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Effects of male age and female presence on male associations in a large, polygynous mammal in southern India

We present a detailed study of male associations in a roving species, the Asian elephant, using six years of data on identified, nonmusth males. Adult males spent greater proportions of their time solitarily than in mixed-sex or in all-male groups. Old (over 30 years) males were sighted more frequently with their age-peers and less frequently with young (15-30 years) males than expected at random in all-male groups. Young males were not sighted more frequently with old males than with young males, and did not disproportionately initiate associations with old males. These results suggest that male associations, in the absence of females, primarily allow for old nonmusth males to test strengths against age-peers. Social learning from older individuals did not seem to be important in male associations, unlike that observed in African savannah elephants. We also found a constraint on the sizes of all-male groups, similar to that seen in female groups in our study population, and with male group sizes being smaller than that of African savannah elephants. However, most males had a significant top associate in female absence. In mixed-sex groups, male associations occurred at random, suggesting that males were tracking female groups independently. Thus, we find some differences in male social organisation compared to the phylogenetically related African savannah elephant that occupies a similar niche, and suggest that ecological factors might have shaped the differences in these male societies.Competing Interest StatementThe authors have declared no competing interest.View Full Text

animal behavior and cognition

Evolutionary history of phycoerythrin pigmentation in the water bloom-forming cyanobacterium Microcystis aeruginosa

Microcystis aeruginosa is a bloom-forming cyanobacterium found in eutrophic fresh-and brackish water bodies worldwide. As typical for cyanobacteria, most M. aeruginosa strains are blue-green in color owing to the concomitance of two photosynthetic pigments, phycocyanin (PC) and chlorophyll a. Although less common, M. aeruginosa strains that are brownish in color owing to the presence of another pigment phycoerythrin (PE) have been documented. However, the genomic basis, phylogeny, and evolutionary origin of PE pigmentation in M. aeruginosa have only been poorly characterized until date. In the present study, we sequenced and characterized the genomes of five PE-containing M. aeruginosa strains. Putative PE synthesis and regulation genes (the cpe cluster) were identified in all five sequenced genomes as well as in three previously published M. aeruginosa genomes. Of note, Absorption spectra indicated that the PE content, but not PC content, was markedly altered in response to availability of red/green light in all PE-containing strains. This was consistent with the presence of ccaS/ccaR, a hallmark of type II chromatic adapter, in the cpe cluster. Phylogenetic analyses of core genome genes indicated that PE-containing genotypes were located in three different phylogenetic groups. In contrast, the genomic organization of the cpe cluster was mostly conserved regardless of genomic background. Additionally, the phylogenies of PE genes were found to be congruent, consistent with the core genome phylogeny. A comparison of core genome and PE genes showed a similar level of genetic divergence between two PE-containing groups. These results suggest that genes responsible for PE pigmentation were introduced into M. aeruginosa early during evolution and were repeatedly lost thereafter possibly due to ecological adaptation. Additional horizontal gene transfer (HGT) later during evolution also contributed to the present phylogenetic distribution of PE in M. aeruginosa.

microbiology

Genetic interactions among Ghd7, Ghd7.1, Ghd8 and Hd1 contribute to large variation in heading date in rice

Several major heading date genes are sensitive to photoperiod and jointly regulate heading date in rice. However, it is not clear how these genes coordinate rice heading. In this study, a near-isogenic F2 population with Ghd7, Ghd7.1, Ghd8 and Hd1 segregating in the Zhenshan 97 (ZS97) background was used to evaluate the genetic interactions among these four genes under natural long-day (NLD) and natural short-day (NSD) conditions, and a series of Ghd7.1-segregating populations in different backgrounds were developed to estimate the genetic effects of Ghd7.1 on heading date under both conditions. Tetragenic, trigenic and digenic interactions among these four genes were observed under both conditions. In the functional Hd1 backgrounds, the strongest digenic interaction was Ghd7 by Ghd8 under NLD conditions but was Ghd7 by Ghd7.1 under NSD conditions. Interestingly, Ghd7.1 acted as a flowering suppressor under NLD conditions, while it functioned alternatively as an activator or a suppressor under NSD conditions depending on the status of the other three genes. Based on the performances of 16 homozygous four-gene combinations, a positive correlation between heading date and yield was found under NSD conditions, but changed to a negative correlation when heading date was over 90 days under NLD conditions. These results demonstrate the importance of genetic interactions in the rice flowering regulatory network and will help breeders to select favorable combinations to maximize rice yield potential for different ecological areas.

