Sexual selection may support phenotypic plasticity in male coloration of an African cichlid fish.

The expression of sexually selected traits, such as ornaments or body coloration, is often influenced by environmental conditions. While such phenotypic plasticity is often thought to precede evolutionary change, plasticity itself can also be a target of selection. However, the selective forces supporting the evolution and persistence of plasticity in sexual traits are often unclear. Using the cichlid fish Astatotilapia burtoni, we show that variation in the level of mate competition may promote plasticity in body coloration. In this species, males can change between yellow and blue colour. We found that experimentally increased competition over mating territories led to a higher proportion of males expressing the yellow phenotype. The expression of yellow coloration was found to be beneficial because yellow males won more staged dyadic contests and exhibited a lower level of oxidative stress than blue males. However, females were more likely to spawn with blue males in mate choice experiments, suggesting that expression of blue coloration is sexually more attractive. The ability to adjust colour phenotype according to the local competitive environment could therefore promote the persistence of plasticity in coloration.

Patrolling the area, not ousting intruders, relates to reproductive success for territorial male Leon Springs pupfish, Cyprinodon bovinus.

We considered the relationship between the benefits and costs of territorial defense in a wild population of the Leon Springs pupfish, Cyprinodon bovinus. We defined benefit as the number of eggs deposited on an artificial substratum placed within the defender's territory. Costs included two defensive behaviors. First, males frequently "patrolled" their territories, swimming back-and-forth across their area. Second, males chased intruding Pecos gambusia (Gambusia nobilis) as well as small male and female conspecific C. bovinus from their territories. Both of these species prey on the territorial defenders' eggs; additionally, small male C. bovinus will attempt to "steal" spawns from the territorial defender by spawning with females in the territory. Our analyses revealed that only patrol frequency was related to the reproductive benefit of the territory. Neither chases against gambusia nor conspecifics were predicted by egg numbers on the breeding substrata. We speculate that the frequency of patrolling is an indicator of territorial value and note the qualitative differences in chasing behavior against the different species of intruder.

The social and defensive function of olfactory behaviors in a pair-living sexually monogamous primate.

Olfactory behaviors serve a wide variety of social functions in mammals. Odor may signal information about attributes of individuals important for mating and reproduction. Olfactory behaviors, such as scent-marking, may also function as part of home range or resource defense strategies. We assessed the potential social and home range defense functions of olfactory behavior in a pair-living and sexually monogamous primate, Azara's owl monkey (Aotus azarae), in the Argentinian Chaco. This is the most extensive investigation of owl monkey olfactory behaviors in the wild. Individuals regularly performed olfactory behaviors (group mean + SD = 1.3 + 0.5 per hour). The patterns were generally comparable to those observed in studies of captive owl monkeys, except that urine washing was the most common behavior in the wild, as opposed to scent-marking and genital inspections. Most olfactory behaviors were performed by adults, and there were striking sex differences in genital inspections: almost all consisted of an adult male inspecting the paired adult female. These findings suggest that olfactory behaviors play an important role in signaling and coordinating reproduction among owl monkeys, particularly during periods of female conception and pregnancy. Additionally, our research indicates that these behaviors may also serve as a defense strategy for maintaining the core area of their home ranges. This study offers the first assessment of the role of olfactory behaviors in reproductive contexts and home range defense in pair-living, monogamous platyrrhine primates.

Wing mechanics and acoustic communication of a new genus of sylvan katydid (Orthoptera: Tettigoniidae: Pseudophyllinae) from the Central Cordillera cloud forest of Colombia.

