Browsing Biology by Title
Now showing items 166-185 of 207
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Scents and Sense Ability: The evolution and role of chemical cues in the pollination and herbivory of Passiflora
Pollination and herbivory play a critical role in both wild ecosystems and agricultural ones, factoring in to their maintenance, evolution, and ecology. Insects, for whom chemical cues are often more important than those ... -
Sea urchin sperm chemotaxis: individual effects and fertilization success
Egg chemoattraction of conspecific sperm mediates fertilization, a critical juncture in reproduction, especially in broadcast-spawning organisms like sea urchins. In the century that sea urchin sperm chemotaxis was studied ... -
Seasonal Circuitry: transcriptional and post-translational regulation of photoperiodic flowering in Arabidopsis thaliana
For plants, the transition towards reproductive development is timed so that it coincides with the most optimal external conditions. For many plant species, day length is an important cue in mediating this process. At the ... -
Seasonal Migration, Gene Flow, and Speciation in North American Birds
Around 20% of bird species migrate annually between distinct breeding and wintering ranges and many sedentary populations shift cyclically within a single range in response to varying climates and food availability. Migration ... -
Sensory ecology, morphology and behavior of Neotropical leaf-nosed bats
Sensory systems perform fitness-relevant functions, and specialized sensory structures and behavior allow organisms to accomplish challenging tasks. Furthermore, echolocation is a highly complex sense, and in function, is ... -
Sex and Fear: Mathematical models of mate choice, parental care, and maladaptive anxiety
In many contexts, animals must infer salient information about another individual indirectly by observing some other characteristic of that individual. In Chapter 1 of this thesis, a model of costly signaling is developed ... -
Shape matters: corolla curvature improves nectary discovery in the hawkmoth Manduca sexta
I measured the effects of variation in corolla curvature and nectary aperture radius on pollinator foraging ability using the hawkmoth Manduca sexta and 3D-printed artificial flowers whose shapes were mathematically ... -
Sleepless in Seattle: How Human Sleep Patterns Kept Me Up At Night
There is a sleep deprivation epidemic in the United States, particularly amongst teens and young adults. During puberty, teens undergo biological changes to their circadian system that leads to a preference for later ... -
Social Determinants of Sleep
Humans typically sleep in highly built settings that isolate them from environmental regulators of sleep. In postindustrial, highly urbanized environments, these conditions are combined with social schedules that include ... -
Socioenvironmental and demographic modifiers of aging in nonhuman animals
Across many species, chronological age is the greatest predictor of mortality and the leading risk factor for many non-communicable diseases. However, not all individuals within a species exhibit the same age-related ... -
Species from feces: Decoding the secrets of genetic resilience, microbiome shift and niche partitioning from droppings
Effective species recovery plans rely on adequate scientific data, being tailored to the species’ natural history and keeping up with rapid socioeconomic changes. My dissertation focuses on two great conservation success ... -
Stem cells and fate control in plant stomatal development
(2013-07-25)The plant epidermis is a critical interface between the atmosphere and internal plant tissues, which allows plants to succeed on land by restricting their exposure to the environment. Stomata, closable pores on the plant ... -
Studies on the Mechanism of Phosphate Accumulation by Sea Urchin Embryos
(1954)The problem of phosphate entry into cells has been the subject of many studies with radioactive phosphorus during the past fifteen years. These studies, when compared with similar experiments with monovalent cations or ... -
The systematics and evolution of Lantaneae (Verbenaceae), a molecular phylogenetic approach
(2013-07-25)Lantaneae are a morphologically variable group of 300-400 species, representing the largest tribe within Verbenaceae. They are widespread and diverse in the new world tropics and subtropics; some members are native to ... -
Systematics of Buddleja (Scrophulariaceae): phylogenetic relationships, historical biogeography, and phylogenomics
Plants display incredible diversity, in morphology and spatial distribution, which can best be understood in an evolutionary context. The reconstruction of how this diversity has evolved can illuminate patterns and trends ... -
Systematics of Ulvaceae (Ulvales, Ulvophyceae) and the genus Ulva L. based on nuclear and chloroplast sequence data
(2001)Systematic hypotheses for Ulvaceae were tested using sequences for the chloroplast gene encoding the large subunit of RUBISCO (rbc L) and nuclear small subunit ribosomal DNA (18S rDNA). Ulvaceae sensu Floyd and O'Kelly ... -
Telomere Dynamics in Magellanic penguins (Spheniscus magellanicus)
Lifespans among taxa vary widely, however, most all species undergo a reduction in physiological function with increasing age, often termed aging. One theory suggest that aging occurs as a result of the accumulation of ... -
Temperature gradients drive functional heterogeneity within muscle
(2012-09-13)During locomotion, muscles respond to an animal's varying need for speed, endurance, strength, and agility. Therefore, in addition to operating as motors, muscles also act as brakes, springs, and struts. Interestingly, if ... -
Testing the Limits: Understanding How Climate and Competition Affect Species' Ranges in a Warming World
(2013-11-14)What factors determine where species occur, known as their geographic range limits? This classic ecological question has fascinated scientists for centuries, and is even more relevant today, in the face of anthropogenic ... -
Testosterone, estrogen, and breeding behavior in an Arctic bird, the Lapland longspur
(1997)Successful breeding in the Arctic requires precisely timed changes in reproductive behavior and physiology, and usually only one reproductive attempt per year is possible. Hormone and behavior patterns of Arctic breeders ...