scholarly journals Multilevel and sex-specific selection on competitive traits in North American red squirrels

2017 ◽  
Author(s):  
David N. Fisher ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
Murray M. Humphries ◽  
Jeffrey E. Lane ◽  
...  
Keyword(s):  
Growth Rate ◽  
Natural Selection ◽  
North American ◽  
Postnatal Growth ◽  
Birth Date ◽  
Red Squirrels ◽  
Data Set ◽  
Individual Level ◽  
In The Wild ◽  
North American Red Squirrels

AbstractIndividuals often interact more closely with some members of the population (e.g. offspring, siblings or group members) than they do with other individuals. This structuring of interactions can lead to multilevel natural selection, where traits expressed at the group-level influence fitness alongside individual-level traits. Such multilevel selection can alter evolutionary trajectories, yet is rarely quantified in the wild, especially for species that do not interact in clearly demarcated groups. We quantified multilevel natural selection on two traits, postnatal growth rate and birth date, in a population of North American red squirrels (Tamiasciurus hudsonicus). The strongest level of selection was typically within-acoustic social neighbourhoods (within 130m of the nest), where growing faster and being born earlier than nearby litters was key, while selection on growth rate was also apparent both within-litters and within-study areas. Higher population densities increased the strength of selection for earlier breeding, but did not influence selection on growth rates. Females experienced especially strong selection on growth rate at the within-litter level, possibly linked to the biased bequeathal of the maternal territory to daughters. Our results demonstrate the importance of considering multilevel and sex-specific selection in wild species, including those that are territorial and sexually monomorphic.Data archival: the data set is archived on Dryad (info XXX), with a five-year embargo from the date of publication.

scholarly journals Maternal glucocorticoids promote offspring growth without inducing oxidative stress or shortening telomeres in wild red squirrels

2019 ◽  
Author(s):  
Ben Dantzer ◽  
Freya van Kesteren ◽  
Sarah E. Westrick ◽  
Stan Boutin ◽  
Andrew G. McAdam ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Body Mass ◽  
North American ◽  
Life Histories ◽  
Postnatal Growth ◽  
Red Squirrels ◽  
Oxidative Protein Damage ◽  
Offspring Growth ◽  
Stress Levels ◽  
North American Red Squirrels

AbstractElevations in glucocorticoid levels (GCs) in breeding females may induce adaptive shifts in offspring life histories. Offspring produced by mothers with elevated GCs may be better prepared to face harsh environments where a faster pace of life is beneficial. We examined how experimentally elevated GCs in pregnant or lactating North American red squirrels (Tamiasciurus hudsonicus) affected offspring postnatal growth, structural size, oxidative stress levels (two antioxidants and oxidative protein damage) in three different tissues (blood, heart, liver), and liver telomere lengths. We predicted that offspring from mothers treated with GCs would grow faster but would also have higher levels of oxidative stress and shorter telomeres, which may predict reduced longevity. Offspring from mothers treated with GCs during pregnancy were 8.3% lighter around birth but grew (in body mass) 17.0% faster than those from controls, whereas offspring from mothers treated with GCs during lactation grew 34.8% slower than those from controls and did not differ in body mass around birth. Treating mothers with GCs during pregnancy or lactation did not alter the oxidative stress levels or telomere lengths of their offspring. Fast-growing offspring from any of the treatment groups did not have higher oxidative stress levels or shorter telomere lengths, indicating that offspring that grew faster early in life did not exhibit oxidative costs after this period of growth. Our results indicate that elevations in maternal GCs may induce plasticity in offspring growth without long-term oxidative costs to the offspring that might result in a shortened lifespan.Summary StatementWe show that experimental increases in glucocorticoids in breeding female North American red squirrels affects offspring postnatal growth but not levels of oxidative damage and antioxidants or telomere lengths.

scholarly journals ECOLOGY OF NORTH AMERICAN RED SQUIRRELS ACROSS CONTRASTING HABITATS: RELATING NATAL DISPERSAL TO HABITAT

