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Balčiauskas L, Balčiauskienė L. Insight into Body Condition Variability in Small Mammals. Animals (Basel) 2024; 14:1686. [PMID: 38891733 PMCID: PMC11171198 DOI: 10.3390/ani14111686] [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: 05/08/2024] [Revised: 06/01/2024] [Accepted: 06/03/2024] [Indexed: 06/21/2024] Open
Abstract
The body condition index (BCI) is an indicator of both reproductive success and health in small mammals and might help to understand ecological roles of species. We analyzed BCI data from 28,567 individuals trapped in Lithuania between 1980 and 2023. We compared BCIs between species and examined differences in age groups, gender, and reproductive statuses within each species. Seven out of eighteen species had sample sizes with N < 100. In terms of species, we found that seven of the eight species with the highest average BCIs are granivores or omnivores, which can consume animal-based food at least seasonally. The two contrasting (decreasing or increasing) BCI patterns observed during ontogeny can be related to diet differences among juveniles, subadults, and adult animals. Our results demonstrate that reproductive stress has a negative impact on the BCI of adult females in all analyzed species and nearly all adult males. Although the animals with extremely low BCI consisted mostly of shrews, for the first time we found 23 common and pygmy shrews exhibiting the Chitty effect, i.e., a very high body mass resulting in a BCI > 5.0. This is the first multi-species approach of body condition at middle latitudes. The results increase our understanding of how changing environmental conditions are affecting small mammals.
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Dubiner S, Meiri S, Levin E. Seasonal remodeling of visceral organs in the invasive desert gecko Tarentola annularis. Integr Zool 2024. [PMID: 38348500 DOI: 10.1111/1749-4877.12814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
In winter, many reptiles have a period of inactivity ("brumation"). During brumation there is no energetic intake, therefore there would be an advantage to reducing energetic expenditure. The size of energetically costly organs, a major determinant of metabolic rate, is known to be flexible in many tetrapods. Seasonal plasticity of organ size could serve as both an energy-saving mechanism and a source of nutrients for brumating reptiles. We studied a population of an invasive gecko, Tarentola annularis, to test for seasonal changes in activity, metabolic rate, and mass of various organs. The observed period of inactivity was December-February. Standard metabolic rates during the activity season were 1.85 times higher than in brumating individuals. This may be attributed to decreased organ mass during winter: heart mass decreased by 37%, stomach mass by 25%, and liver mass by 69%. Interestingly, testes mass increased by 100% during winter, likely in preparation for the breeding season, suggesting that males prioritize breeding over other functions upon return to activity. The size of the kidneys and lungs remained constant. Organ atrophy occurred only after geckos reduced their activity, so we hypothesize that organ mass changes in response to (rather than in anticipation of) cold winter temperatures and the associated fasting. Degradation of visceral organs can maintain energy demands in times of low supply, and catabolism of the protein from these organs can serve as a source of both energy and water during brumation. These findings bring us closer to a mechanistic understanding of reptiles' physiological adaptations to environmental changes.
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Affiliation(s)
- Shahar Dubiner
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Shai Meiri
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- The Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel
| | - Eran Levin
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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3
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McGrosky A, Pontzer H. The fire of evolution: energy expenditure and ecology in primates and other endotherms. J Exp Biol 2023; 226:297166. [PMID: 36916459 DOI: 10.1242/jeb.245272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Total energy expenditure (TEE) represents the total energy allocated to growth, reproduction and body maintenance, as well as the energy expended on physical activity. Early experimental work in animal energetics focused on the costs of specific tasks (basal metabolic rate, locomotion, reproduction), while determination of TEE was limited to estimates from activity budgets or measurements of subjects confined to metabolic chambers. Advances in recent decades have enabled measures of TEE in free-living animals, challenging traditional additive approaches to understanding animal energy budgets. Variation in lifestyle and activity level can impact individuals' TEE on short time scales, but interspecific differences in TEE are largely shaped by evolution. Here, we review work on energy expenditure across the animal kingdom, with a particular focus on endotherms, and examine recent advances in primate energetics. Relative to other placental mammals, primates have low TEE, which may drive their slow pace of life and be an evolved response to the challenges presented by their ecologies and environments. TEE variation among hominoid primates appears to reflect adaptive shifts in energy throughput and allocation in response to ecological pressures. As the taxonomic breadth and depth of TEE data expand, we will be able to test additional hypotheses about how energy budgets are shaped by environmental pressures and explore the more proximal mechanisms that drive intra-specific variation in energy expenditure.