genetics

Why Put-Up with Immunity when there is Resistance: An Excursion into the Population and Evolutionary Dynamics of Restriction-Modification and CRISPR-Cas

Bacteria can readily generate mutations that prevent bacteriophage (phage) adsorption and thus make bacteria resistant to infections with these viruses. Nevertheless, the majority of bacteria carry complex innate and/or adaptive immune systems: restriction-modification (RM) and CRISPR-Cas, respectively. Both RM and CRISPR-Cas are commonly assumed to have evolved and be maintained to protect bacteria from succumbing to infections with lytic phage. Using mathematical models and computer simulations, we explore the conditions, under which selection mediated by lytic phage will favor such complex innate and adaptive immune systems, as opposed to simple envelope resistance. The results of our analysis suggest that when populations of bacteria are confronted with lytic phage: (i) In the absence of immunity, resistance to even multiple bacteriophage species with independent receptors can evolve readily. (ii) RM immunity can benefit bacteria by preventing phage from invading established bacterial populations and particularly so when there are multiple bacteriophage species adsorbing to different receptors. (iii) Whether CRISPR-Cas immunity will prevail over envelope resistance depends critically on the length of the co-evolutionary arms race between the bacteria acquiring spacers and the phage generating CRISPR-escape mutants. We discuss the implications of these results in the context of the evolution and maintenance of RM and CRISPR-Cas and highlight fundamental questions that remain unanswered.\n\nSummaryThe two most widely used tools for manipulating and editing DNA restriction and Cas9 endonucleases both originate from studies of mechanisms that provide bacteria with immunity to infections with lytic bacteriophage (phage): restriction modification and CRISPR-Cas. Using mathematical and computer simulations, we explore the a priori conditions under which selection mediated by lytic phage will favor the evolution and maintenance of restriction-modification and CRISPR-Cas immunity in bacteria that, by mutation, can generate envelope resistance to these phage. The results of our analysis make predictions and raise testable-hypotheses about the genetic and ecological conditions under which these immune systems, rather than envelope resistance, will evolve and be maintained as the dominant mechanism of protecting bacteria from succumbing to infections with these viruses.

evolutionary biology

Thyroid cancer incidence and mortality in Latin America

This study analyzed trends in thyroid cancer incidence and mortality in countries of Latin America. Ecological study of time series, with incidence data extracted from the International Agency for Research on Cancer (IARC), in the 1990-2012 period and mortality data obtained from 16 countries of the World Health Organization (WHO), in the 1995-2013 period. The trend of incidence rate was analyzed by the Joinpoint regression. The average annual percentage change (AAPC) and the 95% confidence interval (CI 95%) were calculated for incidence and mortality. The average rate of thyroid cancer incidence was higher in Quito (Ecuador) between the ages of 40 to 59 years old, 42.2 new cases per 100,000 inhabitants, as well as mortality 4.8 deaths per 100,000 women inhabitants above 60 years old. There was an increase in thyroid cancer incidence trends in women, for all age groups, in Cali, Costa Rica and Quito and men in Costa Rica; there was stability above the age of 60 years old in Cali, Goiania, Quito and Valdivia in men, as well as women in Goiania and Valdivia. There was a trend of increasing mortality for females in three countries: Ecuador (AAPC= 3,28 CI 95% 1,36;5,24), Guatemala (AAPC= 6,14 CI 95% 2,81;9,58) and Mexico (AAPC= 0,67 CI 95% 0,16;1,18). Thyroid cancer in Latin America showed a high incidence, with increased incidence in women. Stability in mortality was observed for most countries of Latin America.

epidemiology

Culturomics of Aerobic Anoxygenic Phototrophic Bacteria in Wheat Phyllosphere Revealed a Divergent Evolutionary Pattern of Photosynthesis Genes in Methylobacterium spp.

