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Boonstra R. Population regulation and limitation-insights from lemming cycles: past, present and future. Proc Biol Sci 2024; 291:20240660. [PMID: 38835279 DOI: 10.1098/rspb.2024.0660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 04/15/2024] [Indexed: 06/06/2024] Open
Affiliation(s)
- Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough , Toronto, Ontario M1C 1A4, Canada
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2
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Krebs CJ. Lemming population fluctuations around the Arctic. Proc Biol Sci 2024; 291:20240399. [PMID: 38864322 DOI: 10.1098/rspb.2024.0399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 04/24/2024] [Indexed: 06/13/2024] Open
Affiliation(s)
- Charles J Krebs
- Department of Zoology, University of British Columbia , Vancouver, British Columbia V6T 1Z4, Canada
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3
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Krebs CJ, Kenney AJ, Gilbert BS, Boonstra R. Long-term monitoring of cycles in Clethrionomys rutilus in the Yukon boreal forest. Integr Zool 2024; 19:27-36. [PMID: 36892189 DOI: 10.1111/1749-4877.12718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
Baseline studies of small rodent populations in undisturbed ecosystems are rare. We report here 50 years of monitoring and experimentation in Yukon of a dominant rodent species in the North American boreal forest, the red-backed vole Clethrionomys rutilus. These voles breed in summer, weigh 20-25 g, and reach a maximum density of 20 to 25 per ha. Their populations have shown consistent 3-4-year cycles for the last 50 years with the only change being that peak densities averaged 8/ha until 2000 and 18/ha since that year. During the last 25 years, we have measured food resources, predator numbers, and winter weather, and for 1-year social interactions, to estimate their contribution to changes in the rate of summer increase and the rate of overwinter decline. All these potential limiting factors could contribute to changes in density, and we measured their relative contributions statistically with multiple regressions. The rate of winter decline in density was related to both food supply and winter severity. The rate of summer increase was related to summer berry crops and white spruce cone production. No measure of predator numbers was related to winter or summer changes in vole abundance. There was a large signal of climate change effects in these populations. There is no density dependence in summer population growth and only a weak one in winter population declines. None of our results provide a clear understanding of what generates 3-4-year cycles in these voles, and the major missing piece may be an understanding of social interactions at high density.
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Affiliation(s)
- Charles J Krebs
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alice J Kenney
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - B Scott Gilbert
- Renewable Resources Management Program, Yukon University, Whitehorse, Yukon, Canada
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
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4
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Edwards PD, Palme R, Boonstra R. Is chronic stress a causal mechanism for small mammal population cycles? Reconciling the evidence. Oecologia 2023; 201:609-623. [PMID: 36864247 DOI: 10.1007/s00442-023-05338-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 02/17/2023] [Indexed: 03/04/2023]
Abstract
Chronic stress has long been hypothesized to play a role in driving population cycles. Christian (1950) hypothesized that high population density results in chronic stress and mass "die-offs" in small mammal populations. Updated variations of this hypothesis propose that chronic stress at high population density may reduce fitness, reproduction, or program aspects of phenotype, driving population declines. We tested the effect of density on the stress axis in meadow voles (Microtus pennsylvanicus) by manipulating population density in field enclosures over three years. Using fecal corticosterone metabolites as a non-invasive measure of glucocorticoid (GC) concentrations, we found that density alone was not associated with GC differences. However, we found that the seasonal relationship of GC levels differed by density treatment, with high-density populations having elevated GC levels early in the breeding season and decreasing towards late summer. We additionally tested hippocampal glucocorticoid receptor and mineralocorticoid receptor gene expression in juvenile voles born at different densities, with the hypothesis that high density may reduce receptor expression, altering negative feedback of the stress axis. We found that females had marginally higher glucocorticoid receptor expression at high density, no effect in males, and no detectable effect of density on mineralocorticoid receptor expression in either sex. Hence, we found no evidence that high density directly impairs negative feedback in the hippocampus, but rather female offspring may be better equipped for negative feedback. We compare our findings with prior studies to attempt to disentangle the complicated relationship between density, seasonality, sex, reproduction and the stress axis.
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Affiliation(s)
- Phoebe D Edwards
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 1A1, Canada.
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, M1C 1A4, Canada.
