Intrapopulation Variation Research Articles

Individual specialization is the highest in generalist populations from intermediary to high trophic positions in tropical freshwater fishes

AbstractIndividual specialization (IS) refers to intrapopulation variation in resource use unrelated to ontogeny, sexual dimorphism, or discrete morphological variation. A broad niche increases individual specialization because individuals might segregate in niche space. If trophic position influences niche breadth, it would indirectly constrain the degree of individual specialization. Intermediate trophic levels, usually associated with omnivory, might display fewer constraints on their trophic niche, leading to high levels of individual specialization. We investigate the degree of individual specialization and its relationship to the trophic position in 121 fish populations belonging to 32 species from the upper Tocantins River, Central Brazil. We calculated IS using the index V based on the stomach contents of individuals, whereas values close to 1 indicate strong IS. IS ranged from 0 to 0.87 and greatly varied among species. We showed that niche breadth positively affects a population's individual specialization regardless of its trophic position. Populations occupying intermediate and high trophic positions displayed the highest degrees of individual specialization. Omnivory has no significant effect over individual specialization values. We argue that the intricate relationship among individual specialization, trophic position, and niche breadth relates to the great ecological opportunity and trophic plasticity in tropical fishes.

Ancestry evaluation from subtrochanteric shape of femur using Tallman and Winburn's Adjusted Platymeric Index: A validation study in the Northern Thai population

Background: Ancestry estimation of unidentified human skeletons using metric parameters of bones other than the skull, such as the subtrochanteric shape of the femur, is a challenging method in cases with limited information from cranial examination. The results of multiple studies show that the subtrochanteric shape can differentiate Asian and non-Asian individuals. However, the cut-point of the platymeric index for subtrochanteric shape might need adjustment for each region or country for higher accuracy, due to interpopulation and intrapopulation variation. Objectives: This study aims to validate the cut-point adjusted for the Thai population suggested by Tallman and Winburn and observes the differences between each sex within the same population. Materials and methods: The researchers conduct the study by collecting and calculating multiple parameters (such as femoral subtrochanteric diameters and shape, and platymeric index) from 130 northern Thai individuals collected from the Chiang Mai University bone collection, then making comparisons with the traditional cut-point, and comparing these parameters between different populations and sex. Results: The results show that the accuracy of ancestry estimation is improved from 46.38% to 57.49%, using an adjusted cut-point. This study also notes that the platymeric index of the northern Thai samples is significantly higher (p<0.05) than the north-eastern samples recorded by Tallman and Winburn. Moreover, the index of the male Thai samples is significantly higher (p<0.05) than the female samples from the same bone collection. Conclusion: This study approves the use of the adjusted cut-point in the northern Thai region and indicates an intrapopulation variation and sexual dimorphism of subtrochanteric shape which might influence ancestry assessment.

Distinct inter and intrapopulation variation in the otolith shape and size of Mullus barbatus (Actinopterygii: Mullidae) from the Bizerte and Ghar El Melh lagoons in Tunisian waters

ABSTRACT This study aimed to assess the geographic variation in otoliths’ shape and size and the effect of potential fluctuating asymmetry (FA) in otolith size on the stock structure of Mullus barbatus collected from the Bizerte and Ghar El Melh lagoons located in northeastern Tunisia and to evaluate the relationship between the otolith mass asymmetry (OMA) and total length (TL). Analysis of the otolith shape showed a statistically significant intersexual shape difference, i.e. asymmetry, in the left and right and left-left and right-right otoliths between populations of the two lagoons. In addition, significant intersexual differences were detected in Lo, Wo, and Mo, as well as in FA, between the left and right otoliths among the two populations. Moreover, no statistically significant relationship (P > 0.05) was found between OMA and TL between and within the two populations. At the intrapopulation level, a significant intrasexual asymmetry was observed in the left and right, as well as on left-left and right-right sides, otoliths’ shape and size only within the Ghar El Melh lagoon. Discriminant function analysis of the otoliths’ contour shape confirmed the presence of two separate stocks representing the Bizerte and Ghar El Melh lagoons, which should be managed separately. This significant inter and intrapopulation asymmetry detected in otolith shape and size due to FA can be attributed to the instability of larval development caused either by environmental stress associated with variation in water temperature, salinity, feeding conditions and pollutants or due to poor living conditions of larvae resulting from unfavourable environments.

