311 research outputs found
The neural basis of defensive behaviour evolution in Peromyscus mice
No full textEvading imminent predator threat is critical for survival. Effective defensive strategies can vary, even between closely related species. However, the neural basis of such species-specific behaviours is still poorly understood. Here we find that two sister species of deer mice (genus Peromyscus) show different responses to the same looming stimulus: P. maniculatus, which occupy densely vegetated habitats, predominantly dart to escape, while the open field specialist, P. polionotus, pause their movement. This difference arises from species-specific escape thresholds, is largely context-independent, and can be triggered by both visual and auditory threat stimuli. Using immunohistochemistry and electrophysiological recordings, we find that although visual threat activates the superior colliculus in both species, the role of the dorsal periaqueductal gray (dPAG) in driving behaviour differs. While dPAG activity scales with running speed and involves both excitatory and inhibitory neurons in P. maniculatus, the dPAG is largely silent in P. polionotus, even when darting is triggered. Moreover, optogenetic activation of excitatory dPAG neurons reliably elicits darting behaviour in P. maniculatus but not P. polionotus. Together, we trace the evolution of species-specific escape thresholds to a central circuit node, downstream of peripheral sensory neurons, localizing an ecologically relevant behavioural difference to a specific region of the complex mammalian brain
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EVOLUTION: Parallel Evolution Is in the Genes
No full textComplex plumage patterns seem to have evolved independently among many very different bird species, a striking example of parallel evolution. In their Perspective, Hoekstra and Price discuss the molecular basis for similar dark plumage patterns between two very different arctic bird species ( Mundy et al.).Organismic and Evolutionary BiologyVersion of Recor
An Examination of Hopimomngwit: Hopi Leadership
No full textabstract: The Hopi people have the distinct term mongwi applied to a person who is charged with leadership of a group. According to Hopi oral history and some contemporary Hopi thought, a mongwi (leader) or group of momngwit (leaders), gain their foremost positions in Hopi society after being recognizably able to fulfill numerous qualifications linked to their respective clan identity, ceremonial initiation, and personal conduct. Numerous occurrences related to the Hopis historical experiences have rendered a substantial record of what are considered the qualifications of a Hopi leader. This thesis is an extensive examination of the language used and the context wherein Hopi people express leadership qualities in the written and documentary record.Dissertation/ThesisMasters Thesis American Indian Studies 201
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(Re)Reading The Origin
No full textCharles Darwin's 1859 book On the Origin of Species is much referenced, especially in this double anniversary year. But, does anyone still read it? And, if so, what is the book itself like as a text? We have asked biologists from a range of fields — evolutionary biologists, but also geneticists, ecologists, paleontologists and molecular biologists — to re-read (or read) The Origin for Current Biology. Below are the responses, contributed by: Andrew Berry, Matthew Cobb, Simon Conway Morris, Jerry Coyne, Hopi Hoekstra, Peter Lawrence, Robert May, Christiane Nüsslein-Volhard, Mark Ptashne, Matt Ridley and Marlene Zuk.Organismic and Evolutionary BiologyVersion of Recor
Contention through Education: From Indian Education to Hopi Education
No full textabstract: This paper primarily focuses on the Hopi Tribe of northeastern Arizona and how historical events shaped the current perception and applications of educational systems on the Hopi reservation. This thesis emphasizes the importance of understanding historical contexts of a community in order to understand the current predicament and to devise solutions to contemporary issues in which I primarily focus on education. Education is broken down in regards to the Hopi communities by history, how this history has affected those communities, ideas of sovereignty and power within education and then future probable solutions to integrating language and culture into Hopi schools.
