Hunting promotes spatial reorganization and sexually selected infanticide

Molecular tracking and prevalence of the red colour morph restricted to a harvested leopard population in South Africa

The red leopard (Panthera pardus) colour morph is a colour variant that occurs only in South Africa, where it is confined to the Central Bushveld bioregion. Red leopards have been spreading over the past 40 years, which raises the speculation that the prevalence of this phenotype is related to low dispersal of young individuals owing to high off‐take in the region. Intensive selective hunting tends to remove large resident male leopards from the breeding population, which gives young male leopards the chance to mate with resident female leopards that are more likely to be their relatives, eventually increasing the frequency of rare genetic variants. To investigate the genetic mechanisms underlying the red coat colour morph in leopards, and whether its prevalence in South Africa relates to an increase in genetic relatedness in the population, we sequenced exons of six coat colour‐associated genes and 20 microsatellite loci in twenty Wild‐type and four red leopards. The results were combined with demographic data available from our study sites. We found that red leopards own a haplotype in homozygosity identified by two SNPs and a 1 bp deletion that causes a frameshift in the tyrosinase‐related protein 1 (TYRP1), a gene known to be involved in the biosynthesis of melanin. Microsatellite analyses indicate clear signs of a population bottleneck and a relatedness of 0.11 among all pairwise relationships, eventually supporting our hypothesis that a rare colour morph in the wild has increased its local frequency due to low natal dispersal, while subject to high human‐induced mortality rate.

Wild Boar Survives in a Landscape That Prohibits Anthropogenic Persecution

Geopolitical borderlands are politically sensitive areas and biodiversity hotspots, strictly controlled by the government and military. How to ensure political security, while protecting the biodiversity in borderlands is a problem for ecologists and governments. In this study, the nest site selection of the wild boar Sus scrofa was a case study in the Sino-Russia borderland to understand the survival strategy of wild life under anthropogenic pressure. We investigated (a) how the spatial distribution of anthropogenic pressure and wild boar nests in the borderland and (b) how anthropogenic pressure and the border influence on the wild boars’ nest site selection. The Getis-Ord Gi* analysis was used to analyze the distribution patterns of wild boar nest sites and anthropogenic pressures in the borderland, the Structural Equation Models was used to explore the influence of border, roads, settlements, agricultural land, grassland and anthropogenic pressure on wild boars’ nest site selection. The results indicated that wild boar nest sites are close to the border, roads and agricultural land and away from settlements and grassland. Regardless of the combination of anthropogenic pressure, wild boars make the most advantageous choice and prefer to be closer to the borderland. We speculated that military control played a vital role in borderlands for animal protection under anthropogenic pressure. Wild boars benefit from the prohibition of anthropogenic persecution due to military control. Compared with existing measures, we suggest a different protection/wildlife management strategy, what we need to do may be to prohibit anthropogenic persecution rather than perform other human interventions to protect animals. However, for a species with trouble potential, we need to base our conservation strategies on the recovery of top predators, and play the community control role of top predators to avoid the occurrence of trouble.

Harvest is associated with the disruption of social and fine-scale genetic structure among matrilines of a solitary large carnivore

Harvest can disrupt wildlife populations by removing adults with naturally high survival. This can reshape sociospatial structure, genetic composition, fitness, and potentially affect evolution. Genetic tools can detect changes in local, fine-scale genetic structure (FGS) and assess the interplay between harvest-caused social and FGS in populations. We used data on 1614 brown bears, Ursus arctos, genotyped with 16 microsatellites, to investigate whether harvest intensity (mean low: 0.13 from 1990 to 2005, mean high: 0.28 from 2006 to 2011) caused changes in FGS among matrilines (8 matrilines; 109 females ≥4 years of age), sex-specific survival and putative dispersal distances, female spatial genetic autocorrelation, matriline persistence, and male mating patterns. Increased harvest decreased FGS of matrilines. Female dispersal distances decreased, and male reproductive success was redistributed more evenly. Adult males had lower survival during high harvest, suggesting that higher male turnover caused this redistribution and helped explain decreased structure among matrilines, despite shorter female dispersal distances. Adult female survival and survival probability of both mother and daughter were lower during high harvest, indicating that matriline persistence was also lower. Our findings indicate a crucial role of regulated harvest in shaping populations, decreasing differences among "groups," even for solitary-living species, and potentially altering the evolutionary trajectory of wild populations.

