Population Size Of Species Research Articles

Community Structure of Hornbills in an Oil Palm Landscape in East Kalimantan, Indonesia

Conserved land in human dominated landscapes such as oil palm plantations provide habitat for many animal taxa including hornbills. The aim of the study is to quantify species richness, distribution, population size and sex ratio of hornbill community in oil palm landscapes with retained native forest patches. Ecological sampling was conducted in an oil palm plantation in East Kalimantan, Indonesia. Birds were observed using fixed radius point count method. We found that there were six hornbill species belonging to four genera of Bucerotidae including Helmeted Hornbill, Rhinoceros Hornbill, Wreathed Hornbill, Wrinkled Hornbill, Black Hornbill and Oriental Pied Hornbill that occurred in the study site. Population density varied among species ranging from 0.17 to 4.72 individual per km2 in 2012 and 0.34 to 3.35 individual per km2 in 2013. Rhinoceros Hornbill was the most abundant species observed in one location with highest number of individual per group of about 21 individuals during flocking. Sex ratio (M:F) was ranged from 0.31 to 0.95. The dispersion of hornbill species was generally random. Our results show that retention of forest patches on oil palm plantations can help to maintain the diversity and abundance of hornbills in the region.

A unified concept of dominance applicable at both community and species scales

AbstractDominance and evenness can be two sides of the same coin or opposite ends of a spectrum. Although evenness and diversity are community‐level concepts, dominance can be applied at both community and species scales. Nevertheless, there is not a metric applicable at both these scales that are unified with a single mathematical framework in the existing literature. Here, by extending Lloyd's meaning crowding concept from the population to community scale, we propose a dominance concept and associated metrics that are applicable at both scales. Such metrics can act as proxies for diversity in diversity–stability and diversity–ecosystem service analyses or for population abundance in species interaction network analysis and population stability analysis, with advantages in cross‐scale and unified analyses. Our concept of dominance includes three measures (metrics) that link communities and species. The metrics have the same mathematical form, but different interpretations at the community and species scales. Our community‐level metric is a function of Simpson's () diversity index, for which we present a rigorous mathematical proof. Our species‐level metrics quantify the difference between community dominance and the dominance of a virtual community whose mean population size, per species, equals the population size of the focal species. We demonstrate the use of these metrics using data from a longitudinal study of the human vaginal microbiome and provide new insights relevant for microbiome stability and disease etiology at the community scale. The new metrics also can be used for species dominance network (SDN) analysis at the species scale. Since the species dominance is a function of both species (population) abundance and community dominance, it has an advantage of capturing both community‐scale global and species‐scale local information, which becomes even more evident when it is used to construct SDNs. These results demonstrate the significance and applications of our unified dominance concept and metrics.

Cost structure and financial performance of marine commercial fisheries in the South Brazil Bight

In Brazil, economic data on fisheries are generally scarce, and difficult to interpret with respect to costs and fishery viability, thus making it difficult to practice consistent policy and industrial decision-making. Financial performance was assessed, as were the key factors affecting the fishing costs and profitability of the major fisheries fleets that operated in three Southeast and South regions. Through an unprecedented set of field survey data from 160 fishing vessels obtained during 2013–2014, we provide a cost-benefit comparison between different fleets and landing sites. Three generalized additive models (GAMLSS) were explored to identify major factors affecting gross profit. Fuel consumption, vessel repairs, revenue, and volume of catch were the most statistically significant factors explaining gross profit margin. For trawlers and purse-seiners, technical features such as vessel size and the number of fishing trips explained profitability, respectively, while the landing costs were significant to both types of fleet. Gross profits for trawlers also depend on ice cost and fleet type. Large pelagic fisheries showed the highest gross profit, while shrimp-trawlers, bottom-gillnetters and a purse-seining fleet showed the lowest profit, close to unviability. Indirectly, population size of target species may be influencing profitability. Labor wages increase when the financial performance of fleets improve; however, reduced yields and high operational cost levels may decrease the salaries. Specific policy advice and management strategies aiming to protect both financial performance and natural resources are highlighted, including the importance of cost-benefit analysis to help businessmen and vessel owners to identify factors that influence fleet profitability, thereby facilitating the creation of measures for increased efficiency. The approach presented may contribute to standardizing economic knowledge construction in data-poor fisheries, such as S/SE Brazil’s and in other jurisdictions of Brazil or elsewhere.

