Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 43

Full-Text Articles in Life Sciences

Bodybuilding Bumblebees: How Exercise Affects Bumblebee (Bombus Impatiens) Flight Muscle, Kaylee R. Alles May 2017

Bodybuilding Bumblebees: How Exercise Affects Bumblebee (Bombus Impatiens) Flight Muscle, Kaylee R. Alles

Honors Theses AY 16/17

Insect flight muscle is the most metabolically active tissue known, allowing for production of the large forces necessary for flight. Flight ability varies among insects and with insect age, which is partially due to differences in muscle. However, very little work has examined whether and how insect muscle may respond to exercise. One key response may be a change in the amount of flight muscle relative to body mass ("flight muscle ratio", FMR), analogous to bulkier muscle in bodybuilders. We examined differences in FMR among bumblebee (Bombus impatiens) sisters differing in body size and in "training". We trained the bees ...


Observations Of Notable Parental Behaviours Of Northern Spotted Owls (Strix Occidentalis Caurina), Jesse Marion Alston, Janet E. Millard, Jessica A. Rick, Brandon W. Husby, Laurel A. Mundy Jan 2017

Observations Of Notable Parental Behaviours Of Northern Spotted Owls (Strix Occidentalis Caurina), Jesse Marion Alston, Janet E. Millard, Jessica A. Rick, Brandon W. Husby, Laurel A. Mundy

Zoology Faculty Publications

Northern Spotted Owl (Strix occidentalis caurina) is a medium-sized forest owl of conservation concern in the Pacific Northwest of North America. We report two sightings of previously unreported parental behaviour: a Northern Spotted Owl feeding avian nestlings to its young and a Northern Spotted Owl defending a fledgling against a Black Bear (Ursus americanus). Further research may be warranted on the influence of brood size and habitat quality on dietary breadth. Although Black Bears have not been previously documented as Northern Spotted Owl predators, we suggest that they should be considered potential predators of nestling and fledgling owls.


Zooarchaeology Of The Native American Sturgeon Fishery In Coastal Oregon, 350 Bc To Ad 1150, Elizabeth Dalyn Grindle Dec 2016

Zooarchaeology Of The Native American Sturgeon Fishery In Coastal Oregon, 350 Bc To Ad 1150, Elizabeth Dalyn Grindle

Honors Theses AY 16/17

Sturgeons are not found often in the archaeological record due to their largely cartilaginous skeleton. What remains are the scutes, bony scale-like plates found on the outside of the body, and some diagnostic cranial features. Perhaps due to this, little is known about sturgeon or their anthropological uses in the past. Due to the size of a site excavated on the Oregon Coast, the collection contains an uncommon amount of archaeological sturgeon bones. The two sturgeon species on the Northwest coast, the green and white, have historically been heavily fished; resulting in a conservation concern for the fishery. As species ...


Low Levels Of Population Genetic Structure In Pinus Contorta (Pinaceae) Across A Geographic Mosaic Of Co-Evolution, T. L. Parchman, Craig Benkman, B. Jenkins, C. A. Buerkle Apr 2011

Low Levels Of Population Genetic Structure In Pinus Contorta (Pinaceae) Across A Geographic Mosaic Of Co-Evolution, T. L. Parchman, Craig Benkman, B. Jenkins, C. A. Buerkle

Zoology Faculty Publications

Premise of the study : Population genetic analyses provide information on the population context in which evolutionary processes operate and are important for understanding the evolution of geographically variable traits. Earlier studies showed that cone structure of lodgepole pine in the Rocky Mountains diverged among populations because of geographic variation in co-evolutionary interactions involving mammalian and avian seed predators. Analyses of population genetic variation are needed to determine whether this divergence has arisen despite extensive gene flow and whether populations to the east and west of the Rocky Mountains have evolved convergent phenotypes independently. Methods : We investigated genetic structuring across 22 ...


