Changes in unit structures and infanticide observed in Arsi geladas

In 1989 a new gelada baboon (Theropithecus gelada) population was found in Arsi, on the opposite side of the Rift Valley to that of the known gelada populations of Semien and Showa. Previous comparisons of units of the band at Gado Goro, Arsi, in the same season in consecutive years, indicated that unit structure is less stable among Arsi geladas as compared to the Semien population. Gelada units of the band at Gado-Goro were studied for 7 months in order to investigate the processes of social changes. Changes in unit structure were observed. Provisioning was carried out for 1.5 months at the beginning of the 7-month study period, in order to capture and obtain blood samples from the geladas. Following this, changes in male leadership of some units were observed, presumably as a consequence of the capture. However, natural changes also occurred. One change in unit structure occurred after a female gave birth, and changes in another unit occurred after the disappearance of the leader male. These changes involved female desertion of a unit, her subsequent transfer to a male unit, and culminated in the formation of a unit consisting of one female and one male. One successful and one attempted case of unification of units, and one case of change of a unit leader male are reported. These changes occurred among eight resident units in a period of 7 months (196 female months). Though the types of social changes were not much different from previous observations in Semien National Park, their frequencies seemed to be much higher. The characteristics of Arsi gelada social changes are proposed to be related to the small size of the units. We also describe a new confirmed case and one suspected case of infanticide, as well as one case of abortion at the time of male leader change.     

A case of infanticide in a recently found gelada population in Arsi, Ethiopia

There have been no reports of infanticide in wild gelada baboons and it has been argued that infanticide is not necessary in geladas, since the birth interval of female gelada can be shortened after takeover of a unit by a new leader male without infanticide. However, we observed an instance of infanticide in a newly-found wild gelada population in the Arsi Region of Ethiopia. After a leader male of the unit was severely wounded by a leopard attack, he was quite weakened. The second male of the unit, a young adult male, became the leader of the unit three weeks later, but the former leader continued to stay in the unit as a second male. After a week, two other adult males joined the unit which, therefore, came to include four adult males. The infanticide took place nine days later. The perpetrator was one of the immigrant males and he showed great interest in the mother of the unweaned victim infant. Although the perpetrator copulated with her after the infanticide, the usurper was found to own all three adult females after two weeks following the infanticide; i.e. the perpetrator could not own any female. The wounded former leader showed conspicuous protective behavior towards the victim's mother and the dead infant. One possible explanation for the occurrence of infanticide in this population of geladas is as follows. Gelada males in this area may be able to join units more easily to form multi-male units but then have shorter tenure in the units. Facing the unstable condition of units, they may sometimes engage in infanticide to increase their breeding opportunities, even before becoming a leader.     

Blood protein variation of a new population of gelada baboons (Theoropithecus gelada), in the Southern Rift Valley, Arsi Region, Ethiopia

Blood protein polymorphism of gelada baboon (Theropithecus gelada) to the south of the Rift Valley, Arsi Region, were examined for 36 genetic loci using three electrophoresis techniques for 48 blood samples from three localities, and compared with the northern geladas. New variant alleles and genetic markers of Hb-α, PA-2, and TBPA loci were detected. The distribution patterns of the variant alleles of Hb-α, PA-2, TBPA, Pi, Gc, PGM-II, and TBPA loci were localized in the geographic regions of south and north gelada populations, respectively. Genetic variability of southern geladas was estimated as P_poly=0.083 and , which was comparable to northern geladas. A remarkably high genetic differentiation between the two geographic populations was shown byNei's genetic distance=0.071 and G_ST value=0.420. Our results of genetic analysis suggest that the southern and northern gelada populations have been separated for several hundred thousand years, and gene flow between the two geographic populations is severely restricted. The southern gelada baboon may be regarded as a distinct subspecies.     