The phyllosphere is a habitat to a variety of viruses, bacteria, fungi and other microorganisms, which play a fundamental role in maintaining the health of plants and mediating the interaction between plants and ambient environments. A recent addition to this catalogue of microbial diversity was the aerobic anoxygenic phototrophs (AAPs), a group of widespread bacteria that absorb light through bacteriochlorophyll (BChl a) to produce energy without fixing carbon or producing molecular oxygen. However, culture representatives of AAPs from phyllosphere and their genome information are lacking, limiting our capability to assess their potential ecological roles in this unique niche. In this study, we investigated the presence of AAPs in the phyllosphere of a winter wheat (Triticum aestivum L.) in Denmark by employing bacterial colony based infrared imaging and MALDI-TOF mass spectrometry (MS) techniques. A total of ~4480 colonies were screened for the presence of cellular BChl a, resulting in 129 AAP isolates that were further clustered into 25 groups based on MALDI-TOF MS profiling, representatives of which were sequenced using the Illumina NextSeq and Oxford Nanopore MinION platforms. Twenty draft and five complete genomes of AAPs were assembled belonging in Methylobacterium, Rhizobium, Roseomonas and a novel strain in Methylocystaceae. We observed a diverging pattern in the evolutionary rates of photosynthesis genes among the highly homogenous AAP strains of Methylobacterium (Alphaproteobacteria), highlighting an ongoing genomic innovation at the gene cluster level.

microbiology

High temperature limits on developmental canalization in the ascidian Ciona intestinalis

The normal embryogenesis of marine animals is typically confined to a species-specific range of temperatures. Within that temperature range development results in a consistent, or canalized, phenotype, whereas above and below the range abnormal phenotypes are produced. This study reveals an abrupt high temperature limit, occurring over a 1-2{degrees}C range, for normal embryonic development in C. intestinalis. Above that threshold morphological abnormalities in the notochord and other organs are observed, beginning with cleavage and gastrula stages, and becoming more pronounced as embryogenesis proceeds. However, even in highly morphologically abnormal temperature disrupted (TD) embryos, cell type specification, including muscle, endoderm, notochord, and sensory pigment cells is accomplished. An explanation for this finding is that in C. intestinalis cell type specification occurs relatively early in embryogenesis, due to cleavage stage segregation of maternal cytoplasmic determinants and short-range cell interactions, which are largely intact in TD embryos. On the other hand, morphogenesis of the notochord and other structures is dependent on precise cell movement and shape changes after the gastrula stage, which appear to be disrupted above the high temperature threshold. These findings have implications for the relationship between ecology and reproduction in C. intestinalis. More broadly they point to mechanisms behind canalization in animals, such as ascidians, characterized by early, largely autonomous, cell type specification.

developmental biology

Tick-borne pathogen detection in midgut and salivary glands of adult Ixodes ricinus

BackgroundTick midgut and salivary glands represent the primary organs for pathogen acquisition and transmission, respectively. Specifically, the midgut is the first organ to have contact with pathogens during the blood meal uptake, while salivary glands along with their secretions play a crucial role in pathogen transmission to the host. Currently there is little data about pathogen composition and prevalences in I. ricinus midgut and salivary glands. The present study investigated the presence of 32 pathogen species in the midgut and salivary glands of unfed I. ricinus males and females using high-throughput microfluidic real-time PCR. Such an approach is important for enriching the knowledge about pathogen distribution in distinct tick organs which should lead to a better understanding I. ricinus-borne disease epidemiology.\n\nResultsBorrelia lusitaniae, Borrelia spielmanii, and Borrelia garinii, were detected in both midgut and salivary glands suggesting that the migration of these pathogens between these two organs might not be triggered by the blood meal. In contrast, Borrelia afzelii was detected only in the tick midgut. Anaplasma phagocytophilum and Rickettsia helvetica were the most frequently detected in ticks and were found in both males and females in the midgut and salivary glands. In contrast, Rickettsia felis was only detected in salivary glands. Finally Borrelia miyamotoi and Babesia venatorum were detected only in males in both midgut and salivary glands. Among all collected ticks, between 10 and 21% of organs were co-infected. The most common bacterial co-infections in male and female midgut and salivary glands was R. helvetica/A. phagocytophilum and R. helvetica/B. lusitaniae respectively.\n\nConclusionsAnalysing tick-borne pathogen (TBP) presence in specific tick organs enabled us to (i) highlight contrasting results with well-established transmission mechanism postulates, (ii) venture new hypotheses concerning pathogen location and migration from midgut to salivary glands, and (iii) suggest other potential associations between pathogens not previously detected at the scale of the whole tick. This work highlights the importance of considering all tick scales (i.e. whole ticks vs organs) to study TBP ecology and represents another step towards improved understanding of TBP transmission.

epidemiology

Perception is shaped along the (L+M)/S axis (and possibly confused with a memory color effect)

