Conservation: Reproductive collapse in saiga antelope harems

Anisogamy Does Not Always Promote the Evolution of Mating Competition Traits in Males

AbstractAnisogamy has evolved in most sexually reproducing multicellular organisms allowing the definition of male and female sexes, producing small and large gametes. Anisogamy, as the initial sexual dimorphism, is a good starting point to understand the evolution of further sexual dimorphisms. For instance, it is generally accepted that anisogamy sets the stage for more intense mating competition in males than in females. We argue that this idea stems from a restrictive assumption on the conditions under which anisogamy evolved in the first place: the absence of sperm limitation (assuming that all female gametes are fertilized). Here, we relax this assumption and present a model that considers the coevolution of gamete size with a mating competition trait, starting in a population without dimorphism. We vary gamete density to produce different scenarios of gamete limitation. We show that while at high gamete density the evolution of anisogamy always results in male investment in competition, gamete limitation at intermediate gamete densities allows for either females or males to invest more into mating competition. Our results thus suggest that anisogamy does not always promote mating competition among males. The conditions under which anisogamy evolves matter, as does the competition trait.

Animal conflicts escalate in a warmer world

The potential for climate change to affect animal behaviour is widely recognized, yet its possible consequences on aggressiveness are still unclear. If warming and drought limit the availability of food resources, climate change may elicit an increase of intraspecific conflicts stemming from resource competition. By measuring aggressivity indices in a group-living, herbivorous mammal (the Apennine chamois Rupicapra pyrenaica ornata) in two sites differing in habitat quality, and coupling them with estimates of plant productivity, we investigated whether harsh climatic conditions accumulated during the growing season influenced agonistic contests at feeding via vegetation-mediated effects, and their interaction with the site-specific habitat quality. We focused on females, which exhibit intra-group contest competition to access nutritious food patches. Accounting for confounding variables, we found that (1) the aggression rate between foraging individuals increased with the warming accumulated over previous weeks; (2) the probability to deliver more aggressive behaviour patterns toward contestants increased with decreasing rainfall recorded in previous weeks; (3) the effects of cumulative warming and drought on aggressivity indices occurred at time windows spanning 15-30 days, matching those found on vegetation productivity; (4) the effects of unfavourable climatic conditions via vegetation growth on aggressivity were independent of the site-specific habitat quality. Simulations conducted on our model species predict a ~50 % increase in aggression rate following the warming projected over the next 60 years. Where primary productivity will be impacted by warming and drought, our findings suggest that the anticipated climate change scenarios may trigger bottom-up consequences on intraspecific animal conflicts. This study opens the doors for a better understanding of the multifactorial origin of aggression in group-living foragers, emphasising how the escalation of agonistic contests could emerge as a novel response of animal societies to ongoing global warming.

Post-whaling shift in mating tactics in male humpback whales

Recent studies have shown behavioural plasticity in mating strategies can increase a population's ability to cope with anthropogenic impacts. The eastern Australian humpback whale population was whaled almost to extinction in the 1960s (~200 whales) and has recovered to pre-whaling numbers (>20,000 whales). Using an 18-year dataset, where the population increased from approximately 3,700 to 27,000 whales, we found that as male density increased over time, the use of mating tactics shifted towards more males engaging in non-singing physical competition over singing. Singing was the more successful tactic in earlier post-whaling years whereas non-singing behaviour was the more successful tactic in later years. Together, our study uncovers how changes in both local, and population-level male density resulted in a shift in the frequency, and fitness pay-off, of alternative mating tactics in a wild animal. This individual-level plasticity in male humpback whale mating tactics likely contributed to minimising their risk of extinction following a dramatic change in their social landscape due to whaling.

Genetic diversity of the endangered Mongolian saiga antelope Saiga tatarica mongolica (Artiodactyla: Bovidae) provides insights into conservation

The Saiga antelope (Saiga tatarica) is one of the few megafauna species from the mammoth steppe still living today. Currently, saiga are classified as critically endangered, persisting only in small areas of Central Asian steppe and desert ecosystems. The species is divided into two subspecies: Saiga tatarica mongolica and Saiga tatarica tatarica. In this study, we have for the first time characterized the genetic diversity of the Mongolian saiga (S. t. mongolica) using both mitochondrial DNA and microsatellite markers. We also analysed S. t. tatarica specimens in order to genetically compare both subspecies. The mitochondrial control region was sequenced for a total of 89 individuals: 20 skin, 53 umbilical cord, three placentae and a muscle sample from S. t. mongolica, and a total of 12 hair samples from S. t. tatarica. Additionally, 19 microsatellites developed for saiga antelope were also screened. Our results revealed that the Mongolian saiga presents very low genetic diversity at the mitochondrial level, with no shared mitochondrial haplotype between the two subspecies. Low genetic diversity is also present at the autosomal level, with most loci having low heterozygosity (Ho/He) and a low number of alleles per locus. Despite the low genetic diversity, we found no separation between the subpopulations in Mongolia, indicating that conservation corridors are actually promoting contact between different herds. Our results validate current conservation efforts and inform the implementation of new measures to increase the viability of the S. t. mongolica subspecies.