Neogen: A tool to predict genetic effective population size (Ne ) for species with generational overlap and to assist empirical Ne study design.

Molecular genetic estimates of population effective size (Ne ) lose accuracy and precision when insufficient numbers of samples or loci are used. Ideally, researchers would like to forecast the necessary power when planning their project. neogen (genetic Ne for Overlapping Generations) enables estimates of precision and accuracy in advance of empirical investigation and allows exploration of the power available in different user-specified age-structured sampling schemes. neogen provides a population simulation and genetic power analysis framework that simulates the demographics, genetic composition, and Ne , from species-specific life history, mortality, population size, and genetic priors. neogen guides the user to establish a tractable sampling regime and to determine the numbers of samples and microsatellite or SNP loci required for accurate and precise genetic Ne estimates when sampling a natural population. neogen is useful at multiple stages of a study's life cycle: when budgeting, as sampling and locus development progresses, and for corroboration when empirical Ne estimates are available. The underlying model is applicable to a wide variety of iteroparous species with overlapping generations (e.g., mammals, birds, reptiles, long-lived fishes). In this paper, we describe the neogen model, detail the workflow for the point-and-click software, and explain the graphical results. We demonstrate the use of neogen with empirical Australian east coast zebra shark (Stegostoma fasciatum) data. For researchers wishing to make accurate and precise genetic Ne estimates for overlapping generations species, neogen facilitates planning for sample and locus acquisition, and with existing empirical genetic Ne estimates neogen can corroborate population demographic and life history properties.

Influence of habitat suitability and sex-related detectability on density and population size estimates of habitat-specialist warblers.

Knowledge about the population size and trends of common bird species is crucial for setting conservation priorities and management actions. Multi-species large-scale monitoring schemes have often provided such estimates relying on extrapolation of relative abundances in particular habitats to large-scale areas. Here we show an alternative to inference-rich predictive models, proposing methods to deal with caveats of population size estimations in habitat-specialist species, reed warblers (Acrocephalus scirpaceus and Acrocephalus arundinaceus). Reed warblers were only found in pure reedbeds within riparian woodlands or in riparian vegetation scattered within or around reedbed patches, as expected according to their habitat specialization. The proportion of individuals located in reedbed associated with lotic and lentic waters differed between species, and no reed warbler was recorded in reedbed located along dry streams. This indicates that microhabitat features or their effects on reedbed structure and other factors made a proportion of the apparently available habitat unsuitable for both warbler species. Most warblers detected were males performing territorial singing (females seldom sing and do not perform elaborate territorial song, and are undistinguishable from males by plumage). The regional population sizes of the warbler species (~4000 individuals of A. scirpaceus and ~ 1000 individuals of A. arundinaceus) were much smaller than those estimated for the same area by transforming relative abundance obtained at a national scale to population size through extrapolation by habitat at a regional scale. These results highlight the importance of considering the habitat actually used and its suitability, the manner of sex-related detection, population sex-ratio and their interactions in population estimates. Ideally, the value of predictive methods to estimate population size of common species should be tested before conducting large-scale monitoring, rather than a posteriori. Although logistically challenging, this can be achieved by designing monitoring programs including an intensive sampling of abundance in ad hoc reference areas of variable size.

