Evolution Commons^™

Evolutionary Continuity, Anne Benvenuti

Animal Sentience

The principle of evolutionary continuity states that all animal capacities and behaviors exist — with variations in degree — in continuity with other species. Rather than assuming discontinuity, we should ask why any behavior observed in humans would not be found in at least some other sentient animals under similar conditions. In the case of suicide, the more pertinent issue might be the ethical one: our human responsibility for creating conditions under which other animals might deliberately seek to end their own lives.

Non-Human Animal Suicide Could Be Tested, David Lester

Animal Sentience

Schaefer (1967) showed that mice can discriminate live from dead mice and lethal from nonlethal environments, and that they avoid a lethal environment; but the experiment lacked some controls. This might be a way to test whether mice would ever choose a lethal environment. Humans may also choose a potentially lethal environment unconsciously.

Understanding Animal Suicide And Death Can Lead To Better End-Of-Life Care, Jessica Pierce

Animal Sentience

Peña-Guzmán’s target article on animal suicide will help inform end-of-life care for animals by emphasizing the need for a broad research focus on animal thanatology. Greater scientific understanding of the continuum of death-related awareness, experiences, and behaviors will help us improve veterinary care for animals at the end of life.

Complicated Grief, Teya Brooks Pribac

Animal Sentience

My commentary discusses complicated grief and the ensuing sense of helplessness that may lead to suicide. I close with a story about a pygmy pig.

Can Nonhuman Animals Commit Suicide?, David M. Peña-Guzmán

Animal Sentience

Many people believe that only humans have the cognitive and behavioral capacities needed for suicidal behavior, such as reflexive subjectivity, free will, intentionality, or awareness of death. Three counterarguments — based on (i) negative emotions and psychopathologies among nonhuman animals, (ii) the nature of self-destructive behavior, and (iii) the problem of model fidelity in suicide research — suggest that self-destructive and self-injurious behaviors among human and nonhuman animals vary along a continuum.

Tribute To Jaak Panksepp, Jonathan Balcombe

Animal Sentience

No abstract provided.

Getting To The Other Side, Debra Merskin

Animal Sentience

Marino’s comprehensive, detailed, and timely review provides clear evidence of the sentience of chickens and strong support for those wishing to challenge their exclusion from even the limited protections currently accorded to animals grown for food.

Sentience Does Not Require “Higher” Cognition, Giorgio Vallortigara

Animal Sentience

I agree with Marino (2017a,b) that the cognitive capacities of chickens are likely to be the same as those of many others vertebrates. Also, data collected in the young of this precocial species provide rich information about how much cognition can be pre-wired and predisposed in the brain. However, evidence of advanced cognition — in chickens or any other organism — says little about sentience (i.e., feeling). We do not deny sentience in human beings who, because of cognitive deficits, would be incapable of exhibiting some of the cognitive feats of chickens. Moreover, complex problem solving, such as transitive inference, …

Misperceiving And Underestimating The Ubiquitous Chicken, Carrie P. Freeman

Animal Sentience

Marino has provided an accurate and nuanced view about chickens’ complex capabilities as sentient individuals. I explore the implications of these findings for scholars as well as for activists in the protection of farmed animals.

Is Psychological Science Committing “Suicide” By Linguistic Muddling?, Roger K. Thomas

Animal Sentience

Beginning mainly with the “cognitive revolution” in psychology in the latter half of the 20^th century, psychological science has been committing “suicide” slowly via linguistic muddling. Peña-Guzmán’s target article is but one of thousands of cuts contributing to this death by “suicide.” Having said that, given the current state of affairs in animal cognition research, there is much to commend in Peña-Guzmán’s article. I leave that to others, however. This commentary explains how the suicide by muddling of psychological science is happening in general, with the understanding that it applies also to Peña-Guzmán’s target article.

On Assisted Suicide, Clark Glymour

Animal Sentience

What would be the moral implications of the capacity for suicide in nonhuman animals? Humans can be helped to end their lives if they no longer find them bearable. Should captive animals not be given the same possibility?

Self, Death, And Suicide: Does An Animal Know Of These?, Carolyn A. Ristau

Animal Sentience

Peña-Guzmán makes a strong case, using examples from the media and scientific literature, that many captive animals suffer severely. In examining the possibility of animal suicide, he dismisses the need for “reflective self-subjectivity” and “intent” in suicidal behavior. He claims that at least some animals understand “death,” citing examples of behavior he deems to be death “rituals.” But these can be more simply interpreted. The possibility of animal suicide remains more dubious than Peña-Guzmán suggests.