Here human trichromats were presented with two types of scenes - geometric and real-world scenes -tinted with a shade of colour in order to destabilize the perceived illumination, and chromaticity of the retinal image of each scene. Each trichromat was instructed to adjust the chromaticity of the object embedded within each scene until its surface appeared devoid of any hue in the DKL colour space which spans two chromatic opponent axes - the S-(L+M) and L- M axis - and a luminance axis - the L+M axis. The following observations were made : (i) across scenes, adjustments were dispersed along the S-(L+M) axis, along which daylight is known to vary; (ii) across trichromats, for the geometric scenes, adjustments were biased towards the S pole of the S-(L+M) axis for one group (group 1), and towards the (L+M) pole for the other group (group 2); (iii) for the real-world scenes, adjustments for both groups systematically converged towards the (L+M) pole. These results suggest that when the core set of priors upon which the human visual system typically relies become ill-equipped, the human visual system is able to recruit one of the two illumination priors - PriorS or PriorL+M - in combination with the representation it has formed over time about the spectral composition of the illuminant associated with scenes the trichromatic observer is currently being exposed to within its ecological niche, as it attempts to stabilize the chromaticity of the retinal image of real-world scenes.

animal behavior and cognition

Is Anopheles gambiae a natural host of Wolbachia?

Wolbachia (Alphaproteobacteria, Rickettsiales) is an intraovarially-transmitted symbiont of insects able to exert striking phenotypes, including reproductive manipulations and pathogen blocking. These phenotypes make Wolbachia a promising tool to combat mosquito-borne diseases. Although Wolbachia is present in the majority of terrestrial arthropods, including many disease vectors, it was considered absent from Anopheles gambiae mosquitos, the main vectors of malaria in sub-Saharan Africa. In 2014, Wolbachia sequences were detected in A. gambiae samples collected in Burkina Faso. Subsequently, similar evidence came from collections all over Africa, revealing a high Wolbachia 16S sequence diversity, low abundance, and a lack of congruence between host and symbiont phylogenies. Here, we reanalyze and discuss recent evidence on the presence of Wolbachia sequences in A. gambiae. We find that although detected at increasing frequencies, the unusual properties of these Wolbachia sequences render them insufficient to diagnose natural infections in A. gambiae. Future studies should focus on uncovering the origin of Wolbachia sequence variants in Anopheles and seeking sequence-independent evidence for this new symbiosis. Understanding the ecology of Anopheles mosquitos and their interactions with Wolbachia will be key in designing successful, integrative approaches to limit malaria spread. Although the prospect of using Wolbachia to fight malaria is intriguing, the newly discovered strains do not bring it closer to realization.\n\nSignificanceAnopheles gambiae mosquitos are the main vectors of malaria, threatening around half of the worlds population. The bacterial symbiont Wolbachia can interfere with disease transmission by other important insect vectors, but until recently it was thought to be absent from natural A. gambiae populations. Here, we critically analyze the genomic, metagenomic, PCR, imaging and phenotypic data presented in support of the presence of natural Wolbachia infections in A. gambiae. We find that they are insufficient to diagnose Wolbachia infections and argue for the need of obtaining robust data confirming basic Wolbachia characteristics in this system. Determining Wolbachia infection status of Anopheles is critical due to its potential to influence Anopheles population structure and Plasmodium transmission.

microbiology

Italian norms and naming latencies for 357 high quality color images

In the domain of cognitive studies on the lexico-semantic representational system, one of the most important means of ensuring well-suited experimental designs is using ecological stimulus sets accompanied by normative data on the most relevant variables affecting the processing of their items. In the context of image sets, color photographs are particularly suited for this aim as they reduce the difficulty of visual decoding processes that may emerge with traditional image sets of line drawings, especially in clinical populations. We provide Italian norms for a set of 357 high quality image-items belonging to 23 semantic subcategories. Data from several variables affecting image processing: age of acquisition, familiarity, lexical frequency, manipulability, name agreement, typicality and visual complexity; were collected from a sample of 255 Italian-speaking participants. Lexical frequency data were derived from the CoLFIS corpus. Furthermore, we collected data with on image naming latencies aimed at exploring how much of the variance in these latencies could be explained by the above mentioned critical variables. Multiple regression analyses on the naming latencies show classical psycholinguistic phenomena, such as the effects of age of acquisition and name agreement. In addition, manipulability is also a significant predictor. The described Italian normative data and naming latencies are available for download as supplementary material.