The trade of Saiga Antelope horn for traditional medicine in Thailand

Demand for Saiga Antelope Saiga tatarica horn products in Southeast Asia, due to their perceived medicinal value, has drastically impacted the conservation of this species. At the same time, poor understanding of the dynamics of this trade in parts of Southeast Asia continues to impede regulation and conservation efforts. Here we examine the trade of Saiga horn products in Thailand through a rapid physical and online market survey, and via an analysis of Convention on International Trade in Endangered Species of Wild Fauna and Flora  (CITES) trade data. We found an active local trade in Saiga horn products in Thailand, with both physical market surveys and online surveys showing predominantly two forms of Saiga horn products in the market, i.e., cooling water and horn shavings (mostly sold as pre-packaged boiling kits). These products are commercially marketed as staple household medicines. Greater scrutiny, monitoring and research is urgently needed to understand how the use of Saiga horn is being regulated in Thailand including the number of licensed traders, potential stockpiles and management of these. Traditional medicine outlets and online sales of commercial Saiga horn products also requires attention. As a non-native species, the Saiga Antelope is not protected in Thailand which makes it difficult for enforcement authorities to prevent illegal trade of Saiga horn products within the country. Thailand is currently revising its wildlife laws with the intention of addressing the protection of non-native and CITES-listed species. Considering the widespread use of Saiga horn in Thailand, we recommend that Saiga Antelope be included in the revised species protection lists to enable enforcement action against trade in illegally sourced Saiga horn products.  

Female reproductive skew exacerbates the extinction risk from poaching in the eastern black rhino

Variation in individual demographic rates can have large consequences for populations. Female reproductive skew is an example of structured demographic heterogeneity where females have intrinsic qualities that make them more or less likely to breed. The consequences of reproductive skew for population dynamics are poorly understood in non-cooperatively breeding mammals, especially when coupled with other drivers such as poaching. We address this knowledge gap with population viability analyses using an age-specific, female-only, individual-based, stochastic population model built with long-term data for three Kenyan populations of the Critically Endangered eastern black rhino (Diceros bicornis michaeli). There was substantial reproductive skew, with a high proportion of females not breeding or doing so at very low rates. This had a large impact on the projected population growth rate for the smaller population on Ol Jogi. Moreover, including female reproductive skew exacerbates the effects of poaching, increasing the probability of extinction by approximately 70% under a simulated poaching pressure of 5% offtake per year. Tackling the effects of reproductive skew depends on whether it is mediated by habitat or social factors, with potential strategies including habitat and biological management respectively. Investigating and tackling reproductive skew in other species requires long-term, individual-level data collection.

Make flying-fox hunting sustainable again: Comparing expected demographic effectiveness and hunters' acceptance of more restrictive regulations

Hunting is a major threat to many species of wildlife. However, managing hunting systems to ensure their sustainability requires a thorough demographic knowledge about the impact of hunting. Here we develop a framework integrating ecological, modelling and sociological data to achieve a sustainability assessment of flying-fox hunting in New Caledonia and assess the relative merits of alternative management policies. Using age-specific stochastic population models, we found that the current annual hunting rate [5.5-8.5%] is likely to lead to a severe decline (- 79%) of Pteropus populations over the next 30 years. However, a majority of hunters surveyed (60%) were willing to soften their practices, offering an opportunity for adaptive management. Recurrent temporary hunting ban (at least 1 year out of 2) in combination with protected areas (≥ 25%) appears as the most effective and most accepted management option. Our integrative approach appears to be a promising method for ensuring that traditional hunting systems can remain sustainable in a rapidly changing world.

Hunting alters viral transmission and evolution in a large carnivore

Hunting can fundamentally alter wildlife population dynamics but the consequences of hunting on pathogen transmission and evolution remain poorly understood. Here, we present a study that leverages a unique landscape-scale quasi-experiment coupled with pathogen-transmission tracing, network simulation and phylodynamics to provide insights into how hunting shapes feline immunodeficiency virus (FIV) dynamics in puma (Puma concolor). We show that removing hunting pressure enhances the role of males in transmission, increases the viral population growth rate and increases the role of evolutionary forces on the pathogen compared to when hunting was reinstated. Changes in transmission observed with the removal of hunting could be linked to short-term social changes while the male puma population increased. These findings are supported through comparison with a region with stable hunting management over the same time period. This study shows that routine wildlife management can have impacts on pathogen transmission and evolution not previously considered.