Using Historical Dna To Characterize Hybridization Between Baltimore Orioles (Icterus Galbula) And Bullock's Orioles (I. Bullockii), Matthew Carling, L. G. Serene, I. J. Lovette Jan 2011

Using Historical Dna To Characterize Hybridization Between Baltimore Orioles (Icterus Galbula) And Bullock's Orioles (I. Bullockii), Matthew Carling, L. G. Serene, I. J. Lovette

Zoology Faculty Publications

Studies of genetic variation across hybrid zones have demonstrated that the evolutionary dynamics within them are often complicated. Using DNA extracted from toe pads of 701 individuals collected by Sibley and Short (1964) about 50 years ago from across the Icterus bullockii-I. galbula hybrid zone, we calculated mitochondrial cline shape parameters and compared them with plumage-based inferences of the hybrid-zone structure. Genetic and hybrid index score clines, estimated from populations collected along the Platte River in Nebraska, were both concordant (equal widths) and coincident (same center). More generally, the proportion of I. bullockii haplotypes within a sampling locality was strongly ...


Parental Investment Decisions In Response To Ambient Nest-Predation Risk Versus Actual Predation On The Prior Nest, Anna Chalfoun, T. E. Martin Nov 2010

Parental Investment Decisions In Response To Ambient Nest-Predation Risk Versus Actual Predation On The Prior Nest, Anna Chalfoun, T. E. Martin

Zoology Faculty Publications

Theory predicts that parents should invest less in dependent offspring with lower reproductive value, such as those with a high risk of predation. Moreover, high predation risk can favor reduced parental activity when such activity attracts nest predators. Yet, the ability of parents to assess ambient nest-predation risk and respond adaptively remains unclear, especially where nest-predator assemblages are diverse and potentially difficult to assess. We tested whether variation in parental investment by a multi-brooded songbird (Brewer's Sparrow, Spizella breweri) in an environment (sagebrush steppe) with diverse predators was predicted by ambient nest-predation risk or direct experience with nest predation ...


Isolation And Decline Of A Population Of The Orange-Breasted Falcon, R. B. Berry, Craig Benkman, A. Muela, Y. Seminario, M. Curti Aug 2010

Isolation And Decline Of A Population Of The Orange-Breasted Falcon, R. B. Berry, Craig Benkman, A. Muela, Y. Seminario, M. Curti

Zoology Faculty Publications

Probably always rare and local because of its ecology and specialized habitat, the small, isolated population of the Orange-breasted Falcon (Falco deiroleucus) in Belize and Guatemala, likely numbering fewer than 40 territorial pairs, appears to be in steep decline in Belize. Territory occupancy (n = 12 eyries) in the population we studied in Belize declined from 83% (1992 to 1997) to 54% (2003 to 2009), and occupancy in 2009 was only half the mean in the prior decade. Mean annual production of fledglings per territorial pair declined 35% from 0.77 to 0.50. Mean annual population productivity, which measures the ...


Avoidance Of Skeletal Muscle Atrophy In Spontaneous And Facultative Hibernators, Henry Harlow May 2010

Avoidance Of Skeletal Muscle Atrophy In Spontaneous And Facultative Hibernators, Henry Harlow

Zoology Faculty Publications

Smooth and skeletal muscle changes were compared from overwintering white-tailed prairie dogs, spontaneous hibernators that undergo regular, low-temperature torpor bouts, and black-tailed prairie dogs, facultative hibernators that use sporadic, moderate-temperature torpor bouts. The objectives were to assess the abilities of these two species with dramatically different torpor patterns (1) to conserve skeletal muscle morphology, protein, and strength and (2) to use labile protein in the small intestine and liver during the winter season of reduced activity and food intake. Mass and protein concentration of the extensor digitorum longus (EDL), soleus, liver, and small intestine, as well as skeletal muscle strength ...


