Eye size in North American watersnakes (genus Nerodia) correlates with variation in feeding ecology

2020 ◽  
Vol 131 (4) ◽  
pp. 774-784
Author(s):  
Carlos D Camp ◽  
Jessica A Wooten ◽  
Mary Kaytlin Pepper ◽  
Richard M Austin ◽  
J Whitfield Gibbons
Keyword(s):  
Visual Acuity ◽  
Feeding Ecology ◽  
North American ◽  
Positive Association ◽  
Phylogenetic Comparative Methods ◽  
Head Shape ◽  
Eye Morphology ◽  
Eye Size ◽  
Trade Offs ◽  
Selective Forces

Abstract Visual acuity and sensitivity positively correlate to eye size in vertebrates, and eye size relates to the ecology of colubrid snakes. We investigated whether eye morphology of North American colubrids of the genus Nerodia correlates with ecology as well. Although all members of the genus utilize aquatic habits, they differ widely in the proportion of anurans they eat. We specifically tested whether eye size and placement is associated with the proportion of frogs in the diet to determine whether these two aspects of eye morphology relate to feeding ecology. Using phylogenetic comparative methods, we found a significantly positive association between eye size and the proportion of anurans eaten by Nerodia species. Although the evidence is equivocal, the anterior placement of relatively small eyes in one species may also enhance anurophagy. Although eye size may improve a snake’s ability to feed on frogs, eye size must compete with other selective forces on head shape in trade-offs that may also influence eye size.

scholarly journals Vision-Linked Traits Associated With Antenna Size and Foraging Ecology Across Ants

2021 ◽  
Vol 5 (5) ◽  
Author(s):  
Chloe Jelley ◽  
Phillip Barden
Keyword(s):  
Foraging Ecology ◽  
Three Dimensional ◽  
Comparative Approach ◽  
Tactile Acuity ◽  
Eye Morphology ◽  
Eye Size ◽  
Trade Offs ◽  
Wide Range ◽  
Dimensional Measurements ◽  
Ant Ecology

Abstract Visual systems in animals often conspicuously reflect the demands of their ecological interactions. Ants occupy a wide range of terrestrial microhabitats and ecological roles. Additionally, ant eye morphology is highly variable; species range from eyeless subterranean-dwellers to highly visual predators or desert navigators. Through a comparative approach spanning 64 species, we evaluated the relationship between ecology and eye morphology on a wide taxonomic scale. Using worker caste specimens, we developed two- and three-dimensional measurements to quantify eye morphology and position, as well as antennal scape length. Surprisingly, we find limited associations between ecology and most eye traits, however, we recover significant relationships between antennal scape length and some vision-linked attributes. While accounting for shared ancestry, we find that two- and three-dimensional eye area is correlated with foraging niche and ommatidia density is significantly associated with trophic level in our sample of ant taxa. Perhaps signifying a resource investment tradeoff between visual and olfactory or tactile acuity, we find that ommatidia density is negatively correlated with antennal scape length. Additionally, we find that eye position is significantly related to antennal scape length and also report a positive correlation between scape length and eye height, which may be related to the shared developmental origin of these structures. Along with previously known relationships between two-dimensional eye size and ant ecology, our results join reports from other organismal lineages suggesting that morphological traits with intuitive links to ecology may also be shaped by developmental restrictions and energetic trade-offs.

scholarly journals Variation in pleiotropic hub gene expression is associated with interspecific differences in head shape and eye size in Drosophila

2021 ◽  
Author(s):  
Elisa Buchberger ◽  
Anıl Bilen ◽  
Sanem Ayaz ◽  
David Salamanca ◽  
Cristina Matas de las Heras ◽  
...  
Keyword(s):  
Natural Variation ◽  
Compound Eye ◽  
Genetic Manipulation ◽  
Morphological Evolution ◽  
Morphological Diversity ◽  
Network Evolution ◽  
Head Shape ◽  
Eye Size ◽  
Recurrent Mutations ◽  
Repeated Evolution

Abstract Revealing the mechanisms underlying the breath-taking morphological diversity observed in nature is a major challenge in Biology. It has been established that recurrent mutations in hotspot genes cause the repeated evolution of morphological traits, such as body pigmentation or the gain and loss of structures. To date, however, it remains elusive whether hotspot genes contribute to natural variation in the size and shape of organs. Since natural variation in head morphology is pervasive in Drosophila, we studied the molecular and developmental basis of differences in compound eye size and head shape in two closely related Drosophila species. We show differences in the progression of retinal differentiation between species and we applied comparative transcriptomics and chromatin accessibility data to identify the GATA transcription factor Pannier (Pnr) as central factor associated with these differences. Although the genetic manipulation of Pnr affected multiple aspects of dorsal head development, the effect of natural variation is restricted to a subset of the phenotypic space. We present data suggesting that this developmental constraint is caused by the co-evolution of expression of pnr and its co-factor u-shaped (ush). We propose that natural variation in expression or function of highly connected developmental regulators with pleiotropic functions is a major driver for morphological evolution and we discuss implications on gene regulatory network evolution. In comparison to previous findings, our data strongly suggests that evolutionary hotspots are not the only contributors to the repeated evolution of eye size and head shape in Drosophila.