Post-release Movement Behaviour and Survival of Kulan Reintroduced to the Steppes and Deserts of Central Kazakhstan

Asiatic wild ass, or kulan (Equus hemionus kulan) were once a key species of the Eurasian steppes and deserts. In Kazakhstan they went extinct by the 1930s. Early reintroductions have reestablished the species in two protected areas, but the species has reclaimed <1% of their former range and remained absent from central Kazakhstan. To initiate restoration in this vast region, we captured and transported a first group of nine wild kulan to a large pre-release enclosure in the Torgai region in 2017, and two more in 2019. We used direct observations and post-release movement data of four kulan equipped with GPS-Iridium collars to document their adaptation process in a vast novel habitat without conspecifics. For comparison with movements in the source populations, we additionally equipped two kulan in Altyn Emel National Park and six in Barsa Kelmes State Nature Reserve. The nine transported kulan formed a cohesive group with very high movement correlation in the enclosure. After release, the group initially stayed tightly together but started to break up by mid-May and all kulan travelled independently by mid-August. With 48,680–136,953 km2, the 95% Autocorrelated Kernel Density Estimation ranges of the reintroduced kulan were huge and about 10–100 times larger than those in the source populations. The reintroduced mares never reconnected, there was no evidence of successful reproduction, and two of the four collared mares were killed by poachers and one died of natural causes. At least one stallion survived in the wild, but the fate of the other uncollared animals remains unclear. We speculate that the fission-fusion dynamics and low movement correlation of kulan societies and the need for migratory movements harbours the risk that animals released into a novel environment loose contact with each other. This risk is likely enhanced in steppe habitats where movement constraining factors are absent. Further kulan reintroductions to the steppes and deserts of central Kazakhstan should aim to release larger groups and build up the free-ranging population quickly to reach a critical mass, increasing the chance of kulan encountering conspecifics to successfully breed and increase their chances of survival.

A systematic survey of online trade: trade in Saiga antelope horn on Russian-language websites

Trade in wildlife is increasingly moving online, which creates significant challenges for monitoring. Numerous reports have highlighted the extent of the trade but they rarely present a methodology to facilitate replication or any form of meta-analysis. Here we present a systematic approach to surveying online trade in wildlife that builds on the well-established systematic evidence review approach. We apply this approach to investigate the online trade in saiga antelope Saiga tatarica horns on Russian-language websites. Of the 419 advertisements, the majority (217, 52%) were from Ukraine, followed by Russia (122, 29%), and were largely offers to sell (254, 61%), and represented one-off advertisements. Trade was identified on 89 websites, with the majority being on classified ads websites (68, 76%), auction.violity.com being the most popular site (156, 37%). Prices varied significantly depending on the country and how the horn was being offered (i.e. by weight or length). It is clear that saiga horn is being traded over the internet, with Ukraine and Russia comprising c. 80% of advertisements on Russian-language websites. Individuals with single advertisements dominate, suggesting website fidelity, although website usage is country-specific, potentially reflecting domestic trade. This suggests country-specific interventions could be particularly effective. A systematic approach for investigating online wildlife trade provides a clear and transparent methodology, and, given data collection is resource-intensive, allows studies to be replicated so that trends can be identified. However, this is only possible if published studies report the methodology used.

Integrating omics to characterize eco-physiological adaptations: How moose diet and metabolism differ across biogeographic zones

With accelerated land conversion and global heating at northern latitudes, it becomes crucial to understand, how life histories of animals in extreme environments adapt to these changes. Animals may either adapt by adjusting foraging behavior or through physiological responses, including adjusting their energy metabolism or both. Until now, it has been difficult to study such adaptations in free-ranging animals due to methodological constraints that prevent extensive spatiotemporal coverage of ecological and physiological data.Through a novel approach of combining DNA-metabarcoding and nuclear magnetic resonance (NMR)-based metabolomics, we aim to elucidate the links between diets and metabolism in Scandinavian moose Alces alces over three biogeographic zones using a unique dataset of 265 marked individuals.Based on 17 diet items, we identified four different classes of diet types that match browse species availability in respective ecoregions in northern Sweden. Individuals in the boreal zone consumed predominantly pine and had the least diverse diets, while individuals with highest diet diversity occurred in the coastal areas. Males exhibited lower average diet diversity than females.We identified several molecular markers indicating metabolic constraints linked to diet constraints in terms of food availability during winter. While animals consuming pine had higher lipid, phospocholine, and glycerophosphocholine concentrations in their serum than other diet types, birch- and willow/aspen-rich diets exhibit elevated concentrations of several amino acids. The individuals with highest diet diversity had increased levels of ketone bodies, indicating extensive periods of starvation for these individuals.Our results show how the adaptive capacity of moose at the eco-physiological level varies over a large eco-geographic scale and how it responds to land use pressures. In light of extensive ongoing climate and land use changes, these findings pave the way for future scenario building for animal adaptive capacity.

Visual lateralization in artiodactyls: A brief summary of research and new evidence on saiga antelope

The visual system and lifestyle characteristics make the even-toed ungulates an excellent model for the studies of behavioural lateralization. Recent research has focused on these mammals providing evidence of lateralization in a wide range of behaviours. This provides an opportunity for the collation of the current theoretical assumptions and the existing empirical evidence for visual lateralization in artiodactyls. In the present study, we aim first to gain a fuller picture of hemispheric specializations in saiga antelopes by investigating the lateralization of vigilance and novel object inspection in the wild. Second, we summarized the results of the research into visual lateralization in even-toed ungulates and attempted to assess the applicability of two popular hypotheses about the division of hemispheric roles. The results on saigas show a significant preference for head turns to the right visual field during vigilance which was more robust in individuals in larger groups. When an unfamiliar artificial object was placed in their natural setting, saigas preferentially viewed it predominantly with the right eye. These results, together with the cumulative evidence in artiodactyls, do not follow either the approach-withdrawal or positivity-negativity dichotomous patterns widely used to explain the division of functions between the hemispheres.