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Affiliation(s)
- Amanda McGrosky
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA
| | - Herman Pontzer
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA.,Duke Global Health Institute, Durham, NC 27708, USA
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Cossette ML, Stewart DT, Haghani A, Zoller JA, Shafer ABA, Horvath S. Epigenetics and island-mainland divergence in an insectivorous small mammal. Mol Ecol 2023; 32:152-166. [PMID: 36226847 DOI: 10.1111/mec.16735] [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] [Received: 04/15/2022] [Revised: 09/20/2022] [Accepted: 09/28/2022] [Indexed: 12/29/2022]
Abstract
Geographically isolated populations, specifically island-mainland counterparts, tend to exhibit phenotypic variation in many species. The so-called island syndrome occurs when different environmental pressures lead to insular divergence from mainland populations. This phenomenon can be seen in an island population of Nova Scotia masked shrews (Sorex cinereus), which have developed a specialized feeding habit and digestive enzyme compared to their mainland counterparts. Epigenetic modifications, such as DNA methylation (DNAm), can impact phenotypes by altering gene expression without changing the DNA sequence. Here, we used a de novo masked shrew genome assembly and a mammalian methylation array profiling 37 thousand conserved CpGs to investigate morphological and DNA methylation patterns between island and mainland populations. Island shrews were morphologically and epigenetically different than their mainland counterparts, exhibiting a smaller body size. A gene ontology enrichment analyses of differentially methylated CpGs implicated developmental and digestive system related pathways. Based on our shrew epigenetic clock, island shrews might also be aging faster than their mainland counterparts. This study provides novel insight on phenotypic and epigenetic divergence in island-mainland mammal populations and suggests an underlying role of methylation in island-mainland divergence.
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Affiliation(s)
- Marie-Laurence Cossette
- Department of Environmental Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada
| | - Donald T Stewart
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
| | - Amin Haghani
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Joseph A Zoller
- Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, California, USA
| | - Aaron B A Shafer
- Department of Environmental Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada
- Department of Forensic Science, Trent University, Peterborough, Ontario, Canada
| | - Steve Horvath
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA
- Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, California, USA
- Altos Labs, San Diego, California, USA
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Taylor JRE, Muturi M, Lázaro J, Zub K, Dechmann DKN. Fifty years of data show the effects of climate on overall skull size and the extent of seasonal reversible skull size changes (Dehnel's phenomenon) in the common shrew. Ecol Evol 2022; 12:e9447. [PMID: 36311390 PMCID: PMC9609440 DOI: 10.1002/ece3.9447] [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: 01/24/2022] [Revised: 09/22/2022] [Accepted: 09/30/2022] [Indexed: 11/18/2022] Open
Abstract
Global climate change affects many aspects of biology and has been shown to cause body size changes in animals. However, suitable datasets allowing the analysis of long‐term relationships between body size, climate, and its effects are rare. The size of the skull is often used as a proxy for overall body size. Skull size does not change much in fully grown vertebrates; however, some high‐metabolic small mammals shrink in winter and regrow in spring, including their skull and brain. This is thought to be a winter adaptation, as a smaller brain size reduces energy requirements. Climate could thus affect not only the overall size but also the pattern of the size change, that is, Dehnel's phenomenon, in these animals. We assessed the impact of the changes in climate on the overall skull size and the different stages of Dehnel's phenomenon in skulls of the common shrew, Sorex araneus, collected over 50 years in the Białowieża Forest, E Poland. Overall skull size decreased, along with increasing temperatures and decreasing soil moisture, which affected the availability of the shrews' main food source, earthworms. The skulls of males were larger than those of females, but the degree of the decrease in size did not differ between sexes. The magnitude of Dehnel's phenomenon increased over time, indicating an increasing selection pressure on animals in winter. Overall, climate clearly affected the common shrew's overall size as well as its seasonal size changes. With the current acceleration in climate change, the effects on the populations of this cold‐adapted species may be quite severe in a large part of its distribution range.
