Amy E. Dunham

Molecular systematics and origin of sociality in mongooses (Herpestidae, Carnivora)

The Herpestidae are small terrestrial carnivores comprising 18 African and Asian genera, currently split into two subfamilies, the Herpestinae and the Galidiinae. The aim of this work was to resolve intra-familial relationships and to test the origin of sociality in the group. For this purpose we analysed sequences of the complete cytochrome b gene for 18 species of Herpestidae. The results showed that the mongooses were split into three clades: (1) the Malagasy taxa (Galidiinae and Cryptoprocta), (2) the true social mongooses and (3) the solitary mongooses, each group being also supported by morphological and chromosomal data. Our results suggested unexpected phylogenetic relationships: (1) the genus Cynictis is included in the solitary mongoose clade, (2) the genera Liberiictis and Mungos are sister-group, and (3) the genus Herpestes is polyphyletic. We examined the evolution of the sociality in mongooses by combining behavioural traits with the cytochrome b data. Some of the behavioural traits provided good synapomorphies for characterizing the social species clade, showing the potential benefit of using such characters in phylogeny. The mapping of ecological and behavioural features resulted in hypothesizing solitary behavior and life in forest as the conditions at the base of the mongoose clade.

Evolution of sexual size monomorphism: the influence of passive mate guarding

Some species have potential for intense mate competition yet exhibit little or no sexual size dimorphism, despite predictions from sexual selection theory. Using a conceptual model, we show the conditions for which passive mate guarding with copulatory plugs can be an alternative and more successful strategy to active (direct) guarding, reducing selection pressure on large male size. The model predicts that copulatory plugs in mammals should be favoured in species for which females have short sexual receptivity periods. Using data on 62 primate species and a phylogenetic regression approach, we show that, as predicted, copulatory plugs are negatively associated with degree of sexual dimorphism and females’ sexual receptivity length. Penile spines are also significantly associated with plug use and short receptivity periods suggesting a possible offensive role in sperm competition. Results highlight that life‐history characteristics, such as sexual receptivity lengths, may alter the costs and benefits of alternative male strategies and thus alter the strength of sexual selection.

Assessing the impacts of nonrandom seed dispersal by multiple frugivore partners on plant recruitment

Directed dispersal is defined as enhanced dispersal of seeds into suitable microhabitats, resulting in higher recruitment than if seeds were dispersed randomly. While this constitutes one of the main explanations for the adaptive value of frugivore-mediated seed dispersal, the generality of this advantage has received little study, particularly when multiple dispersers are involved. We used probability recruitment models of a long-lived rainforest tree in Madagascar to compare recruitment success under dispersal by multiple frugivores, no dispersal, and random dispersal. Models were parameterized using a three-year recruitment experiment and observational data of dispersal events by three frugivorous lemur species that commonly disperse its seeds. Frugivore-mediated seed dispersal was nonrandom with respect to canopy cover and increased modeled per-seed sapling recruitment fourfold compared to no dispersal. Seeds dispersed by one frugivore, Eulemur rubriventer, had higher modeled recruitment probability than seeds dispersed randomly. However, as a group, our models suggest that seeds dispersed by lemurs would have lower recruitment than if dispersal were random. Results demonstrate the importance of evaluating the contribution of multiple frugivores to plant recruitment for understanding plant population dynamics and the ecological and evolutionary significance of seed dispersal.

Battle of the sexes: Cost asymmetry explains female dominance in lemurs

F emale dominance over males is a rare trait among mammalian social systems and within primates (Ralls 1976; Kappeler 1993), but is the norm among lemurs of Madagascar, occurring in all lemur families regardless of mating system (Kappeler 1991, 1993). Despite 23 years of discussing the mechanism of female dominance in lemurs, including hundreds of publications (based on Web of Science; http://apps.isiknowledge.com), consensus does not yet exist. Current theories have remained unsatisfactory among researchers and empirical tests have contradicted expectations. Uncovering the reasons for female dominance in lemurs has even recently been hailed as the ‘holy grail’ of lemur research (Pochron & Wright 2005). Here I present a simple explanation for the occurrence of female dominance in lemurs and suggest an evolutionary mechanism for its prevalence. The predominant explanation in the current literature is that female dominance is an adaptation to high reproductive costs and scarcity of food in comparison to other primates due to a resource-poor and highly variable island environment (Jolly 1984; Wright 1999; Pochron et al. 2003). Female dominance is considered advantageous to females and their offspring in this case because it provides females priority of access to resources critical to their high cost of reproduction. However, in quantitative comparisons with anthropoid primates, no unusual reproductive or energetic costs for lemur females have been shown (Kappeler 1996). Additionally, if one looks beyond the