The Fate Of Carbon In Growing Fish: An Experimental Study Of Isotopic Routing, L. J. Kelly, Carlos Martinez Del Rio May 2010

The Fate Of Carbon In Growing Fish: An Experimental Study Of Isotopic Routing, L. J. Kelly, Carlos Martinez Del Rio

Zoology Faculty Publications

The application of stable isotope analysis to ecology requires estimating the contribution of different isotopic sources to the isotopic signatures of an animal's tissues using mixing models. These models make the physiologically unrealistic assumption that assimilated nutrients are disassembled into their elemental components and that these atoms are then reassembled into biomolecules. We quantified the extent to which mixing models yield erroneous results with an experiment using Nile tilapia (Oreochromis niloticus). The tilapia were fed synthetic diets that varied in protein content and in which the carbon isotopic composition of protein differed widely from that of carbohydrates and lipids ...


Cone And Seed Trait Variation In Whitebark Pine (Pinus Albicaulis; Pinaceae) And The Potential For Phenotypic Selection, R. Garcia, A. M. Siepielski, Craig Benkman May 2009

Cone And Seed Trait Variation In Whitebark Pine (Pinus Albicaulis; Pinaceae) And The Potential For Phenotypic Selection, R. Garcia, A. M. Siepielski, Craig Benkman

Zoology Faculty Publications

Phenotypic variation among, individuals is necessary for natural selection to operate and is therefore essential for adaptive evolution. However, extensive variation within individuals can mask variation among individuals and weaken the potential for selection. Here we quantify variation among within individuals in female cone and seed traits of whitebark pine (Pinus albicaulis). In many plants the production of numerous reproductive structures creates the potential for considerable variation within a plant. but these same traits should also undergo strong selection because of their direct link to plant fitness. We found about twice as much variation among individuals (overall mean = 65.3 ...


A New Species Of The Red Crossbill (Fringillidae: Loxia) From Idaho, Craig Benkman, J. W. Smith, P. C. Keenan, T. L. Parchman Feb 2009

A New Species Of The Red Crossbill (Fringillidae: Loxia) From Idaho, Craig Benkman, J. W. Smith, P. C. Keenan, T. L. Parchman

Zoology Faculty Publications

The Red Crossbill (Loxia curvirostra complex) endemic to the South Hills and Albion Mountains in southern Idaho has coevolved in a predator-prey arms race with the lodgepole pine (Pines contorta latifolia). The resulting divergent selection has favored a sedentary, locally adapted crossbill population whose size and vocalizations differ from those of co-occurring Red Crossbills of other call types. It has also led to high levels of reproductive isolation between the "South Hills crossbill" and nomadic taxa with different vocalizations that move in and out of the area yearly. Genetic analyses of amplified fragment length polymorphisms (AFLP) indicate that about 5 ...


Call Imitation And Call Modification In Red Crossbills, Patrick C. Keenan, Craig Benkman Feb 2008

Call Imitation And Call Modification In Red Crossbills, Patrick C. Keenan, Craig Benkman

Zoology Faculty Publications

Open-ended learning of flight calls has been found consistently in the subfamily Carduelinae. Understanding call learning is especially important in Red Crossbills (Loxia curvirostra complex) because calls appear to play an instrumental role in assortative mating, perhaps by acting as a marker trait that signals ecological adaptation for foraging on a particular species of conifer. We analyzed flight call recordings from a banded population of the South Hills (call type 9) crossbill to examine whether young birds imitate the calls of their parents and whether, as adults, individuals modify their calls to match those of their mates. The calls of ...


Microsatellite Analysis Reveals Genetic Monogamy Among Female Boreal Owls, M. E. Koopman, David Mcdonald, G. D. Hayward Dec 2007

Microsatellite Analysis Reveals Genetic Monogamy Among Female Boreal Owls, M. E. Koopman, David Mcdonald, G. D. Hayward

Zoology Faculty Publications

No abstract provided.