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada.
| | - Rupert Palme
- Department of Biomedical Sciences, University of Veterinary Medicine, 1210, Vienna, Austria
| | - Rudy Boonstra
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 1A1, Canada
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, M1C 1A4, Canada
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5
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Emery SE, Klapwijk M, Sigvald R, Bommarco R, Lundin O. Cold winters drive consistent and spatially synchronous 8-year population cycles of cabbage stem flea beetle. J Anim Ecol 2023; 92:594-605. [PMID: 36484622 DOI: 10.1111/1365-2656.13866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 11/29/2022] [Indexed: 12/14/2022]
Abstract
Population cycles have been observed in mammals as well as insects, but consistent population cycling has rarely been documented in agroecosystems and never for a beetle. We analysed the long-term population patterns of the cabbage stem flea beetle Psylliodes chrysocephala in winter oilseed rape over 50 years. Psylliodes chrysocephala larval density from 3045 winter oilseed rape fields in southern Sweden showed strong 8-year population cycles in regional mean density. Fluctuations in larval density were synchronous over time across five subregional populations. Subregional mean environmental variables explained 90.6% of the synchrony in P. chrysocephala populations at the 7-11 year time-scale. The number of days below -10°C showed strong anti-phase coherence with larval densities in the 7-11 year time-scale, such that more cold days resulted in low larval densities. High levels of the North Atlantic Oscillation weather system are coherent and anti-phase with cold weather in Scania, Sweden. At the field-scale, later crop planting date and more cold winter days were associated with decreased overwintering larval density. Warmer autumn temperatures, resulting in greater larval accumulated degree days early in the season, increased overwintering larval density. Despite variation in environmental conditions and crop management, 8-year cycles persisted for cabbage stem flea beetle throughout the 50 years of data collection. Moran effects, influenced by the North Atlantic Oscillation weather patterns, are the primary drivers of this cycle and synchronicity. Insect pest data collected in commercial agriculture fields is an abundant source of long-term data. We show that an agricultural pest can have the same periodic population cycles observed in perennial and unmanaged ecosystems. This unexpected finding has implications for sustainable pest management in agriculture and shows the value of long-term pest monitoring projects as an additional source of time-series data to untangle the drivers of population cycles.
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Affiliation(s)
- Sara E Emery
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.,Department of Wildlife Fish and Conservation Biology, University of California Davis, Davis, California, USA
| | - Maartje Klapwijk
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Roland Sigvald
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Riccardo Bommarco
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Ola Lundin
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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6
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Edwards PD, Boonstra R, Oli MK. An experimental analysis of density dependence in meadow voles: Within-season and delayed effects. Ecology 2023; 104:e4008. [PMID: 36807294 DOI: 10.1002/ecy.4008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 12/26/2022] [Accepted: 01/26/2023] [Indexed: 02/20/2023]
Abstract
Wild mammal populations exhibit a variety of dynamics, ranging from fairly stable with little change in population size over time to high-amplitude cyclic or erratic fluctuations. A persistent question in population ecology is why populations fluctuate as they do. Answering this seemingly simple question has proven to be challenging. Broadly, density-dependent feedback mechanisms should allow populations to grow at low density and slow or halt growth at high density. However, experimental tests of what demographic processes result in density-dependent feedback and on what timescale have proven elusive. Here, we used replicated density perturbation experiments and capture-mark-recapture analyses to test density-dependent population growth in populations of meadow voles (Microtus pennsylvanicus) during the summer breeding season by manipulating founding population density and observing the pattern of survival, reproduction, and population growth. High population density had no consistent effect on survival rates but generally negatively influenced recruitment and population growth rates. However, these density-dependent effects varied within the breeding season and across years. Our study provides evidence that density-dependent feedback mechanisms operate at finer time scales than previously believed and that process, additively with delayed year effects, is key to understanding multiyear population demography.