Black kites of different age and sex show similar avoidance responses to wind turbines during migration

Populations of soaring birds are often impacted by wind-power generation. Sex and age bias in turbine collisions can exacerbate these impacts through demographic changes that can lead to population decline or collapse. While several studies have reported sex and age differences in the number of soaring birds killed by turbines, it remains unclear if they result from different abundances or group-specific turbine avoidance behaviours, the latter having severer consequences. We investigated sex and age effects on turbine avoidance behaviour of black kites (Milvus migrans) during migration near the Strait of Gibraltar. We tracked the movements of 135 individuals with GPS data loggers in an area with high density of turbines and then modelled the effect of proximity of turbines on bird utilization distribution (UD). Both sexes and age classes showed similar patterns of displacement, with reduced UD values in the proximity of turbines and a clear peak at 700-850 m away, probably marking the distance at which most birds turn direction to avoid approaching the turbines further. The consistency of these patterns indicates that displacement range can be used as an accurate proxy for collision risk and habitat loss, and should be incorporated in environmental impact assessment studies.

Hunting strategies to increase detection of chronic wasting disease in cervids

The successful mitigation of emerging wildlife diseases may involve controversial host culling. For livestock, ‘preemptive host culling’ is an accepted practice involving the removal of herds with known contact to infected populations. When applied to wildlife, this proactive approach comes in conflict with biodiversity conservation goals. Here, we present an alternative approach of ‘proactive hunting surveillance’ with the aim of early disease detection that simultaneously avoids undesirable population decline by targeting demographic groups with (1) a higher likelihood of being infected and (2) a lower reproductive value. We applied this harvesting principle to populations of reindeer to substantiate freedom of chronic wasting disease (CWD) infection. Proactive hunting surveillance reached 99% probability of freedom from infection (<4 reindeer infected) within 3–5 years, in comparison to ~10 years using ordinary harvest surveillance. However, implementation uncertainties linked to social issues appear challenging also with this kind of host culling.

Rarely are the outcomes of mathematical (probability) models of wildlife disease detection used to inform policy or management changes. Here the authors develop a proactive hunting surveillance program that shortened the time required to establish freedom from chronic wasting disease at the population level in reindeer.

Effects of size- and sex-selective harvesting: An integral projection model approach

Harvesting is often size-selective, and in species with sexual size dimorphism, it may also be sex-selective. A powerful approach to investigate potential consequences of size- and/or sex-selective harvesting is to simulate it in a demographic population model. We developed a population-based integral projection model for a size- and sex-structured species, the commonly exploited pike (Esox lucius). The model allows reproductive success to be proportional to body size and potentially limited by both sexes. We ran all harvest simulations with both lower size limits and slot limits, and to quantify the effects of selective harvesting, we calculated sex ratios and the long-term population growth rate (λ). In addition, we quantified to what degree purely size-selective harvesting was sex-selective, and determined when λ shifted from being female to male limited under size- and sex-selective harvesting. We found that purely size-selective harvest can be sex-selective, and that it depends on the harvest limits and the size distributions of the sexes. For the size- and sex-selective harvest simulations, λ increased with harvest intensity up to a threshold as females limited reproduction. Beyond this threshold, males became the limiting sex, and λ decreased as more males were harvested. The peak in λ, and the corresponding sex ratio in harvest, varied with both the selectivity and the intensity of the harvest simulation. Our model represents a useful extension of size-structured population models as it includes both sexes, relaxes the assumption of female dominance, and accounts for size-dependent fecundity. The consequences of selective harvesting presented here are especially relevant for size- and sex-structured exploited species, such as commercial fisheries. Thus, our model provides a useful contribution toward the development of more sustainable harvesting regimes.

Longest terrestrial migrations and movements around the world

Long-distance terrestrial migrations are imperiled globally. We determined both round-trip migration distances (straight-line measurements between migratory end points) and total annual movement (sum of the distances between successive relocations over a year) for a suite of large mammals that had potential for long-distance movements to test which species displayed the longest of both. We found that caribou likely do exhibit the longest terrestrial migrations on the planet, but, over the course of a year, gray wolves move the most. Our results were consistent with the trophic-level based hypothesis that predators would move more than their prey. Herbivores in low productivity environments moved more than herbivores in more productive habitats. We also found that larger members of the same guild moved less than smaller members, supporting the ‘gastro-centric’ hypothesis. A better understanding of migration and movements of large mammals should aid in their conservation by helping delineate conservation area boundaries and determine priority corridors for protection to preserve connectivity. The magnitude of the migrations and movements we documented should also provide guidance on the scale of conservation efforts required and assist conservation planning across agency and even national boundaries.