Not exodus, but population increase and gene flow restoration in Cantabrian brown bear (Ursus arctos) subpopulations. Comment on Gregório et al. 2020

In a genetic study on brown bears (Ursus arctos) in the Cantabrian Mountains, Gregório et al. (2020) interpreted the asymmetrical gene flow they found from the eastern subpopulation towards the western one as an exodus of bears forced to flee from the eastern nucleus “with higher human disturbance and poaching”, concluding that connectivity may be operating as a means for eastern Cantabrian bears to find more suitable territories. In this reply, we maintain that the explanations of Gregorio et al. contradict the source-sink theory and we also present demographic data not considered by these authors showing that the eastern subpopulation is not declining, but persistently increasing. After reviewing the demographic and genetic studies published during the last 20 years, we conclude that the connectivity between the two subpopulations is operating as a route which allows the regular movement of males and the restoration of the gene flow across the whole Cantabrian population.

Age structure changes indicate direct and indirect population impacts in illegally harvested black rhino

Overharvesting affects the size and growth of wildlife populations and can impact population trajectories. Overharvesting can also severely alter population structure and may result in changes in spatial organisation, social dynamics and recruitment. Understanding the relationship between overharvesting and population growth is therefore crucial for the recovery of exploited species. The black rhinoceros (Diceros bicornis; black rhino) is a long-lived megaherbivore native to sub-Saharan Africa, listed as Critically Endangered on the IUCN Red List of Threatened Species. Since 2009, the targeted illegal killing of rhino for their horns has escalated dramatically in South Africa. Given their slow life trajectories, spatial structure and social dynamics, black rhino may be susceptible to both direct and indirect impacts of overharvesting. Our study compared black rhino demography before and during extensive poaching to understand the impact of illegal killing. The population exhibited significant changes in age structure after four years of heavy poaching; these changes were primarily explained by a decrease in the proportion of calves over time. Population projections incorporating both direct poaching removals and decreased fecundity/recruitment were most similar to the observed demographic profile in 2018, suggesting that indirect impacts are also contributing to the observed population trajectory. These indirect impacts are likely a result of decreased density, through processes such as reduced mate-finding, population disturbance and/or increased calf predation. This study illustrates the combined effect of direct and indirect impacts on an endangered species, providing a more comprehensive approach by which to evaluate exploited populations.

Mortality of a large wide-ranging mammal largely caused by anthropogenic activities

With efforts to restore large mammal populations following extirpations, it is vital to quantify how they are impacted by human activities and gain insights into population dynamics in relation to conservation goals. Our objective was to characterize cause-specific mortality of black bears (Ursus americanus) throughout their range. We first quantified cause-specific mortality for 247 black bears in one harvested and two non-harvested populations. We then simulated a small recolonizing population with and without anthropogenic mortality. Lastly, we conducted a meta-analysis of all published black bear mortality studies throughout North America (31 studies of 2630 bears). We found anthropogenic mortality was greater than natural mortality, non-harvest anthropogenic mortality (e.g. poaching, defense of property, etc.) was greater in non-harvested populations, and harvesting was one of the major causes of mortality for bears throughout their range. Our simulation indicated that removing anthropogenic mortality increased population size by an average of 23% in 15 years. We demonstrated that bears are exposed to high levels of anthropogenic mortality, and the potential for human activities to slow population growth in expanding populations. Management and conservation of wide-ranging mammals will depend on holistic strategies that integrate ecological factors with socio-economic issues to achieve successful conservation and coexistence.

Hunters select for behavioral traits in a large carnivore

Human harvest can induce selection on life history and morphological traits, leading to ecological and evolutionary responses. Our understanding of harvest-induced selection on behavioral traits is, however, very limited. Here, we assessed whether hunters harvest, consciously or not, individuals with specific behavioral traits. We used long-term, detailed behavioral and survival data of a heavily harvested brown bear (Ursus arctos) population in Sweden. We found that hunters harvested male bears that were less active during legal hunting hours and had lower movement rates. Also, hunters harvested male and female bears that used habitats closer to roads. We provide an empirical example that individual behavior can modulate vulnerability to hunting and that hunters could exert a selective pressure on wildlife behaviors. This study increases our understanding of the complex interactions between harvest method, human behavior, and animal behavior that are at play in harvest-induced selection and provides better insight into the full effects of human harvest on wild populations.