Stridulation is used by male katydids to produce sound via the rubbing together of their specialised forewings, either by sustained or interrupted sweeps of the file producing different tones and call structures. There are many species of Orthoptera that remain undescribed and their acoustic signals are unknown. This study aims to measure and quantify the mechanics of wing vibration, sound production and acoustic properties of the hearing system in a new genus of Pseudophyllinae with taxonomic descriptions of two new species. The calling behaviour and wing mechanics of males were measured using micro-scanning laser Doppler vibrometry, microscopy, and ultrasound sensitive equipment. The resonant properties of the acoustic pinnae of the ears were obtained via µ-CT scanning and 3D printed experimentation, and numerical modelling was used to validate the results. Analysis of sound recordings and wing vibrations revealed that the stridulatory areas of the right tegmen exhibit relatively narrow frequency responses and produce narrowband calls between 12 and 20 kHz. As in most Pseudophyllinae, only the right mirror is activated for sound production. The acoustic pinnae of all species were found to provide a broadband increased acoustic gain from ~40-120 kHz by up to 25 dB, peaking at almost 90 kHz which coincides with the echolocation frequency of sympatric bats. The new genus, named Satizabalus n. gen., is here derived as a new polytypic genus from the existing genus Gnathoclita, based on morphological and acoustic evidence from one described (S. sodalis n. comb.) and two new species (S. jorgevargasi n. sp. and S. hauca n. sp.). Unlike most Tettigoniidae, Satizabalus exhibits a particular form of sexual dimorphism whereby the heads and mandibles of the males are greatly enlarged compared to the females. We suggest that Satizabalus is related to the genus Trichotettix, also found in cloud forests in Colombia, and not to Gnathoclita.

Variation in farming damselfish behaviour creates a competitive landscape of risk on coral reefs.

Interspecific interactions are fundamental drivers of animal space use. Yet while non-consumptive effects of predation risk on prey space use are well-known, the risk of aggressive interactions on space use of competitors is largely unknown. We apply the landscape of risk framework to competition-driven space use for the first time, with the hypothesis that less aggressive competitors may alter their behaviour to avoid areas of high competitor density. Specifically, we test how aggressive risk from territorial algal-farming damselfishes can shape the spatial distribution of herbivore fish competitors. We found that only the most aggressive damselfish had fewer competitors in their surrounding area, demonstrating that individual-level behavioural variation can shape spatial distributions. In contradiction to the landscape of risk framework, abundances of farming damselfish and other fishes were positively associated. Our results suggest that reef fishes do not simply avoid areas of high damselfish abundance, but that spatial variation in aggressive behaviour, rather than of individuals, created a competitive landscape of risk. We emphasize the importance of individual-level behaviour in identifying patterns of space use and propose expanding the landscape of risk framework to non-predatory interactions to explore cascading behavioural responses to aggressive risk.

How territoriality and sociality influence the habitat selection and movements of a large carnivore.

While territoriality is one of the key mechanisms influencing carnivore space use, most studies quantify resource selection and movement in the absence of conspecific influence or territorial structure. Our analysis incorporated social information in a resource selection framework to investigate mechanisms of territoriality and intra-specific competition on the habitat selection of a large, social carnivore. We fit integrated step selection functions to 3-h GPS data from 12 collared African wild dog packs in the Okavango Delta and estimated selection coefficients using a conditional Poisson likelihood with random effects. Packs selected for their neighbors' 30-day boundary (defined as their 95% kernel density estimate) and for their own 90-day core (defined as their 50% kernel density estimate). Neighbors' 30-day boundary had a greater influence on resource selection than any habitat feature. Habitat selection differed when they were within versus beyond their neighbors' 30-day boundary. Pack size, pack tenure, pup presence, and seasonality all mediated how packs responded to neighbors' space use, and seasonal dynamics altered the strength of residency. While newly-formed packs and packs with pups avoided their neighbors' boundary, older packs and those without pups selected for it. Packs also selected for the boundary of larger neighboring packs more strongly than that of smaller ones. Social structure within packs has implications for how they interact with conspecifics, and therefore how they are distributed across the landscape. Future research should continue to investigate how territorial processes are mediated by social dynamics and, in turn, how territorial structure mediates resource selection and movement. These results could inform the development of a human-wildlife conflict (HWC) mitigation tool by co-opting the mechanisms of conspecific interactions to manage space use of endangered carnivores.