Geographic distribution of microsatellite alleles in geladas (Primates,Cercopithecidae): Evidence for three evolutionary units

The subspecific taxonomy and distribution of geladas (Theropithecus gelada Rüppell, 1835) remains uncertain. Recent molecular studies based on mitochondrial sequence data revealed a geographically structured, three-deme population, suggesting that there are three evolutionary units of geladas. However, mitochondrial distributions do not always recover population relationships, particularly in taxa with a complex history of isolation and gene flow. We therefore analysed the nuclear genetic population structure of the global gelada population based on 20 microsatellite loci in 43 samples from across its geographic range. F_ST values, a STRUCTURE analysis and a principal coordinate analysis (PCoA) confirmed the three-deme population structure corresponding to the mitochondrial population structure. Therefore, our analyses provide additional support for three evolutionary units in geladas, corresponding to (a) a northern (north of Lake Tana, primarily in the Simien Mountains, previously classified as Theropithecus gelada gelada Rüppell, 1835), (b) a central (between Addis Ababa and the highlands east of Lake Tana, previously classified as Theropithecus gelada obscurus Heuglin, 1863) and (c) a southern (south of the Rift Valley, previously tentatively classified as Theropithecus gelada arsi Shotake et al., 2016, Anthropological Science, 124, 157) population. These results pave the way for future conservation decisions and highlight that the gelada population boundaries need more fine-grained genetic sampling and phenotypic analyses, in particular for their taxonomic ranking.     

The socio‐genetics of a complex society: female gelada relatedness patterns mirror association patterns in a multilevel society

Multilevel societies with fission–fusion dynamics—arguably the most complex animal societies—are defined by two or more nested levels of organization. The core of these societies are modular social units that regularly fission and fuse with one another. Despite convergent evolution in disparate taxa, we know strikingly little about how such societies form and how fitness benefits operate. Understanding the kinship structure of complex societies could inform us about the origins of the social structure as well as about the potential for individuals in these societies to accrue indirect fitness benefits. Here, we combined genetic and behavioural data on geladas (Theropithecus gelada), an Old World Monkey, to complete the most comprehensive socio‐genetic analysis of a multilevel society to date. In geladas, individuals in the core social ‘units’, associate at different frequencies to form ‘teams’, ‘bands’ and, the largest aggregations, ‘communities’. Units were composed of closely related females, and females remained with their close kin during permanent fissions of units. Interestingly, female–female relatedness also significantly predicted between‐unit, between‐team and between‐band association patterns, while male–male relatedness did not. Thus, it is likely that the socio‐genetic structure of gelada society results from females maintaining associations with their female relatives during successive unit fissions—possibly in an attempt to balance the direct and indirect fitness benefits of group living. Overall, the persistence of associations among related females across generations appears to drive the formation of higher levels of gelada society, suggesting that females seek kin for inclusive fitness benefits at multiple levels of gelada society.     

Population dynamics of the solitary digger bee<Emphasis Type="Italic"> Andrena vaga</Emphasis> Panzer (Hymenoptera,Andrenidae) studied using mark-recapture and nest counts

The population size of the solitary digger bee Andrena vaga was documented using mark-recapture methods during 4 consecutive years (1996–1999). Additionally, the numbers of the parasitoids Nomada lathburiana and Bombylius major were estimated. For calculations of the daily population size, the Jolly-Seber model for open populations with time-dependent survival and capture rates was used. The mean daily population size corresponded well to the number of nests marked in the aggregation of A. vaga. The method of mark-recapture achieved the most accurate data when the number of sampling periods and the capture probability was high. The results document a decrease in population size of the investigated A. vaga aggregation during 4 successive years. A population increase of its parasitoids B. major is considered to be one reason for the population decline of A. vaga in 1999. The sex ratio of A. vaga was biased toward females, contrary to the expected higher number of males. Results of the mark-recapture studies showed that up to 50% of females left the aggregation or died at the beginning of the season. The females probably colonized new aggregations at distances further than 200 m away from their birth aggregation, as no marked females were observed in the environs of the study area. This behavior is interpreted as a parasite avoidance strategy. The bee populations in the study area form a web of interconnected aggregations. Apparently a flux of extinction and recolonization exists between the different aggregations.     

