schmidtea nova

The freshwater flatworm genus Schmidtea is endemic in the Western Palearctic region, where it is represented by only four species, thus contrasting with the high species diversity of the closely related genus Dugesia within Europe. Although containing an important model species in developmental and regeneration research, viz. Schmidtea mediterranea, no evolutionary studies on the genus Schmidtea have been undertaken. For the first time, we present a well‐resolved molecular phylogenetic tree of the four species of the genus, inferred on the basis of two molecular markers, and provide also the first detailed morphological account of Schmidtea nova. The phylogenetic tree generated corroborates an earlier speciation hypothesis based on karyological data and points to chromosomal rearrangements as the main drivers of speciation in this genus. The high genetic divergence between the four species, in combination with previous dating studies and their current geographic distribution, suggests that Schmidtea could have originated in Laurasia but lost most of its diversity during the Oligocene. Thus, its present distribution pattern may be the result of the expansion of three of its four relictual species over Europe, probably after the Pleistocene glaciations. Our detailed morphological study of S. nova revealed that it shows a number of remarkable features: interconnected testis follicles, parovaria, an ejaculatory duct exiting into the primary as well as the secondary seminal vesicle by means of a nipple, and the wall of the distal section of the ejaculatory duct being sclerotic or chitinized.     

Diploid hybrid origin of Ostryopsis intermedia (Betulaceae) in the Qinghai‐Tibet Plateau triggered by Quaternary climate change

Despite the well‐known effects that Quaternary climate oscillations had on shaping intraspecific diversity, their role in driving homoploid hybrid speciation is less clear. Here, we examine their importance in the putative homoploid hybrid origin and evolution of Ostryopsis intermedia, a diploid species occurring in the Qinghai‐Tibet Plateau (QTP), a biodiversity hotspot. We investigated interspecific relationships between this species and its only other congeners, O. davidiana and O. nobilis, based on four sets of nuclear and chloroplast population genetic data and tested alternative speciation hypotheses. All nuclear data distinguished the three species clearly and supported a close relationship between O. intermedia and the disjunctly distributed O. davidiana. Chloroplast DNA sequence variation identified two tentative lineages, which distinguished O. intermedia from O. davidiana; however, both were present in O. nobilis. Admixture analyses of genetic polymorphisms at 20 SSR loci and sequence variation at 11 nuclear loci and approximate Bayesian computation (ABC) tests supported the hypothesis that O. intermedia originated by homoploid hybrid speciation from O. davidiana and O. nobilis. We further estimated that O. davidiana and O. nobilis diverged 6–11 Ma, while O. intermedia originated 0.5–1.2 Ma when O. davidiana is believed to have migrated southward, contacted and hybridized with O. nobilis possibly during the largest Quaternary glaciation that occurred in this region. Our findings highlight the importance of Quaternary climate change in the QTP in causing hybrid speciation in this important biodiversity hotspot.     

Can the emergence of pine Diplodia shoot blight in France be explained by changes in pathogen pressure linked to climate change?

Sphaeropsis shoot blight, caused by Diplodia pinea and Diplodia scrobiculata, damage conifers throughout the world. In France, the first disease outbreaks were reported during the 1990s. The factors associated with the pathogen presence in stands and the relationship between pathogen and disease distributions were analysed in order to understand the Sphaeropsis emergence. Eighty‐two stands of Pinus nigra, Pinus sylvestris, Pinus pinaster and Pinus radiata were visited. Cones were collected on the ground to assess the pathogen frequency. Diplodia spp were isolated and determined by a species‐specific PCR test. The role of potential explaining factors of D. pinea prevalence on cones was analysed by logistic regression. D. pinea was the dominant species in visited stands. The main factors influencing the pathogen presence selected in the models were host species (the pathogen being less frequent on P. pinaster than on P. nigra and P. sylvestris cones), winter temperature and summer rain, which were both positively correlated with cone colonization. The climate became more favourable to D. pinea presence within the last 15 years compared with the previous 30‐year period. By contrast, future climatic changes over the next 40 years should have far less impact on the pathogen presence.     