Size matters: Natural experiments suggest the dear enemy effect is moderated by pack size in African wild dogs.

Remote monitoring of communal marking sites, or latrines, provides a unique opportunity to observe undisturbed scent marking behaviour of African wild dogs (Lycaon pictus). We used remote camera trap observations in a natural experiment to test behavioural scent mark responses to rivals (either familiar neighbours or unfamiliar strangers), to determine whether wild dogs exhibit the "dear enemy" or "nasty neighbour" response. Given that larger groups of wild dogs represent a greater threat to smaller groups, including for established residents, we predicted that the overarching categories "dear enemy" vs. "nasty neighbour" may be confounded by varying social statuses that exists between individual dyads interacting. Using the number of overmarks as a metric, results revealed an interaction between sender and receiver group size irrespective of familiarity consistent with this prediction: in general, individuals from large resident packs overmarked large groups more than they overmarked smaller groups, whereas individuals from smaller packs avoided overmarking larger groups, possibly to avoid detection. Monitoring a natural system highlights variables such as pack size that may be either overlooked or controlled during scent presentation experiments, influencing our ability to gain insights into the factors determining territorial responses to rivals.

Genetically identical mice express alternative reproductive tactics depending on social conditions in the field.

In many species, establishing and maintaining a territory is critical to survival and reproduction, and an animal's ability to do so is strongly influenced by the presence and density of competitors. Here we manipulate social conditions to study the alternative reproductive tactics displayed by genetically identical, age-matched laboratory mice competing for territories under ecologically realistic social environmental conditions. We introduced adult males and females of the laboratory mouse strain C57BL/6J into a large, outdoor field enclosure containing defendable resource zones under one of two social conditions. We first created a low-density social environment, such that the number of available territories exceeded the number of males. After males established stable territories, we introduced a pulse of intruder males and observed the resulting defensive and invasive tactics employed. In response to this change in social environment, males with large territories invested more in patrolling but were less effective at excluding intruder males as compared with males with small territories. Intruding males failed to establish territories and displayed an alternative tactic featuring greater exploration as compared with genetically identical territorial males. Alternative tactics did not lead to equal reproductive success-males that acquired territories experienced greater survival and had greater access to females.

Territorial gaps on quality of causes of death statistics over the last forty years in Spain.

BACKGROUND: The quality of the statistics on causes of death (CoD) does not present consolidated indicators in literature further than the coding group of ill-defined conditions of the International Classification of Diseases. Our objective was to assess the territorial quality of CoD by reliability of the official mortality statistics in Spain over the years 1980-2019. METHODS: A descriptive epidemiological design of four decades (1980-, 1990-, 2000-, and 2010-2019) by region (18) and sex was implemented. The CoD cases, age-adjusted rates and ratios (to all-cause) were assigned by reliability to unspecific and ill-defined quality categories. The regional mortality rates were contrasted to the Spanish median by decade and sex by the Comparative Mortality Ratio (CMR) in a Bayesian perspective. Statistical significance was considered when the CMR did not contain the value 1 in the 95% credible intervals. RESULTS: Unspecific, ill-defined, and all-cause rates by region and sex decreased over 1980-2019, although they scored higher in men than in women. The ratio of ill-defined CoD decreased in both sexes over these decades, but was still prominent in 4 regions. CMR of ill-defined CoD in both sexes exceeded the Spanish median in 3 regions in all decades. In the last decade, women's CMR significantly exceeded in 5 regions for ill-defined and in 6 regions for unspecific CoD, while men's CMR exceeded in 4 and 2 of the 18 regions, respectively on quality categories. CONCLUSIONS: The quality of mortality statistics of causes of death has increased over the 40 years in Spain in both sexes. Quality gaps still remain mostly in Southern regions. Authorities involved might consider to take action and upgrading regional and national death statistics, and developing a systematic medical post-grade training on death certification.

