scholarly journals The genetic basis and fitness consequences of sperm midpiece size in deer mice

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Heidi S. Fisher ◽  
Emily Jacobs-Palmer ◽  
Jean-Marc Lassance ◽  
Hopi E. Hoekstra
Keyword(s):  
Genetic Basis ◽  
Deer Mice ◽  
Fitness Consequences ◽  
Sperm Midpiece

scholarly journals The genetics of morphological and behavioural island traits in deer mice

2019 ◽  
Vol 286 (1914) ◽  
pp. 20191697 ◽  
Author(s):  
Felix Baier ◽  
Hopi E. Hoekstra
Keyword(s):  
Genetic Basis ◽  
Genetic Effect ◽  
Deer Mice ◽  
Plastic Response ◽  
Common Environment ◽  
Environmental Extremes ◽  
Laboratory Colonies ◽  
Island Syndrome ◽  
Heritable Change ◽  
Plastic Responses

Animals on islands often exhibit dramatic differences in morphology and behaviour compared with mainland individuals, a phenomenon known as the ‘island syndrome’. These differences are thought to be adaptations to island environments, but the extent to which they have a genetic basis or instead represent plastic responses to environmental extremes is often unknown. Here, we revisit a classic case of island syndrome in deer mice ( Peromyscus maniculatus ) from British Columbia. We first show that Saturna Island mice and those from neighbouring islands are approximately 35% (approx. 5 g) heavier than mainland mice and diverged approximately 10 000 years ago. We then establish laboratory colonies and find that Saturna Island mice are heavier both because they are longer and have disproportionately more lean mass. These trait differences are maintained in second-generation captive-born mice raised in a common environment. In addition, island–mainland hybrids reveal a maternal genetic effect on body weight. Using behavioural testing in the laboratory, we also find that wild-caught island mice are less aggressive than mainland mice; however, laboratory-raised mice born to these founders do not differ in aggression. Together, our results reveal that these mice have different responses to the environmental conditions on islands—a heritable change in a morphological trait and a plastic response in a behavioural trait.

Evaluating body condition in small mammals

2001 ◽  
Vol 79 (6) ◽  
pp. 1021-1029 ◽  
Author(s):  
A I Schulte-Hostedde ◽  
J S Millar ◽  
G J Hickling
Keyword(s):  
Body Condition ◽  
Small Mammals ◽  
Isotope Dilution ◽  
Condition Index ◽  
Dry Mass ◽  
Fat Content ◽  
Body Water ◽  
Deer Mice ◽  
Fitness Consequences ◽  
Neotoma Cinerea

Body condition (energy reserves) can have important fitness consequences. Measuring condition of live animals is typically done by regressing body mass on measures of body size and using the residuals as an index of condition. The validity of this condition index was evaluated by determining whether it reflected measured fat content of five species of small mammals (yellow-pine chipmunks (Tamias amoenus Allen), bushy-tailed wood rats (Neotoma cinerea Ord), deer mice (Peromyscus maniculatus Ord), red-backed voles (Clethrionomys gapperi Vigors), and meadow voles (Microtus pennsylvanicus Ord)). We also determined whether body water could predict fat content, enabling the use of hydrogen-isotope dilution for estimating condition. For all five species, condition estimates weakly predicted fat content and more accurately predicted variation in lean dry mass and water content. The relationship between body water and fat content was inconsistent among the five species, discouraging against the general use of isotope dilution in these animals. Although ecologically important, these indices are best interpreted as explaining variation in all constituents of body composition.

scholarly journals Extreme developmental instability associated with wing plasticity in pea aphids

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201349
Author(s):  
Rachel E. Hammelman ◽  
Carrie L. Heusinkveld ◽  
Emily T. Hung ◽  
Alydia Meinecke ◽  
Benjamin J. Parker ◽  
...  
Keyword(s):  
Developmental Biology ◽  
Genetic Basis ◽  
Phenotypic Diversity ◽  
Evolutionary Developmental Biology ◽  
Developmental Instability ◽  
Wing Development ◽  
Alternative Phenotypes ◽  
Fitness Consequences ◽  
Pea Aphids ◽  
Widespread Phenomenon

A key focus of evolutionary developmental biology is on how phenotypic diversity is generated. In particular, both plasticity and developmental instability contribute to phenotypic variation among genetically identical individuals, but the interactions between the two phenomena and their general fitness impacts are unclear. We discovered a striking example of asymmetry in pea aphids: the presence of wings on one side and the complete or partial absence of wings on the opposite side. We used this asymmetric phenotype to study the connection between plasticity, developmental instability and fitness. We found that this asymmetric wing development (i) occurred equally on both sides and thus is a developmental instability; (ii) is present in some genetically unique lines but not others, and thus has a genetic basis; and (iii) has intermediate levels of fecundity, and thus does not necessarily have negative fitness consequences. We conclude that this dramatic asymmetry may arise from incomplete switching between developmental targets, linking plasticity and developmental instability. We suspect that what we have observed may be a more widespread phenomenon, occurring across species that routinely produce distinct, alternative phenotypes.