Defining Higher Levels in the Multilevel Societies of Geladas (Theropithecus gelada)

Multilevel societies, identified by two or more nested levels (or modules) of organization, have been touted as some of the most complex social systems. However, few empirical studies have effectively quantified the association patterns that delineate the various levels in such societies. In particular, the multiple levels of gelada society were first described >3 decades ago, yet no operational definitions exist for the higher levels, i.e., levels above the one-male unit. In geladas, multiple units form aggregations that fission and fuse throughout the day, and throughout the year, blurring the distinctions between previously described higher social levels: teams, bands, and communities. Here we use 5?yr of data on the daily composition of a population of geladas living in the Simien Mountains National Park, Ethiopia to test the hypothesis that higher levels of gelada organization are discrete entities. If gelada aggregations are nothing more than a group of units that share a home range, then we expect a continuous distribution of unit association. If, however, gelada aggregations are indeed discrete organizational levels, then we expect discontinuity in the patterns of association. We found significant discontinuity at the 50% association level, indicating a sharp distinction between members of the same band (>50% association) and members of the same community (<50% association). We also found evidence that recently fissioned units form teams that associate significantly more than other band members. Thus, despite their extremely fluid social organization, gelada social levels are nevertheless clearly identifiable and quantifiable. Based on these results, we suggest that gelada society is an extremely flexible, multilevel society with fission–fusion dynamics, and as such gelada society presents an unusual example for understanding the evolution of modular societies.     

Effect of salmon carcasses on egg production of a freshwater amphipod, Jesogammarus jesoensis: a field observation

The effect of salmon carcasses on egg production of a freshwater amphipod, Jesogammarus jesoensis, was examined by comparing populations with and without a supply of carcasses in Naibetsu River in Hokkaido, northern Japan. The female body length in the population with carcasses became larger in the years when carcasses were abundant, being significantly larger than that in the population without carcasses. No evidence, however, was found that carcasses influenced the ratio of brooding females to mature females. Every year, the clutch size in the population with carcasses was larger than the clutch size without carcasses. Because clutch size showed a significant correlation with female size, the larger clutch size was considered to be a result of the larger female size. In addition, however, comparison of clutch size using analysis of cavariance revealed that clutch size in the population with carcasses was larger than that without carcasses, even for the same body size. Egg size showed no difference between populations and for different years. These results indicate that salmon carcasses influence egg production of J. jesoensis by increasing female body size and by increasing the investment in each clutch per unit of body size.     

Female philopatry and dominance patterns in wild geladas

Cercopithecines have a highly conserved social structure with strong female bonds and stable, maternally inherited linear dominance hierarchies. This system has been ascribed to the pervasiveness of female philopatry within the typical multi-male, multi-female social groups. We examined the relationship between female philopatry, dominance hierarchies, and reproduction in geladas (Theropithecus gelada), a species with an unusual multi-leveled society. During a 4-year field study on a wild population in the Simien Mountains National Park, Ethiopia, we observed 14 units across two bands of geladas that underwent a number of events, such as male takeovers and female deaths, which could potentially disrupt female relationships and unit structure. First, we corroborate earlier reports that gelada females are natally philopatric: we observed no interunit migrations, and the female mortality rate was comparable to that of philopatric baboons (suggesting all female disappearances were indeed deaths). Second, contrary to previous reports, data from this long-term study show that geladas exhibit the linear and stable dominance hierarchies typical of other Cercopithecines. Moreover, female ranks appear to be maternally inherited. Third, we found no evidence that alpha females aggressively target the lowest ranking individuals, nor did rank confer clear reproductive advantages to dominant females within our 4-year observation period. As such, geladas fit the allostatic load model [Goymann & Wingfield, Animal Behaviour 67:591-602, 2004]. Our study confirms the importance of female philopatry in the kin-based Cercopithecine dominance system.     