Hibernating Bears Conserve Muscle Strength And Maintain Fatigue Resistance, T. D. Lohuis, Henry Harlow, T. Di Beck, P. A. Iaizzo May 2007

Hibernating Bears Conserve Muscle Strength And Maintain Fatigue Resistance, T. D. Lohuis, Henry Harlow, T. Di Beck, P. A. Iaizzo

Zoology Faculty Publications

Black bears spend several months each winter confined to a small space within their den without food or water. In nonhibernating mammals, these conditions typically result in severe muscle atrophy, causing a loss of strength and endurance. However, an initial study indicated that bears appeared to conserve strength while denning. We conducted an in vivo, nonsubjective measurement of strength, resistance to fatigue, and contractile properties on the tibialis anterior muscle of six hibernating bears during both early and late winter using a rigid leg brace and foot force plate. After 110 d of anorexia and confinement, skeletal muscle strength loss ...


High Connectivity And Minimal Genetic Structure Among North American Boreal Owl (Aegolius Funereus) Populations, Regardless Of Habitat Matrix, M. E. Koopman, G. D. Hayward, David Mcdonald Apr 2007

High Connectivity And Minimal Genetic Structure Among North American Boreal Owl (Aegolius Funereus) Populations, Regardless Of Habitat Matrix, M. E. Koopman, G. D. Hayward, David Mcdonald

Zoology Faculty Publications

Habitat connectivity and corridors are often assumed to be critical for the persistence of patchily distributed populations, but empirical evidence for this assumption is scarce. We assessed the importance of connectivity among habitat patches for dispersal by a mature-forest obligate, the Boreal Owl (Aegolius funereus). Boreal Owls demonstrated a lack of genetic structure (theta = 0.004 +/- 0.002 [SE]) among subpopulations, regardless of matrix type and extent, which indicates that unforested matrix does not act as a barrier to dispersal for this vagile species. We found only slightly higher genetic distances (Cavalli-Sforza chord distances ranged from 0.015 to 0 ...


Plumage Development And Molt In Long-Tailed Manakins (Chiroxiphia Linearis): Variation According To Sex And Age, S. M. Doucet, David Mcdonald, M. S. Foster, R. P. Clay Jan 2007

Plumage Development And Molt In Long-Tailed Manakins (Chiroxiphia Linearis): Variation According To Sex And Age, S. M. Doucet, David Mcdonald, M. S. Foster, R. P. Clay

Zoology Faculty Publications

Lek-mating Long-tailed Manakins (Chiroxiphia linearis) exhibit an unusual pattern of delayed plumage maturation. Each year, males progress through a series of predefinitive plumages before attaining definitive plumage in their fifth calendar year. Female


Hummingbirds Fuel Hovering Flight With Newly Ingested Sugar, K. C. Welch, B. H. Bakken, Carlos Martinez Del Rio, R. K. Suarez Nov 2006

Hummingbirds Fuel Hovering Flight With Newly Ingested Sugar, K. C. Welch, B. H. Bakken, Carlos Martinez Del Rio, R. K. Suarez

Zoology Faculty Publications

We sought to characterize the ability of hummingbirds to fuel their energetically expensive hovering flight using dietary sugar by a combination of respirometry and stable carbon isotope techniques. Broadtailed hummingbirds (Selasphorus platycercus) were maintained on a diet containing beet sugar with an isotopic composition characteristic of C3 plants. Hummingbirds were fasted and then offered a solution containing cane sugar with an isotopic composition characteristic of C4 plants. By monitoring the rates of CO2 production and O-2 consumption, as well as the stable carbon isotope composition of expired CO2, we were able to estimate the relative contributions of carbohydrate and fat ...


Sage-Grouse And Indirect Interactions: Potential Implications Of Coyote Control On Sage-Grouse Populations, E. T. Mezquida, S. J. Slater, Craig Benkman Nov 2006

Sage-Grouse And Indirect Interactions: Potential Implications Of Coyote Control On Sage-Grouse Populations, E. T. Mezquida, S. J. Slater, Craig Benkman

Zoology Faculty Publications

Coyotes (Canis latrans) are lethally controlled throughout the range of Greater Sage-Grouse (Centrocercus urophasianus) and it has been suggested that such control may benefit sage-grouse. However, the perceived benefits of control are based on the direct effects of coyotes on sage-grouse and largely ignore potential indirect interactions. Here, we summarize some of the evidence for direct effects in a simplified food web including coyotes and sage-grouse. There is very little evidence to suggest that coyotes have much of a direct negative effect on sage-grouse, but there is considerable evidence supporting direct interactions that would lead to positive indirect effects between ...


