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Social Species (social + species)
Selected AbstractsPatch Occupancy and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South AfricaCONSERVATION BIOLOGY, Issue 4 2000Michael J. Lawes We recorded patch occupancy of blue duiker ( Philantomba monticola), tree hyrax ( Dendrohyrax arboreus), and samango monkey (Cercopithecus mitis labiatus) in 199 forest patches. Their rarity is ascribed to the fragmentation and destruction of their forest habitat. Incidence functions, derived from presence and absence data, were formulated as generalized linear models, and environmental effects were included in the fitted logistic models. The small and mostly solitary hyrax and duiker persisted in smaller patches than the large and social monkey. Although this result follows expectations based on relative home-range sizes of each species, the incidence probability of the samango monkey was invariant with increasing isolation, whereas a gradual decrease with increasing isolation was observed for the hyrax and duiker. Group dynamics may inhibit dispersal and increase the isolation effect in social species such as samango monkeys. A mainland-island metapopulation model adequately describes patterns of patch occupancy by the hyrax and duiker, but the monkeys' poor dispersal ability and obvious area-dependent extirpation suggest that they exist in transient, nonequilibrium (declining) metapopulations. Through identification of large forest patches for careful protection and management, the survival of all three species,especially the monkey,could be prolonged. Because no functional metapopulation may exist for the monkey, however, this is an emergency measure. For the duiker and hyrax, larger patches should form part of a network of smaller and closer patches in a natural matrix. Resumen: Investigamos la persistencia de tres mamíferos forestales raros de tamaño mediano (2,9 kg) en los bosques fragmentados de cinturón de niebla Podocarpus en la región central de la provincia KwaZulu-Natal, Sudáfrica. Registramos la ocupación del duiker azul ( Philantomba monticola), el hyrax arborícola ( Dendrohyrax arboreus) y el mono samango (Cercopithecus mitis labiatus) en 199 parches forestales. Su rareza se atribuye a la fragmentación y destrucción de su hábitat forestal. Las funciones de incidencia, derivadas de datos de presencia y ausencia, fueron formuladas como modelos lineales generalizados, y los efectos ambientales fueron incluidos en los modelos logísticos ajustados. Los pequeños y mayormente solitarios hyrax y duiker persistieron en parches más pequeños que los monos, que son más grandes y más sociables. A pesar de que este resultado obedece a expectativas basadas en tamaños de rango de hogar relativos de cada especie, la probabilidad de incidencia del mono samango no cambió con un incremento en el aislamiento, mientras que una disminución gradual al crecer el aislamiento se observó en hyrax y duiker. Las dinámicas de grupos podrían inhibir la dispersión e incrementar el efecto de aislamiento en especies sociables como lo es el mono samango. Un modelo de metapoblación continente-isla describe adecuadamente los patrones de la ocupación de parches por hyrax y duiker; sin embargo, la pobre capacidad de dispersión de los monos y la obvia extirpación área-dependente sugiere que estos existen en metapoblaciones transitorias, desequilibradas (en disminución). Mediante la identificación de parches forestales grandes para la protección y manejo cuidadosos, la supervivencia de las tres especies ( pero especialmente la de los monos) podría ser prolongada. Sin embargo, debido a que no existen metapoblaciones funcionales de monos, esta es una medida de emergencia. Para el duiker y el hyrax, los parches grandes deberán formar parte de una red de parches más pequeños y más cercanos en una matriz natural. [source] Natal Dispersal Patterns of a Subsocial Spider Anelosimus cf. jucundus (Theridiidae)ETHOLOGY, Issue 9 2003Kimberly S. Powers Species that alternate periods of solitary and social living may provide clues to the conditions that favor sociality. Social spiders probably originated from subsocial-like ancestors, species in which siblings remain together for part of their life cycle but disperse prior to mating. Exploring the factors that lead to dispersal in subsocial species, but allow the development of large multigenerational colonies in social species, may provide insight into this transition. We studied the natal dispersal patterns of a subsocial spider, Anelosimus cf. jucundus, in Southeastern Arizona. In this population, spiders disperse from their natal nests in their penultimate and antepenultimate instars over a 3-mo period. We tracked the natal dispersal of marked spiders at sites with clustered vs. isolated nests. We found that most spiders initially dispersed less than 5 m from their natal nests. Males and females, and spiders in patches with different densities of nests, dispersed similar distances. The fact that both sexes in a group dispersed, the lack of a sex difference in dispersal distance, and the relatively short distances dispersed are consistent with the hypothesis that natal dispersal results from resource competition within the natal nest, rather than inbreeding avoidance in competition for mates. Additionally, an increase in the average distance dispersed with time and with the number of spiders leaving a nest suggests that competition for nest sites in