2004 ◽  
Vol 85 (2) ◽  
pp. 225-236 ◽  
Author(s):  
Diane L. Haughland ◽  
Karl W. Larsen
Keyword(s):  
North American ◽  
Natal Dispersal ◽  
Red Squirrels ◽  
North American Red Squirrels ◽  
Contrasting Habitats

Constraints on First Reproduction in North American Red Squirrels

Oikos ◽  
1998 ◽  
Vol 81 (1) ◽  
pp. 81 ◽  
Author(s):  
C. Dustin Becker ◽  
Stan Boutin ◽  
Karl W. Larsen
Keyword(s):  
North American ◽  
Red Squirrels ◽  
First Reproduction ◽  
North American Red Squirrels

North American red squirrels mitigate costs of territory defence through social plasticity

2019 ◽  
Vol 151 ◽  
pp. 29-42 ◽  
Author(s):  
Erin R. Siracusa ◽  
David R. Wilson ◽  
Emily K. Studd ◽  
Stan Boutin ◽  
Murray M. Humphries ◽  
...  
Keyword(s):  
North American ◽  
Red Squirrels ◽  
Territory Defence ◽  
Social Plasticity ◽  
North American Red Squirrels

scholarly journals The effects of stress and glucocorticoids on vocalizations: a test in North American red squirrels

2019 ◽  
Vol 30 (4) ◽  
pp. 1030-1040 ◽  
Author(s):  
Matt Sehrsweeney ◽  
David R Wilson ◽  
Maggie Bain ◽  
Stan Boutin ◽  
Jeffrey E Lane ◽  
...  
Keyword(s):  
Stress State ◽  
North American ◽  
Physiological Stress ◽  
Physiological State ◽  
Public Information ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Acoustic Structure ◽  
North American Red Squirrels ◽  
Important Means

AbstractAcoustic signaling is an important means by which animals communicate both stable and labile characteristics. Although it is widely appreciated that vocalizations can convey information on labile state, such as fear and aggression, fewer studies have experimentally examined the acoustic expression of stress state. The transmission of such public information about physiological state could have broad implications, potentially influencing the behavior and life-history traits of neighbors. North American red squirrels (Tamiasciurus hudsonicus) produce vocalizations known as rattles that advertise territorial ownership. We examined the influence of changes in physiological stress state on rattle acoustic structure through the application of a stressor (trapping and handling the squirrels) and by provisioning squirrels with exogenous glucocorticoids (GCs). We characterized the acoustic structure of rattles emitted by these squirrels by measuring rattle duration, mean frequency, and entropy. We found evidence that rattles do indeed exhibit a “stress signature.” When squirrels were trapped and handled, they produced rattles that were longer in duration with a higher frequency and increased entropy. However, squirrels that were administered exogenous GCs had similar rattle duration, frequency, and entropy as squirrels that were fed control treatments and unfed squirrels. Our results indicate that short-term stress does affect the acoustic structure of vocalizations, but elevated circulating GC levels do not mediate such changes.

scholarly journals Indirect effects on fitness between individuals that have never met via an extended phenotype

2018 ◽  
Author(s):  
David N. Fisher ◽  
Jessica A. Haines ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
Jeffrey E. Lane ◽  
...  
Keyword(s):  
Population Dynamics ◽  
North American ◽  
Indirect Effects ◽  
Tamiasciurus Hudsonicus ◽  
Extended Phenotype ◽  
Red Squirrels ◽  
Lifetime Fitness ◽  
The Past ◽  
North American Red Squirrels ◽  
The Individual

AbstractInteractions between organisms are ubiquitous and have important consequences for phenotypes and fitness. Individuals can even influence those they never meet, if they have extended phenotypes which mean the environments others experience are altered. North American red squirrels (Tamiasciurus hudsonicus) guard food hoards, an extended phenotype that typically outlives the individual and is almost always inherited by non relatives. Hoarding by previous owners can therefore influence subsequent owners. We found that red squirrels bred earlier and had higher lifetime fitness if the previous owner was a male. This was driven by hoarding behaviour, as males and mid-aged squirrels had the largest hoards, and these effects persisted across owners, such that if the previous owner was male or died in mid-age subsequent occupants had larger hoards. Individuals can, therefore, influence each other’s resource dependent traits and fitness without meeting via extended phenotypes, and so the past can influence contemporary population dynamics.