The importance of core habitat for a threatened species in changing landscapes

Abstract Habitat loss, fragmentation, and alteration of the landscape matrix are interdependent processes, collectively responsible for most recent species extinctions. Thus, determining the extent to which these landscape processes affect animals is critical for conservation. However, researchers have often assumed that interdependent effects are independently related to animals’ responses, underestimating the importance of one or several landscape processes in driving species declines. We demonstrate how to disentangle the interdependent effects of habitat amount, fragmentation, and edge context on population size by assessing abundance of a rapidly declining grassland songbird species (grasshopper sparrow Ammodramus savannarum) in eastern Kansas (USA). We conducted >7,000 point count surveys at >2,000 sites over two breeding seasons, then modelled the direct, interactive, and indirect effects of landscape factors on abundance within spatial scales (200‐, 400‐, 800‐, and 1,600‐m radii) relevant to our focal species’ dispersal behaviour. Sparrow abundance correlated most strongly with landscape structure within 400‐m radii, increasing nonlinearly with grassland area and decreasing with the proportion of grassland near cropland or woody edges. Sparrows’ negative response to cropland edges was mostly an added, indirect consequence of reduced grassland area, whereas sparrows’ stronger negative response to woody edges was not attributable to variation in grassland area. Fragmentation and edge context mattered most in landscapes comprising c. 50%–80% grassland. Synthesis and applications. In our research, abundance of a threatened grassland songbird was influenced more by core grassland area (a function of total grassland area, fragmentation, and edge context) than total grassland area per se. Moreover, a local extinction threshold of c. 50% grassland indicated that small amounts of habitat were unsuitable for our focal species regardless of habitat configuration or matrix type. Local extinction thresholds in response to habitat area provide clear baseline targets for land managers; above those thresholds, configuration and the matrix can be modified to increase abundance of edge‐sensitive animals. Conflicting evidence in the literature regarding the importance of fragmentation and matrix features could be partially explained by species‐level traits, or methodological issues such as defining landscapes at ecologically arbitrary spatial scales, assessing landscape quality using species richness, and ignoring interactive and indirect effects.

Trends in Population Size of Rare Plant Species in the Alpine Habitats of the Ukrainian Carpathians under Climate Change

Population trends in rare alpine plant species in the high-mountain zone of the Ukrainian Carpathians are described with regard to the types of habitats where they occur. Populations of cold-adapted species confined to snowbeds, alpine screes, poorly vegetated rocks, and the highest ridges, as well as mires and springs, are very vulnerable to climate change, while their habitats tend to shrink. The direct impact of warming affects mainly the most cryophilic species. Another driver of changes is climate-induced succession that results in denser vegetation cover and encroachment of more thermophilic plants, which replace low-competitive rare alpine species. Their replacement is largely caused by the loss of open microsites suitable for seed recruitment. However, the climate-driven decrease of snow cover often leads to frost damage to vegetation that provides gaps appropriate for the establishment of many rare species. One of the groups of species that benefit from warming includes rather thermophilic tall herbs that are more common in the subalpine zone but have been actively spreading at higher altitudes lately.

The association between reproductive success with persistent organochlorine pollutants residue in feathers of spur-winged lapwing (Vanellus spinosus L.)

The reproductive and breeding success of wader species is negatively affected by various anthropogenic factors, including persistent organochlorine pollutants (POPs). We aimed to study the association of POPs in feathers with the reproductive success of the spur-winged lapwing (Vanellus spinosus). For this purpose, data on reproductive parameters and feather samples were collected from a breeding population consisting of 19 pairs near Boğazkent district in Antalya, Turkey. Mean concentrations of total polychlorinated biphenyls (ΣPCBs) and organochlorine pesticides (ΣOCPs) were found to be 54 ± 16ng/g and 520ng/g in all samples, respectively. In particular, PCB 151 and β-hexachlorocyclohexane had a negative association the various reproductive parameters in the species under consideration. Fledgling success (n = 25) was calculated to be 37.4%, which was negatively associated with the ΣOCP concentrations (r = - 0.99, p = 0.01). According to the results, POP residues are one of the associated factors on the reproductive success of spur-winged lapwing along, with agricultural activity and predation. It is indicated that the species needs a protection plan for prevention declining reproductive success and population size species in Turkey. Besides, our results suggest that bird feathers are a non-destructive bio-monitoring tools to estimate of contamination levels of organic pollutants in a population.

