Pair-living Species Research Articles

Ecological and genetic variables co-vary with social group identity to shape the gut microbiome of a pair-living primate.

Primates exhibit diverse social systems that are intricately linked to their biology, behavior, and evolution, all of which influence the acquisition and maintenance of their gut microbiomes (GMs). However, most studies of wild primate populations focus on taxa with relatively large group sizes, and few consider pair-living species. To address this gap, we investigate how a primate's social system interacts with key environmental, social, and genetic variables to shape the GMin pair-living, red-bellied lemurs (Eulemur rubriventer). Previous research on this species suggests that social interactions within groups influence interindividual microbiome similarity; however, the impacts of other nonsocial variables and their relative contributions to gut microbial variation remain unclear. We sequenced the 16S ribosomal RNA hypervariable V4-V5 region to characterize the GM from 26 genotyped individuals across 11social groups residing in Ranomafana National Park, Madagascar. We estimated the degree to which sex, social group identity, genetic relatedness, dietary diversity, and home range proximity were associated with variation in the gut microbial communities residing in red-bellied lemurs. All variables except sex played a significant role in predicting GM composition. Our model had high levels of variance inflation, inhibiting our ability to determine which variables were most predictive of gut microbial composition. This inflation is likely due to red-bellied lemurs' pair-living, pair-bonded social system that leads to covariation among environmental, social, and genetic variables. Our findings highlight some of the factors that predict GMcomposition in a tightly bonded, pair-living species and identify variables that require further study. We propose that future primate microbiome studies should simultaneously consider environmental, social, and genetic factors to improve our understanding of the relationships among sociality, the microbiome, and primate ecology and evolution.

Intra-group competition and social dynamics regarding dispersal and maturation in wild Javan gibbon (Hylobates moloch)

Natal dispersal is an important life-history trait in all animal taxa. In pair-living species, parent–offspring competition derived from the offspring’s maturity can motivate the natal dispersal of offspring. However, not much has been known about the dispersal mechanisms of pair-living gibbons. To test food and mate competition as potential reasons for dispersal, we investigated the effect of the offspring age and sex on relationships between parents and offspring in wild Javan gibbon (Hylobates moloch) in Gunung Halimun-Salak National Park, Indonesia. We collected behavioral data for two years between 2016 and 2019. We found that aggression from parents toward offspring increased in both feeding and non-feeding context as the offspring got older. Offspring received more aggression from the parent of the same sex in the general context. While offspring decreased co-feeding and grooming time with parents as they got older, there was no change in the proximity and approach to parents. The results imply the presence of both intra-group food and mate competition which increase with the offspring’s age. We highlight that increased competition between maturing offspring and parents changes their social relationships and peripheralizes offspring from the natal group which will eventually motivate offspring to disperse in Javan gibbons.

Intra- and Intergroup Spatial Dynamics of a Pair-Living Singing Primate, Indri indri: A Multiannual Study of Three Indri Groups in Maromizaha Forest, Madagascar

Territorial pair-living species tend to occupy and defend stable areas, assumed to contain all the resources needed for the lifetime of the group. Furthermore, groups have to mediate spatial relationships with neighboring groups. We investigated the relationship between social and spatial dynamics at the intra- and intergroup level in a pair-living territorial singing primate: the indri (Indri indri). We collected spatial data on three neighboring groups during 396 sampling days between 2009 and 2014 in Maromizaha forest, Madagascar. We evaluated the stability of territories in terms of size and location using minimum convex polygons, defined the presence and stability of core areas, and investigated if singing locations and intergroup encounters were concentrated in the core areas. Territories were generally stable in location and size, although some degree of territorial shift occurred, leading to readjustment of intergroup spacing. Groups had core areas that were not stable across years but were concentrated in the area of the territories that groups occupy consistently over time (stable areas). Singing locations were equally distributed inside and outside core areas, suggesting an even distribution through the territories; meanwhile 9 of 12 intergroup encounters took place in the core areas at the edge of territories. Together, our results support the pattern of territorial stability predicted for a pair-living species, where groups regulate territory exclusivity and spacing with neighbors. Singing behavior also plays an important role in mediating intergroup spatial dynamics. The spatial pattern we found in indris is comparable with that found in other territorial and pair-living primates with different ecological needs, suggesting that in addition to ecological factors, social dynamics influence intergroup spatial dynamics.