the vicinity of the natal nest may affect dispersal distances. The similar distances dispersed in patches with isolated vs. clustered nests, in contrast, suggest that competition among dispersers from different nests may not affect dispersal distances. [source] SOCIALITY IN THERIDIID SPIDERS: REPEATED ORIGINS OF AN EVOLUTIONARY DEAD ENDEVOLUTION, Issue 11 2006Ingi Agnarsson Abstract Evolutionary ,dead ends' result from traits that are selectively advantageous in the short term but ultimately result in lowered diversification rates of lineages. In spiders, 23 species scattered across eight families share a social system in which individuals live in colonies and cooperate in nest maintenance, prey capture, and brood care. Most of these species are inbred and have highly female-biased sex ratios. Here we show that in Theridiidae this social system originated eight to nine times independently among 11 to 12 species for a remarkable 18 to 19 origins across spiders. In Theridiidae, the origins cluster significantly in one clade marked by a possible preadaptation: extended maternal care. In most derivations, sociality is limited to isolated species: social species are sister to social species only thrice. To examine whether sociality in spiders represents an evolutionary dead end, we develop a test that compares the observed phylogenetic isolation of social species to the simulated evolution of social and non-social clades under equal diversification rates, and find that sociality in Theridiidae is significantly isolated. Because social clades are not in general smaller than their nonsocial sister clades, the spindly phylogenetic pattern,many tiny replicate social clades,may be explained by extinction rapid enough that a nonsocial sister group does not have time to diversify while the social lineage remains extant. In this case, this repeated origin and extinction of sociality suggests a conflict between the short-term benefits and long-term costs of inbred sociality. Although benefits of group living may initially outweigh costs of inbreeding (hence the replicate origins), in the long run the subdivision of the populations in relatively small and highly inbred colony lineages may result in higher extinction, thus an evolutionary dead end. [source] THE ADAPTIVE DYNAMICS OF ALTRUISM IN SPATIALLY HETEROGENEOUS POPULATIONSEVOLUTION, Issue 1 2003JEAN-FRANÇOIS LE GALLIARD Abstract., We study the spatial adaptive dynamics of a continuous trait that measures individual investment in altruism. Our study is based on an ecological model of a spatially heterogeneous population from which we derive an appropriate measure of fitness. The analysis of this fitness measure uncovers three different selective processes controlling the evolution of altruism: the direct physiological cost, the indirect genetic benefits of cooperative interactions, and the indirect genetic costs of competition for space. In our model, habitat structure and a continuous life cycle makes the cost of competing for space with relatives negligible. Our study yields a classification of adaptive patterns of altruism according to the shape of the costs of altruism (with decelerating, linear, or accelerating dependence on the investment in altruism). The invasion of altruism occurs readily in species with accelerating costs, but large mutations are critical for altruism to evolve in selfish species with decelerating costs. Strict selfishness is maintained by natural selection only under very restricted conditions. In species with rapidly accelerating costs, adaptation leads to an evolutionarily stable rate of investment in altruism that decreases smoothly with the level of mobility. A rather different adaptive pattern emerges in species with slowly accelerating costs: high altruism evolves at low mobility, whereas a quasi-selfish state is promoted in more mobile species. The high adaptive level of altruism can be predicted solely from habitat connectedness and physiological parameters that characterize the pattern of cost. We also show that environmental changes that cause increased mobility in those highly altruistic species can beget selection-driven self-extinction, which may contribute to the rarity of social species. [source] Reproductive conflict delays the recovery of an endangered social speciesJOURNAL OF ANIMAL ECOLOGY, Issue 1 2009Andrés López-Sepulcre Summary 1Evolutionary theory predicts that individuals, in order to increase their relative fitness, can evolve behaviours that are detrimental for the group or population. This mismatch is particularly visible in social organisms. Despite its potential to affect the population dynamics of social animals, this principle has not yet been applied to real-life conservation. 2Social group structure has been argued to stabilize population dynamics due to the buffering effects of nonreproducing subordinates. However, competition for breeding positions in such species can also interfere with the reproduction of breeding pairs. 3Seychelles magpie robins, Copsychus sechellarum, live in social groups where subordinate individuals do not breed. Analysis of long-term individual-based data and short-term behavioural observations show that subordinates increase the territorial takeover frequency of established breeders. Such takeovers delay offspring production and decrease territory productivity. 4Individual-based simulations of the Seychelles magpie robin population parameterized with the long-term data show that this process has significantly postponed the recovery of the species from the Critically Endangered status. 