scholarly journals Eye shape and the nocturnal bottleneck of mammals

2012 ◽  
Vol 279 (1749) ◽  
pp. 4962-4968 ◽  
Author(s):  
Margaret I. Hall ◽  
Jason M. Kamilar ◽  
E. Christopher Kirk
Keyword(s):  
Visual Acuity ◽  
Detailed Analysis ◽  
Statistical Methods ◽  
Activity Pattern ◽  
Activity Patterns ◽  
Time Of Day ◽  
Visual Sensitivity ◽  
Early Evolution ◽  
Eye Size ◽  
Diurnal Species

Most vertebrate groups exhibit eye shapes that vary predictably with activity pattern. Nocturnal vertebrates typically have large corneas relative to eye size as an adaptation for increased visual sensitivity. Conversely, diurnal vertebrates generally demonstrate smaller corneas relative to eye size as an adaptation for increased visual acuity. By contrast, several studies have concluded that many mammals exhibit typical nocturnal eye shapes, regardless of activity pattern. However, a recent study has argued that new statistical methods allow eye shape to accurately predict activity patterns of mammals, including cathemeral species (animals that are equally likely to be awake and active at any time of day or night). Here, we conduct a detailed analysis of eye shape and activity pattern in mammals, using a broad comparative sample of 266 species. We find that the eye shapes of cathemeral mammals completely overlap with nocturnal and diurnal species. Additionally, most diurnal and cathemeral mammals have eye shapes that are most similar to those of nocturnal birds and lizards. The only mammalian clade that diverges from this pattern is anthropoids, which have convergently evolved eye shapes similar to those of diurnal birds and lizards. Our results provide additional evidence for a nocturnal ‘bottleneck’ in the early evolution of crown mammals.

Positive association between resistance to Bacillus thuringiensis and overwintering survival of cabbage loopers, Trichoplusia ni (Lepidoptera: Noctuidae)

2008 ◽  
Vol 98 (3) ◽  
pp. 317-322 ◽  
Author(s):  
V. Caron ◽  
J.H. Myers
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Positive Association ◽  
Pest Species ◽  
Development Of Resistance ◽  
Trade Offs ◽  
Major Pest ◽  
Selection For ◽  
Overwintering Survival ◽  
Lepidoptera Noctuidae

AbstractDevelopment of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.

scholarly journals Predation selects for smaller eye size in a vertebrate: effects of environmental conditions and sex

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182625 ◽  
Author(s):  
Richard Svanbäck ◽  
Frank Johansson
Keyword(s):  
Visual Acuity ◽  
Phenotypic Plasticity ◽  
Experimental Evidence ◽  
Predation Risk ◽  
Environmental Conditions ◽  
Retinal Image ◽  
The Other ◽  
Eye Size ◽  
Fish Predators ◽  
Resource Levels

Increased eye size in animals results in a larger retinal image and thus improves visual acuity. Thus, larger eyes should aid both in finding food as well as detecting predators. On the other hand, eyes are usually very conspicuous and several studies have suggested that eye size is associated with predation risk. However, experimental evidence is scant. In this study, we address how predation affects variation in eye size by performing two experiments using Eurasian perch juveniles as prey and either larger perch or pike as predators. First, we used large outdoor tanks to compare selection due to predators on relative eye size in open and artificial vegetated habitats. Second, we studied the effects of both predation risk and resource levels on phenotypic plasticity in relative eye size in indoor aquaria experiments. In the first experiment, we found that habitat altered selection due to predators, since predators selected for smaller eye size in a non-vegetated habitat, but not in a vegetated habitat. In the plasticity experiment, we found that fish predators induced smaller eye size in males, but not in females, while resource levels had no effect on eye size plasticity. Our experiments provide evidence that predation risk could be one of the driving factors behind variation in eye size within species.