Gerbillus dasyurus (Rodentia: Gerbillinae) Record from Hatay Province, in the South of Turkey

Wagner’s gerbil, Gerbillus dasyurus, is present in Middle East, Arabian Peninsula and marginally into eastern desert of Egypt. The only records have been taken from Kilis in Turkey. In the present study, 10 specimens were collected from three localities in the Hatay Province. These specimens were captured in rocky hills and slopes with poor soil and vegetation on blocky igneous rocks, and also in the rocky lava flow area in the north eastern part of the Hatay Province. Diploid number of chromosome, number of chromosomes and fundamental number of autosomal arms of the specimens was found as 2n = 60, NF = 70 and NFa = 66, respectively. The relative abundance of species was estimated to be 2.74. The mean of the entire baculum is 2.37 mm long, and 0.52 mm the maximum wide (n=3). Number of roots on molars: 3 (M1 and M2), 2 (M1 and M2) and, 1 M3 and M3. The tail lenght is markedly longer than the total legnth of head and body. Morphological and karyologic characters of the samples verify that the indivuduals investigated belongs to Gerbillus dasyurus. However, it is possible to show inter- and intrapopulational variations because of the differences seen in the root number of M1, the proportion of the tail, and the shape of baculum etc., through a detailed study that covers all distribution area. This record is the second record of the species from Turkey. Since no examples could be obtained in the later studies in Kilis region, which was the first record locality, the protection of the new record localities in Hatay is important for the survival of the species in Turkey.

Stochastic Growth Model of Pollack <i>Gadus chalcogrammus</i> (Pallas, 1814)

A mathematical model is proposed that describes the age-related dynamics of the vector of means and the covariance matrix of characters of individuals in the Sakhalin pollock population Gadus chalcogrammus (Pallas, 1814). The model is based on the Bertalanffy and Gompertz equations. The covariance matrix is composed of two parts: noise (caused by rapid random fluctuations in environmental conditions) and structural (due to intrapopulation variability of the parameters included in the growth equations). The model well reproduces the age dynamics of the distribution of fish according to the quantitative characters of individuals. The age-related increase, the passing through a maximum at a young age, the subsequent decrease in dispersions and their stabilization at low levels in the length and mass of the body of adult fish have been described. The age-related decrease in the correlation between length and body mass has been explained.

Taxonomy of the Iberian species of Pseudochelidura (Dermaptera: Forficulidae)

Male cerci variability was used as the main source of information to separate taxonomic units in the genus Pseudochelidura. Based on these data it was considered that three species of Pseudochelidura coexisted in the Pyrenees: P. sinuata, P. minor and P. montuosa. However, our phylogeographic and phylogenetic analyses based on molecular data (mitochondrial cytb and nuclear ITS2) do not support those conclusions. Combining these analyses with morphological studies we concluded that: 1) the Pyrenees are inhabited by a single evolutionary unit: P. sinuata (Germar, 1825) (= P. minor Steinmann, 1979 syn. nov., = P. montuosa Steinmann, 1981 syn. nov.). 2) Cantabrian and Pyrenean populations are reciprocally monophyletic and morphologically diagnosable representing two independent evolutionary units: Pseudochelidura cantabrica Cuesta-Segura, Jurado-Angulo & García-París sp. nov. and P. sinuata. And, 3) their conservation status needs to be evaluated in the light of current taxonomic changes. We have shown that the use of male cerci for species identification is problematic. Patterns of variation possibly affected by sexual selection (e.g., intrapopulational variability) appear to be very difficult to separate from variation driven by natural selection or genetic drift (i.e., character divergence in geographical isolation). The large sequence divergence observed between Pyrenean and Cantabrian populations of Pseudochelidura suggest a lasting genetic and geographic isolation between them, rendering difficult to ascertain their phylogenetic relationships.

Multi-generation selective landscapes and sub-lethal injuries in stickleback.