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Affiliation(s)
- Phoebe D Edwards
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Madan K Oli
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida, USA.,School of Biological Sciences, University of Aberdeen, Aberdeen, UK
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7
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Xie T, Yuan J, Mei L, Li P, Pan R. Hyperoside ameliorates TNF‑α‑induced inflammation, ECM degradation and ER stress‑mediated apoptosis via the SIRT1/NF‑κB and Nrf2/ARE signaling pathways in vitro. Mol Med Rep 2022; 26:260. [PMID: 35730622 PMCID: PMC9260875 DOI: 10.3892/mmr.2022.12776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 06/07/2022] [Indexed: 11/30/2022] Open
Abstract
Intervertebral disc degeneration (IDD) is the main pathogenesis of numerous cases of chronic neck and back pain, and has become the leading cause of spinal-related disability worldwide. Hyperoside is an active flavonoid glycoside that exhibits anti-inflammation, anti-oxidation and anti-apoptosis effects. The purpose of the present study was to investigate the effect of hyperoside on tumor necrosis factor (TNF)-α-induced IDD progression in human nucleus pulposus cells (NPCs) and its potential mechanism. The activity and apoptosis of NPCs were detected by Cell Counting Kit-8 and flow cytometry analyses, respectively. The expression of interleukin (IL)-6 and IL-1β was detected with ELISA kits. Western blotting was used to detect the expression levels of proteins. The results showed that hyperoside effectively alleviated TNF-α-induced NPC apoptosis, and hyperoside treatment inhibited the upregulation of inducible nitric oxide synthase, cyclooxygenase-2, IL-1β and IL-6 in TNF-α-stimulated NPCs. Compared with the findings in the TNF-α group, the intervention of hyperoside attenuated the upregulated expression of aggrecan and collagen II, and downregulated the expressions of matrix metalloproteinase (MMP) 3, MMP13 and a disintegrin and metalloproteinase with thrombospondin motifs 5. In addition, hyperoside upregulated sirtuin-1 (SIRT1) and nuclear factor E2-related factor 2 (Nrf2) protein expression, and inhibition of SIRT1 or Nrf2 signaling reversed the protective effect of hyperoside on TNF-α-induced NPCs. In summary, hyperoside ameliorated TNF-α-induced inflammation, extracellular matrix degradation, and endoplasmic reticulum stress-mediated apoptosis, which may be associated with the regulation of the SIRT1/NF-κB and Nrf2/antioxidant responsive element signaling pathways by hyperoside.
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Affiliation(s)
- Tian Xie
- Department of Orthopedics, Wuhan Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430014, P.R. China
| | - Jun Yuan
- Department of Orthopedics, Wuhan Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430014, P.R. China
| | - Ling Mei
- Department of Orthopedics, Wuhan Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430014, P.R. China
| | - Ping Li
- Department of Orthopedics, Wuhan Hospital of Traditional Chinese Medicine, Wuhan, Hubei 430014, P.R. China
| | - Ruijie Pan
- College of Acupuncture and Bone Injury, Hubei University of Chinese Medicine, Wuhan, Hubei 430061, P.R. China
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8
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Gettler LT, Rosenbaum S, Kuo PX, Sarma MS, Bechayda SA, McDade TW, Kuzawa CW. Evidence for an adolescent sensitive period to family experiences influencing adult male testosterone production. Proc Natl Acad Sci U S A 2022; 119:e2202874119. [PMID: 35639692 PMCID: PMC9191637 DOI: 10.1073/pnas.2202874119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/11/2022] [Indexed: 11/18/2022] Open
Abstract
Across vertebrates, testosterone is an important mediator of reproductive trade-offs, shaping how energy and time are devoted to parenting versus mating/competition. Based on early environments, organisms often calibrate adult hormone production to adjust reproductive strategies. For example, favorable early nutrition predicts higher adult male testosterone in humans, and animal models show that developmental social environments can affect adult testosterone. In humans, fathers’ testosterone often declines with caregiving, yet these patterns vary within and across populations. This may partially trace to early social environments, including caregiving styles and family relationships, which could have formative effects on testosterone production and parenting behaviors. Using data from a multidecade study in the Philippines (n = 966), we tested whether sons’ developmental experiences with their fathers predicted their adult testosterone profiles, including after they became fathers themselves. Sons had lower testosterone as parents if their own fathers lived with them and were involved in childcare during adolescence. We also found a contributing role for adolescent father–son relationships: sons had lower waking testosterone, before and after becoming fathers, if they credited their own fathers with their upbringing and resided with them as adolescents. These findings were not accounted for by the sons’ own parenting and partnering behaviors, which could influence their testosterone. These effects were limited to adolescence: sons’ infancy or childhood experiences did not predict their testosterone as fathers. Our findings link adolescent family experiences to adult testosterone, pointing to a potential pathway related to the intergenerational transmission of biological and behavioral components of reproductive strategies.