5Social conflict thus can extend the period of high extinction risk, which we show to have population consequences that should be taken into account in management programmes. This is the first quantitative assessment of the effects of social conflict on conservation. [source] The role of prey size and abundance in the geographical distribution of spider socialityJOURNAL OF ANIMAL ECOLOGY, Issue 5 2007KIMBERLY S. POWERS Summary 1Social species in the spider genus Anelosimus predominate in lowland tropical rainforests, while congeneric subsocial species occur at higher elevations or higher latitudes. 2We conducted a comparative study to determine whether differences in total biomass, insect size or both have been responsible for this pattern. 3We found that larger average insect size, rather than greater overall biomass per se, is a key characteristic of lowland tropical habitats correlating with greater sociality. 4Social species occupied environments with insects several times larger than the spiders, while subsocial species nearing dispersal occupied environments with smaller insects in either high or low overall biomass. 5Similarly, in subsocial spider colonies, individuals lived communally at a time when they were younger and therefore smaller than the average insect landing on their webs. 6We thus suggest that the availability of large insects may be a critical factor restricting social species to their lowland tropical habitats. [source] Quantifying the influence of sociality on population structure in bottlenose dolphinsJOURNAL OF ANIMAL ECOLOGY, Issue 1 2006DAVID LUSSEAU Summary 1The social structure of a population plays a key role in many aspects of its ecology and biology. It influences its genetic make-up, the way diseases spread through it and the way animals exploit their environment. However, the description of social structure in nonprimate animals is receiving little attention because of the difficulty in abstracting social structure from the description of association patterns between individuals. 2Here we focus on recently developed analytical techniques that facilitate inference about social structure from association patterns. We apply them to the population of bottlenose dolphins residing along the Scottish east coast, to detect the presence of communities within this population and infer its social structure from the temporal variation in association patterns between individuals. 3Using network analytical techniques, we show that the population is composed of two social units with restricted interactions. These two units seem to be related to known differences in the ranging pattern of individuals. By examining social structuring at different spatial scales, we confirm that the identification of these two units is the result of genuine social affiliation and is not an artefact of their spatial distribution. 4We also show that the structure of this fission-fusion society relies principally on short-term casual acquaintances lasting a few days with a smaller proportion of associations lasting several years. These findings highlight how network analyses can be used to detect and understand the forces driving social organization of bottlenose dolphins and other social species. [source] Individual distinctiveness in the mobbing call of a cooperative bird, the noisy miner Manorina melanocephalaJOURNAL OF AVIAN BIOLOGY, Issue 5 2009Robert A. W. Kennedy Individual differentiation is usually advantageous in maximising the fitness benefits of interactions with conspecifics. In social species, where intraspecific interactions are frequent, this is likely to be particularly important. Indeed, some form of differentiation underpins most hypotheses proposed to account for cooperative behaviour in birds. The auditory modality is a likely candidate for this function, particularly for species where individuals are widely spaced and in dense vegetation. In this study, we examined the acoustic structure of a distinctive mobbing signal, the ,chur' call, of the cooperatively breeding noisy miner Manorina melanocephala. Using 250,calls from 25 individuals, a combination of spectrographic-based measurement of call parameters, cross-correlation and multi-dimensional scaling was used to test for systematic individual differences in call structure. Strong differences between individuals were observed in all measures, indicating that this call encodes sufficient information to facilitate individual differentiation. We then conducted a series of field playbacks to test the effect of the behaviour on conspecifics. Results demonstrated that the call, in isolation, has a clear attractant effect. Given that chur calls are synonymous with the characteristic cooperative mobbing behaviour of this species, these findings suggest they are likely to have an important function in coordinating complex social behaviour. [source] Modelling the role of social behavior in the persistence of the alpine marmot Marmota marmotaOIKOS, Issue 1 2003Volker Grimm A general rule of thumb for biological conservation obtained from simple models of hypothetical species is that for populations with strong environmental noise moderate increases in habitat size or quality do not substantially reduce extinction risk. However, whether this rule also holds for real species with complex behavior, such as social species with breeding