The interaction between predation landscape and phenotypic variability within prey populations is of substantial significance in evolutionary biology. Extending from several decades of studies at a remote freshwater lake on Haida Gwaii, western Canada, we analyze the incidence of predator-induced sub-lethal injuries in 8,069 wild-captured threespine stickleback (Gasterosteus aculeatus) and using cohort analyses test whether the distribution of injuries informs the selective landscape influencing the bell-shaped frequency distribution of the traits. Our results indicate that (1) the incidence of injuries varies among phenotypes differing in the number and position of lateral plates, (2) these differences occur only among younger fish, (3) the incidence of injuries is inversely related to the estimated population frequencies of plate phenotypes, with the modal phenotype generally having the fewest injuries, (4) direct estimates of selective differentials and relative fitness based on analyses of 1,735 fish from 6 independent yearly cohorts indicates statistically informative elevated differentials in phenotypes with greater number of plates and elevated relative fitness of non-modal phenotypes, and (5) there are significant differences among yearly cohorts in strength and direction of selection, and an increased prevalence of diversifying versus stabilizing selection despite longer-term stasis (4 decades) in trait means. We conclude that the presence of multiple "optimal" phenotypes complements the renewed interests in quantifying short-term temporal or spatial variation in ecological processes in studies of fitness landscapes and intrapopulation variability.

Individual and Geographic Variation in Non-Harmonic Phases of Male Capercaillie (Tetrao urogallus) Song

Individually distinct acoustic signals, produced mainly as tonal and harmonic sounds, have been recorded in many species; however, non-tonal 'noisy' signals have received little attention or have not been studied in detail. The capercaillies (Tetrao urogallus) produce complex courtship songs composed of non-tonal noisy signals in four discrete phases. We analyzed recordings from 24 captive male capercaillies in breeding centres in the Czech Republic, Poland, and Germany, and songs from wild males in Sweden, Norway, Finland, and Estonia to test whether a non-harmonic song can encode individual-specific information. We also analyzed the intra-population variation of the male song from three separate areas: Carpathian (Polish and Czech Beskid), Sumava, and Boreal (boreal range of species distribution). Temporal and frequency characteristics can reliably distinguish capercaillies at the individual level (91.7%). DFA model testing geographic variation assigned 91% of songs to the correct area (Carpathian, Sumava, Boreal). The cluster analysis revealed that males from the Boreal area formed a distinct cluster. Our analysis shows clear geographical patterns among our study males and may provide a valuable marker for identifying inter-population dynamics and could help to characterize the evolutionary histories of wood grouse. We discuss the potential use of this marker as a non-invasive monitoring tool for captive and free-roaming capercaillies.

Genetic variations in four geographical isolates of Gohieria fusca based on cytochrome b and internal transcribed spacer genes

To investigate the genetic diversity and genetic differentiation of different geographical isolates of Gohieria fusca. G. fusca isolates were sampled from Wuhu (WH), Bengbu (BB) and Bozhou cities (BZ) of Anhui Province and Jiaxing City of Zhejiang Province (JX). Mitochondrial cytochrome b (Cytb) and ribosomal internal transcribed spacer (ITS) genes were amplified in WH, BB, BZ and JX isolates of G. fusca using PCR assay. The gene sequences were edited and aligned using the software Chromas 2 and DNASTAR 1.00, and the haplotype, haplotype diversity (Hd) and nucleotide polymorphism (Pi) of each isolate were calculated using the software DnaSP 5.10.00. The genetic differentiation among isolates (Fst) and gene flow value (Nm) were estimated using the software MEGA 10.2, and a phylogenetic tree was built. Tests of neutrality and analysis of molecular variance (AMOVA) were performed using the software Arlequin 3.1 and a haplotype network was built based on the Median-Joining network using the software Network 10.2. PCR assay showed that the sizes of the Cytb and ITS genes were 372 bp and 1 301 to 1 320 bp, respectively. All four isolates of G. fusca presented high genetic diversity based on mitochondrial Cytb and ITS genes (Hd = 0.804, Pi = 0.006 91). AMOVA showed genetic differentiation among geographical isolates of G. fusca (Fst = 0.202 40, P < 0.05), and the genetic variation was mainly caused by intra-population variations (79.76%). Gene flow analysis showed a high level of gene flow among G. fusca isolates (Nm > 1). Tests of neutrality based on Cytb gene measured a Tajima's D value of -1.796 31 (P < 0.05) and a Fu's FS value of -3.293 98 (P < 0.05) in WH isolate of G. fusca, indicating population expansion in WH isolate of G. fusca. Haplotype network analysis and phylogenetic analysis revealed no remarkable geographical distribution pattern among different geographical isolates of G. fusca. All four isolates of G. fusca presented high genetic diversity (Hd = 0.985, Pi = 0.011 97). AMOVA showed moderate level of genetic differentiation between four isolates (Fst = 0.104 62, P < 0.05). The tests of neutrality based on ITS genes measured a Tajima's D value of -6.088 20 and a Fu's FS value of -1.935 99 (both P > 0.05) in the whole isolate of G. fusca, indicating no obviously population expansion. The four geographical isolates of G. fusca have high genetic diversity and remarkable genetic differentiation. Since a high level of gene flow is detected among different geographical isolates of G. fusca, no obvious geographical distribution pattern of G. fusca is found.

