scholarly journals Seeing spots: quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes (Giraffa camelopardalis)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5690 ◽  
Author(s):  
Derek E. Lee ◽  
Douglas R. Cavener ◽  
Monica L. Bond
Keyword(s):  
Significant Variation ◽  
Genetic Architecture ◽  
Spot Size ◽  
Juvenile Survival ◽  
Spot Pattern ◽  
Adaptive Value ◽  
Fitness Consequences ◽  
Coat Pattern ◽  
Trait Measurement ◽  
Phenotypic Groups

Polymorphic phenotypes of mammalian coat coloration have been important to the study of genetics and evolution, but less is known about the inheritance and fitness consequences of individual variation in complex coat pattern traits such as spots and stripes. Giraffe coat markings are highly complex and variable and it has been hypothesized that variation in coat patterns most likely affects fitness by camouflaging neonates against visually hunting predators. We quantified complex coat pattern traits of wild Masai giraffes using image analysis software, determined the similarity of spot pattern traits between mother and offspring, and assessed whether variation in spot pattern traits was related to fitness as measured by juvenile survival. The methods we described could comprise a framework for objective quantification of complex mammal coat pattern traits based on photographic coat pattern data. We demonstrated that some characteristics of giraffe coat spot shape were likely to be heritable, as measured by mother-offspring regression. We found significant variation in juvenile survival among phenotypic groups of neonates defined by multivariate clustering based on spot trait measurement variables. We also found significant variation in neonatal survival associated with spot size and shape covariates. Larger spots (smaller number of spots) and irregularly shaped or rounder spots (smaller aspect ratio) were correlated with increased survival. These findings will inform investigations into developmental and genetic architecture of complex mammal coat patterns and their adaptive value.

scholarly journals Seeing spots: Measuring, quantifying heritability, and assessing fitness consequences of coat pattern traits in a wild population of giraffes (Giraffa camelopardalis)

2017 ◽  
Author(s):  
Derek E. Lee ◽  
Douglas R. Cavener ◽  
Monica L. Bond
Keyword(s):  
Coat Color ◽  
Adult Survival ◽  
Stabilizing Selection ◽  
Juvenile Survival ◽  
Spot Pattern ◽  
Trait Variation ◽  
Fitness Consequences ◽  
Coat Pattern ◽  
Study Population

ABSTRACTPolymorphic phenotypes of mammalian coat color have been important to the study of genetics and evolution, but little is known about the heritability and fitness consequences of variation in complex coat pattern traits in wild populations. Understanding the current evolution of coat patterns requires reliably measuring traits, quantifying heritability of the traits, and identifying the fitness consequences of specific phenotypes. Giraffe coat markings are highly variable and it has been hypothesized that variation in coat patterns most likely affects fitness by camouflaging neonates against predators. We quantified spot pattern traits of wild Masai giraffes using image analysis software, determined whether spot pattern traits were heritable, and assessed whether variation in heritable spot pattern traits was related to fitness as measured by juvenile survival. The methods we described comprise a framework for objective quantification of mammalian coat pattern traits based on photographic coat pattern data. We demonstrated that characteristics of giraffe coat spot shape are heritable. We did not find evidence for juvenile survival consequences of variation in spot traits, suggesting that spot traits are currently not under strong directional, disruptive, or stabilizing selection for neonate camouflage in our study population, but our sample size could not detect small differences in survival. Spot trait variation also may be more relevant to other components of fitness, such as adult survival or fecundity. We hope this case study will inspire further investigations of coat pattern traits.

scholarly journals Genetic architecture and lifetime dynamics of inbreeding depression in a wild mammal

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
M. A. Stoffel ◽  
S. E. Johnston ◽  
J. G. Pilkington ◽  
J. M. Pemberton
Keyword(s):  
Inbreeding Depression ◽  
Genetic Architecture ◽  
Wild Populations ◽  
Fitness Component ◽  
Wild Mammal ◽  
Life History Data ◽  
Fitness Consequences ◽  
Genome Wide ◽  
A Genome