units and reproductive suppression, is uncertain. Here we present a population viability analysis of the alpine marmot Marmota marmota, which displays marked social behavior, i.e. it lives in social groups of up to twenty individuals. Our analysis is based on a long-term field study carried out in the Bavarian Alps since 1982. During the first fifteen years of this study, 687 marmots were individually marked and the movements and fate of 98 dispersing marmots were recorded with radio-telemetry. Thus, in contrast to most other viability analyses of spatially structured populations, good data about dispersal exist. A model was constructed which is individual-based, spatially explicit at the scale of clusters of neighbouring territories, and spatially implicit at larger scales. The decisive aspect of marmot life history, winter mortality, is described by logistic regression where mortality is increased by age and the severity of winter, and decreased by the number of subdominant individuals present in a group. Model predictions of group size distribution are in good agreement with the results of the field study. The model shows that the effect of sociality on winter mortality is very effective in buffering environmental harshness and fluctuations. This underpins theoretical results stating that the appropriate measure of the strength of environmental noise is the ratio between the variance of population growth rate and the intrinsic rate of increase. The lessons from our study for biological conservation are that simple, unstructured models may not be sufficient to assess the viability of species with complex behavioral traits, and that even moderate increases in habitat capacity may substantially reduce extinction risk even if environmental fluctuations seem high. [source] Oxytocin and vasopressin receptor distributions in a solitary and a social species of tuco-tuco (Ctenomys haigi and Ctenomys sociabilis)THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2008Annaliese K. Beery Abstract The neuropeptides oxytocin and vasopressin and their receptors have been implicated in elements of mammalian social behavior such as attachment to mates and offspring, but their potential role in mediating other types of social relationships remains largely unknown. We performed receptor autoradiography to assess whether forebrain oxytocin receptor (OTR) or vasopressin V1a receptor (V1aR) distributions differed with social structure in two closely related and ecologically similar species of South American rodents, the colonial tuco-tuco (Ctenomys sociabilis) and the Patagonian tuco-tuco (Ctenomys haigi). Long-term field studies have revealed that C. haigi is solitary, whereas C. sociabilis is social and provides a model of female-based group living. Our analyses revealed marked differences in OTR and V1aR distributions between these species. For example, only C. sociabilis had OTR binding in the piriform cortex and thalamus and V1aR binding in the olfactory bulbs. In contrast, C. haigi exhibited dramatically higher levels of OTR binding throughout the lateral septum and hippocampus. More generally, the group-living C. sociabilis exhibited a pattern of nucleus accumbens OTR and ventral pallidum V1aR binding different from that associated with the formation of opposite-sex pair bonds in microtine rodents. Higher binding in the central nucleus of the amygdala of C. sociabilis was consistent with the hypothesis that formation of social groups in C. sociabilis may be facilitated by reduced social anxiety. Low OTR binding in the lateral septum might also be a permissive factor for group living in C. sociabilis. Future studies will expand on these analyses to explore interspecific differences in ctenomyid receptor binding patterns in a phylogenetic context. J. Comp. Neurol. 507:1847,1859, 2008. © 2008 Wiley-Liss, Inc. [source] Detecting selection on morphological traits in social insect castes: the case of the social wasp Vespula maculifronsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010JENNIFER L. KOVACS Highly social insects dominate terrestrial ecosystems because society members belong to discrete castes that undertake distinct tasks. The distinct functional roles of members of different castes may lead to divergent selective regimes, which may ultimately lead to morphological specialization and differentiation of the castes. This study used morphological and genetic analyses to identify traits that experienced caste-specific selection in the social wasp Vespula maculifrons (Buysson, 1905). Traits putatively under selection were identified based on their degree of caste dimorphism, levels of variability, strength of correlations with other traits, and patterns of allometric scaling. Analyses of trait characteristics suggested that queen thorax length, thorax width, and possibly mass, have experienced queen-specific selection. Additionally, trait dimorphism and intercaste phenotypic correlation values were negatively correlated, as expected if some morphological traits were subject to selection, leading to alternate phenotypic optima in the two castes. Overall, our analyses demonstrate how techniques used to identify selection between dimorphic groups can be applied to social species with distinct castes. In addition, our analyses suggest the operation of selection may be stronger in reproductive than in non-reproductive castes. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 93,102. [source] | ||||||||||