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Affiliation(s)
| | - Marion Muturi
- Department of MigrationMax Planck Institute of Animal BehaviorRadolfzellGermany,Department of BiologyUniversity of KonstanzKonstanzGermany
| | - Javier Lázaro
- Department of MigrationMax Planck Institute of Animal BehaviorRadolfzellGermany,Department of BiologyUniversity of KonstanzKonstanzGermany
| | - Karol Zub
- Mammal Research InstitutePolish Academy of SciencesBiałowieżaPoland
| | - Dina K. N. Dechmann
- Department of MigrationMax Planck Institute of Animal BehaviorRadolfzellGermany,Department of BiologyUniversity of KonstanzKonstanzGermany
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Nováková L, Lázaro J, Muturi M, Dullin C, Dechmann DKN. Winter conditions, not resource availability alone, may drive reversible seasonal skull size changes in moles. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220652. [PMID: 36133148 PMCID: PMC9449468 DOI: 10.1098/rsos.220652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/15/2022] [Indexed: 05/30/2023]
Abstract
Seasonal changes in the environment can lead to astonishing adaptations. A few small mammals with exceptionally high metabolisms have evolved a particularly extreme strategy: they shrink before winter and regrow in spring, including changes of greater than 20% in skull and brain size. Whether this process is an adaptation to seasonal climates, resource availability or both remains unclear. We show that European moles (Talpa europaea) also decrease skull size in winter. As resources for closely related Iberian moles (Talpa occidentalis) are lowest in summer, we predicted they should shift the timing of size changes. Instead, they do not change size at all. We conclude that in moles, seasonal decrease and regrowth of skull size is an adaptation to winter climate and not to a changing resource landscape alone. We not only describe this phenomenon in yet another taxon, but take an important step towards a better understanding of this enigmatic cycle.
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Affiliation(s)
- Lucie Nováková
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, Radolfzell 78315, Germany
- Department of Zoology, Charles University, Viničná 7, Prague 128 00, Czech Republic
| | - Javier Lázaro
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, Radolfzell 78315, Germany
- Javier Lázaro Scientific and Wildlife Illustration, Gere Sopra 17, Noasca 10080, Italy
| | - Marion Muturi
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, Radolfzell 78315, Germany
| | - Christian Dullin
- Department for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Robert-Koch-Straße 40, Goettingen 37075, Germany
- Department Translational Molecular Imaging, Max Planck Institute for Multidisciplinary Sciences, Herman-Rein-Straße 3, Goettingen 37075, Germany
- Department for Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 420, Heidelberg 69120, Germany
| | - Dina K. N. Dechmann
- Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, Radolfzell 78315, Germany
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
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Dissimilar use of an external heat source for thermoregulation by shrews from different geographic regions. J Therm Biol 2022; 104:103193. [DOI: 10.1016/j.jtherbio.2022.103193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 01/19/2022] [Accepted: 01/21/2022] [Indexed: 11/18/2022]
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Abstract
Lázaro and Dechmann explain how some mammals that live through harsh winters exhibit seasonal shrinkage of the brain and skull, a process called Dehnel's phenomenon, which helps to spare energy during times of food shortage and high energetic demands.