AbstractInbreeding depression is ubiquitous, but we still know little about its genetic architecture and precise effects in wild populations. Here, we combine long-term life-history data with 417 K imputed SNP genotypes for 5952 wild Soay sheep to explore inbreeding depression on a key fitness component, annual survival. Inbreeding manifests in long runs of homozygosity (ROH), which make up nearly half of the genome in the most inbred individuals. The ROH landscape varies widely across the genome, with islands where up to 87% and deserts where only 4% of individuals have ROH. The fitness consequences of inbreeding are severe; a 10% increase in individual inbreeding FROH is associated with a 60% reduction in the odds of survival in lambs, though inbreeding depression decreases with age. Finally, a genome-wide association scan on ROH shows that many loci with small effects and five loci with larger effects contribute to inbreeding depression in survival.

scholarly journals The Evolutionary Genomics of Serpentine Adaptation

2020 ◽  
Vol 11 ◽  
Author(s):  
Veronika Konečná ◽  
Levi Yant ◽  
Filip Kolář
Keyword(s):  
Model Systems ◽  
Evolutionary Genomics ◽  
Ancestral Polymorphism ◽  
Phenotypic Effect ◽  
Nutrient Contents ◽  
Adaptive Value ◽  
Fitness Consequences ◽  
Evolutionary Genomic ◽  
Genomic Basis ◽  
Perfect Storm

Serpentine barrens are among the most challenging settings for plant life. Representing a perfect storm of hazards, serpentines consist of broadly skewed elemental profiles, including abundant toxic metals and low nutrient contents on drought-prone, patchily distributed substrates. Accordingly, plants that can tolerate the challenges of serpentine have fascinated biologists for decades, yielding important insights into adaptation to novel ecologies through physiological change. Here we highlight recent progress from studies which demonstrate the power of serpentine as a model for the genomics of adaptation. Given the moderate – but still tractable – complexity presented by the mix of hazards on serpentine, these venues are well-suited for the experimental inquiry of adaptation both in natural and manipulated conditions. Moreover, the island-like distribution of serpentines across landscapes provides abundant natural replicates, offering power to evolutionary genomic inference. Exciting recent insights into the genomic basis of serpentine adaptation point to a partly shared basis that involves sampling from common allele pools available from retained ancestral polymorphism or via gene flow. However, a lack of integrated studies deconstructing complex adaptations and linking candidate alleles with fitness consequences leaves room for much deeper exploration. Thus, we still seek the crucial direct link between the phenotypic effect of candidate alleles and their measured adaptive value – a prize that is exceedingly rare to achieve in any study of adaptation. We expect that closing this gap is not far off using the promising model systems described here.

Mechanical leaf damage causes localized, but not systemic, changes in leaf movement behavior of the Sensitive Plant, Mimosa pudica (Fabaceae) L.

Botany ◽  
2013 ◽  
Vol 91 (1) ◽  
pp. 43-47 ◽  
Author(s):  
James F. Cahill ◽  
Tan Bao ◽  
Megan Maloney ◽  
Carina Kolenosky
Keyword(s):  
Mechanical Damage ◽  
Leaf Damage ◽  
Movement Behavior ◽  
Leaf Movement ◽  
Mimosa Pudica ◽  
Defensive Strategy ◽  
Plant Body ◽  
Adaptive Value ◽  
Fitness Consequences ◽  
Assay Time

A small number of species, including Mimosa pudica, use rapid leaf movement as a presumptive defensive strategy. How movement-based defenses change in response to mechanical damage and whether changes are localized or systemic is unknown. This is in contrast to a substantial literature describing how mechanical leaf damage can cause morphological and chemical responses within a diversity of plant species. Depending on the species and the stimuli, these chemical and morphological responses can be localized to the tissues damaged or systemic throughout the plant body. Here we report the results of a small experiment designed to test the following: (i) whether mechanical leaf damage influences subsequent leaf closure behavior, and (ii) whether changes were systemic or localized. To do this, we scored leaves using a behavioral assay (time-to-reopen leaves following a subsequent touch stimuli) for several days before and following mechanical damage. Leaves above and below the damaged leaf were observed, on damaged and undamaged plants, allowing us to assess whether any change was systemic. We found leaf damage caused strong localized effects, greatly increasing the time-to-reopen of the damaged, but not adjacent, leaves. Neither the physiological cause nor fitness consequences of this behavioral shift are known. Interestingly, this altered behavior resulted in damaged leaves remaining “hidden” longer than undamaged leaves. If leaf closure reduces risk of herbivory, there could be adaptive value, analogous to inducible chemical and morphological defenses.