A review of predation as a limiting factor for bird populations in mesopredator-rich landscapes: a case study of the UK.

The impact of increasing vertebrate predator numbers on bird populations is widely debated among the general public, game managers and conservationists across Europe. However, there are few systematic reviews of whether predation limits the population sizes of European bird species. Views on the impacts of predation are particularly polarised in the UK, probably because the UK has a globally exceptional culture of intensive, high-yield gamebird management where predator removal is the norm. In addition, most apex predators have been exterminated or much depleted in numbers, contributing to a widely held perception that the UK has high numbers of mesopredators. This has resulted in many high-quality studies of mesopredator impacts over several decades. Here we present results from a systematic review of predator trends and abundance, and assess whether predation limits the population sizes of 90 bird species in the UK. Our results confirm that the generalist predators Red Fox (Vulpes vulpes) and Crows (Corvus corone and C. cornix) occur at high densities in the UK compared with other European countries. In addition, some avian and mammalian predators have increased numerically in the UK during recent decades. Despite these high and increasing densities of predators, we found little evidence that predation limits populations of pigeons, woodpeckers and passerines, whereas evidence suggests that ground-nesting seabirds, waders and gamebirds can be limited by predation. Using life-history characteristics of prey species, we found that mainly long-lived species with high adult survival and late onset of breeding were limited by predation. Single-brooded species were also more likely to be limited by predation than multi-brooded species. Predators that depredate prey species during all life stages (i.e. from nest to adult stages) limited prey numbers more than predators that depredated only specific life stages (e.g. solely during the nest phase). The Red Fox and non-native mammals (e.g. the American Mink Neovison vison) were frequently identified as numerically limiting their prey species. Our review has identified predator-prey interactions that are particularly likely to result in population declines of prey species. In the short term, traditional predator-management techniques (e.g. lethal control or fencing to reduce predation by a small number of predator species) could be used to protect these vulnerable species. However, as these techniques are costly and time-consuming, we advocate that future research should identify land-use practices and landscape configurations that would reduce predator numbers and predation rates.

Improving the Estimation of Calling Probability and Correction Factors in Gibbon Monitoring Using the Auditory Point Count Method

Estimating the population size of primate species is very important in identifying appropriate conservation actions and measuring their effectiveness. All 17 species of gibbons recognized by the IUCN are considered threatened with extinction. Thus, there is a great need to determine and monitor their status, to conduct effective conservation interventions. Gibbons can be detected by their loud and long song bouts, and surveys usually rely on auditory point count methods. However, gibbon groups do not call daily, so we need a correction factor based on the daily calling probability to estimate gibbon population size accurately. Several studies have estimated such correction factors, but these estimates might be negatively biased if gibbon groups move beyond the maximum hearing distance or are far from the listening post and their calls are faint. We aimed to address this issue and estimate the calling probability and correction factor accurately. We collected data on southern yellow-cheeked crested gibbon (Nomascus gabriellae) in Cat Tien National Park, Vietnam, from July to October 2016, using an auditory point count method. We explored the influence of the maximum distance between the listening post and the gibbons on estimates of the calling probability, correction factor, and population size. We detected 44 gibbon groups during the survey. The calling probability and correction factor decreased with the maximum distance from the listening post to the gibbon groups. If we used all the gibbon groups to estimate the correction factor, population estimates were 15% and 18% higher than those estimated using only gibbon groups detected within 700 m and 500 m, respectively. Based on these findings, we recommend that researchers calculate the calling probability and correction factor for several maximum distances and determine the percentage overestimation of the gibbon population. They should then choose the correction factor so as to balance sample size and the risk of overestimation of gibbon population size.