Life histories of North American game birds: a reanalysis

1988 ◽  
Vol 66 (8) ◽  
pp. 1906-1912 ◽  
Author(s):  
Todd W. Arnold
Keyword(s):  
Life History ◽  
North American ◽  
Life Histories ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Cost Of Reproduction ◽  
Reproductive Value ◽  
Trade Offs ◽  
Game Birds ◽  
The Cost

Recently, Zammuto (R. M. Zammuto. 1986. Can. J. Zool. 64: 2739–2749) suggested that North American game birds exhibited survival–fecundity trade-offs consistent with the "cost of reproduction" hypothesis. However, there were four serious problems with the data and the analyses that Zammuto used: (i) the species chosen for analysis ("game birds") showed little taxonomic or ecological uniformity, (ii) the measures of future reproductive value (maximum longevity) were severely biased by unequal sample sizes of band recoveries, (iii) the measures of current reproductive effort (clutch sizes) were inappropriate given that most of the birds analyzed produce self-feeding precocial offspring, and (iv) the statistical units used in the majority of analyses (species) were not statistically independent with respect to higher level taxonomy. After correcting these problems, I found little evidence of survival–fecundity trade-offs among precocial game birds, and I attribute most of the explainable variation in life-history traits of these birds to allometry, phylogeny, and geography.

Characterization of elasticity patterns of North American freshwater fishes

2006 ◽  
Vol 63 (9) ◽  
pp. 2050-2066 ◽  
Author(s):  
Luis A Vélez-Espino ◽  
Michael G Fox ◽  
Robert L McLaughlin
Keyword(s):  
Population Growth ◽  
North American ◽  
Growth Rates ◽  
Freshwater Fishes ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Vital Rates ◽  
Population Growth Rates ◽  
North American Freshwater ◽  
Trade Offs

We applied elasticity analysis to 88 North American freshwater fishes to assess the relative impacts of changes in the vital rates on asymptotic population growth. Variance in vital rates was summarized for four distinct functional groups: (i) species with population growth rates strongly sensitive to perturbations in adult survival; (ii) species with population growth rates sensitive to perturbations in overall survival; (iii) species with population growth rates most sensitive to perturbations in juvenile survival; and (iv) species with population growth rates sensitive to perturbations in juvenile survival and fecundity. The results of the present study also showed that (a) elasticity patterns cannot be inferred in a straightforward manner from trade-offs between life-history traits, (b) the sensitivity of a population's growth rate to changes in adult survival and fecundity can be predicted empirically from life span and age at maturity, respectively, (c) elasticities are highly conserved among genera within the same taxonomic family, and (d) there are key divergences between elasticity patterns of freshwater fish and other vertebrate taxa.

scholarly journals Patterns of Life-History Diversification in North American Fishes: implications for Population Regulation

1992 ◽  
Vol 49 (10) ◽  
pp. 2196-2218 ◽  
Author(s):  
Kirk O. Winemiller ◽  
Kenneth A. Rose
Keyword(s):  
Life History ◽  
Parental Care ◽  
North American ◽  
Life Histories ◽  
Egg Size ◽  
Life History Strategies ◽  
Large Species ◽  
High Fecundity ◽  
Adult Growth ◽  
Trade Offs

Interspecific patterns of fish life histories were evaluated in relation to several theoretical models of life-history evolution. Data were gathered for 216 North American fish species (57 families) to explore relationships among variables and to ordinate species. Multivariate tests, performed on freshwater, marine, and combined data matrices, repeatedly identified a gradient associating later-maturing fishes with higher fecundity, small eggs, and few bouts of reproduction during a short spawning season and the opposite suite of traits with small fishes. A second strong gradient indicated positive associations between parental care, egg size, and extended breeding seasons. Phylogeny affected each variable, and some higher taxonomic groupings were associated with particular life-history strategies. High-fecundity characteristics tended to be associated with large species ranges in the marine environment. Age at maturation, adult growth rate, life span, and egg size positively correlated with anadromy. Parental care was inversely correlated with median latitude. A trilateral continuum based on essential trade-offs among three demographic variables predicts many of the correlations among life-history traits. This framework has implications for predicting population responses to diverse natural and anthropogenic disturbances and provides a basis for comparing responses of different species to the same disturbance.

Visual fields of the compound eyes of four species of Cicindelidae (Coleoptera)

1980 ◽  
Vol 58 (3) ◽  
pp. 326-336 ◽  
Author(s):  
J. E. Kuster ◽  
W. G. Evans
Keyword(s):  
Visual Field ◽  
North American ◽  
Visual Fields ◽  
Morphological Characters ◽  
Head Size ◽  
Compound Eyes ◽  
Eye Size ◽  
Nocturnal Species ◽  
The Relationship ◽  
Diurnal Species

Visual field angles were measured around the circumference of the compound eyes of four species of North American Cicindelidae and plotted on Mollweide homolographs. Areas of monoscopic and stereoscopic visual fields and blind areas were calculated. In contrast to the nocturnal species (Amblycheila schwarzi and Omus californicus), the crepuscular species (Megacephala Carolina) and the diurnal species (Cicindela tranquebarica) have more ommatidia and larger eye size: head size ratios, total visual fields, and stereoscopic visual fields. These characters are considered to be derived and confirm the phylogenetic sequence of the four genera that was previously based on other morphological characters. The relationship between these characters and the biology of each species is also discussed.

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