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Affiliation(s)
- Javier Lázaro
- Max Planck Institute of Animal Behavior, Radolfzell, Germany; Department of Biology, University of Konstanz, Konstanz, Germany.
| | - Dina K N Dechmann
- Max Planck Institute of Animal Behavior, Radolfzell, Germany; Department of Biology, University of Konstanz, Konstanz, Germany
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Lázaro J, Nováková L, Hertel M, Taylor JRE, Muturi M, Zub K, Dechmann DKN. Geographic patterns in seasonal changes of body mass, skull, and brain size of common shrews. Ecol Evol 2021; 11:2431-2448. [PMID: 33767812 PMCID: PMC7981214 DOI: 10.1002/ece3.7238] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/20/2020] [Accepted: 12/04/2020] [Indexed: 02/03/2023] Open
Abstract
Some small mammals exhibit Dehnel's Phenomenon, a drastic decrease in body mass, braincase, and brain size from summer to winter, followed by a regrowth in spring. This is accompanied by a re-organization of the brain and changes in other organs. The evolutionary link between these changes and seasonality remains unclear, although the intensity of change varies between locations as the phenomenon is thought to lead to energy savings during winter.Here we explored geographic variation of the intensity of Dehnel's Phenomenon in Sorex araneus. We compiled literature on seasonal changes in braincase size, brain, and body mass, supplemented by our own data from Poland, Germany, and Czech Republic.We analyzed the effect of geographic and climate variables on the intensity of change and patterns of brain re-organization.From summer to winter, the braincase height decreased by 13%, followed by 10% regrowth in spring. For body mass, the changes were -21%/+82%, respectively. Changes increased toward northeast. Several climate variables were correlated with these transformations, confirming a link of the intensity of the changes with environmental conditions. This relationship differed for the decrease versus regrowth, suggesting that they may have evolved under different selective pressures.We found no geographic trends explaining variability in the brain mass changes although they were similar (-21%/+10%) to those of the braincase size. Underlying patterns of change in brain organization in northeastern Poland were almost identical to the pattern observed in southern Germany. This indicates that local habitat characteristics may play a more important role in determining brain structure than broad scale geographic conditions.We discuss the techniques and criteria used for studying this phenomenon, as well as its potential presence in other taxa and the importance of distinguishing it from other kinds of seasonal variation.
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Affiliation(s)
- Javier Lázaro
- Max Planck Institute of Animal BehaviorRadolfzellGermany
- Department of BiologyUniversity of KonstanzKonstanzGermany
| | - Lucie Nováková
- Department of ZoologyFaculty of ScienceCharles UniversityPrague 2Czech Republic
| | - Moritz Hertel
- Department of Behavioural NeurobiologyMax Planck Institute for OrnithologySeewiesenGermany
| | | | - Marion Muturi
- Max Planck Institute of Animal BehaviorRadolfzellGermany
| | - Karol Zub
- Mammal Research Institute Polish Academy of SciencesBiałowieżaPoland
| | - Dina K. N. Dechmann
- Max Planck Institute of Animal BehaviorRadolfzellGermany
- Department of BiologyUniversity of KonstanzKonstanzGermany
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10
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van der Meer J. Production efficiency differences between poikilotherms and homeotherms have little to do with metabolic rate. Ecol Lett 2021; 24:219-226. [PMID: 33166039 PMCID: PMC7821020 DOI: 10.1111/ele.13633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/02/2020] [Accepted: 09/29/2020] [Indexed: 11/29/2022]
Abstract
The idea that homeothermic populations have a much lower production efficiency than poikilothermic populations, because warm-blooded individuals exhibit a higher metabolic rate per gram of body weight, is widespread. Using Dynamic Energy Budget (DEB) theory, in combination with a modelling exercise based on empirical data for over 1000 different species, I show that this idea is wrong. Production efficiency of homeothermic individuals can be as high or even higher than that of poikilotherms. Differences observed are merely the result of different energy allocation and life-history strategies. Birds, for example have evolved to invest a large proportion of the assimilated energy in somatic growth and maintenance and to mature at a relatively large size. Therefore, their production efficiency as an adult is low. This low reproduction efficiency combined with a low mortality rate causes the low production efficiency of bird (and other homeothermic) populations.
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Affiliation(s)
- Jaap van der Meer
- Wageningen Marine ResearchP.O. Box 57Den Helder1780 ABThe Netherlands
- Department of Ecological ScienceVrije Universiteit AmsterdamAmsterdamThe Netherlands
- Department of Coastal SystemsNIOZ Royal Netherlands Institute for Sea ResearchDen BurgThe Netherlands
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