scholarly journals Mothers modify eggs into shields to protect offspring from parasitism

2011 ◽  
Vol 279 (1730) ◽  
pp. 847-853 ◽  
Author(s):  
Joseph B. Deas ◽  
Martha S. Hunter
Keyword(s):  
Parental Investment ◽  
Parasitic Wasp ◽  
Behavioural Plasticity ◽  
Offspring Survival ◽  
Unique Form ◽  
Seed Beetle ◽  
Stage Of Development ◽  
Adaptive Value ◽  
Fitness Consequences ◽  
Parental Resources

Eggs are an immobile, vulnerable stage of development and their success often depends on the oviposition decisions of the mother. Studies show that female animals, and sometimes males, may invest parental resources in order to increase the survival of their offspring. Here, we describe a unique form of parental investment in offspring survival. The seed beetle Mimosestes amicus may lay eggs singly, or may cover eggs with additional egg(s). This egg stacking serves to significantly reduce the mortality of the protected egg from parasitism by the parasitic wasp, Uscana semifumipennis . The smaller top eggs serve only as protective shields; they are inviable, and wasps that develop in them suffer negative fitness consequences. Further, we found egg stacking to be inducible; M. amicus increase the number of stacks they lay when parasitoids are present. However, stacking invokes a cost. When wasps are absent, beetles lay more single eggs, and produce more offspring, highlighting the adaptive value of this extraordinary example of behavioural plasticity in parental investment.

scholarly journals On Trade-offs and Communal Breeding The Behavioural Ecology of Agta Foragers

2021 ◽  
Author(s):  
Abigail Emma Page
Keyword(s):  
Life History Strategies ◽  
Energy Budgets ◽  
Small Scale ◽  
Network Centrality ◽  
Communal Breeding ◽  
Household Energy ◽  
Trade Off ◽  
Adaptive Value ◽  
Trade Offs ◽  
Fitness Consequences

Time is finite and no organism can avoid the allocation dilemma that this necessarily entails. A quintessential trade-off is that between parental investment and reproduction, otherwise known as the quality-quantity trade-off. However, humans may be exceptional among apes given our high quantity production of high quality offspring. This success has been argued only to be possible by breeding communally. In this thesis I explore questions surrounding trade-offs, communal breeding and their fitness consequences in a small-scale foraging society, the Agta. The first analysis examines the composition of Agta childcare using an innovative form of data collection to maximise sample sizes, previously a major limitation in hunter-gatherer research. The Agta, like many small-scale societies are prolific communal breeders. However, contra previous conclusions, juveniles and non-kin appeared to provide more allocare than grandmothers. Interactions with non-kin were associated with significant decreases in maternal workload, while interactions with siblings and grandmothers were not. The next analysis explores why both kin and non-kin behave cooperatively, finding support for kin selection among close kin and reciprocity for distant kin and non-kin allocare. Communal breeding appears to be an important mechanism to ensure enough childcare was received in the absence of other strategies to counter shortfalls in household energy budgets. The next analysis asks, what are the fitness consequences of maternal social networks and allocare? Mothers’ network centrality positively correlated with non-kin allocare as well as reproductive success, revealing the adaptive value of communal breeding. These results highlight the optimising nature of hunter-gatherer cooperation and life history strategies.

scholarly journals Genetic Architecture of Species Differences in Annual Sunflowers: Implications for Adaptive Trait Introgression