animal behavior and cognition

How to Build a Fruit: Transcriptomics of a Novel Fruit Type in the Brassiceae

Comparative gene expression studies are invaluable for predicting how existing genetic pathways may be modified or redeployed to produce novel and variable phenotypes. Fruits are ecologically important organs because of their impact on plant fitness and seed dispersal, modifications in which results in morphological variation across species. A novel fruit type in the Brassicaceae known as heteroarthrocarpy enables distinct dispersal methods in a single fruit through segmentation via a lateral joint and variable dehiscence at maturity. Given the close relationship to Arabidopsis, species that exhibit heteroarthrocarpy are powerful models to elucidate how differences in gene expression of a fruit patterning pathway may result in novel fruit types. Transcriptomes of distal, joint, and proximal regions from Erucaria erucarioides and Cakile lanceolata were analyzed to elucidate within and between species differences in whole transcriptome, gene ontology, and fruit patterning expression profiles. Whole transcriptome expression profiles vary between fruit regions in patterns that are consistent with fruit anatomy. These transcriptomic variances do not correlate with changes in gene ontology, as they remain generally stable within and between both species. Upstream regulators in the fruit patterning pathway, FILAMENTOUS FLOWER and YABBY3, are expressed in the distal and proximal regions of E. erucarioides, but not in the joint, implicating alterations in the pathway in heteroarthrocarpic fruits. Downstream gene, INDEHISCENT, is significantly upregulated in the abscissing joint region of C. lanceolata, which suggests repurposing of valve margin genes for novel joint disarticulation in an otherwise indehiscent fruit. In summary, these data are consistent with modifications in fruit patterning genes producing heteroarthrocarpic fruits through different components of the pathway relative to other indehiscent, non-heteroarthrocarpic, species within the family. Our understanding of fruit development in Arabidopsis is now extended to atypical siliques within the Brassicaceae, facilitating future studies on seed shattering in important Brassicaceous crops and pernicious weeds.

plant biology

Degree of urbanization and predation pressure on artificial lepidopteran caterpillars in Cali, Colombia

Growing urban expansion results in the alteration of ecological processes (i.e. predation) within trophic networks. Predation on herbivores is known to vary with the size of the area covered in vegetation, successional stage, altitude, and the structure of the predator community, but there are gaps in information regarding how this occurs in urban and suburban environments. The purpose of this study was to determine whether the predation pressure on artificial models of lepidopteran larvae varied with degree of urbanization, type of substrate, and group of predators (birds or arthropods) in Cali, Colombia. Five hundred and eighteen artificial larvae were placed in two areas of the city (urban vs. suburban) and in two types of substrate (leaf vs. stem) for 30 continuous days and with two replications over time. Total predation was measured as the number of models with evidence of attack by predators. The overall incidence of predation was 24.13%, and was significantly higher in the urban area (63.20%) when compared to the suburban area (36.80%). The leaf substrate was attacked significantly more than the stem (60% vs. 40%). The proportion of attacks carried out by birds was significantly higher (74.40%) than that carried out by arthropods (24.80%). Together, these results suggest that the incidence of predation varies with the disturbance caused by urbanization and by the type of substrate in which prey organisms are found. In addition, the study confirms that birds are the main controllers of herbivorous insects in urban environments.

animal behavior and cognition

Expected and observed genotype complexity in prokaryotes: correlation between 16S-rRNA phylogeny and protein domain content

BackgroundThe omnipresent 16S ribosomal RNA gene (16S-rRNA) is commonly used to identify and classify bacteria though it does not take into account the distinctive functional characteristics of taxa. We explored functional domain landscapes of over 5700 complete bacterial genomes, representing a wide coverage of the bacterial tree of life, and investigated to what extent the observed protein domain diversity correlates with the expected evolutionary diversity, using 16S-rRNA as metric for evolutionary distance.\n\nResultsAnalysis of protein domains showed that 83% of the bacterial genes code for at least one of the 9722 domain classes identified. By comparing clade specific and global persistence scores, candidate horizontal gene transfer and signifying domains could be identified. 16S-rRNA and functional domain content distances were used to evaluate and compare species divergence and overall a sigmoid curve is observed. Already at close 16S-rRNA evolutionary distances, high levels of functional diversity can be observed. At a larger 16S-rRNA distance, functional differences accumulate at a relatively lower pace.\n\nConclusionsAnalysis of 16S-rRNA sequences in the same taxa suggests that, in many cases, additional means of classification are required to obtain reliable phylogenetic relationships. Whole genome protein domain class phylogenies correlate with, and complement 16S-rRNA sequence-based phylogenies. Moreover, domain-based phylogenies can be constructed over large evolutionary distances and provide an in-depth insight of the functional diversity within and among species and enables large scale functional comparisons. The increased granularity obtained paves way for new applications to better predict the relationships between genotype, physiology and ecology.