ISSR-assisted spatial genetic structure, population admixture, and biodiversity estimates across locally adopted saffron ecotypes from 18 different provenances of Iran

Here, genetic variability and spatial genetic structure patterns governing on a 90-sample collection of Iranian saffron ecotype gathered from 18 provenances were scrutinized using 20 ISSR markers. 17 out of 20 ISSR primers exhibited polymorphism with 130 polymorphic amplicons from 4 to 15 bands per primer, with an average of 7.647. Considering maximum values of PIC (0.37), discrimination power (D; 0.71), and expected heterozygosity (H; 0.497), both ISSR-7 and ISSR-9 primers were nominated to generate maximal discrimination and heterozygosity. Based on phylogenetic tree and PCoA, the ecotypes were classified into two major groups, but inconsistent with the geographical distribution. Similarly, via applying Bayesian population structure clustering, two sub-populations (K = 2) were observed, four ecotypes were admixture (Q < 0.70), and the rest were pure ecotypes (Q ≥ 0.70). Sub-population 1 was less genetically diverse (FST = 0.1658) than sub-population 2 (FST = 0.5593). As to AMOVA, 56.563% and 43.436% of total genetic variation were partitioned into inter- and intra-population variation, respectively. Based on spatial PCA (sPCA), robust signals of “global” and “local” structures were recognized, only the former was statistically significant (p < 0.001). Significant IBD patterns were also observed via Mantel test calculated between original/unbiased Nei’s genetic distances and geographic distances (p < 0.001) across full dataset. The results revealed ISSR capabilities in saffron DNA fingerprinting and biodiversity assessment, moderate-high genetic variability alongside significant global spatial genetic structure among saffron ecotypes, followed by low levels of gene flow (Nm = 0.2801) and admixture patterns.

Inter- and Intra-Population Variation of Foliage Calcium and Magnesium in Two Chinese Pine Species.

Calcium and magnesium are major nutrient elements of plants, and both play an important role in plant growth and development. Pinus massoniana and P. hwangshanensis are important afforestation tree species in barren mountains in China. However, observation and research on calcium and magnesium nutrition of dominant forest species in China are still limited. This study determined the concentration of calcium and magnesium in needles for two species from five sites in East China by inductively coupled plasma optical emission spectrometry (ICP-OES). We then explored the inter- and intra-population variation pattern of calcium and magnesium and their relationship with environmental factors. There were significant differences in traits among populations. The strongest factors, which impacted the variation of calcium and magnesium concentration, were elevation and individual differences, respectively. Element concentration was correlated to environmental factors such as longitude, latitude, elevation, and mean annual temperature. The results of this study can be helpful for a better understanding of tree growth, population survival, and forest succession.

Intra-Population Alteration on Voltinism of Asian Corn Borer in Response to Climate Warming.

The Asian corn borer (ACB) Ostrinia furnacalis (Guenée) can occur in one to seven generations annually from cool (48°00' N) to warm (18°10' N) region of corn cultivation in China. Although ACB is commonly known as a facultative larval diapause insect, the co-existence of various voltinism suggests that intra-population variation may have evolved for the nature of diapause, i.e., voltinism plasticity. Here, we conducted recurrent selection efforts to establish three strains of, respectively, univoltine (with obligate diapause), multivoltine (with facultative diapause), and non-diapausing ACB under various temperature and photoperiod environments. The univoltine (Lu) strain has evolved a stable univoltinism under a diapause suppressing condition (16 h daylength at 28 °C), with the diapause incidence constantly over 80% after three generations of selection. The multivoltine strain (Lm) under the high temperature (28 °C) was shown to have a typical facultative diapause induced by a range of short-day lengths (11-13.5 h). Diapause incidence was constantly <2.6% under the long day length (16 h) when the temperature was from 18 to 28 °C, i.e., low temperature could not enhance the diapause response in the Lm strain. However, the development was prolonged from 14.2 ± 0.3 d to 46.0 ± 0.8 d when the temperature was reduced from 28 °C to 18 °C. The majority (94.4%) of the developed Ln strain still maintained the non-diapausing nature under a diapause enhancing condition, i.e., a short (13 h) daylength at a low temperature (22 °C). Lm and Ln were able to complete their second generation in Heihe (50°14' N) if the first-generation moth oviposits before 18 June. The study suggests that ACB has evolutionary intra-population variation in voltinism. Under the climate change scenario warmer spring and summer might affect the proportion of sympatric voltine biotype populations that evolve toward being multivoltine.

