Variations in age- and sex-specific survival rates help explain population trend in a discrete marine mammal population

Funded by Department of Energy and Climate ChangePeer reviewedPublisher PD

Demography and Life Histories of Sympatric Patas Monkeys, Erythrocebus patas, and Vervets, Cercopithecus aethiops, in Laikipia, Kenya

Mortality patterns are thought to be strong selective forces on life history traits, with high adult mortality and low immature mortality favoring early and rapid reproduction. Patas monkeys (Erythrocebus patas) have the highest potential rates of population increase for their body size of any haplorhine primate because they reproduce both earlier and more often. We report here 10 yr of comparative demographic data on a population of patas monkeys and a sympatric population of vervet monkeys (Cercopithecus aethiops), a closely related species differing in aspects of social system, ecology, and life history. The data reveal that 1) adult female patas monkeys have significantly higher mortality than adult female vervets; 2) infant mortality in patas monkeys is relatively low compared to the norm for mammals because it is not significantly different from that of adult female patas monkeys; and 3) infant mortality is significantly higher than adult female mortality in vervets. For both species, much of the mortality could be attributed to predation. An epidemic illness was also a major contributor to the mortality of adult female patas monkeys whereas chronic exposure to pathogens in a cold and damp microenvironment may have contributed to the mortality of infant vervets. Both populations experienced large fluctuations during the study period. Our results support the prediction from demographic models of life history evolution that high adult mortality relative to immature mortality selects for early maturation

Strength of density feedback in census data increases from slow to fast life histories

Life-history theory predicts an increasing rate of population growth among species arranged along a continuum from slow to fast life histories. We examine the effects of this continuum on density-feedback strength estimated using long-term census data from >700 vertebrates, invertebrates, and plants. Four life-history traits (Age at first reproduction, Body size, Fertility, Longevity) were related statistically to Gompertz strength of density feedback using generalized linear mixed-effects models and multi-model inference. Life-history traits alone explained 10 to 30% of the variation in strength across species (after controlling for time-series length and phylogenetic nonindependence). Effect sizes were largest for body size in mammals and longevity in birds, and density feedback was consistently stronger for smaller-bodied and shorter-lived species. Overcompensatory density feedback (strength <−1) occurred in 20% of species, predominantly at the fast end of the life-history continuum, implying relatively high population variability. These results support the idea that life history leaves an evolutionary signal in long-term population trends as inferred from census data. Where there is a lack of detailed demographic data, broad life-history information can inform management and conservation decisions about rebound capacity from low numbers, and propensity to fluctuate, of arrays of species in areas planned for development, harvesting, protection, and population recovery.Salvador Herrando-Pérez, Steven Delean, Barry W. Brook & Corey J. A. Bradsha

The syntax and morphology of the verb in Chepang

Chepang is a Tibeto-Burman language of Nepal with a complex verb morphology of a type that has been described as 'pronominalized'in the relevant literature on languages of the area. This morphology includes the crossreferencing of up to two participants in the clausal situation by means of affixes related to the independent pronouns. Usually one or other of the subject and object (strictly,Actor or Goal) participants,but not both, can be crossreferenced in this way, so that it is necessary to choose which of these will be so represented. The case role of the chosen participant may be indicated by a verbal affix. Certain of the affixes may be reduplicated once or even twice, and the possessor of a participant can also be crossreferenced in the verb. The result is a verb of considerable complexity, a feature which is, however, not unique to Chepang but is found in various other Tibeto-Burman and non-Tibeto-Burman languages of the south Asian region. This thesis represents an attempt to fully investigate and describe the structure, function and origins of this morphology in Chepang. In seeking to achieve this goal the study is not limited simply to a description of the affixation and grammatical categories that are involved, but rather extends to the total relationships of the verb. This investigation is carried out within a functional framework - that is, the verb, together with the constructions it enters into and its own constituents, is examined in relation to the various functions it performs in speech. These functions, and the notions associated with them, are defined and discussed in the introductory chapter ( chapter 1), in relation to relation to language in general. This is dealt with under the broad heading of content (especially role and referential content), context and cohesion. The three chapters following the introduction describe the part played by the verb with respect to indicating role and reference ( chapter 2), the context, especially the speaker's relation to the content (chapter 3), and the cohesive relations holding within the speech (chapter 4) - the last being particularly concerned with the marking of previous reference and of interclausal relationships. The remaining two chapters examine the verbal morphology from a historical and comparative point of view. In chapter 5 a possible method of development for the verbal affixation is suggested, together with postulated original forms of the pronominal elements . The proposed develpoment is shown to account for a number of otherwise unexplained features of the verbal paradigm. The last chapter looks at the Chepang verb against the wider linguistic background, first of all comparing the main dialect described in the thesis ( that of Maiserang village) with other Chepang dialects. The verbal morphology of Chepang is then compared with that of other Tibeto-Burman and non-Tibeto-Burman languages in the linguistic area