Do Nectar- And Fruit-Eating Birds Have Lower Nitrogen Requirements Than Omnivores? An Allometric Test, E. Tsahar, Z. Ara, I. Izhaki, Carlos Martinez Del Rio Oct 2006

Do Nectar- And Fruit-Eating Birds Have Lower Nitrogen Requirements Than Omnivores? An Allometric Test, E. Tsahar, Z. Ara, I. Izhaki, Carlos Martinez Del Rio

Zoology Faculty Publications

We used an allometric approach to compare the minimum nitrogen requirements (MNR) and the total endogenous nitrogen loss (TENL) of nectar- and fruit-eating birds with those of omnivorous birds. These two parameters were 4x higher in omnivores than in nectarivores and frugivores. In nectarivorous-frugivorous birds, MNR was 152.8 mg N kg(-0.76) day(-1); in omnivorous birds, it was 575.4 mg N kg(-0.76) day(-1). Similarly, TENL was 54.1 mg N kg(-0.69) day(-1) in nectarivores-frugivores, and 215.3 mg N kg(-0.69) day(-1) in omnivores. The residuals of the ...


Burrowing Owl (Athene Cunicularia) Population Genetics: A Comparison Of North American Forms And Migratory Habits, N. M. Korfanta, David Mcdonald, T. C. Glenn Apr 2005

Burrowing Owl (Athene Cunicularia) Population Genetics: A Comparison Of North American Forms And Migratory Habits, N. M. Korfanta, David Mcdonald, T. C. Glenn

Zoology Faculty Publications

We assessed the effects of range disjunction, migratory habit, coloniality, and habitat structure on the genetic differentiation of North American Burrowing Owl (Athene cunicularia) populations. Burrowing Owls in North America comprise two forms or subspecies: A. c. floridana in Florida, separated by ∼ 1,500 km from the western form, A. c. hypugaea, which ranges from Texas to California and north to southern Canada. Burrowing Owls tend to be loosely colonial, and both the Florida populations and southerly populations of A. c. hypugaea from California to Texas are nonmigratory. To assess genetic structure, we examined 201 individuals from nine western and ...


Are The Low Protein Requirements Of Nectarivorous Birds The Consequence Of Their Sugary And Watery Diet? A Test With An Omnivore, E. Tsahar, Carlos Martinez Del Rio, Z. Arad, J. P. Joy, I. Izhaki Mar 2005

Are The Low Protein Requirements Of Nectarivorous Birds The Consequence Of Their Sugary And Watery Diet? A Test With An Omnivore, E. Tsahar, Carlos Martinez Del Rio, Z. Arad, J. P. Joy, I. Izhaki

Zoology Faculty Publications

Nectar-feeding birds have remarkably low nitrogen requirements. These may be due either to adaptation to a low-protein diet or simply to feeding on a fluid diet that minimizes metabolic fecal nitrogen losses. We measured minimal nitrogen requirements (MNR) and total endogenous nitrogen loss (TENL) in the omnivorous European starling Sturnus vulgaris, fed on an artificial nectar-like fluid diet of varying concentrations of sugar and protein. The MNR and TENL of the birds were similar and even slightly higher than allometrically expected values for birds of the starlings' mass (140% and 103%, respectively). This suggests that the low measured nitrogen requirements ...