A Life History Approach to the Female Sexual Orientation Spectrum: Evolution, Development, Causal Mechanisms, and Health

Women's capacity for sexual fluidity is at least as interesting a phenomenon from the point of view of evolutionary biology and behavioral endocrinology as exclusively homosexual orientation. Evolutionary hypotheses for female nonheterosexuality have failed to fully account for the existence of these different categories of nonheterosexual women, while also overlooking broader data on the causal mechanisms, physiology, ontogeny, and phylogeny of female nonheterosexuality. We review the evolutionary-developmental origins of various phenotypes in the female sexual orientation spectrum using the synergistic approach of Tinbergen's four questions. We also present femme-specific and butch-specific hypotheses at proximate and ultimate levels of analysis. This review article indicates that various nonheterosexual female phenotypes emerge from and contribute to hormonally mediated fast life history strategies. Life history theory provides a biobehavioral explanatory framework for nonheterosexual women's masculinized body morphology, psychological dispositions, and their elevated likelihood of experiencing violence, substance use, obesity, teenage pregnancy, and lower general health. This pattern of life outcomes can create a feedback loop of environmental unpredictability and harshness which destabilizes intrauterine hormonal conditions in mothers, leading to a greater likelihood of fast life history strategies, global health problems, and nonheterosexual preferences in female offspring. We further explore the potential of female nonheterosexuality to function as an alloparental buffer that enables masculinizing alleles to execute their characteristic fast life history strategies as they appear in the female and the male phenotype. Synthesizing life history theory with the female sexual orientation spectrum enriches existing scientific knowledge on the evolutionary-developmental mechanisms of human sex differences.

Human-Mediated Dispersal and the Rewiring of Spatial Networks

Humans fundamentally affect dispersal, directly by transporting individuals and indirectly by altering landscapes and natural vectors. This human-mediated dispersal (HMD) modifies long-distance dispersal, changes dispersal paths, and overall benefits certain species or genotypes while disadvantaging others. HMD is leading to radical changes in the structure and functioning of spatial networks, which are likely to intensify as human activities increase in scope and extent. Here, we provide an overview to guide research into HMD and the resulting rewiring of spatial networks, making predictions about the ecological and evolutionary consequences and how these vary according to spatial scale and the traits of species. Future research should consider HMD holistically, assessing the range of direct and indirect processes to understand the complex impacts on eco-evolutionary dynamics.

Female American black bears do not alter space use or movements to reduce infanticide risk

Infanticide occurs in a variety of animal species and infanticide risk has large implications for the evolution of behavior. Further, the sex hypothesis of sexual segregation predicts that for species in which infanticide occurs, females with dependent young will avoid males to reduce risk of sexually-selected infanticide. Infanticide risk-avoidance behavior has been studied primarily in social species, but also occurs in some solitary species. We used generalized linear mixed models to determine if space use and movements of female American black bears (Ursus americanus) during the breeding season were consistent with the sex hypothesis of sexual segregation in the Upper Peninsula of Michigan, USA. Space use and movements of female black bears (n = 16) were not consistent with avoidance behavior to reduce sexually-selected infanticide risk. Females with cubs occupied core areas (mean = 4.64 km2, standard error [SE] = 1.28) and home ranges (mean = 19.46 km2, SE = 5.10) of similar size to females without cubs (core area [mean = 4.11 km2, SE = 0.59]; home range [mean = 16.07 km2, SE = 2.26]), and those core areas and home ranges were not in areas with lesser relative probability of male use. Additionally, females with cubs did not reduce movements during times of day when male movements were greatest. As female bears do avoid potentially infanticidal males in populations with greater levels of infanticide, female black bears may exhibit variation in avoidance behavior based on the occurrence of infanticide.

Hunting regulation favors slow life histories in a large carnivore

As an important extrinsic source of mortality, harvest should select for fast reproduction and accelerated life histories. However, if vulnerability to harvest depends upon female reproductive status, patterns of selectivity could diverge and favor alternative reproductive behaviors. Here, using more than 20 years of detailed data on survival and reproduction in a hunted large carnivore population, we show that protecting females with dependent young, a widespread hunting regulation, provides a survival benefit to females providing longer maternal care. This survival gain compensates for the females’ reduced reproductive output, especially at high hunting pressure, where the fitness benefit of prolonged periods of maternal care outweighs that of shorter maternal care. Our study shows that hunting regulation can indirectly promote slower life histories by modulating the fitness benefit of maternal care tactics. We provide empirical evidence that harvest regulation can induce artificial selection on female life history traits and affect demographic processes.