Structure of social relationships in a captive gelada group: A test of some hypotheses derived from studies of a wild population

Data are presented on the structure of social relationships in a wild group of gelada baboons (Theropithecus gelada). These data lend support to the deduction from wild populations that female grooming dyads are matrilineal in origin. The observations are discussed in relation to a number of other conclusions on the nature of inter-individual relationships in gelada reproductive units.     

Effect of reproductive modes and environmental heterogeneity in the population dynamics of a geographically widespread clonal desert cactus

The dynamics of plant populations in arid environments are largely affected by the unpredictable environmental conditions and are fine-tuned by biotic factors, such as modes of recruitment. A single species must cope with both spatial and temporal heterogeneity that trigger pulses of sexual and clonal establishment throughout its distributional range. We studied two populations of the clonal, purple prickly pear cactus, Opuntia macrocentra, in order to contrast the factors responsible for the population dynamics of a common, widely distributed species. The study sites were located in protected areas that correspond to extreme latitudinal locations for this species within the Chihuahuan Desert. We studied both populations for four consecutive years and determined the demographic consequences of environmental variability and the mode of reproduction using matrix population models, life table response experiments (LTREs), and loop and perturbation analyses. Although both populations seemed fairly stable (population growth rate, λ∼1), different demographic parameters and different life cycle routes were responsible for this stability in each population. In the southernmost population (MBR) LTRE and loop and elasticity analyses showed that stasis is the demographic process with the highest contributions to λ, followed by sexual reproduction, and clonal propagation contributed the least. The northern population (CR) had both higher elasticities and larger contributions of stasis, followed by clonal propagation and sexual recruitment. Loop analysis also showed that individuals in CR have more paths to complete a life cycle than those in MBR. As a consequence, each population differed in life history traits (e.g., size class structure, size at sexual maturity, and reproductive value). Numerical perturbation analyses showed a small effect of the seed bank on the λ of both populations, while the transition from seeds to seedlings had an important effect mainly in the northern population. Clonal propagation (higher survival and higher contributions to vital rates) seems to be more important for maintaining populations over long time periods than sexual reproduction.     

Mating System and Population Fluctuations of the Prairie Vole, Microtus ochrogaster

The basic mating system of the prairie vole, Microtus ochrogaster,consists of monogamous breeding units comprised of one reproductivefemale and male and their offspring. Most surviving young remainat the natal nest; those that do so normally remain non-reproductive.Of 281 total breeding units monitored in free-living populations50.2% were monogamous. Twenty-seven percent consisted of a singlereproductive female that apparently has lost her mate. Theremaining22.8% of the breeding units included two or more unrelated adultsmales and/or females (=‘complex’ breeding units).In general, monogamy was the predominant type of breeding unitat the highest (>100 adults/ha) as well as at low (>20adults/ha) population densities. There was no consistent relationshipbetween the number of residents of a breeding unit and populationdensity. Significantly more young females remaining at the natalnest became reproductive at high rather than at low populationdensities (77.1 and 17.6%, respectively). Monogamy was prevalentduring the winter as well as during the other seasons; however,there were significantly more complex breeding units duringthe winter than during other seasons. Breeding unit size wassignificantly larger during the winter than at other seasons.There was no difference in the proportions of breeding unittypes or the number of residents of a breeding unit during breedingand nonbreeding seasons. Increased breeding unit size appearsrelated to low temperatures and associated physiological stressesduring the winter rather than to population density.     

Degrees of heterogeneity and the survival of an insect population

Summary The results of simulation experiments with a stochastic model incorporating internal and external sources of heterogeneity suggest that the western tent caterpillar is a risk spreader of a type discussed byDen Boer (1968). By maintaining physiological plasticity in its population,M.c. pluviale can survive periods of bad weather and then expand rapidly in an improved climate. Intrinsic variability in the moths’ dispersal capacity also ensures that some will continue to contribute to populations in the climatic refuges where the species persists during unfavorable periods, while others can quickly colonize marginal areas as soon as favorable conditions return. This northern population of the western tent caterpillar seems distinctly less well adapted to a world in which the terrain and the weather are more homogeneous than on the Saanich Peninsula. As this series of papers is jointly produced by our whole group, the order of authorship on each is decided by chance, not protocol.     