Comparative studies need to rely both on sound natural history data and on excellent statistical analysis.

We certainly agree with Schradin [1] that comparative studies need to use the best information available—as well as clear definitions, up-to-date statistical techniques and common sense. We have divided our response into two sections: the first dealing with Schradin's critique of our 2017 paper and the classification of the social organization of shrews; the second dealing with three general issues that his commentary raises. The paper that Schradin is commenting on [2] asks whether cooperative breeders (which we define as species where non-breeding helpers assist breeders to raise their young) in mammals are more commonly found in arid environments than monogamous species (defined as species where breeding pairs of males and females remain together for more than one season) from which cooperative breeders appear to be derived [3]. It shows that, as in birds, cooperative breeders tend to live in relatively arid habitats compared to monogamous species. As we describe below, these conclusions are unaffected by differences between our classification of the social organization of shrews and the classification suggested by Schradin. Schradin's first criticism is that the categorizations of shrews that we have used in this analysis were based on one paper on a single species. This is incorrect, for our categorization of shrews was based on more than 70 separate sources (see electronic supplementary material, appendix S1). When we published our dataset [4], we were required to reduce the associated reference list by the editors of the journal and, to comply, we removed around 75% of our 2000+ sources, often listing a single reference per species or group of species, and frequently using generic reviews for particular groups where these were available: for example, for many rodent species, we simply listed Wolff and Sherman's Rodent Societies [5], and …

Communal range defence in primates as a public goods dilemma.

Classic socio-ecological theory holds that the occurrence of aggressive range defence is primarily driven by ecological incentives, most notably by the economic defendability of an area or the resources it contains. While this ecological cost-benefit framework has great explanatory power in solitary or pair-living species, comparative work on group-living primates has always found economic defendability to be a necessary, but not sufficient condition to account for the distribution of effective range defence across the taxon. This mismatch between theory and observation has recently been ascribed to a collective action problem among group members in, what is more informatively viewed as, a public goods dilemma: mounting effective defence of a communal range against intrusions by outgroup conspecifics. We here further develop this framework, and report on analyses at three levels of biological organization: across species, across populations within a single lineage and across groups and individuals within a single population. We find that communal range defence in primates very rarely involves collective action sensu stricto and that it is best interpreted as the outcome of opportunistic and strategic individual-level decisions. Whether the public good of a defended communal range is produced by solitary, joint or collective action is thus the outcome of the interplay between the unique characteristics of each individual, local and current socio-ecological conditions, and fundamental life-history traits of the species.

The Evolution of Eulemur Social Organization

Recent comparative studies on the evolution of mammalian sociality came to opposite conclusions regarding the direction and drivers of evolutionary transitions in social organization, particularly concerning the evolution of pair-living among primates. Because the genus Eulemur is one of the few exceptional primate genera that contain both group- and pair-living species, eulemurs offer a rare opportunity to illuminate the processes driving social diversity among species with very similar life histories and ecologies. The aims of our study were therefore 1) to reconstruct the evolution of social organization in eulemurs with new demographic and phylogenetic data and 2) to evaluate several hypotheses about the evolution of pair-living with data from our long-term study of Eulemur rufifrons and published data on other eulemurs. Our review of published data confirmed that E. mongoz and E. rubriventer are pair-living, whereas the 10 other species of Eulemur live in groups with multiple adult males and females. Furthermore, pair-living evolved at least once among eulemurs from group-living ancestors. The available comparative evidence indicated that this evolutionary transition was probably not driven by male infanticide, social instability, or singular ecological factors. Instead, we propose that female competition has favored small female group size and that this effect may have been exacerbated by interspecific competition with sympatric congeners in the ancestors of the pair-living species. In conclusion, we confirmed that the evolution of pair-living from group-living ancestors among true lemurs is exceptional, but not unique, among mammals, and that commonly invoked hypotheses for the evolution of pair-living do not appear to be supported for this genus.