Changes In Behavior And Emotion Under Chicken Domestication, Martin Johnsson

Animal Sentience

Marino’s target article provides an overview of chickens’ cognition, emotion, and personality, with the aim of changing how people view chickens. In this commentary, I will agree that chickens deserve better than their reputation, but contend with a statement about the lack of behavioral change under chicken domestication.

Experiment Versus Analogy In The Search For Animal Sentience, Geoffrey Hall

Animal Sentience

Deciding between rival accounts of an instance of an animal’s behavior can frequently be achieved by experimental tests of different predictions made by the alternatives. When, however, one (or both) of the alternatives is expressed in terms of the mental state of the animal, an experimental test to distinguish them can be hard to find. Although it is unsatisfactory in many ways, it may be necessary to fall back on argument from analogy with human behavior and experience.

Cognitive Continuity In Cognitive Dissonance, David R. Brodbeck, Madeleine I. R. Brodbeck

Animal Sentience

Zentall’s (2016) model of cognitive dissonance is compatible with cognitive continuity between humans and nonhumans. It may help explain cognitive dissonance-like behavior in many species, including humans. It is also consistent with Tinbergen’s (1963) ‘four whys’ in ethological explanation.

Phylogeography And Vicariant Separation Of Two River Darters, Percina Uranidea And Percina Vigil, From Rivers That Drain The North American Interior Highlands, T. Yamashita, J. M. Rigsby, J. Stoeckel

Journal of the Arkansas Academy of Science

The phylogeography and separation of two river darters, Percina uranidea and P. vigil were investigated through sequencing of the mitochondrial Cytochrome B and Cytochrome Oxidase genes. These molecular markers revealed the darters exhibit moderate genetic divergence between two large river drainage systems within the Mississippi River basin associated with the Interior Highlands of midwestern North America. An additional haplotype network analysis also supported these trends. Phylogenetic divergence dating indicated that population separation between the river systems occurred after recent Pleistocene glacial events rather than an early Pleistocene separation.

Intertemporal Choice And Delayed Gratification, Jeffrey R. Stevens

Jeffrey Stevens Publications

A parasitoid wasp has deposited half of her eggs in a host. She now faces the choice between depositing her remaining eggs in the same host or searching for another. Continuing to deposit in the current host provides the immediate payoff of completing her reproductive duties, allowing her to move on to other activities such as foraging or searching for another mate. Searching for another host, in contrast, delays the payoffs of reproducing until a suitable host is found. This wasp faces an intertemporal choice—that is, a choice between options that involve payoffs available at different times (Read, 2004; Stevens, …

Differentiation, Distribution, And Diversity Of The Borrelia Burgdorferi Sensu Lato Virulence Gene, Ospc, And The Overwintering Survivability Of The Tick Vector, Ixodes Scapularis, Melissa Beth Stone

Legacy Theses & Dissertations (2009 - 2024)

The causative agents of Lyme disease, or Lyme Borreliosis, are spirochetes in the Borrelia burgdorferi sensu lato (s.l.) species complex that are transmitted by ticks in the genus Ixodes. Certain B. burgdorferi s.l. genotypes are more likely to cause invasive, disseminated infection in humans, and the gene, ospC, has been identified as a molecular marker that can be used to predict virulence. ospC is the most polymorphic locus in the B. burgdorferi s.l. genome, and different alleles have been assigned to Major ospC Groups based on sequence dissimilarity. Issues with the Major ospC Group definition and nomenclature are pervasive in …

Five Species Of Fossil Equids Preserved In-Situ At Ashfall Fossil Beds, Rick E. Otto

University of Nebraska State Museum: Programs Information

Fully articulated, three-dimensionally preserved skeletons from five species of fossil Equids are now represented, and preserved in-situat the Ashfall Fossil Beds in northcentral Nebraska. The site is well known for dozens of barrel-bodied rhino (Teleoceras major) skeletons. A diversity of horse species that inhabited Nebraska during the late Miocene Epoch have been exposed in the fossil bed. Genera include Cormohipparion, Neohipparon, Pliohippus, Protohippus, and Pseudhipparion. An exceptionally well-preserved skeleton of the small-sized, three-toed species Pseudhipparion gratumwas recently exposed, and is on display only a few feet from where visitors stand.