Latrine site selection by African clawless otters, Aonyx capensis, and their behavior during latrine visitations.

Latrine sites are used as areas for the deposition of scent-containing excretions and play important roles in intraspecific olfactory communication, territoriality, sexual attraction, and defense behaviors of many mammals. African clawless otters (Aonyx capensis) likely use latrine sites as primary areas for scent marking and scent communication but no studies to date have investigated their potential role or site selection. We assessed latrine site selection at 2 spatial scales (micro- and macroscale) and recorded behaviors via camera trap recordings. Thirty-eight latrine sites were identified and assessed at 2 locations in Mtunzini on the north coast of KwaZulu-Natal, South Africa (uMlalazi Nature Reserve and Zini Fish Farm) during the months of August to November 2021. Latrine sites were identified through several intensive surveys, while we characterized nonselected sites through a systematic sampling approach. Latrine and control sites were inventoried along a 52-m buffer around all water bodies in both study areas. At each site we measured a series of potential environmental predictors, including horizontal and vertical vegetation cover, surface slope, and averaged wind speeds for days classified as relatively wind-still and relatively windy. To assess the relative role of various environmental predictors, we used a binomial generalized linear model resource selection function to model both spatial scales of latrine site selection. The majority of latrine sites were located at the ecotone between 2 vegetation units or between a vegetation unit and a water source. At a macroscale, latrine sites were associated with areas containing little vegetative substrate cover and minimal canopy cover. The top-ranked models at the microscale also indicated that latrine sites were characterized as occurring in open areas with less canopy and horizontal cover and on flatter areas that are relatively protected against wind. The most common behaviors recorded at 3 latrine sites were the "jiggle dance" (42%) and sniffing (29%). We hypothesize that otters evaluate numerous environmental parameters to enhance the functionality of latrine sites. For example, sites with little vegetative cover may increase the conspicuousness of latrines to conspecifics, while areas exposed to less wind likely aid in the retention of scent. Ongoing research is characterizing the behaviors of otters around latrines and chemical signatures of latrine sites in an effort to facilitate interpretation of their social function to African clawless otters.

Competitive Displacement and Agonistic Character Displacement, or the Ghost of Interference Competition.

AbstractInterference competition can drive species apart in habitat use through competitive displacement in ecological time and agonistic character displacement (ACD) over evolutionary time. As predicted by ACD theory, sympatric species of rubyspot damselflies (Hetaerina spp.) that respond more aggressively to each other in staged encounters differ more in microhabitat use. However, the same pattern could arise from competitive displacement if dominant species actively exclude subordinate species from preferred microhabitats. The degree to which habitat partitioning is caused by competitive displacement can be assessed with removal experiments. We carried out removal experiments with three species pairs of rubyspot damselflies. With competitive displacement, removing dominant species should allow subordinate species to shift into the dominant species' microhabitat. Instead, we found that species-specific microhabitat use persisted after the experimental removals. Thus, the previously documented association between heterospecific aggression and microhabitat partitioning in this genus is most likely a product of divergence in habitat preferences caused by interference competition in the evolutionary past.

What Is a Society? Building an Interdisciplinary Perspective and Why That's Important.

I submit the need to establish a comparative study of societies, namely groups beyond a simple, immediate family that have the potential to endure for generations, whose constituent individuals recognize one another as members, and that maintain control over access to a physical space. This definition, with refinements and ramifications I explore, serves for cross-disciplinary research since it applies not just to nations but to diverse hunter-gatherer and tribal groups with a pedigree that likely traces back to the societies of our common ancestor with the chimpanzees. It also applies to groups among other species for which comparison to humans can be instructive. Notably, it describes societies in terms of shared group identification rather than social interactions. An expansive treatment of the topic is overdue given that the concept of a society (even the use of such synonyms as primate "troop") has fallen out of favor among biologists, resulting in a semantic mess; while sociologists rarely consider societies beyond nations, and social psychologists predominantly focus on ethnicities and other component groups of societies. I examine the relevance of societies across realms of inquiry, discussing the ways member recognition is achieved; how societies compare to other organizational tiers; and their permeability, territoriality, relation to social networks and kinship, and impermanence.We have diverged from our ancestors in generating numerous affiliations within and between societies while straining the expectation of society memberships by assimilating diverse populations. Nevertheless, if, as I propose, societies were the first, and thereafter the primary, groups of prehistory, how we came to register society boundaries may be foundational to all human "groupiness." A discipline-spanning approach to societies should further our understanding of what keeps societies together and what tear them apart.