Effect of reproductive function on cold tolerance in deer mice

1992 ◽  
Vol 263 (4) ◽  
pp. R820-R826 ◽  
Author(s):  
J. L. Blank ◽  
T. Ruf
Keyword(s):  
Cold Tolerance ◽  
Heat Production ◽  
Genetic Basis ◽  
Functional Relationship ◽  
Reproductive Function ◽  
Day Length ◽  
Deer Mice ◽  
Long Day ◽  
Breeding Populations ◽  
Natural Breeding

Thermoregulatory responses were evaluated in male deer mice (Peromyscus maniculatus nebrascensis) after exposure to short photoperiod and either warm or cold ambient temperature (T(a)). Deer mice were chosen for this study because males exhibit differential reproductive responses to short day length (SD); this difference has a genetic basis, and both phenotypes are found within natural breeding populations. Deer mice undergoing SD-induced gonadal regression significantly improved their cold limit to -32.9 degrees C after exposure to SD/warm T(a) and to -47.4 degrees C after SD/cold T(a) exposure, relative to long day length/warm T(a) controls (-17.4 degrees C). In contrast, deer mice maintaining reproductive function despite SD exposure significantly improved cold limit to -27.2 degrees C only after exposure to SD/cold T(a), relative to controls (-16.3 degrees C). Maximum norepinephrine-induced nonshivering thermogenesis (NST) did not vary with reproductive state, indicating differences in cold tolerance were not due to capacity to produce heat by NST. Comparison between phenotypes of heat production during cold tolerance tests indicated that greater cold tolerance among mice exhibiting SD-induced gonadal regression can be accounted for by 1) lower rates of heat loss and 2) greater improvement of heat production. These findings suggest a functional relationship between reproductive function and seasonal thermoregulatory adjustments and indicate a significant cost to breeding during the winter months.

scholarly journals The evolution of group differences in changing environments

PLoS Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. e3001072
Author(s):  
Arbel Harpak ◽  
Molly Przeworski
Keyword(s):  
Environmental Effects ◽  
Complex Traits ◽  
Genetic Basis ◽  
Rapid Evolution ◽  
Group Differences ◽  
Stabilizing Selection ◽  
Trait Variation ◽  
Fitness Consequences ◽  
The Face ◽  
Selection For

The selection pressures that have shaped the evolution of complex traits in humans remain largely unknown, and in some contexts highly contentious, perhaps above all where they concern mean trait differences among groups. To date, the discussion has focused on whether such group differences have any genetic basis, and if so, whether they are without fitness consequences and arose via random genetic drift, or whether they were driven by selection for different trait optima in different environments. Here, we highlight a plausible alternative: that many complex traits evolve under stabilizing selection in the face of shifting environmental effects. Under this scenario, there will be rapid evolution at the loci that contribute to trait variation, even when the trait optimum remains the same. These considerations underscore the strong assumptions about environmental effects that are required in ascribing trait differences among groups to genetic differences.

scholarly journals The genetic basis and fitness consequences of sperm midpiece size in deer mice

2016 ◽  
Author(s):  
Heidi S. Fisher ◽  
Emily Jacobs-Palmer ◽  
Jean-Marc Lassance ◽  
Hopi E. Hoekstra
Keyword(s):  
Swimming Performance ◽  
Rapid Evolution ◽  
Reproductive Traits ◽  
Forward Genetics ◽  
Regulatory Subunit ◽  
Deer Mice ◽  
Male Reproductive Success ◽  
Monogamous Species ◽  
Sperm Midpiece ◽  
Genetic Mechanisms

An extraordinary array of reproductive traits vary among species, yet the genetic mechanisms that enable divergence, often over short evolutionary timescales, remain elusive. Here we examine two sister-species ofPeromyscusmice with divergent mating systems. We find that the promiscuous species produces sperm with longer midpiece than the monogamous species, and midpiece size correlates positively with competitive ability and swimming performance. Using forward genetics, we identify a gene associated with midpiece length:Prkar1a, which encodes the R1α regulatory subunit of PKA. R1α localizes to midpiece inPeromyscusand is differentially expressed in mature sperm of the two species yet is similarly abundant in the testis. We also show that genetic variation at this locus accurately predicts male reproductive success. Our findings suggest that rapid evolution of reproductive traits can occur through cell type-specific changes to ubiquitously expressed genes and have an important effect on fitness.

scholarly journals Inbred or Outbred? Genetic diversity in laboratory rodent colonies

2017 ◽  
Author(s):  
Thomas D. Brekke ◽  
Katherine A. Steele ◽  
John F. Mulley
Keyword(s):  
Genetic Diversity ◽  
Genetic Divergence ◽  
Genetic Basis ◽  
High Throughput Sequencing ◽  
Meriones Unguiculatus ◽  
Biological Research ◽  
Deer Mice ◽  
Replication Crisis ◽  
Genetic Crossing ◽  
Very High