Bayesian Poisson tree processes and multispecies coalescent models shed new light on the diversification of Nawab butterflies in the Solomon Islands (Nymphalidae,Charaxinae, Polyura)

Butterflies of the genus Polyura form a widespread tropical group distributed from Pakistan to Fiji. The rare endemic Polyura epigenes Godman & Salvin, 1888 from the Solomon Islands archipelago represents a case of marked island polymorphism. We sequenced museum specimens of this species across its geographic range to study the phylogeography and genetic differentiation of populations in the archipelago. We used the Bayesian Poisson tree processes and multispecies coalescent models, to study species boundaries. We also estimated divergence times to investigate the biogeographic history of populations. Our molecular species delimitation and nuclear DNA network analyses unambiguously indicate that Malaita populations form an independent metapopulation lineage, as defined in the generalized lineage concept. This lineage, previously ranked as a subspecies, is raised to species rank under the name Polyura bicolor Turlin & Sato, 1995  stat. nov. Divergence time estimates suggest that this lineage split from its sister taxon in the late Pleistocene. At this time, the bathymetric isolation of Malaita from the rest of the archipelago probably prevented gene flow during periods of lower sea level, thereby fostering allopatric speciation. The combination of molecular species delimitation methods, morphological comparisons, and divergence time estimation is useful to study lineage diversification across intricate geographic regions.     

A complex pattern of post‐divergence expansion,contraction, introgression,and asynchronous responses to Pleistocene climate changes in two Dipelta sister species from western China

The well‐known vicariance and dispersal models dominate in understanding the allopatric pattern for related species and presume the simultaneous occurrence of speciation and biogeographic events. However, the formation of allopatry could postdate the species divergence. We examined this hypothesis using DNA sequence data from three chloroplast fragments and five nuclear loci of Dipelta floribunda Maxim. and D. yunnanensis Franch, two shrub species with the circum Sichuan Basin distribution, combining the climatic niche modeling approach. The best‐fit model supported by the approximate Bayesian computation analysis indicated that D. floribunda and D. yunnanensis diverged during the mid‐Pleistocene period, consistent with the largest glacial period in the Qinghai–Tibet Plateau. The historically interspecific gene flow was identified, but seemed to have ceased after the last interglacial period, when the range of D. floribunda moved northward from the south of the Sichuan Basin. Furthermore, populations of D. floribunda had expanded obviously in the north of the Sichuan Basin after the last glacial maximum (LGM). Relatively, the range of D. yunnanensis expanded before the LGM, and reduced during the post‐LGM especially in the north of the Sichuan Basin, reflecting the asynchronous responses of related species to contemporary climate changes. Our results suggested that complex topography should be considered in understanding distributional patterns, even for closely related species and their demographic responses.     

Evolutionary response to Quaternary climate aridification and oscillations in north‐western China revealed by chloroplast phylogeography of the desert shrub Nitraria sphaerocarpa (Nitrariaceae)

To investigate the influence of climate aridification and oscillations on the genetic diversity and evolutionary processes of organisms in the Quaternary in north‐western China, we selected Nitraria sphaerocarpa and examined the phylogeographical structure and response to historical and environmental factors in populations of this species across most of its covered range. We found twelve haplotypes on the basis of two chloroplast DNA sequences (trnH‐psbA and rpl32‐trnL). The drying climate during the Quaternary is proposed to have been a driver for significant genetic isolation and divergence among populations in N. sphaerocarpa. Except for the sharing of haplotype D between the Hami Basin and Hexi Corridor, as well as of haplotype F between the Hexi Corridor and Alxa Desert, network analysis showed haplotypes to be almost completely different from region to region. Analysis of molecular variance indicated that genetic variation primarily occurred among populations and among nine geographical groups that were distinguished by spatial analysis of molecular variance, and a Mantel test showed that the correlation between genetic and geographical distances was significant. On the other hand, there was evidence for the occurrence of an episode of more favourable conditions in some regions. Geographical range expansion of two groups of N. sphaerocarpa populations was supported by significant values for Fu's F_S and unimodel mismatch distributions. During the last interglacial period, a warmer and wetter climate contributed to range expansion within portions of the Hexi Corridor. By contrast, based on ecological niche modelling, N. sphaerocarpa was indicated to have had a shrunken and more fragmented range during the Last Glacial Maximum. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 757–770.