scholarly journals Gone girl: Richardson's ground squirrel offspring and neighbours are resilient to female removal

2019 ◽  
Vol 6 (9) ◽  
pp. 190904 ◽  
Author(s):  
Angela R. Freeman ◽  
Thomas J. Wood ◽  
Kevin R. Bairos-Novak ◽  
W. Gary Anderson ◽  
James F. Hare
Keyword(s):  
Reproductive Success ◽  
Ground Squirrels ◽  
Offspring Survival ◽  
Alarm Calling ◽  
Territory Defence ◽  
Faecal Glucocorticoid Metabolites ◽  
Fitness Consequences ◽  
High Predation ◽  
Pituitary Adrenal Axis ◽  
Urocitellus Richardsonii

Within matrilineal societies, the presence of mothers and female kin can greatly enhance survival and reproductive success owing to kin-biased alarm calling, cooperation in territory defence, protection from infanticidal conspecifics, joint care of young and enhanced access to resources. The removal of mothers by predators or disease is expected to increase the stress experienced by offspring via activation of their hypothalamic-pituitary-adrenal axis, increasing circulating glucocorticoids and reducing offspring survival and reproductive success. Yet, few studies have removed mothers in the post-weaning period to examine the assumed physiological and fitness consequences associated with these mortality events. We examined how the loss of a mother affects juvenile Richardson's ground squirrels' ( Urocitellus richardsonii ) faecal glucocorticoid metabolites and their survival. Given that neighbours are often close kin, we further hypothesized that conspecific removal would similarly diminish the fitness of neighbouring individuals. Upon removing the mother, we detected no impact on offspring or neighbouring conspecific faecal glucocorticoid metabolites in the removal year, or on overwinter survival in the following year. Furthermore, no impact on neighbour reproductive success was detected. Given the high predation rates of ground squirrels in wild populations, resilience to a changing social environment would prove adaptive for both surviving kin and non-kin.

Variation in reproductive success of male and female Columbian ground squirrels (Urocitellus columbianus)

2012 ◽  
Vol 90 (6) ◽  
pp. 736-743 ◽  
Author(s):  
Philip H. Jones ◽  
Jeffrey L. Van Zant ◽  
F. Stephen Dobson
Keyword(s):  
Reproductive Success ◽  
Mating System ◽  
Multiple Paternity ◽  
Ground Squirrels ◽  
Male Reproductive Success ◽  
Offspring Production ◽  
Bateman Gradient ◽  
Coefficients Of Variation ◽  
Males And Females ◽  
Columbian Ground Squirrels

The imbalanced reproductive success of polygynous mammals results in sexual selection on male traits like body size. Males and females might have more balanced reproductive success under polygynandry, where both sexes mate multiply. Using 4 years of microsatellite DNA analyses of paternity and known maternity, we investigated variation in reproductive success of Columbian ground squirrels, Urocitellus columbianus (Ord, 1815); a species with multiple mating by both sexes and multiple paternity of litters. We asked whether male reproductive success was more variable than that of females under this mating system. The overall percentage of confirmed paternity was 61.4% of 339 offspring. The mean rate of multiple paternity in litters with known fathers was 72.4% (n = 29 litters). Estimated mean reproductive success of males (10.27 offspring) was about thrice that of females (3.11 offspring). Even after this difference was taken into account statistically, males were about three times as variable in reproductive success as females (coefficients of variation = 77.84% and 26.74%, respectively). The Bateman gradient (regression slope of offspring production on number of successful mates) was significantly greater for males (βM = 1.44) than females (βF = 0.28). Thus, under a polygynandrous mating system, males exhibited greater variation in reproductive success than females.

scholarly journals Polygyny and Extra-Pair Paternity in a Population of Southwestern Willow Flycatchers

The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 571-578
Author(s):  
Talima Pearson ◽  
Mary J. Whitfield ◽  
Tad C. Theimer ◽  
Paul Keim
Keyword(s):  
Reproductive Success ◽  
Microsatellite Markers ◽  
Mating Strategy ◽  
Male Reproductive Success ◽  
Offspring Survival ◽  
Extra Pair Paternity ◽  
Study Population ◽  
Willow Flycatcher ◽  
Empidonax Traillii ◽  
Disproportionate Number