Genetics ◽  
1999 ◽  
Vol 153 (2) ◽  
pp. 965-977 ◽  
Author(s):  
Seung-Chul Kim ◽  
Loren H Rieseberg
Keyword(s):  
Morphological Traits ◽  
Genetic Architecture ◽  
Natural Populations ◽  
Introgressive Hybridization ◽  
Pollen Sterility ◽  
Subsequent Work ◽  
Fitness Consequences ◽  
Genomic Location ◽  
Tight Linkage ◽  
Trait Introgression

Abstract Genetic architecture may profoundly influence the ability of adaptive traits to spread between species via introgressive hybridization. Here, we examine the genomic location of quantitative trait loci (QTL) associated with pollen sterility and morphological traits distinguishing two annual sunflowers, Helianthus annuus and H. debilis ssp. cucumerifolius. These species are of particular interest since they hybridize naturally, and the form of H. annuus in Texas (called ssp. texanus) is thought to have arisen through introgression. Analysis of 226 BC1 progeny from a cross between H. annuus and H. debilis revealed 56 QTL for 15 morphological traits and 2 QTL for pollen sterility. Four morphological QTL are tightly linked (<10 cM) to one or more sterility factors and 7 are closely allied with underrepresented and presumably negatively selected chromosomal blocks. Although these 11 QTL seem unlikely to move between the species, no barrier to introgression was detected for the remaining 45 morphological QTL. In fact, due to widespread pleiotropy (or tight linkage), the introgression of just three small chromosomal blocks appears sufficient to largely recover the phenotype of ssp. texanus. Subsequent work will test for the occurrence and fitness consequences of the identified QTL in natural populations of ssp. texanus.

Remarks on the application of backscattered electron imaging (BEI) to the scanning electron microscopy (SEM) of biological structures

1983 ◽  
Vol 41 ◽  
pp. 484-487
Author(s):  
Etienne de Harven
Keyword(s):  
High Resolution ◽  
Incident Beam ◽  
Spot Size ◽  
Primary Electron ◽  
Critical Point Drying ◽  
Cell Shapes ◽  
High Resolution Images ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Scanning Electron

Biological ultrastructures have been extensively studied with the scanning electron microscope (SEM) for the past 12 years mainly because this instrument offers accurate and reproducible high resolution images of cell shapes, provided the cells are dried in ways which will spare them the damage which would be caused by air drying. This can be achieved by several techniques among which the critical point drying technique of T. Anderson has been, by far, the most reproducibly successful. Many biologists, however, have been interpreting SEM micrographs in terms of an exclusive secondary electron imaging (SEI) process in which the resolution is primarily limited by the spot size of the primary incident beam. in fact, this is not the case since it appears that high resolution, even on uncoated samples, is probably compromised by the emission of secondary electrons of much more complex origin.When an incident primary electron beam interacts with the surface of most biological samples, a large percentage of the electrons penetrate below the surface of the exposed cells.

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

Image registration with a computer driven S.T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 98-99
Author(s):  
A.M.H. Schepman ◽  
J.A.P. van der Voort ◽  
J.E. Mellema
Keyword(s):  
Spot Size ◽  
Scanning Transmission Electron Microscope ◽  
Small Computer ◽  
Structural Studies ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Specimen Area ◽  
On Line ◽  
Minimum Distances

A Scanning Transmission Electron Microscope (STEM) was coupled to a small computer. The system (see Fig. 1) has been built using a Philips EM400, equipped with a scanning attachment and a DEC PDP11/34 computer with 34K memory. The gun (Fig. 2) consists of a continuously renewed tip of radius 0.2 to 0.4 μm of a tungsten wire heated just below its melting point by a focussed laser beam (1). On-line operation procedures were developped aiming at the reduction of the amount of radiation of the specimen area of interest, while selecting the various imaging parameters and upon registration of the information content. Whereas the theoretical limiting spot size is 0.75 nm (2), routine resolution checks showed minimum distances in the order 1.2 to 1.5 nm between corresponding intensity maxima in successive scans. This value is sufficient for structural studies of regular biological material to test the performance of STEM over high resolution CTEM.

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