Taxonomy and phylogenetics of the Synalpheus paraneptunus-species-complex (Decapoda: Alpheidae), with a description of two new species

The species-complex of Synalpheus paraneptunusCoutiere, 1909 is one of the most behaviorally and sexually diverse groups of sponge-dwelling shrimp in Synalpheus, containing both eusocial and pair-living species. Accurate resolution of this taxonomically challenging group is crucial to examining the evolution of social behavior in the genus. New collections from the US Florida Keys and Cuba, along with examination of previous collections from Jamaica, Panama and Belize, have yielded two new species: the eusocial Synalpheus cayoneptunusn. sp. (described from type material from the Florida Keys), and Synalpheus ankerin. sp. (described from type material from Belize). Synalpheus duffyiAnker and Toth, 2008 is reported from new locations in Cuba and the Florida Keys. A phylogenetic analysis of six of the nine species in the S. paraneptunus-species-complex indicates that eusociality likely arose only once in this complex but was secondarily lost in the pair-living species S. ankeri. A key to the nine known species in the complex is presented based on morphological characters.

Extra‐pair paternity confirmed in wild white‐handed gibbons

Knowledge of the genetic mating system of animal species is essential for our understanding of the evolution of social systems and individual reproductive strategies. In recent years, genetic methods have uncovered an unexpected diversity of paternal genetic contributions across diverse animal social mating systems, but particularly in pair-living species. In most pair-living birds, for example, genetic and behavioral observations have confirmed a previously unknown significance of extra-pair copulations (EPCs) and extra-pair paternity. Among mammals, white-handed gibbons (Hylobates lar) are also known to live in pairs and are traditionally believed to be single-male single-female breeders. However, at Khao Yai National Park, Thailand, behavioral observations have confirmed the occurrence of both EPCs and functional multi-male grouping, but knowledge about the genetic mating system is still unavailable. In this study, we genotyped 89 white-handed gibbons of the Khao Yai population based on fecal samplings and were able to determine paternity for 41 offspring through short tandem repeat analysis. We found that females' stable social partners sired the majority (90.5%) of offspring (N = 38), while only a few (7.1%) offspring (n = 2 confirmed cases; n = 1 inferred case) were conceived with extra-pair partners. The paternity of one offspring remained inconclusive (2.4%), because the offspring's genotype did not mismatch with the genotypes of two potential sires. Like other predominantly pair-living species, gibbons appear to follow a mixed-reproductive strategy. The genetic mating system of wild white-handed gibbons is best described as flexible, primarily monogamous and opportunistically promiscuous. Inc.

Leading Ladies: Leadership of Group Movements in a Pair‐Living, Co‐Dominant, Monomorphic Primate Across Reproductive Stages and Fruit Availability Seasons

For gregarious species, individuals must maintain cohesion while minimizing the costs of coordinated travel. Leaders of group movements potentially influence energy expenditure, energy intake, and predation risk for individuals in the group, which can have important fitness consequences. Models of pair-living species predict that energetic asymmetries lead to an emergent leader, with those in greater need leading. We investigated sex differences in leadership in pairs of red-bellied lemurs, Eulemur rubriventer, a monomorphic species with bisexual dispersal and no discernible hierarchy, to determine whether higher energetic requirements by adult females lead to female leadership. We collected leadership data in Ranomafana National Park, Madagascar on six groups of habituated E. rubriventer for 13 consecutive months between 2004-2005. To determine whether females led group movements more than males, we examined the difference in leadership frequencies of progressions in adult males and adult females within each group (n = 1,346 progressions). We further investigated the behavioral context (i.e. travel followed by feeding or not) and seasonal contexts (fruit availability, reproduction) of leadership. Group leadership was distributed, with different individuals leading the group at different times. However, females led significantly more than males, a pattern which was consistent in both feeding and non-feeding contexts and throughout all fruiting seasons and reproductive stages. While disparities in energetic status among the sexes may impact leadership in this species, leadership did not differ with changes in food availability or reproductive stage, and thus we were unable to determine whether female leadership might be related to changes in energetic status. Females may have higher energetic needs than males at all times, not merely seasonally, or female leadership may be unrelated to immediate energetic need. Rather, female leadership may be a legacy of female dominance not currently expressed in other contexts.