Female behavior drives the formation of distinct social structures in C57BL/6J versus wild-derived outbred mice in field enclosures.

BACKGROUND: Social behavior and social organization have major influences on individual health and fitness. Yet, biomedical research focuses on studying a few genotypes under impoverished social conditions. Understanding how lab conditions have modified social organizations of model organisms, such as lab mice, relative to natural populations is a missing link between socioecology and biomedical science. RESULTS: Using a common garden design, we describe the formation of social structure in the well-studied laboratory mouse strain, C57BL/6J, in replicated mixed-sex populations over 10-day trials compared to control trials with wild-derived outbred house mice in outdoor field enclosures. We focus on three key features of mouse social systems: (i) territory establishment in males, (ii) female social relationships, and (iii) the social networks formed by the populations. Male territorial behaviors were similar but muted in C57 compared to wild-derived mice. Female C57 sharply differed from wild-derived females, showing little social bias toward cage mates and exploring substantially more of the enclosures compared to all other groups. Female behavior consistently generated denser social networks in C57 than in wild-derived mice. CONCLUSIONS: C57 and wild-derived mice individually vary in their social and spatial behaviors which scale to shape overall social organization. The repeatable societies formed under field conditions highlights opportunities to experimentally study the interplay between society and individual biology using model organisms.

Counter-strategies to infanticide: The importance of cubs in determining lion habitat selection and social interactions.

Animal social and spatial behaviours are inextricably linked. Animal movements are driven by environmental factors and social interactions. Habitat structure and changing patterns of animal space use can also shape social interactions. Animals adjust their social and spatial behaviours to reduce the risk of offspring mortality. In territorial infanticidal species, two strategies are possible for males: they can stay close to offspring to protect them against rivals (infant-defence hypothesis) or patrol the territory more intensively to prevent rival intrusions (territorial-defence hypothesis). Here, we tested these hypotheses in African lions (Panthera leo) by investigating how males and females adjust their social and spatial behaviours in the presence of offspring. We combined datasets on the demography and movement of lions, collected between 2002 and 2016 in Hwange National Park (Zimbabwe), to document the presence of cubs (field observations) and the simultaneous movements of groupmates and competitors (GPS tracking). We showed a spatial response of lions to the presence of offspring, with females with cubs less likely to select areas close to waterholes or in the periphery of the territory than females without cubs. In contrast, these areas were more selected by males when there were cubs in the pride. We also found social responses. Males spent more time with females as habitat openness increased but the presence of cubs in the pride did not influence the average likelihood of observing males with females. Furthermore, rival males relocated further after an encounter with pride males when cubs were present in the prides, suggesting that the presence of cubs leads to a more vigorous repulsion of competitors. Males with cubs in their pride were more likely to interact with male competitors on the edge of the pride's home range and far from the waterholes, suggesting that they are particularly assiduous in detecting and repelling rival males during these periods. In general, the strategies to avoid infanticide exhibited by male lions supported the territorial-defence hypothesis. Our study contributes to answer the recent call for a behavioural ecology at the spatial-social interface.

Examining Cybersexism in Online Gaming Communities: A Scoping Review.