Inbreeding affects personality and fitness of a leaf beetle

Habitat loss and fragmentation, which are mostly anthropogenically caused, can lead to decreasing population sizes for many species. Consequently, the risk of inbreeding increases and inbreeding depression can be induced, which is likely to lead to a decline in fitness in inbred individuals. We investigated effects of inbreeding on fitness-related traits during ontogeny of a wild leaf beetle, Phaedon cochleariae, population. We also examined whether the behavioural phenotype, that is, personality, of adult beetles is affected by inbreeding, sex and/or age. We found evidence for inbreeding depression both at the larval stage and in adulthood. We tested the behaviour twice during adulthood and found that beetles show personality, that is, activity, exploration and boldness traits were repeatable and consistent across contexts. Moreover, the personality of inbred and outbred beetles differed significantly. In detail, boldness and exploration traits were affected by inbreeding, partly interacting with the beetles' sex or age. Most notably, inbred beetles were bolder in an unprotected environment than outbred beetles. Inbred individuals may be more risk prone in specific situations, because they have less to lose, since they reproduce less. As well as inbreeding effects on fitness-related traits, the results also show that the personality of arthropods can be affected by inbreeding. This is potentially related to inbreeding depression and thus to fitness declines in inbred individuals. Overall, decreased fitness combined with personality alterations of inbred individuals might affect the further development and survival of populations and thus possibly also (interactions with) other trophic levels of the ecosystem.

Effects of diffusion on total biomass in simple metacommunities

This paper analyzes the effects of diffusion on the overall population size of the different species of a metacommunity. Depending on precise thresholds, we determine whether increasing the dispersal rate of a species has a positive or negative effect on population abundance. These thresholds depend on the interaction type of the species and the quality of the patches. The motivation for researching this issue is that spatial structure is a source of new biological insights with management interest. For instance, in a metacommunity of two competitors, the movement of a competitor could lead to a decrease of the overall population size of both species. On the other hand, we discuss when some classic results of metapopulation theory are preserved in metacommunities. Our results complement some recent experimental work by Zhang and collaborators.

Historical changes in grassland area determined the demography of semi-natural grassland butterflies in Japan

Semi-natural grassland areas expanded worldwide several thousand years ago following an increase in anthropogenic activities. However, semi-natural grassland habitat areas have been declining in recent decades due to changes in landuse, which have caused a loss of grassland biodiversity. Reconstructing historical and recent demographic changes in semi-natural grassland species will help clarify the factors affecting their population decline. Here we quantified past and recent demographic histories of Melitaea ambigua (Lepidoptera; Nymphalidae), an endangered grassland butterfly species in Japan. We examined changes in demography over the past 10,000 years based on 1378 bp of mitochondrial COI gene. We then examined changes in its genetic diversity and structure during the last 30 years using nine microsatellite DNA markers. The effective population size of M. ambigua increased about 3000-6000 years ago. In contrast, the genetic diversity and effective population sizes of many populations significantly declined from the 1980s to 2010s, which is consistent with a recent decline in the species population size. Our data suggest that the M. ambigua demography can be traced to changes in area covered by semi-natural grasslands throughout the Holocene.

Birdsong characteristics are related to fragment size in a neotropical forest

The oscine passerines, an avian suborder that comprises almost half of all bird species worldwide, learn their song primarily through cultural transmission. As the world's forests become increasingly fragmented and the population sizes of many forest-dwelling species decline, there may be increasingly restricted opportunities for the transmission of cultural information. However, the effects of forest fragmentation on birdsong have not been well documented. In this paper, we examine the relationship between forest fragment size and song characteristics for two forest bird species, an oscine passerine (orange-billed sparrow, Arremon aurantiirostris) that learns its song culturally, and a suboscine passerine (scale-crested pygmy tyrant, Lophotriccus pileatus) that does not. Recordings were taken from individuals in 12 premontane wet forest fragments ranging in size from approximately 1.4 ha–360 ha in southern Costa Rica. As predicted under the ‘cultural erosion’ hypothesis, we found that acoustic characteristics associated with song complexity such as the number of syllables per song and song duration decreased with decreasing fragment size for the oscine but not for the suboscine species. This study supports the idea that learned cultural elements are sensitive to fragment size and that cultural diversity should be considered along with other forms of biodiversity in the conservation of social learning species.