Abstract Although polygyny can potentially increase male reproductive success, the benefits of this strategy could be offset by losses to extra-pair paternity or reduced offspring survival. We developed microsatellite markers to assess the influence of extra-pair offspring (EPO) on reproductive success and paternity in monogamous and polygynous pairs of the facultatively polygynous Southwestern Willow Flycatcher (Empidonax traillii extimus). Based on genotypes of 140 offspring from 56 clutches over six years, 14% of nestlings in our study population were extra-pair offspring, with 23% of all successful nests containing at least one EPO. We found that polygynous males produced 2.11 ± 0.35 offspring per season, compared to 1.15 ± 0.18 for monogamous males. This increased reproductive success was due primarily to the increased number of nests of polygynous males, as the number of offspring per pair did not differ between monogamous and polygynous males. Twenty of the 140 genotyped nestlings were extra-pair offspring. Sires could be assigned to 16 of these; one polygynous male sired two EPO in one nest, two monogamous males sired eight EPO in two nests, and four nonterritorial males sired six EPO in four nests. Overall, these results indicate that in this population, females of polygynous males did not raise a disproportionate number of EPO as a result of the polygynous mating strategy of their mate, and that both territorial and nonterritorial males sired EPO.

Shyness-Boldness, but not Exploration, Predicts Glucocorticoid Stress Response in Richardson's Ground Squirrels (Urocitellus richardsonii)

Ethology ◽  
2014 ◽  
Vol 120 (11) ◽  
pp. 1101-1109 ◽  
Author(s):  
Dawson Clary ◽  
Lindsay J. Skyner ◽  
Calen P. Ryan ◽  
Laura E. Gardiner ◽  
W. Gary Anderson ◽  
...  
Keyword(s):  
Stress Response ◽  
Ground Squirrels ◽  
Urocitellus Richardsonii

scholarly journals The effect of sexual selection on adaptation and extinction under increasing temperatures

2018 ◽  
Vol 285 (1877) ◽  
pp. 20180303 ◽  
Author(s):  
Jonathan M. Parrett ◽  
Robert J. Knell
Keyword(s):  
Sexual Selection ◽  
Environmental Changes ◽  
Population Level ◽  
Offspring Survival ◽  
Positive Effects ◽  
Fitness Consequences ◽  
Indian Meal ◽  
Mating Opportunities ◽  
Entire Experiment ◽  
Positive Effect

Strong sexual selection has been reported to both enhance and hinder the adaptive capacity and persistence of populations when exposed to novel environments. Consequently, how sexual selection influences population adaption and persistence under stress remains widely debated. Here, we present two empirical investigations of the fitness consequences of sexual selection on populations of the Indian meal moth, Plodia interpunctella, exposed to stable or gradually increasing temperatures. When faced with increasing temperatures, strong sexual selection was associated with both increased fecundity and offspring survival compared with populations experiencing weak sexual selection, suggesting sexual selection acts to drive adaptive evolution by favouring beneficial alleles. Strong sexual selection did not, however, delay extinction when the temperature became excessively high. By manipulating individuals' mating opportunities during fitness assays, we were able to assess the effect of multiple mating independently from the effect of population-level sexual selection, and found that polyandry has a positive effect on both fecundity and offspring survival under increasing temperatures in those populations evolving with weak sexual selection. Within stable temperatures, there were some benefits from strong sexual selection but these were not consistent across the entire experiment, possibly reflecting changing costs and benefits of sexual selection under stabilizing and directional selection. These results indicate that sexual selection can provide a buffer against climate change and increase adaptation rates within a continuously changing environment. These positive effects of sexual selection may, however, be too small to protect populations and delay extinction when environmental changes are relatively rapid.

Ancient DNA reveals northwest range extension of Richardson’s ground squirrel (Urocitellus richardsonii) into northeastern British Columbia, Canada, during the Late Pleistocene

2020 ◽  
Vol 57 (7) ◽  
pp. 855-866
Author(s):  
Thomas C.A. Royle ◽  
Dongya Y. Yang ◽  
Jonathan C. Driver
Keyword(s):  
British Columbia ◽  
Ancient Dna ◽  
Ground Squirrel ◽  
Mitochondrial Control Region ◽  
Archaeological Site ◽  
Ground Squirrels ◽  
Vegetation Communities ◽  
Peace River ◽  
River Region ◽  
Urocitellus Richardsonii