Patterns of movement and seed dispersal by three lemur species

We combined data on gut‐passage times, feeding, and movement to explore the patterns of seed dispersal by Eulemur rubriventer, Eulemur rufrifrons, and Varecia variegata editorum lemurs in Ranomafana National Park, Madagascar. These lemur species deposited less than half of their consumed seeds >100 m away from conspecific trees (40–50%). Long‐distance dispersal (>500 m) was rare and average dispersal distances were short relative to those reported of similar‐sized haplorrhine primates. The three lemur species showed no significant differences in mean seed‐dispersal distances. However, they differed in the shape of their frequency distributions of seed‐dispersal distances as a result of differences in how they moved through their habitats. The short distances of seed dispersal we observed and the depauperate frugivorous fauna in Madagascar suggest seed‐dispersal may be more limited than in other tropical forests with important implications for plant‐community dynamics, biodiversity maintenance, and restoration efforts in Madagascar. Am. J. Primatol. 76:84–96, 2014.

Life history predicts risk of species decline in a stochastic world

Understanding what traits determine the extinction risk of species has been a long-standing challenge. Natural populations increasingly experience reductions in habitat and population size concurrent with increasing novel environmental variation owing to anthropogenic disturbance and climate change. Recent studies show that a species risk of decline towards extinction is often non-random across species with different life histories. We propose that species with life histories in which all stage-specific vital rates are more evenly important to population growth rate may be less likely to decline towards extinction under these pressures. To test our prediction, we modelled declines in population growth rates under simulated stochastic disturbance to the vital rates of 105 species taken from the literature. Populations with more equally important vital rates, determined using elasticity analysis, declined more slowly across a gradient of increasing simulated environmental variation. Furthermore, higher evenness of elasticity was significantly correlated with a reduced chance of listing as Threatened on the International Union for Conservation of Nature Red List. The relative importance of life-history traits of diverse species can help us infer how natural assemblages will be affected by novel anthropogenic and climatic disturbances.

Body size and sexual size dimorphism in primates: influence of climate and net primary productivity.

Understanding the evolution of body size and sexual size dimorphism has been a longstanding goal in evolutionary biology. Previous work has shown that environmental stress can constrain male‐biased sexual size dimorphism at the population level, but we know little about how this might translate to geographical patterns of body size and sexual size dimorphism at the species level. Environmental constraints due to a highly seasonal, resource‐poor and/or variable environment have often been cited to explain the unusual lack of sexual size dimorphism among Madagascars diverse and numerous primate taxa; however, empirical tests of this hypothesis are lacking. Using a phylogenetic approach and a geographical information system platform, we explored the role of seasonality, interannual variability and annual measures of temperature and rainfall, and net primary productivity on patterns of body size and sexual size dimorphism across 130 species of primates. Phylogenetically controlled comparisons showed no support for a role of environmental constraints in moderating sexual size dimorphism at the interspecific level, despite significant associations of environmental variables with body mass. Results suggest that the focus of discussions that have dominated in the last two decades regarding the role of environmental constraints in driving patterns of monomorphism of Madagascars lemurs should be reconsidered; however, the conundrum remains.

