Tracking greenery across a latitudinal gradient in central Asia – the migration of the saiga antelope

Aim Long‐distance migrations of terrestrial animals, driven by needs such as food, water and escaping predators and harsh climatic conditions, are widely known phenomena. The saiga antelope (Saiga tatarica tatarica) migrates over long distances in the semi‐arid rangelands of Central Asia. Both the saiga’s range and its populations have been severely affected by socio‐political and land use changes over the last century, related to the formation and dissolution of the Soviet Union. We identified ecological drivers of saiga migration, compared four populations in terms of differences in the geographical characteristics of their ranges and the factors affecting habitat selection within the seasonal ranges. Location Kazakhstan and pre‐Caspian Russia. Methods Using 40 years of direct observations, we tested for differences between the four saiga populations’ ranges in terms of precipitation, seasonal productivity and topographical variables using discriminant analyses. We tested hypotheses concerning the drivers of migration to their seasonal ranges and assessed the impact of peak and average values and the predictability of drivers of habitat use within the seasonal ranges using logistic regressions. Results Three of the four populations migrate in a similar way, following a latitudinal gradient driven by seasonal changes in productivity, which is closely related to broad‐scale differences in precipitation. Intermediate productivity and its low interannual variability determine habitat selection within the seasonal ranges of all the populations. Main conclusions Migration of all four populations is driven by productivity and precipitation. The migrations in Kazakhstan are still intact despite major recent disruption to the populations, whereas their status in the pre‐Caspian region is unknown. All four populations are under severe threat from habitat loss, poaching, lack of protection and gaps in ecological knowledge. A better understanding of the drivers of saiga migration at multiple scales is a key step towards addressing these threats.     

Notes on skulls of Pleistocene Saiga of Northern Eurasia

Eighteen fossil skulls of male Saiga from Northern Eurasia and 33 recent skulls from Kalmykia and Kazakhstan have been studied. Saiga from both the Khazarian Fauna of the Volga and Mammoth Fauna of Europe and Siberia are referred to Saiga horealis Tschersky, 1876. During the Pleistocene, 5. borealis distribution extended from England in the west to Alaska in the east and is characterized by an elongated neurocranium, small frontal angle of the temporal bone from the plane of the frontal, and long nasal bones.

S. borealis was a typical representative of the “mammoth biome”; in the Pleistocene periglacial steppes and cryogenic savannahs. Two subspecies are recognized: S. borealis borealis Tschersky (Eastern Sibera and Alaska); and S.b. prisca Nehring, 1891 (Europe, Urals and Western Siberia). At the end of the Pleistocene, when the mammoth disappeared, the range of S. borealis was reduced. Today they live only in West Mongolia (S. borealis mongolica Bannikov, 1946). S. tatarica tatarica was widely distributed in the other territories of the steppe and semidesert zones of Eurasia. The arid landscapes of Transcaucasia and Kazakhstan were inhabited by Saiga with thinner legs and shorter nasal bones, such as S. tatarica binagadensis Alekperova, 1953, from the middle Pleistocene of Azerbaijan (Bynagady). Fossil skulls from the Ural River that are large, but with a short neurocranium are identified as Saiga sp. cf. S. tatarica Linnaeus, 1766.     

脑红蛋白在赛加羚羊主要内脏器官中的表达与定位

赛加羚羊(Saiga tatarica)属于我国一级重点保护野生动物,其原产地主要为高寒低氧地区,现存种群则主要栖息于中亚地区的荒漠及半荒漠草原上。脑红蛋白是一种存在于脊椎动物体内具有运输和储存血氧能力的球蛋白,在动物适应低氧过程中具有重要的生理功能。为了初步探究赛加羚羊对低氧环境的耐受性机制,运用免疫组织化学染色法与实时荧光定量PCR技术,对脑红蛋白及脑红蛋白基因(NGB)在赛加羚羊的心、肝、脾、肺、肾等5种主要内脏器官中的分布规律与表达情况进行了探究。免疫组织化学染色结果显示,脑红蛋白在赛加羚羊的心、肝、脾、肺、肾中均有分布,阳性表达主要分布在其心肌细胞、肝细胞、脾白髓区中的淋巴细胞、肺泡细胞以及肾小球内皮细胞。实时荧光定量PCR结果显示,脑红蛋白基因在赛加羚羊心、肝、脾、肺、肾中的表达量不同,脾的表达量最高,心的表达量次之,两者均显著高于肝、肺和肾(P < 0.05);其后依次为肝、肾、肺,其中,肝的表达量显著高于肾和肺(P < 0.05),肾和肺之间表达量差异不显著(P > 0.05),肺的表达量最低。上述研究表明,脑红蛋白在赛加羚羊的主要内脏器官中均有阳性表达,不同内脏器官中的表达量不同,这表明脑红蛋白可能参与了这些内脏器官的氧利用过程,具体机制有待进一步探讨。     