Genetic variation of Limnophora marginata Stein, 1904 (Diptera: Muscidae), associated with an altitudinal gradient in Pedro Moncayo Canton, Pichincha, Ecuador

Abstract. Aguilar KEV, Vivas AYS, Acosta-López C. 2023. Genetic variation of Limnophora marginata Stein, 1904 (Diptera: Muscidae), associated with an altitudinal gradient in Pedro Moncayo Canton, Pichincha, Ecuador. Biodiversitas 24: 269-275. Analyzing heterogeneity in insect populations is relevant to understanding its biology. Thus, we analyzed the genetic variability of two populations of “hunter-flies”, Limnophora marginata Stein, 1904 associated with an altitudinal gradient in the Tocachi and Jerusalem localities, in the Pedro Moncayo Canton, Ecuador, using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) of the mitochondrial Cytochrome oxidase I gene. Thirty alleles were detected from analysis with five restriction enzymes; the percentage of polymorphic loci was higher in Tocachi (96.67%) than in Jerusalem (80%). Haplotypes were generated with the corresponding alleles, resulting in a different haplotype for each analyzed individual. Several estimators were used to characterize the population structure. The Analysis of Molecular Variance (AMOVA) evidenced the existence of higher intra-population variability (94%) than inter-population (6%), showing similar information to that found through haplotype analysis. The Fst fixation index indicated that there is no genetic difference between populations (0.056, P&lt;0.05). Nei's genetic distance and Nei's similarity index indicated that L. marginata populations did not show differences between populations. From the results we deduce that the evolutionary force that may be modelling the existent genetic variability may be gene flow, thus establishing a low inter-population genetic structure. The mitochondrial DNA Cytochrome oxidase I gene was an advantageous molecular marker to obtain results that established intra and inter population variability. The characteristics of the mitochondrial DNA were useful to successfully apply the PCR-RFLP technique. Our findings highlight the existence of ecosystem connectivity between L. marginata populations despite altitudinal and habitat differences.

High-Resolution Bacterial Cytological Profiling Reveals Intrapopulation Morphological Variations upon Antibiotic Exposure.

Phenotypic heterogeneity is crucial to bacterial survival and could provide insights into the mechanism of action (MOA) of antibiotics, especially those with polypharmacological actions. Although phenotypic changes among individual cells could be detected by existing profiling methods, due to the data complexity, only population average data were commonly used, thereby overlooking the heterogeneity. In this study, we developed a high-resolution bacterial cytological profiling method that can capture morphological variations of bacteria upon antibiotic treatment. With an unprecedented single-cell resolution, this method classifies morphological changes of individual cells into known MOAs with an overall accuracy above 90%. We next showed that combinations of two antibiotics induce altered cell morphologies that are either unique or similar to that of an antibiotic in the combinations. With these combinatorial profiles, this method successfully revealed multiple cytological changes caused by a natural product-derived compound that, by itself, is inactive against Acinetobacter baumannii but synergistically exerts its multiple antibacterial activities in the presence of colistin. The findings have paved the way for future single-cell profiling in bacteria and have highlighted previously underappreciated intrapopulation variations caused by antibiotic perturbation.

Variation in scent amount but not in composition correlates with pollinator visits within populations of deceptive Arum maculatum L. (Araceae).