Co‐fruiting plant species share similar fruit and seed traits while phylogenetic patterns vary through time

Summary 1.Co-fruiting plant species are subject to a variety of biotic and abiotic processes that may influence patterns of fruiting phenology and the functional and phylogenetic diversity of co-fruiting taxa in a community. Understanding the seasonal patterns of functional and phylogenetic diversity of fruiting in a community will shed new light on potential mechanisms structuring plant communities. 2.Using rainforest trees in south-eastern Madagascar as our system, we predicted there would be clustering of fruit and seed traits and phylogenetic relationships among co-fruiting species because plants are vying for seed dispersal services from a limited set of generalist frugivore taxa. We also predicted that seasonal variations in rainfall would mediate fluctuations in functional trait and phylogenetic diversity of co-fruiting assemblages. 3.Despite fluctuating patterns in their functional trait diversity over time, co-fruiting assemblages displayed consistent clustering of fruit/seed traits across time. Phylogenetic diversity was not clustered overall, but fluctuated non-randomly, in time between clustered and overdispersed, such that strong shifts in rainfall were associated with the co-fruiting of more closely related species. 4.Synthesis: We suggest that it may be more beneficial for co-fruiting plant species to share similar fruit and seed traits than to diversify traits, when they rely on a comparatively small set of generalist frugivorous taxa for seed dispersal. Results also demonstrate that rainfall-driven environmental filtering may cause seasonal fluctuations in the phylogenetic patterns of phenology in a community. Results highlight the importance of a temporal context in examining structural patterns of communities. This article is protected by copyright. All rights reserved.

Soil disturbance by vertebrates alters seed predation, movement and germination in an African rain forest

Biopedturbation,oranimal-causedsoildisturbance,maybeimportantfordevelopmentandmaintenanceof small-scaleheterogeneityinecosystemswiththepotentialtoalterseedmortalityandrecruitment.However,itsrolein tropicalforestshasbeenlargelyignored.Thisstudyexploredeffectsofvertebratebiopedturbationonseed(1)microsite heterogeneity, (2) predation and (3) germination in a West African rain forest. Exclosure experiments were used to studyhowbiopedturbationalteredburialandmovementsofseedsoffourcommoncanopyspecies.Effectofseedburial on removal by seed predators was also examined. Germination of the dominant canopy species (Raphia palma-pinus)in swamp forest was tested within artificial disturbances mimicking that of a locally common but endangered mammal, the Liberian mongoose (Liberiictis kuhni), which was estimated to turn over the entire forest floor in this habitat in c. 8 mo. Seed exposure to biopedturbation for 20 d (n =80) led to an overall 6.5-fold increase in small-scale horizontal movement and increased probability of burial (6-52% higher), varying by species. Burial effectively eliminated seed removal for all four species (n = 160) by seed predators over 20 d. Germination of Raphia palma-pinus seeds (n = 100) was enhanced by 17.5% on average over 4 mo in simulated disturbances. Results suggest biopedturbation may be important for seedling recruitment and that loss of species with this functional role could have underappreciated yet important impacts on tropical plant communities.

Seed dispersal increases local species richness and reduces spatial turnover of tropical tree seedlings

Significance Dispersal is considered a key process underlying the high spatial diversity of tropical forests, with the seeds of most tropical tree species dispersed by vertebrates, particularly birds. Although it has proven very difficult to quantify the contribution of dispersal to tree species diversity, it is increasingly important to do so in the face of global declines in vertebrate disperser populations. We show that the complete loss of native seed dispersers on the island of Guam is having a major impact on tree seedling regeneration in canopy gaps, leading to species-poor and spatially aggregated seedling communities. These pronounced changes in patterns of seedling regeneration highlight the importance of dispersal in maintaining patterns of diversity in tropical forests. Dispersal is thought to be a key process underlying the high spatial diversity of tropical forests. Just how important dispersal is in structuring plant communities is nevertheless an open question because it is very difficult to isolate dispersal from other processes, and thereby measure its effect. Using a unique situation, the loss of vertebrate seed dispersers on the island of Guam and their presence on the neighboring islands of Saipan and Rota, we quantify the contribution of vertebrate seed dispersal to spatial patterns of diversity of tree seedlings in treefall gaps. The presence of vertebrate seed dispersers approximately doubled seedling species richness within canopy gaps and halved species turnover among gaps. Our study demonstrates that dispersal plays a key role in maintaining local and regional patterns of diversity, and highlights the potential for ongoing declines in vertebrate seed dispersers to profoundly alter tropical forest composition.