Examining The Role Of Host Use On Divergence In The Redheaded Pine Sawfly, Neodiprion Lecontei, Across Multiple Spatial Scales, Robin Kimberly Bagley

Theses and Dissertations--Biology

Phytophagous insects make up over one quarter of described species on Earth, and this incredible diversity seems directly linked to feeding on plants. Comparative studies of sister groups have shown shifts to herbivory are consistently associated with increased species diversity in insects, but the reasons for this diversification remain unclear. While other explanations, such as decreased extinction rates or influences on population structure, exist, one prominent hypothesis suggests shifts and subsequent adaptation to novel host plants can lead to the evolution of reproductive barriers.

Given their extreme specialization on host plants in the genus Pinus and intimate, life-long association with …

Evolution Of Equine Arteritis Virus During Persistent Infection In The Reproductive Tract Of The Stallion And The Male Donkey, Bora Nam

Theses and Dissertations--Veterinary Science

Equine arteritis virus (EAV) establishes persistent infection in the stallion reproductive tract, and the carrier stallion continues to shed virus in semen for weeks to years or lifelong. The objective of this study was to elucidate the intra-host evolution of EAV during persistent infection in stallions. Seven EAV seronegative stallions were experimentally infected with EAV KY84 strain and followed for 726 days post-infection, and sequential clinical samples including semen were collected for virus isolation and next-generation sequencing (NGS). In addition, archived sequential semen samples from two stallions that were naturally infected with EAV KY84 for a long-period (up to 10 …

Darwinian Evolutionary Theory And Constructions Of Race In Nazi Germany: A Literary And Cultural Analysis Of Darwin’S Works And Nazi Rhetoric, Emily M. Wollmuth

Departmental Honors Projects

First published in 1856, Charles Darwin’s Origin of Species is one of the most impactful scientific writings in history. While the influence of Darwinian evolutionary theory on historical events has been widely studied, no single work of scholarship has previously combined close reading of Origin’s representations of “race” with analysis of how those constructions of “racial” difference are (mis)translated across the cultural discourses of the eugenics movement and Nazi Germany. Through comparative cultural studies and close literary analysis of Hitler’s Mein Kampf and Darwin’s works—including Origin, Descent of Man, and Voyage of the Beagle, this paper examines how evolutionary …

Genetic Perspectives On Biodiversity In Rocky Mountain Alpine Streams, Scott Hotaling

Theses and Dissertations--Biology

In alpine regions worldwide, climate change is dramatically altering ecosystems, affecting biodiversity across habitats and taxonomic scales. For streams, the associated recession of mountain glaciers and snowfields, paired with altered precipitation regimes, are driving shifts in hydrology, species distributions, and basal resources – often threatening the very existence of some habitats and biota. Globally, alpine streams harbor particularly substantial species and genetic diversity due to significant habitat insularity and environmental heterogeneity: however, anthropogenic warming threatens to homogenize habitats through the reduction of the cryosphere, thereby reducing biodiversity from micro- to macroscopic organisms and genes to communities. Still, alpine stream biodiversity, …

Mitochondrial And Nuclear Patterns Of Conflict And Concordance At The Gene, Genome, And Behavioral Scales In Desmognathus Salamanders, Justin D. Kratovil

Theses and Dissertations--Biology

Advancements in molecular sequencing have revealed unexpected cryptic genetic diversity and contrasting evolutionary histories within genes and between genomes of many organisms; often in disagreement with recognized taxonomy. Incongruent patterns between the mitochondrial and nuclear evolutionary history can have several plausible explanations, but widespread systematic conflict inevitably challenges our conceptions of species boundaries when there is discordance between coevolving and coinherited genomes. It is unknown to what degree mitonuclear conflict drives the process of divergence, or how ubiquitous these patterns are across the tree of life. To understand the evolutionary relevance of intergenomic discordance we must identify the conflicting patterns …

Genomic Perspectives On Amphibian Evolution Across Multiple Phylogenetic Scales, Paul Michael Hime