scholarly journals Glucocorticoids coordinate changes in gut microbiome composition in wild North American red squirrels

2021 ◽  
Author(s):  
Lauren Petrullo ◽  
Tiantian Ren ◽  
Martin Wu ◽  
Rudy Boonstra ◽  
Rupert Palme ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
North American ◽  
Gut Microbiome ◽  
Pathogenic Bacteria ◽  
Experimental Studies ◽  
Ecological Framework ◽  
Ecological Change ◽  
Red Squirrels ◽  
Microbiome Diversity ◽  
North American Red Squirrels

Gut microbiome diversity plays an important role in host health and fitness, in part through the diversification of gut metabolic function and pathogen protection. Elevations in glucocorticoids (GCs) appear to reduce gut microbiome diversity in experimental studies, suggesting that a loss of microbial diversity may be a negative consequence of increased GCs. However, given that ecological factors like food availability and population density may independently influence both GCs and microbial diversity, understanding how these factors structure the GC-microbiome relationship is crucial to interpreting its significance in wild populations. Here, we used an ecological framework to investigate the relationship between GCs and gut microbiome diversity in wild North American red squirrels (Tamiasciurus hudsonicus). We found that higher GCs predicted lower gut microbiome diversity and an increase in metabolic taxa. In addition, we identified a loss of potentially pathogenic bacteria with increasing GCs. Both dietary heterogeneity and an upcoming masting event exhibited direct effects on gut microbiome diversity, whereas conspecific density and host reproductive activity impacted diversity indirectly via changes in GCs. Together, our results suggest that GCs coordinate the effects of ecological change and host biology on gut microbiome diversity, and highlight the importance of situating the GC-microbiome relationship within an ecological framework.

BREEDING DISPERSAL IN FEMALE NORTH AMERICAN RED SQUIRRELS

Ecology ◽  
2000 ◽  
Vol 81 (5) ◽  
pp. 1311-1326 ◽  
Author(s):  
Dominique Berteaux ◽  
Stan Boutin
Keyword(s):  
North American ◽  
Breeding Dispersal ◽  
Red Squirrels ◽  
North American Red Squirrels

scholarly journals The nature of nurture in a wild mammal's fitness

2015 ◽  
Vol 282 (1806) ◽  
pp. 20142422 ◽  
Author(s):  
S. Eryn McFarlane ◽  
Jamieson C. Gorrell ◽  
David W. Coltman ◽  
Murray M. Humphries ◽  
Stan Boutin ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Maternal Effects ◽  
Adaptive Evolution ◽  
Genetic Effects ◽  
Adaptive Potential ◽  
Red Squirrels ◽  
Trade Offs ◽  
The Face ◽  
North American Red Squirrels

Genetic variation in fitness is required for the adaptive evolution of any trait but natural selection is thought to erode genetic variance in fitness. This paradox has motivated the search for mechanisms that might maintain a population's adaptive potential. Mothers make many contributions to the attributes of their developing offspring and these maternal effects can influence responses to natural selection if maternal effects are themselves heritable. Maternal genetic effects (MGEs) on fitness might, therefore, represent an underappreciated source of adaptive potential in wild populations. Here we used two decades of data from a pedigreed wild population of North American red squirrels to show that MGEs on offspring fitness increased the population's evolvability by over two orders of magnitude relative to expectations from direct genetic effects alone. MGEs are predicted to maintain more variation than direct genetic effects in the face of selection, but we also found evidence of maternal effect trade-offs. Mothers that raised high-fitness offspring in one environment raised low-fitness offspring in another environment. Such a fitness trade-off is expected to maintain maternal genetic variation in fitness, which provided additional capacity for adaptive evolution beyond that provided by direct genetic effects on fitness.

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