Hunting and harvesting are generally expected to select for faster life histories in the exploited species. Here, the authors analyse data from a hunted population of brown bears in Sweden and show that regulations protecting females with dependent young lead hunting to favor prolonged maternal care.

Sociodemographic factors modulate the spatial response of brown bears to vacancies created by hunting

There is a growing recognition of the importance of indirect effects from hunting on wildlife populations, e.g. social and behavioural changes due to harvest, which occur after the initial offtake. Nonetheless, little is known about how the removal of members of a population influences the spatial configuration of the survivors. We studied how surviving brown bears (Ursus arctos) used former home ranges that had belonged to casualties of the annual bear hunting season in southcentral Sweden (2007-2015). We used resource selection functions to explore the effects of the casualty's and survivor's sex, age and their pairwise genetic relatedness, population density and hunting intensity on survivors' spatial responses to vacated home ranges. We tested the competitive release hypothesis, whereby survivors that increase their use of a killed bear's home range are presumed to have been released from intraspecific competition. We found strong support for this hypothesis, as survivors of the same sex as the casualty consistently increased their use of its vacant home range. Patterns were less pronounced or absent when the survivor and casualty were of opposite sex. Genetic relatedness between the survivor and the casualty emerged as the most important factor explaining increased use of vacated male home ranges by males, with a stronger response from survivors of lower relatedness. Relatedness was also important for females, but it did not influence use following removal; female survivors used home ranges of higher related female casualties more, both before and after death. Spatial responses by survivors were further influenced by bear age, population density and hunting intensity. We have shown that survivors exhibit a spatial response to vacated home ranges caused by hunting casualties, even in nonterritorial species such as the brown bear. This spatial reorganization can have unintended consequences for population dynamics and interfere with management goals. Altogether, our results underscore the need to better understand the short- and long-term indirect effects of hunting on animal social structure and their resulting distribution in space.

Adaptive social strategies in a solitary carnivore

Cost-benefit trade-offs for individuals participating in social behaviors are the basis for current theories on the evolution of social behaviors and societies. However, research on social strategies has largely ignored solitary animals, in which we assume that rare interactions are explained by courtship or territoriality or, in special circumstances, resource distributions or kinship. We used directed network analysis of conspecific tolerance at food sources to provide evidence that a solitary carnivore, the puma (Puma concolor), exhibited adaptive social strategies similar to more social animals. Every puma in our analysis participated in the network, which featured densely connected communities delineated by territorial males. Territorial males also structured social interactions among pumas. Contrary to expectations, conspecific tolerance was best characterized by direct reciprocity, establishing a fitness benefit to individuals that participated in social behaviors. However, reciprocity operated on a longer time scale than in gregarious species. Tolerance was also explained by hierarchical reciprocity, which we defined as network triangles in which one puma (generally male) received tolerance from two others (generally females) that also tolerated each other. Hierarchical reciprocity suggested that males might be cheating females; nevertheless, we suspect that males and females used different fitness currencies. For example, females may have benefited from tolerating males through the maintenance of social niches that support breeding opportunities. Our work contributes evidence of adaptive social strategies in a solitary carnivore and support for the applicability of theories of social behavior across taxa, including solitary species in which they are rarely tested.

A case for considering individual variation in diel activity patterns

There is a growing recognition of the role of individual variation in patterns emerging at higher levels of biological organization. Despite the importance of the temporal configuration of ecological processes and patterns, intraspecific individual variation in diel activity patterns is almost never accounted for in behavioral studies at the population level. We used individual-based monitoring data from 98 GPS-collared brown bears in Scandinavia to estimate diel activity patterns before the fall hunting season. We extracted 7 activity measures related to timing and regularity of activity from individual activity profiles. We then used multivariate analysis to test for the existence of distinct activity tactics and their environmental determinants, followed by generalized linear regression to estimate the extent of within-individual repeatability of activity tactics. We detected 4 distinct activity tactics, with a high degree of individual fidelity to a given tactic. Demographic factors, availability of key foraging habitat, and human disturbance were important determinants of activity tactics. Younger individuals and those with higher bear and road densities within their home range were more nocturnal and more likely to rest during the day. Good foraging habitat and increasing age led to more diurnal activity patterns and nocturnal resting periods. We did not find evidence of diel activity tactics influencing survival during the subsequent hunting season. We conclude that individual variation in activity deserves greater attention than it currently receives, as it may help account for individual heterogeneity in fitness and could facilitate within-population niche partitioning that can have population- or community-level consequences.