genomics

Establishment of the mayfly Cloeon dipterum as a new model system to investigate insect evolution

The great capability of insects to adapt to new environments promoted their extraordinary diversification, resulting in the group of Metazoa with the largest number of species distributed worldwide. To understand this enormous diversity, it is essential to investigate lineages that would allow the reconstruction of the early events in the evolution of insects. However, research on insect ecology, physiology, development and evolution has mostly focused on few well-established model species. The key phylogenetic position of mayflies within Paleoptera, as the sister group of the rest of winged insects and life history traits of mayflies make them an essential order to understand insect evolution. Here, we describe the established of a continuous culture system of the mayfly Cloeon dipterum and a series of experimental protocols and -omics resources that allow the study of its development and its great regenerative capability. Thus, the establishment of Cloeon as an experimental platform paves the way to understand genomic and morphogenetic events that occurred at the origin of winged insects.

evolutionary biology

Human sequence learning involves creating new neural representations not strengthening old ones

We contrast two computational models of sequence learning. The associative learner posits that learning proceeds by strengthening existing association weights. Alternatively, recoding posits that learning creates new and more efficient representations of the learned sequences. Importantly, both models propose that humans act as optimal learners but capture different statistics of the stimuli in their internal model. Furthermore, these models make dissociable predictions as to how learning changes the neural representation of sequences. We tested these predictions by using fMRI to extract neural activity patters from the dorsal visual processing stream during a sequence recall task. We observed that only the recoding account can explain the similarity of neural activity patterns, suggesting that participants recode the learned sequences using chunks. We show that associative learning can theoretically store only very limited number of overlapping sequences, such as common in ecological working memory tasks, and hence an efficient learner should recode initial sequence representations.

neuroscience

The Bayesian Superorganism II: optimal foraging and the information theory of gambling

At a macroscopic level, part of the ant colony life-cycle is simple: a colony collects resources; these resources are converted into more ants, and these ants in turn collect more resources. Because more ants collect more resources, this is a multiplicative process, and the expected logarithm of the amount of resources determines how successful the colony will be in the long run. Over 60 years ago, Kelly showed, using information theoretic techniques, that the rate of growth of resources for such a situation is optimised by a strategy of betting in proportion to the probability of payoff. Thus, in the case of ants the fraction of the colony foraging at a given location should be proportional to the probability that resources will be found there, a result widely applied in the mathematics of gambling. This theoretical optimum generates predictions for which collective ant movement strategies might have evolved. Here, we show how colony level optimal foraging behaviour can be achieved by mapping movement to Markov chain Monte Carlo methods, specifically Hamiltonian Markov chain Monte Carlo (HMC). This can be done by the ants following a (noisy) local measurement of the (logarithm of) the resource probability gradient (possibly supplemented with momentum, i.e. a propensity to move in the same direction). This maps the problem of foraging (via the information theory of gambling, stochastic dynamics and techniques employed within Bayesian statistics to efficiently sample from probability distributions) to simple models of ant foraging behaviour. This identification has broad applicability, facilitates the application of information theory approaches to understanding movement ecology, and unifies insights from existing biomechanical, cognitive, random and optimality movement paradigms. At the cost of requiring ants to obtain (noisy) resource gradient information, we show that this model is both efficient, and matches a number of characteristics of real ant exploration.

animal behavior and cognition

Strong and lasting impacts of past global warming on baleen whale and prey abundance

AbstractThe demography of baleen whales and their prey during the past 30 thousand years was assessed to understand the effects of past rapid global warming on marine ecosystems. Mitochondrial and genome-wide DNA sequence variation in eight baleen whale and seven prey species revealed strong, ocean-wide demographic changes that were correlated with changes in global temperatures and regional oceanographic conditions. In the Southern Ocean baleen whale and prey abundance increased exponentially and in apparent synchrony, whereas changes in abundance varied among species in the more heterogeneous North Atlantic Ocean. The estimated changes in whale abundance correlated with increases in the abundance of prey likely driven by reductions in sea-ice cover and an overall increase in primary production. However, the specific regional oceanographic environment, trophic interactions and species ecology also appeared to play an important role. Somewhat surprisingly the abundance of baleen whales and prey continued to increase for several thousand years after global temperatures stabilized. These findings warn of the potential for dramatic, long-term effects of current climate changes on the marine ecosystem.\n\nOne Sentence SummaryThe effects of past global warming on marine ecosystems were drastic, system-wide and long-lasting.

evolutionary biology