Managing the Cayo Santiago rhesus macaque population: The role of density

Hernández‐Pacheco, Raisa; Delgado, Diana L.; Rawlins, Richard G.; Kessler, Matthew J.; Ruíz-Lambides, Angelina; Maldonado, Elizabeth; Sabat, Alberto M.

doi:10.1002/ajp.22375

Cited by 35 publications

(35 citation statements)

References 25 publications

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“…Specifically, the decreased proportion of nonbreeders transitioning to breeders, followed closely by the decrease in remaining breeders in consecutive years (B stasis), contributed the most to the decrease in λ. Changes in Cayo Santiago female fertility may involve density-dependent mechanisms [12,16]. After controlling for density effects, our analysis shows that major hurricanes also contribute to the population dynamics of Cayo Santiago monkeys through reductions in mean fertility across the lifespan.…”

Section: Discussionmentioning

confidence: 80%

“…Veterinary intervention is restricted to the annual trapping season where yearlings are captured, marked for identification using ear notches and a unique three-character ID tattoo, physical samples are collected, and tetanus inoculation at 1 year of age and booster at 2 years of age is administered. During the trapping season, some individuals have been permanently removed from the island to control for population size [16]. Annual removal strategies have varied (from no removal to up to 596 individuals removed [16, for details]) and include removal events of entire social groups, as well as age-specific and sex specific removal events.…”

Section: The Cayo Santiago Field Stationmentioning

confidence: 99%

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Hurricane-induced demographic changes in a nonhuman primate population

Morcillo

Steiner

Grayson

et al. 2020

Preprint

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Major disturbance events can have large impacts on the demography and dynamics of animal populations. Hurricanes are one example of an extreme climatic event, predicted to increase in frequency due to climate change, and thus expected to be a considerable threat to population viability. However, little is understood about the underlying demographic mechanisms shaping population response following these extreme disturbances. Here, we analyze 45 years of the most comprehensive free-ranging nonhuman primate demographic dataset to determine the effects of major hurricanes on the variability and maintenance of long-term population fitness. For this, we use individual-level data to build matrix population models and perform perturbation analyses.Despite reductions in population growth rate mediated through reduced fertility, our study reveals a demographic buffering during hurricane years. As long as survival does not decrease, our study shows that hurricanes do not result in detrimental effects at the population level, demonstrating the unbalanced contribution of survival and fertility to population fitness in longlived animal populations.

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Section: Discussionmentioning

confidence: 80%

Section: The Cayo Santiago Field Stationmentioning

confidence: 99%

Hurricane-induced demographic changes in a nonhuman primate population

Morcillo

Steiner

Grayson

et al. 2020

Preprint

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“…Changes in density are clearly identifiable because it is a closed island population. More importantly, this primate population exhibits a high annual population growth rate (λ > 1.10) (Rawlins and Kessler 1986, Blomquist et al 2011, Kessler et al 2015, and exists frequently at relatively high densities where population dynamics are regulated by reduced reproduction (Hernández-Pacheco et al 2013, Hernández-Pacheco et al 2016b).…”

Section: The Cayo Santiago Rhesus Macaque Populationmentioning

confidence: 99%

“…In order to avoid underestimation of a particular annual stage distribution in a period with adult female removal (total of 11 periods), the annual proportion of females was estimated using the total number of females alive at period t after censoring removed adult females during the same period. Although selective culling in the population has been practiced, adult females have never been the main target or their reproductive stage (Hernández-Pacheco et al 2016b). We determined mean annual fertility (F t ) as the proportion of successful breeders (B) relative to the total number of adult females (NB, FB, B) during the birth season of period t. In our annual models, only stage B contributes to reproduction, while stage FB contributes to an absorbing stage (dead infants).…”

Section: Patterns In Reproductive Stage Distributionmentioning

confidence: 99%

Drivers of diversification in individual life courses

Hernández‐Pacheco¹,

Steiner²

2017

Preprint

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Heterogeneity in life courses among individuals of a population influences the speed of adaptive evolutionary processes, but it is less clear how biotic and abiotic environmental fluctuations influence such heterogeneity. We investigate principal drivers of variability in sequence of stages during an individual's life in a stage-structured population. We quantify heterogeneity by measuring population entropy, which computes the rate of diversification of individual life courses of a Markov chain. Using individual data of a primate population, we show that density regulates the stage composition of the population, but its entropy and the generating moments of heterogeneity are independent of density. This lack of influence of density on heterogeneity is neither due to low year-to-year variation in entropy nor due to differences in survival among stages, but due to differences in stage transitions. Our analysis thus shows that well-known classical ecological selective forces, such as density regulation, are not linked to potential selective forces governing heterogeneity through underlying stage dynamics. Despite evolution acting heavily on individual variability in fitness components, our understanding is poor whether observed heterogeneity is adaptive and how it evolves and is maintained. Our analysis illustrates how entropy represents a more integrated measure of diversity compared to the population structural composition, giving us new insights about the underlying drivers of individual heterogeneity within populations and potential evolutionary mechanisms.

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“…This implies that females mating earlier in a season would trigger a significant advance in mating activities at the population level when density is high by affecting the reproductive behavior of both females from their group and females from adjacent groups. During the last three decades population density at Cayo Santiago has increased significantly, resulting in more frequent culling, and thus, a higher proportionof females losing offspring [Hern andez-Pacheco et al, 2015]. A higher proportion of females exhibiting IBIs <365 days coupled with a higher degree of synchronization over time, would cause a further advance and accelerate the change in the rate of advance in reproduction at the population level.…”

Section: Discussionmentioning

confidence: 99%

Discovery of a secular trend in Cayo Santiago macaque reproduction

Hernández‐Pacheco

Rawlins

Kessler

et al. 2015

American J Primatol

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Reproductive synchrony and the consequent clustering of births are hypothesized to be regulated by seasonal changes in rainfall and food availability. Such climate-related seasonality is, however, questionable in tropical populations occupying temporally invariant habitats year round. Using the long-term data of the Cayo Santiago rhesus macaques from 1973 to 2013, this study distinguishes synchrony (a greater than chance clustering of births) from seasonality (a cluster of births during a period of the year when abiotic conditions are favorable) and shows that females are highly synchronized (>72% of births in a 3-month period) but the effects of environmental zeitgebers on reproduction are overridden by biological factors. Specifically, biotic and abiotic factors including (i) loss of immature offspring; (ii) population density; (iii) age at delivery; (iv) rainfall; and (v) changes in colony management were modeled in relation to the annual onset of births and the median birth date. Females experiencing loss of immature offspring had an interbirth interval of <365 days in average and the proportion of these females increased up to 48% due to changes in colony management overtime, although reproductive synchrony increased with increasing population density. A secular trend in both the onset of births and the median date of birth is documented and the model predicts that the median birth date will advance across all calendar-based seasons by 2050. The secular trend in reproduction appears to be triggered by changes in the age at delivery of females, the absence of physiological constraints from maternal investment due to offspring loss, shorter interbirth interval, and a higher degree of coordination due to increasing population density. This study challenges the reproductive phenology previously described for rhesus macaques highlighting the importance of long-term studies in addressing the ultimate causes of reproductive synchrony.

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Managing the Cayo Santiago rhesus macaque population: The role of density

Cited by 35 publications

References 25 publications

Hurricane-induced demographic changes in a nonhuman primate population

Hurricane-induced demographic changes in a nonhuman primate population

Drivers of diversification in individual life courses

Discovery of a secular trend in Cayo Santiago macaque reproduction

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