ABSTRACTNon-model rodents are widely used as subjects for both basic and applied biological research, but the genetic diversity of the study individuals is rarely quantified. University-housed colonies tend to be small and subject to founder effects and genetic drift and so may be highly inbred or show substantial genetic divergence from other colonies, even those derived from the same source. Disregard for the levels of genetic diversity in an animal colony may result in a failure to replicate results if a different colony is used to repeat an experiment, as different colonies may have fixed alternative variants. Here we use high throughput sequencing to demonstrate genetic divergence in three isolated colonies of Mongolian gerbil (Meriones unguiculatus) even though they were all established recently from the same source. We also show that genetic diversity in allegedly ‘outbred’ colonies of non-model rodents (gerbils, hamsters, house mice, and deer mice) varies considerably from nearly no segregating diversity, to very high levels of polymorphism. We conclude that genetic divergence in isolated colonies may play an important role in the ‘replication crisis’. In a more positive light, divergent rodent colonies represent an opportunity to leverage genetically distinct individuals in genetic crossing experiments. In sum, awareness of the genetic diversity of an animal colony is paramount as it allows researchers to properly replicate experiments and also to capitalize on other, genetically distinct individuals to explore the genetic basis of a trait.

scholarly journals The genetics of morphological and behavioural island traits in deer mice

2018 ◽  
Author(s):  
Felix Baier ◽  
Hopi E. Hoekstra
Keyword(s):  
Body Weight ◽  
Lean Mass ◽  
Genetic Basis ◽  
Genetic Effect ◽  
Deer Mice ◽  
Common Environment ◽  
Environmental Extremes ◽  
Laboratory Colonies ◽  
Island Syndrome ◽  
Plastic Responses

ABSTRACTAnimals on islands often exhibit dramatic differences in morphology and behaviour compared to mainland individuals, a phenomenon known as the “island syndrome”. These differences are thought to be adaptations to island environments, but the extent to which they have a genetic basis or instead represent plastic responses to environmental extremes is often unknown. Here, we revisit a classic case of island syndrome in deer mice (Peromyscus maniculatus) from British Columbia. We first show that Saturna Island mice and those from neighbouring islands are ∼35% (∼5g) heavier than mainland mice and diverged approximately 10 thousand years ago. We then established laboratory colonies and find that Saturna Island mice are heavier both because they are longer and have disproportionately more lean mass. These trait differences are maintained in second-generation captive-born mice raised in a common environment. In addition, island-mainland hybrids reveal a maternal genetic effect on body weight. Using behavioural testing in the lab, we also find that wild-caught island mice are less aggressive than mainland mice; however, lab-raised mice born to these founders do not differ in aggression. Together, our results reveal that these mice respond differently to environmental conditions on islands – evolving both heritable changes in a morphological trait and also expressing a plastic phenotypic response in a behavioural trait.

An Ultrastructural Comparison of Hepatocytes from ADH+ and ADH−Peromyscus Maniculatus

1996 ◽  
Vol 54 ◽  
pp. 30-31
Author(s):  
J. T. Ellzey ◽  
D. Borunda ◽  
B. P. Stewart
Keyword(s):  
South Carolina ◽  
Adult Male ◽  
Uranyl Acetate ◽  
Model System ◽  
Deer Mice ◽  
En Bloc ◽  
Genetic Stock ◽  
Hepes Buffer ◽  
Transmission Electron ◽  
Color Scanner

Genetically alcohol deficient deer mice (ADHN/ADHN) (obtained from the Peromyscus Genetic Stock Center, Univ. of South Carolina) lack hepatic cytosolic alcohol dehydrogenase. In order to determine if these deer mice would provide a model system for an ultrastructural study of the effects of ethanol on hepatocyte organelles, 75 micrographs of ADH+ adult male deer mice (n=5) were compared with 75 micrographs of ADH− adult male deer mice (n=5). A morphometric analysis of mitochondrial and peroxisomal parameters was undertaken.The livers were perfused with 0.1M HEPES buffer followed by 0.25% glutaraldehyde and 2% sucrose in 0.1M HEPES buffer (4C), removed, weighed and fixed by immersion in 2.5% glutaraldehyde in 0.1M HEPES buffer, pH 7.4, followed by a 3,3’ diaminobenzidine (DAB) incubation, postfixation with 2% OsO4, en bloc staining with 1% uranyl acetate in 0.025M maleate-NaOH buffer, dehydrated, embedded in Poly/Bed 812-BDMA epon resin, sectioned and poststained with uranyl acetate and lead citrate. Photographs were taken on a Zeiss EM-10 transmission electron microscope, scanned with a Howtek personal color scanner, analyzed with OPTIMAS 4.02 software on a Gateway2000 4DX2-66V personal computer and stored in Excel 4.0.

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