Aesthetascs in Lysmata spp. shrimp: sexual dimorphism and relationship with social environments

Aesthetascs are the olfactory receptor organs responsible for mate recognition in many decapod crustacean species. The number of aesthetascs varies greatly among species in different environments, but the functional significance of this variation is poorly understood. This study examined the relationship between social environment and the number of aesthetascs in six species of caridean shrimp in the genus Lysmata. Generally, the number of aesthetascs was greater in group-living species (L. boggessi and L. wurdemanni) than in low-density (L. ankeri and L. pederseni) and pair-living species (L. amboinensis and L. debelius). Aesthetascs are innervated by olfactory receptor neurons (ORNs). The total number of ORNs is related to the sensitivity of olfactory odor detection, and it was higher in group-living species than in pair-living species. Sexual dimorphism in the number of aesthetascs was present in L. boggessi, L. wurdemanni, and L. ankeri but not in L. pederseni and L. amboinensis.

Morphology and Distribution of Antennal and Antennular Setae inLysmataShrimp

In decapod crustaceans, chemical cues are usually detected by antennal and antennular setae. Different types of setae have been identified in various decapod species. In Lysmata shrimp, aesthetascs have been identified to be responsible for distance sex pheromone detection, whereas some other nonaesthetasc setae can detect contact sex pheromones. In this study, the morphology of antennal and antennular setae in six species of Lysmata shrimp was examined using scanning electron microscopy. The number of nonaesthetasc setae was counted and compared among the species with different social environments. Four types of antennal and antennular setae were identified, and their morphology was similar in all the Lysmata species studied. No sexual dimorphism was found in the morphology of setae. The total number of nonaesthetasc setae increased with shrimp size, whereas the density of nonaesthetasc setae did not change with growth. In general, the number and density of nonaesthetasc setae was greater in pair-living cleaner shrimp than in group-living and low-density peppermint shrimp, indicating that contact sex pheromones may be more important in pair-living species. Among peppermint shrimp, there were no significant differences in the number and density of nonaesthetasc setae between group-living species and low-density species, which suggests that social environments may not be the only factor that is related to the higher setae number and density in pair-living species.

The evolution of euhermaphroditism in caridean shrimps: a molecular perspective of sexual systems and systematics.

BackgroundThe hippolytid genus Lysmata is characterized by simultaneous hermaphroditism, a very rare sexual system among Decapoda. Specialized cleaning behavior is reported in a few pair-living species; these life history traits vary within the genus. Unfortunately, the systematics of Lysmata and the Hippolytidae itself are in contention, making it difficult to examine these taxa for trends in life history traits. A phylogeny of Lysmata and related taxa is needed, to clarify their evolutionary relationships and the origin of their unique sexual pattern. In this study, we present a molecular phylogenetic analysis among species of Lysmata, related genera, and several putative hippolytids. The analysis is based upon DNA sequences of two genes, 16S mtDNA and nuclear 28S rRNA. Phylogenetic trees were estimated using Bayesian Inference, Maximum Likelihood, and Maximum Parsimony.ResultsPhylogenetic analysis of 29 species of Lysmata, eight genera of Hippolytidae and two genera of Barbouriidae based on a single (16S, 28S) and combined gene approach (16S+28S) indicates that three groups of Lysmata differentiate according to antennular morphology: (1) Lysmata, having a multi-segmented accessory branch, (2) Hippolysmata (prior to Chace 1972), with a one-segmented accessory branch, and (3) a third group of Lysmata outliers, with one-segmented unguiform accessory branch, and close affinity to the genera Exhippolysmata and Lysmatella. The monophyly of the clade bearing a multi-segmented accessory branch is robust. Within the short accessory branch clade, species with specialized cleaning behaviors form a monophyletic clade, however, the integrity of the clade was sensitive to alignment criteria. Other hippolytid and barbouriid genera used in the analysis are basal to these three groups, including one displaying simultaneous hermaphroditism (Parhippolyte). The two barbouriid species occur in a separate clade, but among hippolytid taxa.ConclusionsThe data support the historical morphological division of Lysmata into clades based on accessory branch morphology. The position of the "cleaner" shrimps, indicates that specialized cleaning behavior is a derived trait. The topologies of the cladograms support the monophyly of the barbouriids, but do not support their elevation to familial status. Taxa ancestral to the genus Lysmata display simultaneous hermaphroditism, suggesting that this life history trait evolved outside the genus Lysmata.