A positive relationship between spring temperature and productivity in 20 songbird species in the boreal zone.

Anthropogenic climate warming has already affected the population dynamics of numerous species and is predicted to do so also in the future. To predict the effects of climate change, it is important to know whether productivity is linked to temperature, and whether species' traits affect responses to climate change. To address these objectives, we analysed monitoring data from the Finnish constant effort site ringing scheme collected in 1987-2013 for 20 common songbird species together with climatic data. Warm spring temperature had a positive linear relationship with productivity across the community of 20 species independent of species' traits (realized thermal niche or migration behaviour), suggesting that even the warmest spring temperatures remained below the thermal optimum for reproduction, possibly due to our boreal study area being closer to the cold edge of all study species' distributions. The result also suggests a lack of mismatch between the timing of breeding and peak availability of invertebrate food of the study species. Productivity was positively related to annual growth rates in long-distance migrants, but not in short-distance migrants. Across the 27-year study period, temporal trends in productivity were mostly absent. The population sizes of species with colder thermal niches had decreasing trends, which were not related to temperature responses or temporal trends in productivity. The positive connection between spring temperature and productivity suggests that climate warming has potential to increase the productivity in bird species in the boreal zone, at least in the short term.

Population estimation, distribution, and habitat preference of Irrawaddy dolphins Orcaella brevirostris (Owen in Gray, 1866) in the Brunei Bay, Malaysian waters

The population of Irrawaddy dolphins in Brunei Bay, Malaysia is currently under threat by anthropogenic activities. This study is aimed at contributing information on population size, group composition, spatial occurrence and habitat preferences of this dolphin species in the bay area. A total of 36 individuals (adults) of Irrawaddy dolphins were identified using dorsal fin photo match software (DARWIN) by undertaking 297.91 h of boat‐based dedicated surveys (April 2013 – October 2015). By using the mark–recapture open‐population parameterization, the estimated population size (adult) was 33 (95% CI = 28–39) with the apparent survival rate of 0.98 (0.89–0.99, SE = 0.01). Also, the recapture rate was 0.27 (0.14–0.45, SE = 0.07) and the estimated individual entry rate from super‐population was 0.15 (0.10–0.22, SE = 0.03). The estimated entire population size was 41 (95% CI = 36–49) including calves. The observed mean group size was 6 (SE = 0.66, range 1–18). Two hotspots were identified for dolphin occurrences near Lawas and Labuan Island at a sighting rate of 2.8–12.3 km‐2. The dolphins were encountered in the bay over the entire year with no seasonal differences. The observation of dolphin calves in the groups are a positive indicator that the dolphins are breeding successfully in the Bay area and provide hope that the population will remain stable or increase in number. The dolphins showed habitat preferences of sea depths (2 to 9.99 m), surface water temperature (29 to 31.99°C), and coastline distance (1.5 to 4.49 km). This study provides the first detailed information about Irrawaddy dolphins in the Brunei Bay, Malaysia, and may serve as a baseline for future comparisons. It can help researchers, conservationists, local marine park managers and policy makers to propose effective conservation and management plans in the Brunei Bay area.