Cybersexism in the context of online gaming communities, as epitomized by the Gamergate incident back in 2014, has been an issue for a while for gamer women, yet it has not received proper attention. In this scoping review, we have aimed to assess its main characteristics, its consequences for gamer women, its triggers and predictors, and related prevention and mitigation policies provided by the existing research. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR) guidelines were applied to the design of the scoping review. Empirical studies were accessed via database searches. The following databases were prospected: Scopus, ProQuest, Web of Science, PsycINFO, PubMed, and ACM from March to May 2021. A total of 33 studies were included in the final analysis after database searching, filtering, and snowballing. Most of the selected studies (66%, n = 22) were focused on the manifestations of cybersexism in gaming communities, with gender-driven trash-talking being the main one. The main drivers and triggers behind cybersexist behaviors were also the research topic in 66% (n = 22) of the studies and the consequences and coping strategies were studied in 52% (n = 17) of the articles. Furthermore, 12% (n = 4) of the studies assessed policies and actions to prevent cybersexism. Cybersexism and its manifestations are a reality that conditions gamer women, provoking avoidance and ultimately withdrawal from gaming and, therefore, creating inequality, impairing full digital citizenship, and widening the digital gender gap.

A territorialidade da Atenção Básica à Saúde do SUS: a difusão das clínicas médicas populares na Região Metropolitana de Belém, Pará, Brasil / The territorial nature of the Primary Health Care of Brazil's Unified Health System (SUS): the proliferation of community medical clinics in the Metropolitan Region of Belém, State of Pará, Brazil

Resumo O artigo apresenta uma análise sobre a difusão das clínicas médicas populares nos municípios que compõem a Região Metropolitana de Belém (RMB). Com o propósito de compreender as razões e as origens do avanço do setor de saúde popular, promoveu-se uma investigação sobre a atuação da rede de atenção básica à saúde (ABS) do Sistema Único de Saúde (SUS). A discussão se fundamenta na revisão de dados primários e secundários, captados via trabalho de campo nas 119 clínicas populares da RMB e via informações do DATASUS. Constatou-se que o setor das clínicas de saúde popular foi beneficiado amplamente nos últimos anos, mediante a intensificação do subfinanciamento do SUS, em particular da rede de ABS, que passa por um processo de fragmentação, responsáveis pela redução e pela desarticulação das equipes multiprofissionais de ABS, além das perdas apresentadas no setor de saúde suplementar. As clínicas populares seguem um modelo assistencial inacabado e contraditório, criado pela própria iniciativa privada para o preenchimento da demanda reprimida do SUS em razão de o acesso a essas instituições não garantir uma assistência universal e gratuita ou assegurar um tratamento continuo, motivo pelo qual uma ampla parcela destes usuários é devolvida ao SUS.

Abstract The scope of this article is an analysis of the proliferation of community medical clinics in the municipalities that comprise the Metropolitan Region of Belem. An investigation was conducted into the performance of the primary health care network of Brazil's Unified Health System, with a view to getting a better understanding of the reasons for, and origins of, the proactive stance of the community health sector. The discussion is based on the review of primary and secondary data, obtained via fieldwork in 119 community clinics in the Metropolitan Region of Belem, and information from Brazil's Unified Health System data center. It was revealed that the community health clinic sector has benefited extensively in recent years from the intensification of underfunding of Brazil's Unified Health System, especially the primary health care network, which is undergoing a process of fragmentation. This is directly responsible for the reduction and disruption of multiprofessional primary health care teams, in addition to the losses suffered in the supplementary health sector. The community clinics adopt an spontaneous and contradictory care model created by the private sector to meet the repressed demand of Brazil's Unified Health System

A territorialidade da alta complexidade na Região Metropolitana de Belém, Brasil: a saúde especializada é subsidiada pelo SUS? / Territorial dynamics of highly complex health services in the Belém Metropolitan Region, Brazil: is specialized health care subsidized by the SUS?