Floral scent is vital for pollinator attraction and varies among and within plant species. However, little is known about how inter-individual variation in floral scent affects the abundance and composition of floral visitor assemblages within populations. Moreover, for deceptive plants it is predicted that intra-population variation in scent can be maintained by negative frequency-dependent selection, but empirical evidence is still lacking. To investigate the ecological and evolutionary relations between inter-individual scent variation (i.e., total emission and composition) and floral visitors in deceptive plants, we studied floral scent, visitor assemblages, and fruit set in two populations of fly-pollinated (Psychodidae, Sphaeroceridae; Diptera) and deceptive Arum maculatum from Austria (JOS) and northern Italy (DAO). By correlating individual data on floral scent and visitor assemblages, we show that inter-individual variation in floral scent partly explains variation in visitor assemblages. The quantity of floral scent emitted per individual correlated positively with visitor abundance in both populations but explained visitor composition only in DAO, where strongly scented inflorescences attracted more sphaerocerid flies. However, in each population, the composition of floral scent did not correlate with the composition of floral visitors. There was also no evidence of negative frequency-dependent selection on floral scent. Instead, in JOS, more frequent scent phenotypes attracted more pollinators and were more likely to set an infructescence than rarer ones. Our results show that floral scent, despite being key in pollinator attraction in A. maculatum, only partly explains variation in pollinator abundance and composition. Overall, this study is the first to shed light on the importance of inter-individual variation in floral scent in explaining floral visitor assemblages at the population level in a deceptive plant species.

Delayed effect of thermal treatment on breaking physical seed dormancy: intrapopulation variation and implications for soil seed banks

Background Many studies have focused on the dormancy-breaking response to heat treatment of freshly matured seeds and immediately after thermal shock. Aims We evaluated whether the full effect of dry heat scarification in freshly matured seeds could be delayed over time and the possible influence of previous storage in the soil. Methods Adenocarpus argyrophyllus was the model species selected to explore our hypotheses by analysing the: (a) influence of scarification treatments; (b) seedling emergence during 5 years after dry heat scarification of freshly matured seeds, and evaluating intrapopulation variation; (c) seedling emergence after dry heat scarification of seeds rescued from soil; and (d) ability to form persistent soil seed banks. Key results Dry heat scarification of freshly matured seeds only resulted in 22.5% germination. However, exposure to pre-sowing thermal shock stimulated seedling emergence during the first few years post-planting, with high intrapopulation variation. In seeds recovered from soil, thermal shock before reseeding increased the seedling emergence rate. Conclusions and implications Our results show that, to avoid incomplete interpretation, studies of thermal treatment on the breaking of physical seed dormancy should allow the seeds sufficient time to exhibit the complete effects of high temperature treatment, thereby preventing underestimation.

Parasite communities and genetic structure of non-native pumpkinseed,Lepomis gibbosus, in different Black Sea drainages of Ukraine

In recent years, pumpkinseedLepomis gibbosus(Actinopterygii: Centrarchidae) have spread intensively to many parts of Europe, including Ukraine. In this study, we (1) assess intra-population genetic variability in five widely-spaced Ukrainian pumpkinseed populations and compare their population genetic structure with other European populations and (2) provide a comprehensive survey of pumpkinseed parasites across the region. Discriminant analysis of principal components and FSTanalyses based on microsatellites indicated that all five populations formed discrete clusters. Within Europe, Ukrainian populations were most closely associated with populations from the River Danube, suggesting that the Danube is the main source of all Ukrainian pumpkinseed populations. The parasite fauna comprised 15 taxa, most of which (92%) were native to North America (monogeneaOnchocleidus similisandO. dispar; myxozoanMyxobolus dechtiari). Parasites acquired in the species' new range occurred accidentally, with onlyTrichodinaciliates found relatively frequently and the eye flukesDiplostomum pseudospathaceumandTylodelphys clavataoccurring at higher prevalence. Absence of specific monogeneans in pumpkinseed from estuaries (Khadzhibey and Sukhyi Lymans) indicates low tolerance ofOnchocleidusspecies to salinity.