Estimating the population sizes of rainforest birds of the Tweed Caldera

Climate change is likely to negatively impact populations of rainforest birds along Australia’s eastern seaboard. To this end, accurate estimations of species’ current population sizes are necessary for future monitoring and conservation. Here, we used distance sampling protocols to generate abundance and density estimates for 11 species of birds occupying the Gondwanan rainforests of the Tweed Caldera on the Queensland–New South Wales border. Data were collected along two elevational gradients in subtropical rainforest between September 2015 and October 2016. Half-normal functions with cosine adjustments were used to calculate the density of each species per km 2 . We used a GIS to determine the total area of suitable habitat available in protected areas adjacent to the sampling locations (~425 km 2 ) and then extrapolated the density estimates to generate estimates of population size for each target species in the study area. Estimated population sizes ranged from 473 719 (Yellow-throated Scrubwren Sericornis citreogularis ) to 21 841 (White-throated Treecreeper Cormobates leucophaea ). The standard error (SE) associated with the population estimate of the White-throated Treecreeper was large, as was the SE associated with the Eastern Yellow Robin Eopsaltria australis (estimated population 235 084), Green Catbird Ailuroedus crassirostris (69 731) and Grey Fantail Rhipidura fuliginosa (124 534). Accurate abundance estimates (SE <20% of total abundance) were obtained for the Brown Gerygone Gerygone mouki (193 919), Brown Thornbill Acanthiza pusilla (198 801), Golden Whistler Pachycephala pectoralis (72 730), Lewin’s Honeyeater Meliphaga lewinii (190 389), Silvereye Zosterops lateralis (92 268), White-browed Scrubwren Sericornis frontalis (94 426) and Yellow throated Scrubwren (473 719). Species specific surveys would provide more accurate results, but given the declines expected for many species in the region, and the current lack of estimates of population sizes in these protected areas, the baseline data presented here are of importance from ecological and conservation perspectives.

Demographic structure and population size of rare endemic Oxytropis species from Priol’khonye steppe

Demographic structure and population size of rare endemic Oxytropis species from Priol’khonye steppe

Mitogenome evolution in the last surviving woolly mammoth population reveals neutral and functional consequences of small population size.

The onset of the Holocene was associated with a global temperature increase, which led to a rise in sea levels and isolation of the last surviving population of woolly mammoths on Wrangel Island. Understanding what happened with the population's genetic diversity at the time of the isolation and during the ensuing 6000 years can help clarify the effects of bottlenecks and subsequent limited population sizes in species approaching extinction. Previous genetic studies have highlighted questions about how the Holocene Wrangel population was established and how the isolation event affected genetic diversity. Here, we generated high‐quality mitogenomes from 21 radiocarbon‐dated woolly mammoths to compare the ancestral large and genetically diverse Late Pleistocene Siberian population and the small Holocene Wrangel population. Our results indicate that mitogenome diversity was reduced to one single haplotype at the time of the isolation, and thus that the Holocene Wrangel Island population was established by a single maternal lineage. Moreover, we show that the ensuing small effective population size coincided with fixation of a nonsynonymous mutation, and a comparative analysis of mutation rates suggests that the evolutionary rate was accelerated in the Holocene population. These results suggest that isolation on Wrangel Island led to an increase in the frequency of deleterious genetic variation, and thus are consistent with the hypothesis that strong genetic drift in small populations leads to purifying selection being less effective in removing deleterious mutations.

Intra- and Interspecific Abundance of Birds Affects Detection of Novel Food Sources by Great TitsParus major

Unpredictable resources in seasonal environments may favour innovative individuals that efficiently explore and exploit such resources. We tested the hypothesis that potential intraspecific abundance is a more powerful predictor of detection of a novel food source than interspecific abundance and predation risk. The hypothesis was tested using latency of Great Tits Parus major to find bird-feeders in relation to the abundance of Great Tit and other birds, as well as cats recorded close to novel feeders in urban and rural habitats. Data were collected during winter 2013/2014 in eight cities and nearby rural areas across Poland. Generalized linear models, multimodel inference and hierarchical partitioning showed that the probability that Great Tits used a novel birdfeeder was positively correlated both with the number of Great Tits and all other tits combined in the vicinity of feeders. Latency in feeder usage was negatively related to the number of conspecifics, and it was less strongly negatively related to the number of other tits and the abundance of all other species. The effect of the number of other tits interacted with the environment; the number of tits positively correlated with latency in rural areas, while this relationship was negative in urban areas. Latency until arrival at a feeder was shorter for males than for females. The effect of cats at feeders on bird behaviour was statistically non-significant. Thus, latency until arrival at novel birdfeeders was predicted by local population size and abundance of other bird species, but not mammalian predators, and this relationship may be altered by the environment.