Ancient DNA was extracted from 12 500 to 10 500 year old ground squirrel bones from Tse’K’wa, an archaeological site in the Peace River region of northeastern British Columbia, Canada. Analysis of mitochondrial DNA from seven individuals demonstrates that all are Urocitellus richardsonii (Richardson’s ground squirrel), a species not found in the region today. Phylogenetic and sequence analyses indicate these individuals share a previously undocumented mitochondrial control region haplotype that is most closely related to haplotypes observed in modern specimens from Saskatchewan and Montana. At the end of the Pleistocene these ground squirrels extended their range north and west into open vegetation communities that developed when ice sheets melted and glacial lakes drained. They were subsequently extirpated from the Peace River region when forests replaced earlier pioneering vegetation communities.

scholarly journals Does vegetation change over 28 years affect habitat use and reproductive success?

The Auk ◽  
2019 ◽  
Vol 137 (1) ◽  
Author(s):  
Karolina Fierro-Calderón ◽  
Thomas E Martin
Keyword(s):  
Reproductive Success ◽  
Habitat Use ◽  
Nest Survival ◽  
Selection Function ◽  
Patch Use ◽  
Fitness Consequences ◽  
Long Term Changes ◽  
Changes Over Time ◽  
Over Time

Abstract Individuals should prefer and use habitats that confer high fitness, but habitat use is not always adaptive. Vegetation in natural landscapes changes gradually and the ability of species to adaptively adjust their habitat use to long-term changes is largely unstudied. We studied nest patch and territory use over 28 yr in Orange-crowned Warblers (Oreothlypis celata) in a system that has undergone natural long-term changes in vegetation. Abundance of maple (Acer grandidentatum), its preferred nesting habitat, gradually declined from 1987 to 2015. We examined whether habitat use and its fitness consequences changed as the availability of preferred habitat decreased. We used resource selection function models to determine changes over time in the probability of using a nest patch given available patches, and the probability of using a territory given available territories. We estimated nest survival to evaluate changes over time in the fitness consequences of nest patch use. We also compared habitat use (nest patch and territory) and fitness (nest survival) between areas with naturally reduced abundance of maple and experimentally increased abundance of maple (fenced areas). Nest patch use depended on maple abundance and did not change drastically across 28 yr, even though the availability of preferred maple patches decreased over time. In contrast, nest survival tended to decrease over time. We did not see differences in nest patch use and nest survival between unfenced and fenced areas, unlike territory use, which increased with the abundance of maple in fenced areas and decreased in unfenced areas. Our study depicts one example of relatively unchanged habitat use in the face of decreased availability of preferred vegetation across years, with a resulting decrease in reproductive success. Investigating changes in habitat use and fitness consequences for animals exposed to long-term habitat change is necessary to understand adaptive behavioral responses.

scholarly journals How Truly Conserved Is the “Well-Conserved” Vertebrate Stress Response?

2019 ◽  
Vol 59 (2) ◽  
pp. 273-281 ◽  
Author(s):  
L M Romero ◽  
B M G Gormally
Keyword(s):  
Nervous System ◽  
Autonomic Nervous System ◽  
Stress Response ◽  
Stress Responses ◽  
Species Variation ◽  
Functional Variation ◽  
Fitness Consequences ◽  
Fight Or Flight Response ◽  
Pituitary Adrenal Axis ◽  
Functional Output

Abstract The vertebrate stress response is considered to be a highly conserved suite of responses that are evolved to help animals survive noxious environmental stimuli. The two major pathways of the stress response include the catecholamine release that is part of the autonomic nervous system and comprises the immediate fight-or-flight response, and the slower release of corticosteroids from the hypothalamic–pituitary–adrenal axis that help orchestrate longer-term responses. These two pathways are present in every vertebrate yet examined, and the anatomical and physiological architecture underlying these pathways are consistent. Despite these structural similarities, however, recent data indicate substantial temporal and species variation in the actual regulation of these pathways. For example, activation of both pathways varies seasonally in some species but not others, and responses of both pathways can be extensively modulated by an individual’s previous experience. Consequently, even though the anatomy of the stress response is highly conserved, the activation and functional output is not highly conserved. Given this variation, it is perhaps not surprising that it is proving difficult to correlate individual stress responses with differences in fitness outcomes. This review summarizes the challenge of making broad generalized assumptions about fitness consequences of the stress response given the functional variation we observe.