This research is primarily literature and educational reports on the Hopi Tribe and other American Indian communities. The research was then compiled to find commonalities with other Indian communities to depict barriers to educational success as well as effects of western education such as traditional culture and language decline. Solutions and results that other Indian communities had devised were also researched to determine if they could be incorporated into the Hopi educational system and if they supported the language and culture that the Hopi people are trying to retain.Dissertation/ThesisMasters Thesis Social and Cultural Pedagogy 201
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Computational Bioacoustics of Deer Mice: Identifying and Comparing Vocal Syllables Across Species and Infant Development
No full textVocal behaviors are diverse across mammals, but the mechanisms underlying this diversity are poorly understood. Unlike traditional models of vocal behavior such as the laboratory mouse (Mus musculus), deer mice (genus Peromyscus) exhibit variation in vocal behaviors that has evolved in natural environments. Furthermore, this rodent group is abundant across North American habitats and inter-fertile among distinct species, providing a unique opportunity to study the evolution of vocalization. Yet their vocal ontogeny lacks quantitative description, data necessary to investigate the biological causes of this variation. In pursuit of describing the deer mouse vocal repertoire and its changes across development, I recorded vocalizations from mice belonging to 9 deer mouse species and subspecies (vocal development in 3 of which has not been previously described) at 1, 3, 5, 7, 9, 11, and 13 days of age. I then built a computational bioacoustics pipeline to detect, quantify, and compare vocal syllables across development and between species. These data reveal that infant deer mouse vocalizations cluster into two types—which I refer to as cries and whistles—that are markedly different in their spectrographic and acoustic features. Over the course of development, pups switch from almost exclusively crying to almost exclusively whistling. Furthermore, these two types are differentially stereotyped in their spectrographic representations by species across development. These results lay the foundation for genetic mapping and tissue staining, among other tools, to be used to identify biological mechanisms underlying these cross-specific differences. This work will ultimately contribute to our understanding of the evolution of mammalian behavior
Population genetic analysis of the DARC locus (Duffy) reveals adaptation from standing variation associated with malaria resistance in humans.
No full textThe human DARC (Duffy antigen receptor for chemokines) gene encodes a membrane-bound chemokine receptor crucial for the infection of red blood cells by Plasmodium vivax, a major causative agent of malaria. Of the three major allelic classes segregating in human populations, the FY*O allele has been shown to protect against P. vivax infection and is at near fixation in sub-Saharan Africa, while FY*B and FY*A are common in Europe and Asia, respectively. Due to the combination of strong geographic differentiation and association with malaria resistance, DARC is considered a canonical example of positive selection in humans. Despite this, details of the timing and mode of selection at DARC remain poorly understood. Here, we use sequencing data from over 1,000 individuals in twenty-one human populations, as well as ancient human genomes, to perform a fine-scale investigation of the evolutionary history of DARC. We estimate the time to most recent common ancestor (TMRCA) of the most common FY*O haplotype to be 42 kya (95% CI: 34-49 kya). We infer the FY*O null mutation swept to fixation in Africa from standing variation with very low initial frequency (0.1%) and a selection coefficient of 0.043 (95% CI:0.011-0.18), which is among the strongest estimated in the human genome. We estimate the TMRCA of the FY*A mutation in non-Africans to be 57 kya (95% CI: 48-65 kya) and infer that, prior to the sweep of FY*O, all three alleles were segregating in Africa, as highly diverged populations from Asia and ≠Khomani San hunter-gatherers share the same FY*A haplotypes. We test multiple models of admixture that may account for this observation and reject recent Asian or European admixture as the cause
From many, one: genetic control of prolificacy during maize domestication.
No full textA reduction in number and an increase in size of inflorescences is a common aspect of plant domestication. When maize was domesticated from teosinte, the number and arrangement of ears changed dramatically. Teosinte has long lateral branches that bear multiple small ears at their nodes and tassels at their tips. Maize has much shorter lateral branches that are tipped by a single large ear with no additional ears at the branch nodes. To investigate the genetic basis of this difference in prolificacy (the number of ears on a plant), we performed a genome-wide QTL scan. A large effect QTL for prolificacy (prol1.1) was detected on the short arm of chromosome 1 in a location that has previously been shown to influence multiple domestication traits. We fine-mapped prol1.1 to a 2.7 kb "causative region" upstream of the grassy tillers1 (gt1) gene, which encodes a homeodomain leucine zipper transcription factor. Tissue in situ hybridizations reveal that the maize allele of prol1.1 is associated with up-regulation of gt1 expression in the nodal plexus. Given that maize does not initiate secondary ear buds, the expression of gt1 in the nodal plexus in maize may suppress their initiation. Population genetic analyses indicate positive selection on the maize allele of prol1.1, causing a partial sweep that fixed the maize allele throughout most of domesticated maize. This work shows how a subtle cis-regulatory change in tissue specific gene expression altered plant architecture in a way that improved the harvestability of maize
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