Growth and body size in populations of mink frogs Rana septentrionalis from two latitudes

Age, longevity, and growth in mink frogs Rana septentrionalis from two latitudes in Quebec, Canada, were assessed by skeletochronological and back-calculation methods in order to document proximate causes for intraspecific variations in adult body size. In both study sites, females grew faster and were on average 11% larger than males. Mean age and maximal longevity were significantly higher in females than in males only in the southern populations. There was thus an interpopulation difference in the relative contribution of age and growth to sexual size dimorphisms. Sex-ratio also favored females (males sulfering higher mortality) only in the southern populations. Specimens from the northern population had higher mean ages (but not higher longevities) and were 17% larger than specimens from the southern populations. Annual growth rate appeared similar at the two study sites despite a shorter growing season at the northern locality. Maturity was reached by both sexes after 1 yr of post-metamorphic life (PML) in the southern populations but after 2 yr of PML in the northern population. There are indications that tadpoles metamorphose at larger body size at the northern locality after a prolonged larval period. It is concluded that growth rate, delayed maturity, greater mean ages, and eventually size at transformation, all contribute to the larger size of adult mink frogs at northern localities.     

One-male harems and female social dynamics in Guinea baboons

Little is known about the mating system and social organization of Guinea baboons. This study investigated whether Guinea baboons have a harem-based mating system similar to that of hamadryas and gelada baboons and whether one-male mating units also correspond to social units. Ten adult females in a captive multi-male multi-female group of Guinea baboons were focally observed 2 h per week for 12 weeks, and all observed copulations within the group were recorded. Some males copulated with a single female while others had harems of 2-4 females. All females copulated with a single male except 1 female that switched harems early in the study. The focal females had higher rates of social interaction with their harem members, especially their harem male, than with individuals outside the harem. Females appeared to be subordinate to the harem male but little or no physical aggression or herding behavior from the male was observed. Variation in female social interactions within the harem was not accounted for by their sexual interactions with the male or their genetic relatedness with the females. Females, however, appeared to maintain social relationships with their female relatives in other harems. Taken together, the results of this study show that both mating and affiliative interactions in Guinea baboons are concentrated within one-male units and that the social dynamics within and between these units share some similarities as well as differences with those of hamadryas and gelada baboons.     

Integrating population genetics to define conservation units from the core to the edge of Rhinolophus ferrumequinum western range

The greater horseshoe bat (Rhinolophus ferrumequinum) is among the most widespread bat species in Europe but it has experienced severe declines, especially in Northern Europe. This species is listed Near Threatened in the European IUCN Red List of Threatened Animals, and it is considered to be highly sensitive to human activities and particularly to habitat fragmentation. Therefore, understanding the population boundaries and demographic history of populations of this species is of primary importance to assess relevant conservation strategies. In this study, we used 17 microsatellite markers to assess the genetic diversity, the genetic structure, and the demographic history of R. ferrumequinum colonies in the western part of its distribution. We identified one large population showing high levels of genetic diversity and large population size. Lower estimates were found in England and northern France. Analyses of clustering and isolation by distance suggested that the Channel and the Mediterranean seas could impede R. ferrumequinum gene flow. These results provide important information to improve the delineation of R. ferrumequinum management units. We suggest that a large management unit corresponding to the population ranging from Spanish Basque Country to northern France must be considered. Particular attention should be given to mating territories as they seem to play a key role in maintaining high levels of genetic mixing between colonies. Smaller management units corresponding to English and northern France colonies must also be implemented. These insular or peripheral colonies could be at higher risk of extinction in the near future.     