What do wild saiga antelopes tell us about the relative roles of the two brain hemispheres in social interactions?

Two brain hemispheres are unequally involved in the processing of social stimuli, as demonstrated in a wide range of vertebrates. A considerable number of studies have shown the right hemisphere advantage for social processing. At the same time, an approach-withdrawal hypothesis, mainly based on experimental evidence, proposes the involvement of both brain hemispheres according to approach and withdrawal motivation. The present study aimed to test the relative roles of the two hemispheres in social responses displayed in a natural context. Visual biases, implicating hemispheric lateralization, were estimated in the social interactions of saiga antelope in the wild. In individually identified males, the left/right visual field use during approach and withdrawal responses was recorded based on the lateral head/body position, relative to the conspecific. Lateralized approach responses were investigated in three types of interactions, with left visual field bias found for chasing a rival, no bias-for attacking a rival, and right visual field bias-for pursuing a female. In two types of withdrawal responses, left visual field bias was found for retreating after fighting, while no bias was evident in fight rejecting. These findings demonstrate that neither the right hemisphere advantage nor the approach-withdrawal distinction can fully explain the patterns of lateralization observed in social behaviour. It is clear that both brain hemispheres play significant roles in social responses, while their relative contribution is likely determined by a complex set of motivational and emotional factors rather than a simple dichotomous distinction such as, for example, approach versus withdrawal motivation.

Selective harvest focused on sexual signal traits can lead to extinction under directional environmental change

Humans commonly harvest animals based on their expression of secondary sexual traits such as horns or antlers. This selective harvest is thought to have little effect on harvested populations because offtake rates are low and usually only the males are targeted. These arguments do not, however, take the relationship between secondary sexual trait expression and animal condition into account: there is increasing evidence that in many cases the degree of expression of such traits is correlated with an animal's overall well-being, which is partly determined by their genetic match to the environment. Using an individual-based model, we find that when there is directional environmental change, selective harvest of males with the largest secondary sexual traits can lead to extinction in otherwise resilient populations. When harvest is not selective, the males best suited to a new environment gain the majority of matings and beneficial alleles spread rapidly. When these best-adapted males are removed, however, their beneficial alleles are lost, leading to extinction. Given the current changes happening globally, these results suggest that trophy hunting and other cases of selective harvest (such as certain types of insect collection) should be managed with extreme care whenever populations are faced with changing conditions.

Predicted effects of landscape change, sea level rise, and habitat management on the extirpation risk of the Hawaiian common gallinule (Gallinula galeata sandvicensis) on the island of O'ahu

We conducted a spatially explicit, stochastic, individually based population viability analysis for the Hawaiian common gallinule (Gallinula galeata sandvicensis), an endangered subspecies of waterbird endemic to fragmented coastal wetlands in Hawai'i. This subspecies persists on two islands, with no apparent movement between them. We assessed extirpation risk for birds on O'ahu, where the resident gallinule population is made up of several fragmented subpopulations. Data on genetic differentiation were used to delineate subpopulations and estimate dispersal rates between them. We used sensitivity analyses to gauge the impact of current uncertainty of vital rate parameters on population projections, to ascertain the relative importance of gallinule vital rates to population persistence, and to compare the efficacy of potential management strategies. We used available sea level rise projections to examine the relative vulnerability of O'ahu's gallinule population to habitat loss arising from this threat. Our model predicted persistence of the island's gallinule population at 160 years (∼40 generations), but with high probabilities of extirpation for small subpopulations. Sensitivity analyses highlighted the importance of juvenile and adult mortality to population persistence in Hawaiian gallinules, justifying current predator control efforts and suggesting the need for additional research on chick and fledgling survival. Subpopulation connectivity from dispersal had little effect on the persistence of the island-wide population, but strong effects on the persistence of smaller subpopulations. Our model also predicted island-wide population persistence under predicted sea level rise scenarios, but with O'ahu's largest gallinule populations losing >40% of current carrying capacity.

Development and validation of a multi-locus DNA metabarcoding method to identify endangered species in complex samples

DNA metabarcoding provides great potential for species identification in complex samples such as food supplements and traditional medicines. Such a method would aid Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) enforcement officers to combat wildlife crime by preventing illegal trade of endangered plant and animal species. The objective of this research was to develop a multi-locus DNA metabarcoding method for forensic wildlife species identification and to evaluate the applicability and reproducibility of this approach across different laboratories. A DNA metabarcoding method was developed that makes use of 12 DNA barcode markers that have demonstrated universal applicability across a wide range of plant and animal taxa and that facilitate the identification of species in samples containing degraded DNA. The DNA metabarcoding method was developed based on Illumina MiSeq amplicon sequencing of well-defined experimental mixtures, for which a bioinformatics pipeline with user-friendly web-interface was developed. The performance of the DNA metabarcoding method was assessed in an international validation trial by 16 laboratories, in which the method was found to be highly reproducible and sensitive enough to identify species present in a mixture at 1% dry weight content. The advanced multi-locus DNA metabarcoding method assessed in this study provides reliable and detailed data on the composition of complex food products, including information on the presence of CITES-listed species. The method can provide improved resolution for species identification, while verifying species with multiple DNA barcodes contributes to an enhanced quality assurance.