Social structure influences extra-pair paternity in socially monogamous mammals

Using the genetic estimates of paternity available for 22 species of socially monogamous mammals, we investigated the impact of the social structure and of the type of pair bonding on the interspecific variations of extra-pair paternity rates. To this purpose, we classified species in three categories of social structure-solitary, pair or family-living species-and in two categories of pair bonding-intermittent or continuous. We show that interspecific variations of extra-pair paternity rates are better explained by the social structure than by the type of pair bonding. Species with intermittent and continuous pair bonding present similar rates of extra-pair paternity, while solitary and family-living species present higher extra-pair paternity rates than pair-living species. This can be explained by both higher male-male competition and higher female mate choice opportunities in solitary and family-living species than in pair-living species.

A preliminary revision of the Synalpheus paraneptunus Coutière, 1909 species complex (Crustacea: Decapoda: Alpheidae)

The western Atlantic Synalpheus paraneptunus Coutiere, 1909 species complex is revised based on the type material kept in the National Museum of Natural History, Smithsonian Institution, Washington DC (USNM), specimens from Dominica, Puerto Rico and some other Caribbean localities (USNM), and fresh material recently collected in Belize and Panama. The type material of S. paraneptunus, composed of three specimens, appears to include more than one species. Therefore, S. paraneptunus is restricted to the holotype from Morrosquillo, Colombia, dredged from 77 m. The identity of the two paratypes, one of them an abnormal female, could not be satisfyingly determined. Five species are described as new. Synalpheus duffyi n. sp. is described based on the recently collected material from Isla Grande, Panama. The colony structure of S. duffyi n. sp., including the large number of sexually undeveloped individuals and one larger breeding female, suggests eusocial life style. A further presumably eusocial species, S. riosi n. sp., significantly larger than S. duffyi n. sp., is described based on 139 specimens from Dominica, all apparently forming a single colony. Furthermore, three pair-living species are recognized: S. brevidactylus n. sp. from Isla Grande and Bocas del Toro, Panama; S. bocas n. sp. from Bocas del Toro, Panama, S. belizensis n. sp. from Carrie Bow Cay, Belize. All reported species are contrasted to each other morphologically; occurrence (in large groups vs. pairwise) and colour patterns are also considered where data is available. A provisionary key to six known species of the S. paraneptunus complex is provided.

A preliminary revision of the Synalpheus paraneptunus Coutière, 1909 species complex (Crustacea: Decapoda: Alpheidae)

The western Atlantic Synalpheus paraneptunus Coutière, 1909 species complex is revised based on the type material kept in the National Museum of Natural History, Smithsonian Institution, Washington DC (USNM), specimens from Dominica, Puerto Rico and some other Caribbean localities (USNM), and fresh material recently collected in Belize and Panama. The type material of S. paraneptunus, composed of three specimens, appears to include more than one species. Therefore, S. paraneptunus is restricted to the holotype from Morrosquillo, Colombia, dredged from 77 m. The identity of the two paratypes, one of them an abnormal female, could not be satisfyingly determined. Five species are described as new. Synalpheus duffyi n. sp. is described based on the recently collected material from Isla Grande, Panama. The colony structure of S. duffyi n. sp., including the large number of sexually undeveloped individuals and one larger breeding female, suggests eusocial life style. A further presumably eusocial species, S. riosi n. sp., significantly larger than S. duffyi n. sp., is described based on 139 specimens from Dominica, all apparently forming a single colony. Furthermore, three pair-living species are recognized: S. brevidactylus n. sp. from Isla Grande and Bocas del Toro, Panama; S. bocas n. sp. from Bocas del Toro, Panama, S. belizensis n. sp. from Carrie Bow Cay, Belize. All reported species are contrasted to each other morphologically; occurrence (in large groups vs. pairwise) and colour patterns are also considered where data is available. A provisionary key to six known species of the S. paraneptunus complex is provided.