The role of demography,intra‐species variation,and species distribution models in species' projections under climate change

Organisms are projected to shift their distribution ranges under climate change. The typical way to assess range shifts is by species distribution models (SDMs), which predict species’ responses to climate based solely on projected climatic suitability. However, life history traits can impact species’ responses to shifting habitat suitability. Additionally, it remains unclear if differences in vital rates across populations within a species can offset or exacerbate the effects of predicted changes in climatic suitability on population viability. In order to obtain a fuller understanding of the response of one species to projected climatic changes, we coupled demographic processes with predicted changes in suitable habitat for the monocarpic thistle Carlina vulgaris across northern Europe. We first developed a life history model with species‐specific average fecundity and survival rates and linked it to a SDM that predicted changes in habitat suitability through time with changes in climatic variables. We then varied the demographic parameters based upon observed vital rates of local populations from a translocation experiment. Despite the fact that the SDM alone predicted C. vulgaris to be a climate ‘winner’ overall, coupling the model with changes in demography and small‐scale habitat suitability resulted in a matrix of stable, declining, and increasing patches. For populations predicted to experience declines or increases in abundance due to changes in habitat suitability, altered fecundity and survival rates can reverse projected population trends.     

Assessing occupancy and habitat connectivity for Baird’s tapir to establish conservation priorities in the Sierra Madre de Chiapas,Mexico

Baird’s tapir (Tapirus bairdii) is the largest native mammal that inhabits the Neotropics, and it is enlisted as Endangered by the IUCN Red List. The historic distribution of this species included the area from southern Mexico to northern Colombia. However, its distribution and populations have been reduced drastically during the past 30 years. The main threats for Baird’s tapir are the direct persecution for subsistence hunting, habitat destruction, and habitat fragmentation. In this study, we used camera traps and occupancy models to identify the landscape characteristics that were associated with the occurrence of tapirs in the Sierra Madre de Chiapas, which is one of the most important populations of the species in Mexico, with the aim to identify areas with habitat suitability for the species. We used our best occupancy model to generate a resistance matrix to develop a model of habitat connectivity using Circuit Theory. According to the best occupancy model, the most suitable areas for this species were the forested areas located at the highest elevations of the mountain ranges that provided rugged terrain. We identified three critical corridors to allow for the connectivity of tapir populations in the Sierra Madre de Chiapas, and one of these corridors provides connectivity between this population and the population in the Ocote Biosphere Reserve. With this approach, we propose a conservation strategy for the species that incorporates a more realistic and detailed scheme of Baird’s tapir occurrence in the Sierra Madre de Chiapas region. Priority actions to conserve tapirs in the Sierra Madre de Chiapas over the long term include ensuring the complete protection of prime habitat for the species, improved connectivity by protecting forest cover, implementation mitigation measures in areas where paved roads interrupt connectivity of populations, and eradicating poaching of the species in the region completely.     

Spatial heterogeneity in the effects of climate change on the population dynamics of a Mediterranean tortoise

Climatic shifts may increase the extinction risk of populations, especially when they are already suffering from other anthropogenic impacts. Our ability to predict the consequences of climate change on endangered species is limited by our scarce knowledge of the effects of climate variability on the population dynamics of most organisms and by the uncertainty of climate projections, which depend strongly on the region of the earth being considered. In this study, we analysed a long‐term monitoring programme (1988–2009) of Hermann's tortoise (Testudo hermanni) aimed at evaluating the consequences of the drastic changes in temperature and precipitation patterns predicted for the Mediterranean region on the demography of a long‐lived species with low dispersal capability and already suffering a large number of threats. Capture–recapture modelling of a population in the Ebro Delta (NE Spain) allowed us to assess the effect of climate variability on the survival of tortoises. Winter rainfall was found to be the major driver of juvenile and immature survival, whereas that of adults remained high and constant across the study. Furthermore, local climate series obtained ad hoc from regional climate simulations, for this and 10 additional Mediterranean locations where tortoises occurred, provided us with reliable future climate forecasts, which were used to simulate the fate of these populations under three precipitation scenarios (mean, wet and dry) using stochastic population modelling. We show that a shift to a more arid climate would have negative consequences for population persistence, enhancing juvenile mortality and increasing quasiextinction risk because of a decrease in recruitment. These processes varied depending on the population and the climate scenario we considered, but our results suggest that unless other human‐induced causes of mortality are suppressed (e.g. poaching, fire, habitat fragmentation), climate variability will increase extinction risk within most of the species’ current range.     