Exploring saiga horn consumption in Singapore

The Critically Endangered saiga antelope Saiga tatarica faces an uncertain future, with populations dwindling from epidemics in its range countries, and ongoing demand for its horns in the traditional Chinese medicine trade. Singapore is a major hub for the global trade in saiga horn and an important consumer country, with saiga horn products widely available in the domestic market. Despite this, little is known about the consumers that drive domestic demand. Before interventions are carried out, it is important to understand who the consumers are, and their motivations. We conducted an investigation into consumption prevalence and consumer demographics, knowledge and motivations. We surveyed 230 Chinese Singaporeans, through a combination of face-to-face interviews and self-administered questionnaires. Recent consumption incidence (in the previous 12 months) was relatively high, at 13%. Younger respondents (18–35 years) had the highest prevalence of recent consumption (25%), often as a result of influence from an older family member or friend. Bottled saiga horn cooling water was the most popular product among recent users (50%), followed by horn shavings (31%) and tablets (13%). Awareness of conservation issues and regulations was uniformly low. Awareness raising may have an effect in reducing consumer demand in Singapore. However, given the exploratory nature of this study, it is best used to guide and inform future research underlying behavioural change interventions in a relatively understudied but important consumer group, Chinese Singaporeans.

Changing of the dynamics modes in populations with age and sex structure

Using a mathematical model of the number dynamics in a population with age and sex structure, the relationships were studied between the number of newborns and that of mature females and males. In addition, we studied transitions between different modes of population dynamics which were dependent on changes in not only the population parameters, such as reproduction intensity, survival, and self-regulation, but also in mating pair formation. Population dynamics was found to manifest multistability; i.e., the alternative dynamics modes were observed at the same values of the population parameters but under different initial conditions.

Effective size of density-dependent two-sex populations: the effect of mating systems

Density dependence in vital rates is a key feature affecting temporal fluctuations of natural populations. This has important implications for the rate of random genetic drift. Mating systems also greatly affect effective population sizes, but knowledge of how mating system and density regulation interact to affect random genetic drift is poor. Using theoretical models and simulations, we compare N_e in short-lived, density-dependent animal populations with different mating systems. We study the impact of a fluctuating, density-dependent sex ratio and consider both a stable and a fluctuating environment. We find a negative relationship between annual N_e /N and adult population size N due to density dependence, suggesting that loss of genetic variation is reduced at small densities. The magnitude of this decrease was affected by mating system and life history. A male-biased, density-dependent sex ratio reduces the rate of genetic drift compared to an equal, density-independent sex ratio, but a stochastic change towards male bias reduces the N_e /N ratio. Environmental stochasticity amplifies temporal fluctuations in population size and is thus vital to consider in estimation of effective population sizes over longer time periods. Our results on the reduced loss of genetic variation at small densities, particularly in polygamous populations, indicate that density regulation may facilitate adaptive evolution at small population sizes.

Climate change increases the production of female hatchlings at a northern sea turtle rookery

The most recent climate change projections show a global increase in temperatures, along with major adjustments to precipitation, throughout the 21st century. Species exhibiting temperature-dependent sex determination are highly susceptible to such changes since the incubation environment influences critical offspring characteristics such as survival and sex ratio. Here we show that the mean incubation duration of loggerhead sea turtle (Caretta caretta) nests from a high-density nesting beach on Bald Head Island, North Carolina, USA has decreased significantly over the past 25 yr. This decrease in incubation duration is significantly positively correlated with mean air temperature and negatively correlated with mean precipitation during the nesting season. Additionally, although no change in hatching success was detected during this same period, a potentially detrimental consequence of shorter incubation durations is that they lead to the production of primarily female offspring. Given that global temperatures are predicted to increase by as much as 4°C over the next century, the mass feminization of sea turtle hatchlings is a high-priority concern. While presently limited in number, studies using long-term data sets to examine the temporal correlation between offspring characteristics and climatic trends are essential for understanding the scope and direction of climate change effects on species persistence.