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Affiliation(s)
- Lee T. Gettler
- Department of Anthropology, University of Notre Dame, Notre Dame, IN 46556
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556
- William J. Shaw Center for Children and Families, University of Notre Dame, South Bend, IN 46635
| | - Stacy Rosenbaum
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109
| | - Patty X. Kuo
- Department of Child, Youth, and Family Studies, University of Nebraska, Lincoln, NE 68588
| | - Mallika S. Sarma
- Department of Otolaryngology, School of Medicine, The Johns Hopkins University, Baltimore, MD 21218
| | - Sonny Agustin Bechayda
- University of San Carlos Office of Population Studies Foundation, Department of Anthropology, Sociology, and History, University of San Carlos, 6016 Metro Cebu, Philippines
| | - Thomas W. McDade
- Department of Anthropology, Northwestern University, Evanston, IL 60208
- Institute for Policy Research, Northwestern University, Evanston, IL 60208
| | - Christopher W. Kuzawa
- Department of Anthropology, Northwestern University, Evanston, IL 60208
- Institute for Policy Research, Northwestern University, Evanston, IL 60208
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9
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Gonadotropin-inhibitory hormone as a regulator of social interactions in vertebrates. Front Neuroendocrinol 2022; 64:100954. [PMID: 34757092 DOI: 10.1016/j.yfrne.2021.100954] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/12/2021] [Accepted: 10/11/2021] [Indexed: 12/14/2022]
Abstract
The social environment changes circulating hormone levels and expression of social behavior in animals. Social information is perceived by sensory systems, leading to cellular and molecular changes through neural processes. Peripheral reproductive hormone levels are regulated by activity in the hypothalamic-pituitary-gonadal (HPG) axis. Until the end of the last century, the neurochemical systems that convey social information to the HPG axis were not well understood. Gonadotropin-inhibitory hormone (GnIH) was the first hypothalamic neuropeptide shown to inhibit gonadotropin release, in 2000. GnIH is now regarded as a negative upstream regulator of the HPG axis, and it is becoming increasingly evident that it responds to social cues. In addition to controlling reproductive physiology, GnIH seems to modulate the reproductive behavior of animals. Here, we review studies investigating how GnIH neurons respond to social information and describe the mechanisms through which GnIH regulates social behavior.
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10
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Huang S, Li G, Pan Y, Liu J, Zhao J, Zhang X, Lu W, Wan X, Krebs CJ, Wang Z, Han W, Zhang Z. Population variation alters aggression-associated oxytocin and vasopressin expressions in brains of Brandt's voles in field conditions. Front Zool 2021; 18:56. [PMID: 34717666 PMCID: PMC8557550 DOI: 10.1186/s12983-021-00441-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 10/12/2021] [Indexed: 11/29/2022] Open
Abstract
Density-dependent change in aggressive behavior contributes to the population regulation of many small rodents, but the underlying neurological mechanisms have not been examined in field conditions. We hypothesized that crowding stress and aggression-associated oxytocin (OT) and arginine vasopressin (AVP) in specific regions of the brain may be closely related to aggressive behaviors and population changes of small rodents. We analyzed the association of OT and AVP expression, aggressive behavior, and population density of Brandt’s voles in 24 large semi-natural enclosures (0.48 ha each) in Inner Mongolia grassland. We tested the effects of population density on the OT/AVP system and aggressive behavior by experimentally manipulating populations of Brandt’s voles in the grassland enclosures. High density was positively and significantly associated with more aggressive behavior, and increased expression of mRNA and protein of AVP and its receptor, but decreased expression of mRNA and protein of OT and its receptor in specific brain regions of the voles. Our study suggests that changes in OT/AVP expression are likely a result of the increased psychosocial stress that these voles experience during overcrowding, and thus the OT/AVP system can be used as indicators of density-dependent stressors in Brandt’s voles.
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Affiliation(s)
- Shuli Huang
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guoliang Li
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yongliang Pan
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,School of Medicine, Huzhou University, Huzhou, 313000, China
| | - Jing Liu
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jidong Zhao
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xin Zhang
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei Lu
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinrong Wan
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Charles J Krebs
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Zuoxin Wang
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL, 32306-1270, USA
| | - Wenxuan Han
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China
| | - Zhibin Zhang
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China. .,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China.