Discordance Between Genetic Structure And Morphological, Ecological, And Physiological Adaptation In Lake Magadi Tilapia, P. J. Wilson, C. M. Wood, P. J. Walsh, A. N. Bergman, Harold Bergman, P. Laurent, B. N. White Jul 2004

Discordance Between Genetic Structure And Morphological, Ecological, And Physiological Adaptation In Lake Magadi Tilapia, P. J. Wilson, C. M. Wood, P. J. Walsh, A. N. Bergman, Harold Bergman, P. Laurent, B. N. White

Zoology Faculty Publications

The Magadi tilapia (Alcolapia grahami, formerly Oreochromis alcalicus grahami) is a remarkable example of teleost life in an extreme environment. Typical conditions include water, pH=10, titration alkalinity >300 mM, osmolality=525 mOsm, temperatures ranging from 23degrees to 42degreesC, and O-2 levels fluctuating diurnally between extreme hyperoxia and anoxia. A number of relatively small tilapia populations are present in various thermal spring lagoons around the margin of the lake separated by kilometers of solid trona crust (floating Na2CO3) underlain by anoxic water. Despite the apparent isolation of different populations, annual floods may provide opportunities for exchange of fish across the ...


Infection In The Classroom: Parasites As Models To Teach Biology, R. Scott Seville, L. Couch, R. Seed, C. Chappell, J. Caira, S. Patton Jan 2004

Infection In The Classroom: Parasites As Models To Teach Biology, R. Scott Seville, L. Couch, R. Seed, C. Chappell, J. Caira, S. Patton

Zoology Faculty Publications

No abstract provided.


Are Hummingbirds Facultatively Ammonotelic? Nitrogen Excretion And Requirements As A Function Of Body Size, T. J. Mcwhorter, D. R. Powers, Carlos Martinez Del Rio Sep 2003

Are Hummingbirds Facultatively Ammonotelic? Nitrogen Excretion And Requirements As A Function Of Body Size, T. J. Mcwhorter, D. R. Powers, Carlos Martinez Del Rio

Zoology Faculty Publications

Most birds are uricotelic. An exception to this rule may be nectar-feeding birds, which excrete significant amounts of ammonia under certain conditions. Although ammonia is toxic, because it is highly water soluble its excretion may be facilitated in animals that ingest and excrete large amounts of water. Bird-pollinated plants secrete carbohydrate- and water-rich floral nectars that contain exceedingly little protein. Thus, nectar-feeding birds are faced with the dual challenge of meeting nitrogen requirements while disposing of large amounts of water. The peculiar diet of nectar-feeding birds suggests two hypotheses: (1) these birds must have low protein requirements, and (2) when ...


Microsatellite Dna Evidence For Gene Flow In Neotropical Lek-Mating Long-Tailed Manakins, David Mcdonald Aug 2003

Microsatellite Dna Evidence For Gene Flow In Neotropical Lek-Mating Long-Tailed Manakins, David Mcdonald

Zoology Faculty Publications

I genotyped lek-mating Long-tailed Manakins (Chiroxiphia linearis) at Monteverde and Santa Rosa, Costa Rica, 115 km apart. Cavalli-Sforza distance was 0.04, D-LR was 0.18, and R-ST and theta were both 0.02. Bayesian clustering analysis indicated that both populations were part of a single cluster rather than from distinct clusters. I present a binomial test for probability of allelic absence as a function of sample size. Genotypic likelihood tests assigned 50% of Monteverde birds to Santa Rosa, versus 26% of Santa Rosa birds to Monteverde. Two lines of evidence supported the idea of asymmetric gene flow up the ...