Antennal Sensilla in the Genus Lysmata (Caridea)

Our previous studies have found that euhermaphrodite-phase shrimp of Lysmata secrete both distance and contact sex pheromones, unique among the shrimp. To gain a better understanding of the chemo-sensory system of shrimp, we studied the setae on the first (antennules) and second antennae of four species of Lysmata, which represent the two social groups (low and high densities) and three distinct external morphological patterns (peppermint shrimp, scarlet lady shrimp, and fire shrimp) in the genus. There were four types of setae in the four species: aesthetascs, denticulate setae, and two types of simple setae. Aesthetascs are only distributed on the proximal lateral antennular flagella, while the other three setae are located on the antennules and the second antenna. Aesthetascs are believed to be olfactory organs in detecting soluble chemical signals, especially for male-female communication during mating, while one or more of the other three setae are responsible for detecting contact pheromones. Lysmata boggessi and L. wurdemanni, peppermint shrimp that live in aggregations, possess significantly higher number of aesthetascs than pair-living species of L. amboinensis (scarlet lady shrimp) and L. debelius (fire shrimp), suggesting a possible correlation between the aesthetasc number and social environment. Sexual dimorphism in the aesthetasc number is found in L. boggessi and L. wurdemanni, with significantly higher numbers in the male-phase shrimp than in the euhermaphrodite-phase shrimp.

So near and yet so far: territorial pairs but low cohesion between pair partners in a nocturnal lemur, Phaner furcifer

Among pair-living species, which represent a simple form of gregariousness, the degree of cohesion appears to be highly variable, but the mechanisms responsible for the maintenance of cohesiveness have been poorly studied. We present data from long-term behavioural observations of eight pairs of fork-marked lemurs, including year-round data on their sleeping site use and spatial data from simultaneous focal follows of both pair partners, that characterize its social organization as ‘dispersed pairs’. Although pairs were stable over several years, territories of pair partners overlapped almost perfectly and interactions between them were frequent, the cohesiveness of pairs was extremely low. High rates of conflict relative to frequencies of affiliative interactions indicated that avoidance of the pair partner is the key mechanism responsible for the observed pattern of space use. The repeated use of the same predictable food resources during the night, frequent conflicts over food and patterns of vocal communication imply that avoidance of direct feeding competition, together with incomplete knowledge about the pair partner's position, lead to the observed low cohesiveness. The freedom to forage solitarily and the associated lack of information about the pair partner's position found in fork-marked lemurs are in contrast to most group-living species and qualify dispersed pairs as a focus for future studies of models on animal movement decisions. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

MHC diversity of endemic Malagasy rodents in relation to geographic range and social system

