Mortality in relation to season, age, sex, and reproduction in Columbian ground squirrels (<i>Spermophilus columbianus</i>)

Neuhaus, Peter; Pelletier, Nathan

doi:10.1139/z00-225

Cited by 44 publications

(38 citation statements)

References 36 publications

(28 reference statements)

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“…Columbian ground squirrels are colonial, hibernating rodents that inhabit subalpine and alpine meadows of the northern regions of the Rocky Mountains. The active season is short and adult males are typically the first to emerge from hibernation around mid-April, followed by females a few days to a week later (Murie and Harris 1982;Dobson et al 1992;Neuhaus 2000;Neuhaus and Pelletier 2001;Raveh et al 2010).…”

Section: Study Area and Speciesmentioning

confidence: 99%

Male reproductive tactics to increase paternity in the polygynandrous Columbian ground squirrel (Urocitellus columbianus)

Raveh

Heg

Viblanc

et al. 2010

Behav Ecol Sociobiol

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In polyandrous and polygynandrous species where females mate with multiple partners, males are expected to maximize their fitness by exhibiting an array of reproductive behaviors to ensure fertilization success, such as competing for the best mating order within a mating sequence, optimizing their investment in copulation, and mate guarding. Though there is genetic evidence of a first-male precedence in siring success for many mammalian species, the causes of this effect are poorly understood. We studied influences on first-male precedence in Columbian ground squirrels (Urocitellus columbianus). We found that the time a male spent consorting and mate guarding declined with his mating order (both the highest for the first male to mate). Mate guarding by the first male significantly reduced, but did not exclude, the number of additional males a female accepted. Later mating males reduced the time spent consorting, suggesting a perceived decreased chance of fertilization success. Consortship and mate guarding durations were positively related to the male's siring success and to each other, suggesting that males adjusted these behaviors strategically to increase their chances of fertilization success. Our results suggest that besides being the first male to consort, first-male sperm precedence is further enhanced through longer mating bouts and by suppressing the chances and/or efforts of later mating males.

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Section: Study Area and Speciesmentioning

confidence: 99%

Male reproductive tactics to increase paternity in the polygynandrous Columbian ground squirrel (Urocitellus columbianus)

Raveh

Heg

Viblanc

et al. 2010

Behav Ecol Sociobiol

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“…In polygynous or promiscuous mammals, male mating effort can have significant costs due to the risks associated with dispersal, energy expenditure for mate attraction displays or intrasexual competition, fighting, and increased exposure to predation (e.g., see Promislow 1992). Accordingly, male mating effort is often associated with lower survival (e.g., red deer, Clutton-Brock et al 1982; elephant seals, Mirounga angustirostris , Clinton and LeBoeuf 1993; Columbian ground squirrels, Spermophilus columbianus , Neuhaus and Pelletier 2001). By contrast, castration can significantly extend male lifespan (e.g., Soay sheep, Ovis aries , Jewell 1997).…”

Section: Introductionmentioning

confidence: 99%

Sex differences in survival costs of reproduction in a promiscuous primate

Hoffman

Ruíz-Lambides

Davila

et al. 2008

Behav Ecol Sociobiol

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In sexually promiscuous mammals, female reproductive effort is mainly expressed through gestation, lactation, and maternal care, whereas male reproductive effort is mainly manifested as mating effort. In this study, we investigated whether reproduction has significant survival costs for a seasonally breeding, sexually promiscuous species, the rhesus macaque, and whether these costs occur at different times of the year for females and males, namely in the birth and the mating season, respectively. The study was conducted with the rhesus macaque population on Cayo Santiago, Puerto Rico. Data on 7,402 births and 922 deaths over a 45-year period were analyzed. Births were concentrated between November and April, while conceptions occurred between May and October. As predicted, female mortality probability peaked in the birth season whereas male mortality probability peaked in the mating season. Furthermore, as the onset of the birth season gradually shifted over the years in relation to climatic changes, there was a concomitant shift in the seasonal peaks of male and female mortality. Taken together, our findings provide the first evidence of sex differences in the survival costs of reproduction in nonhuman primates and suggest that reproduction has significant fitness costs even in environments with abundant food and absence of predation.

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“…So δ might Control effectiveness with asymptotic incidence, as a function of: a the (scaled) disease transmission efficiency β/(K /(c + K )) and the proportional reduction of the intrinsic mortality rate in those infected individuals that become sterilized (δ), b the intrinsic mortality rate d and the proportional reduction of the intrinsic mortality rate in those infected individuals that become sterilized (δ). Other parameter values: Neuhaus and Pelletier (2001) also decrease due to predators or parasitoids, and thus possibly attain relatively low values. One of our main results is that an increase in longevity of the sterilized infected individuals further enhances their ability to spread the disease.…”

Section: Discussionmentioning

confidence: 99%

“…Yet, none of these models has ever accounted for a well-known aspect of life-history theory, namely the cost of reproduction or a trade-off between reproduction and survival-by decreasing the energy outlay on reproduction, individuals with lowered reproduction can live longer. This trade-off predicts that "non-reproducing females have a higher chance of surviving than reproducing females" (Neuhaus and Pelletier 2001), that there is "a negative relationship between the mean female fecundity and the mean [female] longevity" (Thomas et al 2000), or that "early reproduction may increase mortality to such an extent that delaying reproduction may increase survival and lifetime reproductive success" (Bennett and Owens 2002). These trade-offs have indeed been found to occur in birds (Bennett and Owens 2002), insect parasitoids (Ellers 1995;Ramesh and Manickavasagam 2003), mammals (Neuhaus and Pelletier 2001) and even humans (Thomas et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Double impact of sterilizing pathogens: added value of increased life expectancy on pest control effectiveness

Berec

Maxin

2011

J. Math. Biol.

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Sterilizing pathogens are commonly assumed not to affect longevity of infected individuals, and if they do then negatively. Examples abound, however, of species in which the absence of reproduction actually increases life expectancy. This happens because by decreasing the energy outlay on reproduction individuals with lowered reproduction can live longer. Alternatively, fertile individuals are more susceptible to predators or parasitoids if the latter can capitalize on mating signals of the former. Here we develop and analyze an SI epidemiological model to explore whether and to what extent does such a life expectancy prolongation due to sterilizing pathogens affect host dynamics. In particular, we are interested in an added value of increased life expectancy on the possibility of successful pest control, that is, the effect of increased lifespan and hence increased potential of the infected individuals to spread the disease on pest control effectiveness. We show that although the parameter range in which we observe an effect of increased lifespan of the sterilized individuals is not large, the effect itself can be significant. In particular, the increase in pest control effectiveness can be very dramatic when disease transmission efficiency is close to birth rate, mortality rate of susceptibles is relatively high (i.e., the species is relatively short-lived), and sterilization efficiency is relatively high. Our results thus characterize pathogens that are promising candidates for an effective pest control and that might possibly be engineered if not occurring naturally.

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Mortality in relation to season, age, sex, and reproduction in Columbian ground squirrels (Spermophilus columbianus)

Cited by 44 publications

References 36 publications

Male reproductive tactics to increase paternity in the polygynandrous Columbian ground squirrel (Urocitellus columbianus)

Male reproductive tactics to increase paternity in the polygynandrous Columbian ground squirrel (Urocitellus columbianus)

Sex differences in survival costs of reproduction in a promiscuous primate

Double impact of sterilizing pathogens: added value of increased life expectancy on pest control effectiveness

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