Obligatory Urea Production And The Cost Of Living In The Magadi Tilapia Revealed By Acclimation To Reduced Salinity And Alkalinity, C. M. Wood, P. Wilson, Harold Bergman, A. N. Bergman Mar 2002

Obligatory Urea Production And The Cost Of Living In The Magadi Tilapia Revealed By Acclimation To Reduced Salinity And Alkalinity, C. M. Wood, P. Wilson, Harold Bergman, A. N. Bergman

Zoology Faculty Publications

Alcolapia grahami is a unique ureotelic tilapia that lives in the highly alkaline, saline Lake Magadi, Kenya (pH, similar to 10.0; alkalinity, similar to380 mmol L-1; Na+, similar to350 mmol L-1; Cl-, similar to110 mmol L-1; osmolality, similar to580 mosm kg(-1)). The fish survived well upon gradual exposure to dilute lake water (down to 1%, essentially freshwater). Urea excretion continued, and there was no ammonia excretion despite favorable conditions, indicating that ureotelism is obligatory. Levels of most ornithine-urea cycle enzymes in the liver were unchanged relative to controls kept for the same period in 100% lake water. The ...


Preliminary Assessment Of Burrowing Owl Population Status In Wyoming, N. M. Korfanta, L. W. Ayers, S. H. Anderson, David Mcdonald Dec 2001

Preliminary Assessment Of Burrowing Owl Population Status In Wyoming, N. M. Korfanta, L. W. Ayers, S. H. Anderson, David Mcdonald

Zoology Faculty Publications

Currently, little is known about Burrowing Owl (Athene cunicularia) abundance in Wyoming. The Wyoming Game and Fish Department (WCFD) classifies the Burrowing Owl as a Species of Special Concern. We identified available data sources to assess Burrowing Owl distribution and population trends in Wyoming and conducted a population survey in eastern Wyoming. The WGFD's Wildlife Observation System (WOS), initiated in 1974, shows a decline in Burrowing Owl records, particularly during the 12-yr period 1986-97. However, trends in WOS records over time likely reflect changing interest in the database, rather than real population trends. Likewise, Breeding Bird Survey data since ...


It Takes Guts (And More) To Eat Fruit: Lessons From Avian Nutritional Ecology, D. J. Levey, Carlos Martinez Del Rio Oct 2001

It Takes Guts (And More) To Eat Fruit: Lessons From Avian Nutritional Ecology, D. J. Levey, Carlos Martinez Del Rio

Zoology Faculty Publications

No abstract provided.


The Membrane-Bound Intestinal Enzymes Of Waxwings And Thrushes: Adaptive And Functional Implications Of Patterns Of Enzyme Activity, M. C. Witmer, Carlos Martinez Del Rio Jul 2001

The Membrane-Bound Intestinal Enzymes Of Waxwings And Thrushes: Adaptive And Functional Implications Of Patterns Of Enzyme Activity, M. C. Witmer, Carlos Martinez Del Rio

Zoology Faculty Publications

Cedar waxwings (Bombycilla cedrorum) feed predominantly on fruits that are rich in simple sugars and low in nitrogen, supplementing this diet with arthropod prey during the summer months as well as flowers and tree sap in springtime. In contrast, thrushes feed extensively on fatty, protein-rich invertebrate prey, supplemented with sugary and lipid-rich fruits. Simple sugars and fats are digested and/or absorbed by distinctly different physiological mechanisms, which suggests the possibility of contrasting digestive strategies in animals specialized to diets containing one of these two energy sources. In this study, we quantified enzymatic activity of three membrane-bound intestinal enzymes of ...


Does Gut Function Limit Hummingbird Food Intake?, T. J. Mcwhorter, Carlos Martinez Del Rio May 2000

Does Gut Function Limit Hummingbird Food Intake?, T. J. Mcwhorter, Carlos Martinez Del Rio

Zoology Faculty Publications

Many nectar-feeding bird species decrease food intake when sugar concentration in food is increased. This feeding response can be explained by two alternative hypotheses: compensatory feeding and physiological constraint. The compensatory feeding hypothesis predicts that if birds vary intake to maintain a constant energy intake to match energy expenditures, then they should increase intake when expenditures are increased. Broad-tailed hummingbirds were presented with sucrose solutions at four concentrations (292, 584, 876, and 1,168 mmol L-1) and exposed to two environmental temperatures (10 degrees and 22 degrees C). Birds decreased volumetric food intake in response to sugar concentration. However, when ...