Ground survey of red lechwe in the Linyanti swamps and Chobe floodplains, northern Botswana

A ground survey of red lechwe was carried out in the Linyanti swamps and the Chobe floodplains of northern Botswana in the dry and wet seasons of 2012 and 2013, respectively. We documented numbers, sex ratio and age structure of red lechwe within the linear strips of 25 km × 300 m along the Linyanti swamps and the Chobe floodplains. Results indicated a significant difference in the numbers of red lechwe between sites and seasons. About 66 and 755 red lechwe were estimated for Chobe in the dry and wet season, respectively, with 343 and 261 of them estimated for Linyanti in the dry and wet season, respectively. In Chobe, the red lechwe densities varied widely between seasons (9 red lechwe/km2 – 101 red lechwe/km2 ) compared with Linyanti, where the densities did not vary much between seasons (35 red lechwe/km2 – 46 red lechwe/km2 ). The lower densities of red lechwe in Chobe in the dry season when compared with the wet season suggest a possible seasonal shift in the distribution of red lechwe to the nearby Zambezi floodplains in Namibia.Conservation implications: The higher number of red lechwe in the Chobe floodplains in the wet season indicates the potential of the floodplains as a habitat for this species in that season. The dry season shift in the distribution of red lechwe in Chobe presents an opportunity for local communities in Namibia to engage in tourism, whereas the return of the red lechwe to the floodplains in the wet season ensures protection of the animals as well as boosts the tourism potential of the Chobe National Park.

Embracing uncertainty in applied ecology

Applied ecologists often face uncertainty that hinders effective decision-making.Common traps that may catch the unwary are: ignoring uncertainty, acknowledging uncertainty but ploughing on, focussing on trivial uncertainties, believing your models, and unclear objectives.We integrate research insights and examples from a wide range of applied ecological fields to illustrate advances that are generally underused, but could facilitate ecologists' ability to plan and execute research to support management.Recommended approaches to avoid uncertainty traps are: embracing models, using decision theory, using models more effectively, thinking experimentally, and being realistic about uncertainty.Synthesis and applications. Applied ecologists can become more effective at informing management by using approaches that explicitly take account of uncertainty.

Hunting promotes sexual conflict in brown bears

The removal of individuals through hunting can destabilize social structure, potentially affecting population dynamics. Although previous studies have shown that hunting can indirectly reduce juvenile survival through increased sexually selected infanticide (SSI), very little is known about the spatiotemporal effects of male hunting on juvenile survival. Using detailed individual monitoring of a hunted population of brown bears (Ursus arctos) in Sweden (1991-2011), we assessed the spatiotemporal effect of male removal on cub survival. We modelled cub survival before, during and after the mating season. We used three proxies to evaluate spatial and temporal variation in male turnover; distance and timing of the closest male killed and number of males that died around a female's home range centre. Male removal decreased cub survival only during the mating season, as expected in seasonal breeders with SSI. Cub survival increased with distance to the closest male killed within the previous 1·5 years, and it was lower when the closest male killed was removed 1·5 instead of 0·5 year earlier. We did not detect an effect of the number of males killed. Our results support the hypothesis that social restructuring due to hunting can reduce recruitment and suggest that the distribution of the male deaths might be more important than the overall number of males that die. As the removal of individuals through hunting is typically not homogenously distributed across the landscape, spatial heterogeneity in hunting pressure may cause source-sink dynamics, with lower recruitment in areas of high human-induced mortality.

Epigenetic-induced alterations in sex-ratios in response to climate change: An epigenetic trap?

We hypothesize that under the predicted scenario of climate change epigenetically mediated environmental sex determination could become an epigenetic trap. Epigenetically regulated environmental sex determination is a mechanism by which species can modulate their breeding strategies to accommodate environmental change. Growing evidence suggests that epigenetic mechanisms may play a key role in phenotypic plasticity and in the rapid adaptation of species to environmental change, through the capacity of organisms to maintain a non-genetic plastic memory of the environmental and ecological conditions experienced by their parents. However, inherited epigenetic variation could also be maladaptive, becoming an epigenetic trap. This is because environmental sex determination can alter sex ratios by increasing the survival of one of the sexes at the expense of negative fitness consequences for the other, which could lead not only to the collapse of natural populations, but also have an impact in farmed animal and plant species.

Microhabitat selection in the common lizard: implications of biotic interactions, age, sex, local processes, and model transferability among populations

Modeling species' habitat requirements are crucial to assess impacts of global change, for conservation efforts and to test mechanisms driving species presence. While the influence of abiotic factors has been widely examined, the importance of biotic factors and biotic interactions, and the potential implications of local processes are not well understood. Testing their importance requires additional knowledge and analyses at local habitat scale. Here, we recorded the locations of species presence at the microhabitat scale and measured abiotic and biotic parameters in three different common lizard (Zootoca vivipara) populations using a standardized sampling protocol. Thereafter, space use models and cross-evaluations among populations were run to infer local processes and estimate the importance of biotic parameters, biotic interactions, sex, and age. Biotic parameters explained more variation than abiotic parameters, and intraspecific interactions significantly predicted the spatial distribution. Significant differences among populations in the relationship between abiotic parameters and lizard distribution, and the greater model transferability within populations than between populations are in line with effects predicted by local adaptation and/or phenotypic plasticity. These results underline the importance of including biotic parameters and biotic interactions in space use models at the population level. There were significant differences in space use between sexes, and between adults and yearlings, the latter showing no association with the measured parameters. Consequently, predictive habitat models at the population level taking into account different sexes and age classes are required to understand a specie's ecological requirements and to allow for precise conservation strategies. Our study therefore stresses that future predictive habitat models at the population level and their transferability should take these parameters into account.