Theses and Dissertations--Biology

Genomes provide windows into the evolutionary histories of species. The recent accessibility of genome-scale data in non-model organisms and the proliferation of powerful statistical models are now providing unprecedented opportunities to uncover evolutionary relationships and to test hypotheses about the processes that generate and maintain biodiversity. This dissertation work reveals shallow-scale species boundaries and population genetic structure in two imperiled groups of salamanders and demonstrates that the number and information content of genomic regions used in species delimitation exert strong effects on the resulting inferences. Genome scans are employed to test hypotheses about the mechanisms of genetic sex determination in …

Rewiring Metabolism Under Oxygen Deprivation: Naked Mole-Rats Evolved A Means To Cope With Anoxia, Jay F. Storz, Grant B. Mcclelland

Jay F. Storz Publications

When faced with a reduced availability of oxygen in the environment (hypoxia), vertebrates can make a variety of respiratory, cardiovascular, and hematological adjustments to ensure an uninterrupted supply of oxygen to the cells of metabolizing tissues (1, 2). These are adaptive solutions for “aerobic organisms in an aerobic world” (3). Coping with the complete absence of oxygen (anoxia) requires more fundamental alterations of cellular metabolism that are typically nothing more than emergency stopgap measures to buy time until the oxygen supply is (hopefully) reestablished (4). On page 307 of this issue [Science 356 (6335)], Park et al. (5) identify a …

Effects Of Silencing Cyc2-Like Genes On Floral Development In Solanum Lycopersicum L. And Nicotiana Obtusifolia M. Martens & Galeotti (Solanaceae), Joonseog Kim

Theses and Dissertations

CYCLOIDEA (CYC) and DICHOTOMA (DICH) of the CYC2 clade of the TCP gene family have been shown to play a significant role in regulating the identity of the dorsal petals and abortion of the single dorsal stamen in Antirrhinum majus. It is believed that CYC2-like genes are responsible for the convergent evolution of floral zygomorphy, but their role in the development of actinomorphic flowers is still unknown. In Solanaceae, previous analysis has identified two paralogs of CYC2-like genes, CYC2A and CYC2B, resulting from a gene duplication that predates the origin the family. …

Evolution Of Antagonistic Relationships In Proteins: A Case Study Of Radialis- And Diviricata-Like Genes, Ao Gao

Theses and Dissertations

The antagonistic relationship of proteins describes the opponent interactions that result in one protein suppressing the function of another. Developmental genetic studies of Antirrhinum majus demonstrated that two transcription factors from the MYB gene family, RAD and DIV, interact through antagonism to regulate floral dorsoventral asymmetry. Interestingly, similar antagonistic interactions were found among proteins of FSM1 (RAD-like), MYBI (DIV-like), and DRIF in Solanum lycopersicum, which is involved in fruit development. Here, we report on the homology of these antagonistic MYB proteins based on reconstruction of the phylogeny of I-box-like and R-R-type clades, where RAD- and DIV-like belong, …

Evolutionary Linkage Of Mimetic And Non-Mimetic Color Traits In A Coral Snake Mimicry Complex, John D. Curlis Jr

College of Graduate Studies: Theses & Dissertations

Color polymorphism in aposematic mimicry systems is a perplexing phenomenon for evolutionary biologists, as theoretically the benefits of converging on a model phenotype should constrain the evolution of phenotypic diversity in these systems (i.e., color polymorphism should not occur). Nevertheless, color polymorphism in mimicry systems is prevalent throughout many taxa. In some of these systems, the evolution of color polymorphism results in the existence of non-mimetic morphs, such as those that are cryptic. The case of ground snakes (Sonora semiannulata) is unique in that color polymorphism encompasses both mimetic and cryptic morphs, as well as individual mimetic and …

Are Weevils Picky Eaters? Community Structure And Host Specificity Of Neotropical Saproxylic Beetles (Coleoptera: Curculionidae), Jhunior A. Morillo

Dissertations and Theses

Abstract Primary saproxylic beetles play a major role in forest nutrient cycling and making deadwood accessible to other decomposers. Understanding beetle host preferences and patterns of community assembly is critical for their conservation, and for predicting which species might become invasive. This project aims to investigate the ecological and host specificity, as well as the community composition of curculionids in a mosaic of old-growth (OG) and secondary forest on the Osa Peninsula, Costa Rica. The subfamily Scolytinae was expected to be the most species-rich and abundant. Ambrosia beetles were expected to have more generalist species than other curculionids. Old growth …