scholarly journals Faecal glucocorticoid metabolites and alarm calling in free-living yellow-bellied marmots

2005 ◽  
Vol 2 (1) ◽  
pp. 29-32 ◽  
Author(s):  
Daniel T Blumstein ◽  
Marilyn L Patton ◽  
Wendy Saltzman
Keyword(s):  
Present Finding ◽  
Physiological Arousal ◽  
Alarm Calls ◽  
Marmota Flaviventris ◽  
Free Living ◽  
Potential Predator ◽  
Alarm Calling ◽  
Faecal Glucocorticoid Metabolites ◽  
Metabolite Concentrations

When individuals of a variety of species encounter a potential predator, some, but not all, emit alarm calls. To explain the proximate basis of this variation, we compared faecal glucocorticoid metabolite concentrations in live-trapped yellow-bellied marmots ( Marmota flaviventris ) between occasions when they did and did not emit alarm calls. We found that marmots had significantly higher glucocorticoid levels when they called than when they did not call, suggesting that stress or arousal may play an important role in potentiating alarm calls. Marmots are sensitive to variation in the reliability of callers. The present finding provides one possible mechanism underlying caller variation: physiological arousal influences the propensity to emit alarm calls.

Timing is the only thing: reproduction in female yellow ground squirrels (Spermophilus fulvus)

2014 ◽  
Vol 92 (8) ◽  
pp. 737-747 ◽  
Author(s):  
N.A. Vasilieva ◽  
A.V. Tchabovsky
Keyword(s):  
Litter Size ◽  
Body Condition ◽  
Reproductive Effort ◽  
Individual Characteristics ◽  
Ground Squirrels ◽  
Offspring Survival ◽  
Litter Mass ◽  
Individual Offspring ◽  
Female Survival ◽  
Spermophilus Fulvus

Based on 4-year field observations of yellow ground squirrels (Spermophilus fulvus (Lichtenstein, 1823)), we determined whether female reproductive effort, annual reproductive success, and survival were dependent on age, body condition, time of emergence from hibernation, and previous reproduction. The probability of weaning a litter did not vary with female age, body condition, time of emergence, or previous reproduction. Litter size, litter mass, and offspring survival did not vary with age, whereas individual offspring mass was lower in yearlings than in older females. Body condition upon emergence had no effect on litter size, litter mass, offspring mass, and survival. Reproduction did not influence female survival, physical condition upon emergence next spring, or subsequent reproductive efforts. The only factor that affected the extent of reproductive effort and offspring survival was the date of emergence: the later a female emerged, the lower the total and mean offspring mass, and fewer offspring survived. The modulation of reproduction in female S. fulvus by only the timing of vernal emergence and independent of other individual characteristics can be explained by the high costs of missed reproductive opportunity because of short longevity combined with low costs of reproduction when resources are abundant enough to meet both somatic and reproductive needs.

Reproductive strategies in hermaphroditic gastropods: conceptual and empirical approaches

2013 ◽  
Vol 91 (6) ◽  
pp. 367-381 ◽  
Author(s):  
Yumi Nakadera ◽  
Joris M. Koene
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Experimental Research ◽  
Reproductive System ◽  
Reproductive Strategy ◽  
Reproductive Strategies ◽  
Sex Allocation ◽  
Fitness Consequences ◽  
The Individual ◽  
Empirical Approaches

An individual optimizes its reproductive success by adopting a particular reproductive strategy. Studying the details of a reproductive strategy leads to an understanding of how sexual selection acts, as the former is the process via which the individual reproduces successfully. Hermaphroditic gastropods display a bewildering diversity of reproductive strategies, which may be due to their mode of gender expression, when compared with well-studied separate-sexed species. Extensive theoretical, observational, and experimental research has been conducted on this topic. However, despite our knowledge about the reproductive system of hermaphroditic gastropods, we still need to fill the gap between pre- and post-copulatory processes and reproductive success. Here, we review and propose conceptual and empirical approaches aimed at understanding reproductive strategies of hermaphroditic gastropods. In sum, our suggestions are (i) to focus on sex-biased traits, (ii) to take biologically reliable measurements at both the pre- and post-copulatory level that relate to reproductive success, and (iii) to examine the fitness consequences of biased sex allocation.

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