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11
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Lavergne SG, Krebs CJ, Kenney AJ, Boutin S, Murray D, Palme R, Boonstra R. The impact of variable predation risk on stress in snowshoe hares over the cycle in North America's boreal forest: adjusting to change. Oecologia 2021; 197:71-88. [PMID: 34435235 DOI: 10.1007/s00442-021-05019-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/16/2021] [Indexed: 11/26/2022]
Abstract
The boreal forest is one of the world's ecosystems most affected by global climate warming. The snowshoe hare, its predators, and their population dynamics dominate the mammalian component of the North American boreal forest. Our past research has shown the 9-11-year hare cycle to be predator driven, both directly as virtually all hares that die are killed by their predators, and indirectly through sublethal risk effects on hare stress physiology, behavior, and reproduction. We replicated this research over the entire cycle by measuring changes in predation risk expected to drive changes in chronic stress. We examined changes in hare condition and stress axis function using a hormonal challenge protocol in the late winter of 7 years-spanning all phases of the cycle from the increase through to the low (2014-2020). We simultaneously monitored changes in hare abundance as well as those of their primary predators, lynx and coyotes. Despite observing the expected changes in hare-predator numbers over the cycle, we did not see the predicted changes in chronic stress metrics in the peak and decline phases. Thus, the comprehensive physiological signature indicative of chronic predator-induced stress seen from our previous work was not present in this current cycle. We postulate that hares may now be increasingly showing behavior-mediated rather than stress-mediated responses to their predators. We present evidence that increases in primary productivity have affected boreal community structure and function. We speculate that climate change has caused this major shift in the indirect effects of predation on hares.
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Affiliation(s)
- Sophia G Lavergne
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Charles J Krebs
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Alice J Kenney
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Stan Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Dennis Murray
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Rupert Palme
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada.
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12
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Freeman AR. Female-female reproductive suppression: impacts on signals and behavior. Integr Comp Biol 2021; 61:1827-1840. [PMID: 33871603 DOI: 10.1093/icb/icab027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Female-female reproductive suppression is evident in an array of mammals, including rodents, primates, and carnivores. By suppressing others, breeding females can benefit by reducing competition from other females and their offspring. There are neuroendocrinological changes during suppression which result in altered behavior, reproductive cycling, and communication. This review, which focuses on species in Rodentia, explores the current theoretical frameworks of female-female reproductive suppression, how female presence and rank impacts reproductive suppression, and some of the proposed mechanisms of suppression. Finally, the understudied role of olfactory communication in female-female reproductive suppression is discussed to identify current gaps in our understanding of this topic.
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Affiliation(s)
- Angela R Freeman
- Department of Psychology, Cornell University, 211 Uris Hall, Cornell University, Ithaca, NY 14853
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13
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Montgomery WI. Molecular mechanisms of self-regulation in multiannual rodent populations: Experimental test of an updated hypothesis. J Anim Ecol 2021; 90:780-783. [PMID: 33821481 DOI: 10.1111/1365-2656.13458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 02/20/2021] [Accepted: 02/23/2021] [Indexed: 11/28/2022]
Abstract
IN FOCUS Edwards, P. D., Frenette-Ling, C., Palme, R., & Boonstra, R. (2021). Social density suppresses GnRH expression and reduces reproductivity in voles: A mechanism for population self-regulation. Journal of Animal Ecology, 90, 784-795. Intrinsic population processes are important in the regulation of populations of small rodents, including those which display multiannual cycles. By measuring reproductive parameters, faecal androgen metabolites, and gene expression and DNA methylation in the CNS of juvenile voles, this paper demonstrates that suppression of reproduction occurs in female voles at high density compared to low density in enclosures, and that this maternal, epigenetic effect is also apparent in their offspring. This suggsests that direct density dependence influences reproduction and, hence, immediate rate of population growth, while gene expression mediated by DNA methylation blocking transcription, may have a delayed density-dependent effect in juveniles. Both direct and delayed density dependence are necessary to generate multiannual population cycles. Edwards et al. (2021) break new ground in demonstrating the molecular and physiological basis of variation in population dynamics of small mammals ranging from multiannual cycles to stability that have fascinated researchers for nearly a century.
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Affiliation(s)
- W Ian Montgomery
- Institute of Global Food Security, School of Biological Sciences, Queen's University of Belfast, Belfast, UK
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