Differences in individual bowhead whale Balaena mysticetus habitat use, foraging dive depth and diet during the peak feeding season

Shifts in zooplankton quantity and quality caused by climate change could challenge the ability of bowhead whales to meet their energetic requirements. When facing such selection pressure, intra-population variation dampens the negative effects and provides population-level resilience. Previous studies observed inter-individual diet variation in bowhead whales, but the mechanism responsible for the variation was undetermined. We investigated foraging variability in Eastern Canada-West Greenland bowhead whales using dietary biomarkers (stable isotopes, fatty acids) and movement data (satellite telemetry with time-depth recorders) from the same individuals. We found that bowhead whale individuals using distinct summer and fall foraging habitats displayed differences in horizontal movements, foraging dive depth, and diet. For individuals using the Canadian Arctic Archipelago habitat (Foxe Basin, Gulf of Boothia, Prince Regent Inlet, Lancaster Sound and Admiralty Inlet, Nunavut), they performed long distance movements across regions, and their foraging dive depth was generally shallow, but increased from July to November. These whales displayed higher δ13C and δ15N values and ratios of C16:1n7/C16:0. Individuals using the West Baffin Bay habitat (Cumberland Sound, Baffin Bay, Davis Strait) were more localized in their horizontal movements and consistent over time in their foraging dive depth, which was generally deeper. These whales displayed lower δ13C and δ15N values and ratios of C16:1n7/C16:0. Overall, this inter-individual variation in diet and foraging behaviour could indicate some niche variation which would be beneficial for the population under changing habitats and prey availability.

Вариабельность морфологических и генетических признаков Macrohectopus branickii (Dyb., 1874)

Macrohectopus branickii is the only pelagic amphipod from Lake Baikal. Until now, despite the uniqueness of M. branickii, its genetic diversity at the intraspecific level, as well as its intraspecific morphological diversity, have not been studied. In this work, we present the result of a morphological analysis of intrapopulation variability of the species M. branickii from the northern basin of Lake Baikal, as well as the result of a molecular analysis based on the sequence of a fragment of the mitochondrial Nad5 gene of several individuals of this species from three basins of the lake. The material for the study was collected using a plankton net and trawl from all basins and shores of Lake Baikal at depths of 100-300 m. We measured 21 morphological characters according to the scheme previously proposed in Tikhonova’s work for sexually mature females of M. branickii living on different shores of the northern basin of Lake Baikal. The coefficient of variation of the values of all characteristics was determined. Morphological analysis revealed different degrees of variability in the studied characters for M. branickii. The most variable characters are: the length of 1 segment of the peduncle of the upper antennae; length of 4 and 5 segments of the stalk of the lower antennae; length of gnathopod propodites 2 pairs; width and length of basipodites of the third pair of pereiopods; length of the stalk, external and internal branches of the uropods of the third pair; telson width and length. Analysis of the nucleotide sequences of the Nad5 gene fragment showed their low variability. The haplotype network was reconstructed using the pegas package for the R programming language. M. branickii forms a single panmictic population, consistent with the absence of geographic and environmental barriers in the pelagic zone of the lake.

New insights into the variability of upper airway morphology in modern humans.

The biological adaptation of the human lineage to its environment is a recurring question in paleoanthropology. Particularly, how eco-geographic factors (e.g., environmental temperature and humidity) have shaped upper airway morphology in hominins have been subject to continuing debate. Nasal shape is the result of many intertwined factors that include, but are not limited to, genetic drift, sexual selection, or adaptation to climate. A quantification of nasal airway (NA) morphological variation in modern human populations is crucial to better understand these multiple factors. In the present research, we study 195 in vivo CT scans of adult individuals collected in five different geographic areas (Chile, France, Cambodia, Russia, and South Africa). After segmentation of the nasal airway, we reconstruct 3D meshes that are analyzed with a landmark-free geometric morphometrics method based on surface deformation. Our results highlight subtle but statistically significant morphological differences between our five samples. The two morphologically closest groups are France and Russia, whose NAs are longer and narrower, with an important protrusion of the supero-anterior part. The Cambodian sample is the most morphologically distinct and clustered sample, with a mean NA that is wider and shorter. On the contrary, the Chilean sample form the most scattered cluster with the greatest intra-population variation. The South African sample is morphologically close to the Cambodian sample, but also partially overlaps the French and Russian variation. Interestingly, we record no correlation between NA volume and geographic groups, which raises the question of climate-related metabolic demands for oxygen consumption. The other factors of variation (sex and age) have no influence on the NA shape in our samples. However, NA volume varies significantly according both to sex and age: it is higher in males than in females and tends to increase with age. In contrast, we observe no effect of temperature or humidity on NA volume. Finally, we highlight the important influence of asymmetries related to nasal septum deviations in NA shape variation.