Mobility and metapopulation structure of Geocrinia alba and Geocrinia vitellina,two endangered frog species from southwestern Australia

Abstract Dispersal rates can have an important impact on many population processes. Dispersal can lead to population regulation and regional stability in the face of local instability through the formation of a metapopulation. This may be particularly true for frogs because they often have patchy distributions. In this paper I investigate dispersal by male Geocrinia alba and Geocrinia vitellina, using a mark-recapture study. Pit traps were used to determine whether frogs move out of their breeding habitat. I found that both species were very philopatric. Between the 1993 and 1994 breeding seasons, 76–86% of individuals were displaced less than 10m and 90–97% were displaced less than 20m. Dispersal was even lower within each breeding season, with 92–95% of individuals being displaced less than 5 m. Pit trapping indicated that some individuals of both species move out of the swamps in late autumn and return at the beginning of the breeding season, in late winter and early spring. Therefore, although displacement may be very restricted, the frogs are likely to move greater distances. The extreme breeding-site philopatry exhibited by G. alba and G. vitellina suggests that movement between disjunct populations is unlikely and that populations in continuous habitat may be relatively isolated from one another by distance alone. This is consistent with previous predictions based on genetic studies, which suggested there was very little migration between populations. These data support the contention that neither species is likely to exist as a metapopulation because recolonization of vacant habitat is improbable.     

Long-term dynamics of wild primate populations across forests with contrasting protection in Tanzania

Anthropogenic activities driving tropical forests' loss imperil global biodiversity and provision of ecosystem services. In this context, systematic monitoring programs evaluating wildlife trends are essential. Non-human primates are relevant conservation targets since they represent vital components of tropical forests by serving as pollinators and seed dispersers. Here, we present primate group counts data collected over 19 years in a primate hotspot in Tanzania. We analyzed data with a hierarchical dynamic model accounting for imperfect detection that estimates local group abundance and temporal rates of change, to assess whether habitat protection explained trends of the arboreal and diurnal Peters' Angola colobus (Colobus angolensis palliatus), Udzungwa red colobus (Piliocolobus gordonorum), and Tanzania Sykes' monkey (Cercopithecus mitis subsp. moloneyi). We targeted populations occurring in two forest blocks with contrasting protection regimes, with one block impacted by targeted poaching of the two Colobus species. We found that these latter species were much less abundant in the more human impacted forest, underwent a rapid decline, and subsequently remained at low abundance and without signs of recovery once this forest was granted greater protection. Instead, Sykes' abundance did not differ between forests, and improved protection was associated with a slight increase in abundance. Age class composition for social groups of both Colobus species differed between forests, indicating altered births and survivorship rates in the impacted forest. Results suggest that targeted hunting can prevent recovery for several years and even after increased habitat protection. Our approach appears valuable to monitor population dynamics over the long term, highlighting species-specific variations in both vulnerability to anthropogenic disturbance and recovery patterns in primate populations.     

Social information and emigration: lessons from immigrants

‘Should I stay or should I go?’ is a fundamental question facing any candidate for emigration, as emigrating without outside information has major costs. Most studies on this topic have concentrated on risk‐reducing strategies (e.g. exploration) developed after leaving the natal habitat. The idea that information might be acquired before leaving has not been investigated. Immigrants carrying information about their origins could provide such information to potential emigrants in their initial habitat. We manipulated the density of common lizard (Lacerta vivipara) populations, to investigate whether immigrants originating from these populations transmitted such information to the population they joined. Emigration of the residents of this new population clearly depended on the origin of the immigrant. Immigrants are therefore a source of information, in this case about surrounding population densities, and may have a major effect on dispersal and species persistence in a fragmented habitat.     

Population Dynamics of the Andean Lizard Anolis heterodermus: Fast‐slow Demographic Strategies in Fragmented Scrubland Landscapes

Habitat fragmentation and loss affect population stability and demographic processes, increasing the extinction risk of species. We studied Anolis heterodermus populations inhabiting large and small Andean scrubland patches in three fragmented landscapes in the Sabana de Bogotá (Colombia) to determine the effect of habitat fragmentation and loss on population dynamics. We used the capture‐mark‐recapture method and multistate models to estimate vital rates for each population. We estimated growth population rate and the most important processes that affect λ by elasticity analysis of vital rates. We tested the effects of habitat fragmentation and loss on vital rates of lizard populations. All six isolated populations showed a positive or an equilibrium growth rate (λ = 1), and the most important demographic process affecting λ was the growth to first reproduction. Populations from landscapes with less scrubland natural cover showed higher stasis of young adults. Populations in highly fragmented landscapes showed highest juvenile survival and growth population rates. Independent of the landscape's habitat configuration and connectivity, populations from larger scrubland patches showed low adult survivorship, but high transition rates. Populations varied from a slow strategy with low growth and delayed maturation in smaller patches to a fast strategy with high growth and early maturation in large patches. This variation was congruent with the fast‐slow continuum hypothesis and has serious implications for Andean lizard conservation and management strategies. We suggest that more stable lizard populations will be maintained if different management strategies are adopted according to patch area and habitat structure.