The major histocompatibility complex (MHC) encodes a group of closely linked genes that play a central role in the vertebrate immune system. Most natural mammal populations studied so far possess high levels of diversity within the MHC. However, recent investigations in the MHC class II gene DQA of the critically endangered Malagasy giant jumping rat (Hypogeomys antimena) revealed very low variability compared to other mammalian species. The low genetic variability was confirmed in the present study through analyses of the MHC class II gene DRB exon 2. This codes for the antigen-binding site and is therefore considered as one of the most important parts of the MHC. The species' geographic distribution has been reduced recently to a fragmented area of suitable habitat within a geographic range of less than 20×40 km of dry deciduous forest at the west coast of Madagascar. H. antimena has some unusual life history characteristics for a rodent species, such as living in obligate monogamy, with pairs staying together until one mate dies, a low reproduction rate (one to two offspring/couple per year), high site and mate fidelity, short dispersal distances, almost no adult migration, and therefore a constant gene pool with very limited gene flow. Current hypotheses usually interpret low MHC polymorphism either as a consequence of reduced selection pressure, bottleneck effects or by constraints of the mating system. To differentiate between these hypotheses, the MHC variability of the DQA and DRB gene of two additional sympatric, but widely distributed rodent species, Macrotarsomys bastardi and Eliurus myoxinus, were studied by using universal primers and single-strand conformation polymorphism. The two species differ in their mating systems: M. bastardi also lives in pairs but E. myoxinus is a promiscuous species. Whereas the investigated MHC class II genes DQA and DRB had low levels of polymorphism in the pair-living species H. antimena and M. bastardi (DQA: 2 and 3 alleles, DRB: 5 and 6 alleles, respectively), higher levels of variation (DQA: 11 alleles, DRB: 9 alleles) were recorded in the promiscuous species, E. myoxinus. Gene diversity was also higher in E. myoxinus (DQA: 0.85, DRB: 0.86) than in the two pair-living species (DQA: 0.41–0.45, DRB: 0.55–0.63). The results suggest that low MHC variability might not only result from bottleneck effects due to recent declines in population size, but also from a monogamous mating system.

Phylogenetic analysis of coadaptation in behavior, diet, and body size in the African antelope

Several authors have suggested that African antelope (family Bovidae) exemplify coadaptation of ecological, behavioral, and morphological traits. We tested four hypotheses related to the ecology and behavior of 75 species of African antelope using both conventional statistical techniques and techniques that account for the nonindependence of species by considering their phylogenetic relationships. Specifically, we tested the hypotheses that (1) dietary selectivity is correlated negatively with body mass, (2) dietary selectivity is correlated negatively with group size, (3) gregarious species either flee or counterattack when approached by predators, but solitary and pair-living species seek cover to hide, and (4) body mass and group size are correlated positively. Each of these hypotheses was examined for the global data set (family Bovidae) and, when possible, within the two antelope subfamilies (Antilopinae and Bovinae) and within 7 of the 10 antelope tribes. The results of our conventional and phylogenetically corrected analyses supported the hypotheses that group and body size vary predictably with feeding style and that antipredator behavior varies with group size. The hypothesis that body mass and group size are correlated positively was supported by conventional statistics, but these two traits were only weakly related using a phylogenetically corrected analysis. Moreover, qualitative and quantitative comparisons within each of the eight major African antelope tribes generally gave little support for the four hypotheses tested. Thus, although our analyses at the subfamily level provided results that were consistent with prior hypotheses, our analyses at the level of tribes were equivocal. We discuss several possible explanations for these differences.

Nonconvergence in the evolution of primate life history and socio-ecology

The goal of this study was to investigate the extent of convergence in four basic life history and socio-ecological traits among the primates of Africa, Asia, South America and Madagascar. The convergence hypothesis predicts that similar abiotic conditions should result in similar adaptations in independent taxa. Because primates offer a unique opportunity among mammals to examine adaptations of independent groups to tropical environments, we collected information on body mass, activity pattern, diet and group size from all genera for quantitative tests of this hypothesis. We revealed a number of qualitative and quantitative differences among the four primate groups, indicating a lack of convergence in these basic aspects of life history and socio-ecology. Our analyses demonstrated that New World primates are on average significantly smaller than primates in other regions and characterized by a lack of species larger than about 10 kg. Madagascar harbours significantly more nocturnal species than the other regions and is home to all but one of the primates with irregular bursts of activity. Asia is the only region with strictly faunivorous primates, but lacks primarily gummivorous ones. The Neotropics are characterized by the absence of primarily folivorous primates. Solitary species are not represented in the New World, whereas solitary and pair-living species make up the majority of Malagasy primates. Lemurs live in significantly smaller groups than other primates, even after controlling for differences in body size. The lack of convergence among the major primate groups is neither primarily due to phylogenetic constraints as a result of founder effects, nor can it be sufficiently explained as a passive consequence of body size differences. However, because the role of adaptive forces, such as interspecific competition, predation or phenology in shaping the observed differences is largely unexplored, we conclude that it is premature to discard the convergence hypothesis without further tests.