Resumo O artigo apresenta uma análise sobre a atuação da rede de atenção especializada do SUS, com a delimitação dos serviços de média e de alta complexidade da rede hospitalar dos municípios que compõem a Região Metropolitana de Belém. A discussão se fundamenta na revisão dos dados secundários captados na plataforma do DATASUS e disponibilizados no Cadastro Nacional de Estabelecimentos de Saúde do Brasil (CNES) até janeiro de 2022. Constatou-se que a territorialidade da alta complexidade é formada majoritariamente pela rede privada, contudo a capacidade de atendimento da rede SUS sobrepôs à oferta direcionada ao atendimento não universal, em razão da ampla reserva de serviços privados ao convênio SUS, na qual os hospitais filantrópicos apresentaram maior disposição à demanda universal. Em contrapartida, a ampla presença do Estado nos serviços de alta complexidade não deve ser pensada como uma cobertura universal, devido ao fato de as formas de acesso a esses serviços apresentarem filtros de natureza jurídico-institucional, ou, em outras palavras, o que o SUS denomina de hospitais de portas abertas ou fechadas.

Abstract This article presents an analysis of the territorial dynamics of the specialized healthcare network, focusing on medium and high complexity care in hospitals in the municipalities that make up the Belém Metropolitan Region. The analysis is based on secondary data from DATASUS available on the National Health Facility Registry (CNES) up to January 2022. The findings show that the private network accounts for the largest proportion of services in the region; however, the service capacity of the SUS is greater than that of the private sector due to the large volume of services outsourced to private facilities via public-private partnerships, with philanthropic hospitals allocating the largest proportion of services to public patients. This should not be confused with universal coverage, as public patient access to private services may be restricted by legal and institutional barriers depending on the form of access (open-door or closed-door).

Ontogeny and phylogeny of mating behaviour: social heteroch rony in primates.

Based on the Recognition Concept of species, the specific-mate contact model posits that mating systems develop as combinations of two fundamental courtship strategies that we interpret here in terms of behavioural heterochrony: territorial mate-attraction evolved as an effect of peramorphosis whereas group-living mate-seeking evolved as an effect of paedomorphosis. We tested this hypothesis on primates in a phylogenetic and paleo-climatic context. Our results suggest that primate promiscuity (both males and females are mate-seekers) evolved with group-living from ancestral pair-living monogamy (both males and females are mate-attractors) in the Palaeogene, as the result of a slowdown in growth (neoteny) caused by increased environmental predictability. A secondary return to territorial monogamy probably evolved as the result of accelerated growth driven by seasonality (acceleration). Polygamy evolved in the Neogene during periods of forest fragmentation and environmental unpredictability. Small monogamous ancestors evolved seasonal polyandry (female attraction) as an effect of truncated development (progenesis). Large promiscuous, neotenic ancestors evolved non-seasonal polygyny (male attraction) as an effect of prolonged development (hypermorphosis) in males. We conclude that social heterochrony offers alternative explanations for the coevolution of life history and mating be-haviour; and we discuss the implications of our model for human social evolution.

Territorial behaviour of thrush nightingales outside the breeding season.

Territoriality is a common pattern of space use in animals that has fundamental consequences for ecological processes. In the tropics, all-year resident songbirds usually hold territories throughout the year, whereas most all-year resident temperate species are territorial only during the breeding season. In long-distance migrants, however, the situation is mostly unexplored. Here, we report findings from a Palaearctic-African migrant, the thrush nightingale Luscinia luscina. We found that only a fraction of the males was territorial in their East African winter quarters and that this was related to the stage of their song development. Individuals with full song were territorial towards other full songsters, but not towards birds that sang plastic song (i.e. an earlier stage of song development). Plastic singers were not territorial towards full songsters and often settled closely to territorial males. We suggest that territoriality of thrush nightingales in the winter quarters may be a by-product of rising testosterone levels that trigger song crystallization. Collectively, our study indicates that changes in territoriality can occur rapidly, giving rise to shifting proportions of territorial and non-territorial individuals in a population, which may lead to complex dynamics in settlement patterns and resulting ecological interactions.