A shortage of males causes female reproductive failure in yellow ground squirrels

Sexual conflict theory suggests that female breeding success is strongly influenced by individual life history and environmental conditions and is much less affected by mate availability. Female mating failure due to a shortage of males remains poorly studied and understood. We present data on the effects of male availability on female breeding success in a wild colony of yellow ground squirrels (Spermophilus fulvus). A female's probability of breeding increased with the local density of males and was higher with higher male-biased operational sex ratio (OSR) but was independent of local female density, female age, and body condition, which are factors commonly assumed to influence female reproduction. The positive effect of male availability (as measured by OSR) on female breeding success was consistent across the years, and we conclude that male limitation contributes to female mating failure. This pattern, which is not commonly recorded in species with conventional sex roles, can be explained by a combination of sociodemographic and life history traits (sex differences in age of maturation, female-skewed adult sex ratio and seasonally varying OSR, solitary living at low population density, and low mobility of females combined with mate-searching tactics of males) that are not confined to S. fulvus. Our findings indicate that the role of female mating failure (due to a shortage of males) in shaping mammalian life history may be underestimated.

Transgenerational plasticity mitigates the impact of global warming to offspring sex ratios

Global warming poses a threat to organisms with temperature-dependent sex determination because it can affect operational sex ratios. Using a multigenerational experiment with a marine fish, we provide the first evidence that parents developing from early life at elevated temperatures can adjust their offspring gender through nongenetic and nonbehavioural means. However, this adjustment was not possible when parents reproduced, but did not develop, at elevated temperatures. Complete restoration of the offspring sex ratio occurred when parents developed at 1.5 °C above the present-day average temperature for one generation. However, only partial improvement in the sex ratio occurred at 3.0 °C above average conditions, even after two generations, suggesting a limitation to transgenerational plasticity when developmental temperature is substantially increased. This study highlights the potential for transgenerational plasticity to ameliorate some impacts of climate change and that development from early life may be essential for expression of transgenerational plasticity in some traits.

Dynamics of populations with two sexes

A mathematical model is presented in order to describe the dynamics of polygamous populations, bearing in mind single individuals of both sexes and the development of reproductive groups. In this context, the description leads us to consider positive homogeneous dynamical systems, establishing conditions for the stationary state existence and its local stability. A fourth pre-reproductive stage was considered, i.e. males and females spend part of their lives before being in condition to reproduce, as a first step to consider more general models. Finally, we parametrized the proposed model using southern elephant seal data, to analyze the direct applicability to a real population.

The danger within: the role of genetic, behavioural and ecological factors in population persistence of colour polymorphic species

Polymorphic species have been the focus of important work in evolutionary biology. It has been suggested that colour polymorphic species have specific evolutionary and population dynamics that enable them to persist through environmental changes better than less variable species. We suggest that recent empirical and theoretical work indicates that polymorphic species may be more vulnerable to extinction than previously thought. This vulnerability arises because these species often have a number of correlated sexual, behavioural, life history and ecological traits, which can have a simple genetic underpinning. When exacerbated by environmental change, these alternate strategies can lead to conflict between morphs at the genomic and population levels, which can directly or indirectly affect population and evolutionary dynamics. In this perspective, we identify a number of ways in which the nature of the correlated traits, their underpinning genetic architecture, and the inevitable interactions between colour morphs can result in a reduction in population fitness. The principles illustrated here apply to all kinds of discrete polymorphism (e.g. behavioural syndromes), but we focus primarily on colour polymorphism because they are well studied. We urge further empirical investigation of the genetic architecture and interactions in polymorphic species to elucidate the impact on population fitness.

Who bites the bullet first? The susceptibility of leopards Panthera pardus to trophy hunting

Reliable data is fundamentally important for managing large carnivore populations, and vital for informing hunting quota levels if those populations are subject to trophy hunting. Camera-trapping and spoor counts can provide reliable population estimates for many carnivores, but governments typically lack the resources to implement such surveys over the spatial scales required to inform robust quota setting. It may therefore be prudent to shift focus away from estimating population size and instead focus on monitoring population trend. In this paper we assess the susceptibility of African leopards Panthera pardus to trophy hunting. This has management ramifications, particularly if the use of harvest composition is to be explored as a metric of population trend. We explore the susceptibility of different leopard age and sex cohorts to trophy hunting; first by examining their intrinsic susceptibility to encountering trophy hunters using camera-traps as surrogates, and second by assessing their extrinsic susceptibility using photographic questionnaire surveys to determine their attractiveness to hunters. We show that adult male and female leopards share similar incident rates to encountering hunters but adult males are the most susceptible to hunting due to hunter preference for large trophies. In contrast, sub-adult leopards rarely encounter hunters and are the least attractive trophies. We suggest that our findings be used as a foundation for the exploration of a harvest composition scheme in the Kwazulu-Natal and Limpopo provinces where post mortem information is collected from hunted leopards and submitted to the local provincial authorities.