Management units of the endangered herb Primula sieboldii based on microsatellite variation among and within populations throughout Japan

To promote programs for the conservation and restoration of the endangered species Primula sieboldii, we examined genetic variation at eight microsatellite loci among and within 32 remnant wild populations throughout Japan. Total allelic diversity within a population was higher in larger populations, but not so after rarefaction adjustment. The positive relationship between population size and the inbreeding coefficient may suggest that more heterozygous genets tend to survive the habitat contraction possibly because of the higher fitness associated with heterozygosity. By principal coordinate analysis and Bayesian analysis, we detected four genetic groups (Hokkaido, northern Honshu, central Honshu, and western Japan), which could be recognized as management units of P. sieboldii. If supplementation with plants from other populations were planned, it should be conducted among populations which belong to the same management unit and which are likely to represent the same adaptive variation.     

Geographic variation in offspring size of a widespread lizard (Takydromus septentrionalis): importance of maternal investment

Geographic variation in offspring size is widespread, but the proximate causes of this variation have not yet been explicitly determined. We compared egg size and egg contents among five populations of a lizard (Takydromus septentrionalis, Günther, 1864) along a latitudinal gradient, and incubated eggs at two temperatures to determine the influence of maternal investment and incubation temperature on offspring size. The mean values for female size and egg size were both greater in the two northern populations (Chuzhou and Anji) than in the three southern populations (Lishui, Dongtou, and Ningde). The larger eggs were entirely attributable to the body size of females in the Anji population, but their increased size also stemmed from further enlargement of egg size relative to female body size in Chuzhou, the northernmost population sampled in this study. Eggs of the Chuzhou population contained more yolk and less water than those of southern populations. Despite the lower lipid content in the yolk, eggs from the Chuzhou population had higher energy contents than those from the two southern populations, owing to the larger egg size and increased volume of yolk. Hatchling size was not affected by incubation temperature, but differed significantly among populations, with hatchlings being larger in the Chuzhou population than in the other populations. Our data provide an inference that oviparous reptiles from cold climates may produce larger offspring, not only by increasing egg size but also by investing more energy into their eggs. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 59–67.     

Life history and population dynamics of the western mosquitofish: a comparison of natural and introduced populations

Life history and population dynamic patterns of Gambusia affinis in southeastern Louisiana varied spatially and temporally in 1990 and 1991, but were consistent with previous reports of this species in the southern regions of its natural range. Several differences exist among populations in different geographic regions within the United States, as reported in the literature, which do not follow a' native v . introduced' dichotomy: (1) brood size decreases and offspring size increases from north to south; (2) large overwintered females in northern areas produce more broods within a season than those in southern populations, while the reverse is true for young-of–year females; (3) minimum size at first reproduction follows a seasonal pattern within populations, but tends to be smaller in southern and larger in northern and Hawaiian populations; (4) synchronous reproduction early in the season is characteristic of northern populations, but does not occur in southern areas; and (5) mosquitofish reproduce year–round in Hawaii, while 'southern' populations within the continental U.S. cease reproduction during winter.     

Female social dynamics in a provisioned free-ranging band of the Sichuan snub-nosed monkey (Rhinopithecus roxellana) in the Qinling Mountains, China

Little information is available on the social dynamics of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana). Here, we provide 5-year observational data on a provisioned free-ranging band in the Qinling Mountains, central China, from October 2001 to December 2005. The results of this study suggested that females place a high priority on maintaining long-term relationships with other female in their one-male units (OMUs). Females had more social interactions with unit members than with nonunit individuals. They showed relatively high rates of affiliation with their unit females, intermediate levels with the resident males, and low levels with individuals outside the unit. Females had few interactions with other resident males. Social interactions, especially affiliative interactions, were more symmetrical between focal females and their unit females than between focal females and the resident males. Thus female social interactions appeared to resemble those of other female-bonded primate societies. On the other hand, female transfers occurred sometimes. We recorded 11 cases of female immigration and 5 cases of female disappearance, 1 case of female intraband shift, and 2 cases of "merging of OMUs," which suggested that unit females might be loose-knit in this species. We discussed influencing factors on female Sichuan snub-nosed monkey social dynamics, by comparing them with those of Hamadryas and gelada baboons that also have multilevel societies.