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Full-Text Articles in Life Sciences

Mitochondrial Metabolism In Blood More Reliably Predicts Whole-Animal Energy Needs Compared To Other Tissues, Stefania Casagrande, Maciej Dzialo, Lisa Trost, Kasja Malkoc, Edyta T. Sadowska, Michaela Hau, Barbara J. Pierce, Scott R. Mcwilliams, Ulf Bauchinger Dec 2023

Mitochondrial Metabolism In Blood More Reliably Predicts Whole-Animal Energy Needs Compared To Other Tissues, Stefania Casagrande, Maciej Dzialo, Lisa Trost, Kasja Malkoc, Edyta T. Sadowska, Michaela Hau, Barbara J. Pierce, Scott R. Mcwilliams, Ulf Bauchinger

Biology Faculty Publications

Understanding energy metabolism in free-ranging animals is crucial for ecological studies. In birds, red blood cells (RBCs) offer a minimally invasive method to estimate metabolic rate (MR). In this study with European starlings Sturnus vulgaris, we examined how RBC oxygen consumption relates to oxygen use in key tissues (brain, liver, heart, and pectoral muscle) and versus the whole-organism measured at basal levels. The pectoral muscle accounted for 34-42% of organismal MR, while the heart and liver, despite their high mass-specific metabolic rate, each contributed 2.5-3.0% to organismal MR. Despite its low contribution to organismal MR (0.03-0.04%), RBC MR best predicted …


How Birds During Migration Maintain (Oxidative) Balance, Scott R. Mcwilliams, Wales A. Carter, Clara Cooper-Mullin, Kristen J. Demoranville, Abigail E. Frawley, Barbara J. Pierce, Megan Skrip Oct 2021

How Birds During Migration Maintain (Oxidative) Balance, Scott R. Mcwilliams, Wales A. Carter, Clara Cooper-Mullin, Kristen J. Demoranville, Abigail E. Frawley, Barbara J. Pierce, Megan Skrip

Biology Faculty Publications

Animals dynamically adjust their physiology and behavior to survive in changing environments, and seasonal migration is one life stage that demonstrates these dynamic adjustments. As birds migrate between breeding and wintering areas, they incur physiological demands that challenge their antioxidant system. Migrating birds presumably respond to these oxidative challenges by up-regulating protective endogenous systems or accumulating dietary antioxidants at stopover sites, although our understanding of the pre-migration preparations and mid-migration responses of birds to such oxidative challenges is as yet incomplete. Here we review evidence from field and captive-bird studies that address the following questions: (1) Do migratory birds build …


Salad With Clams: Prey Choice Of An Intentionally Carnivorous Turtle, Kayleigh R. Erazmus, Luca Luiselli, Russell L. Burke Jan 2021

Salad With Clams: Prey Choice Of An Intentionally Carnivorous Turtle, Kayleigh R. Erazmus, Luca Luiselli, Russell L. Burke

Biology Faculty Publications

Prey choice is the non-random foraging and consumption of prey species by their predators, and is therefore the basis for studies of topics as diverse as quantifying food webs, predator–prey relationships, and optimal-foraging models. Malaclemys terrapin (Diamond-back Terrapin) is a diet generalist with a large geographic distribution: the US Atlantic and Gulf coasts from Massachusetts to Texas. Individual terrapins have relatively small home ranges and feed primarily on local mollusc species. In feeding trials with 1 prey species and 2 prey species, wild-caught terrapins from New York readily consumed Mya arenaria (Soft-shelled Clam) and Geukensia demissa (Atlantic Ribbed Mussel), preferring …


Flight And Dietary Antioxidants Influence Antioxidant Expression And Activity In A Migratory Bird, Kristen J. Demoranville, Wales A. Carter, Barbara J. Pierce, Scott R. Mcwilliams Jan 2021

Flight And Dietary Antioxidants Influence Antioxidant Expression And Activity In A Migratory Bird, Kristen J. Demoranville, Wales A. Carter, Barbara J. Pierce, Scott R. Mcwilliams

Biology Faculty Publications

Ecologically-relevant factors such as exercise and diet quality can directly influence how physiological systems work including those involved in maintaining oxidative balance; however, to our knowledge, no studies to date have focused on how such factors directly affect expression of key components of the endogenous antioxidant system (i.e., transcription factors, select antioxidant genes, and corresponding antioxidant enzymes) in several metabolically active tissues of a migratory songbird. We conducted a 3-factor experiment that tested the following hypotheses: (H1) Daily flying over several weeks increases the expression of transcription factors NRF2 and PPARs as well as endogenous antioxidant genes (i.e., CAT, SOD1, …


The Energy Savings-Oxidative Cost Trade-Off For Migratory Birds During Endurance Flight, Scott R. Mcwilliams, Barbara J. Pierce, Andrea Wittenzellner, Lillie A. Langlois, Sophia Engel, John R. Speakman, Olivia Fatica, Kristen J. Demoranville, Wolfgang Goymann, Lisa Trost, Amadeusz Bryla, Maciej Dzialo, Edyta T. Sadowska, Ulf Bauchinger Dec 2020

The Energy Savings-Oxidative Cost Trade-Off For Migratory Birds During Endurance Flight, Scott R. Mcwilliams, Barbara J. Pierce, Andrea Wittenzellner, Lillie A. Langlois, Sophia Engel, John R. Speakman, Olivia Fatica, Kristen J. Demoranville, Wolfgang Goymann, Lisa Trost, Amadeusz Bryla, Maciej Dzialo, Edyta T. Sadowska, Ulf Bauchinger

Biology Faculty Publications

Elite human and animal athletes must acquire the fuels necessary for extreme feats, but also contend with the oxidative damage associated with peak metabolic performance. Here, we show that a migratory bird with fuel stores composed of more omega-6 polyunsaturated fats (PUFA) expended 11% less energy during long-duration (6 hr) flights with no change in oxidative costs; however, this short-term energy savings came at the long-term cost of higher oxidative damage in the omega-6 PUFA-fed birds. Given that fatty acids are primary fuels, key signaling molecules, the building blocks of cell membranes, and that oxidative damage has long-term consequences for …


The Effects Of Dietary Linoleic Acid And Hydrophilic Antioxidants On Basal, Peak, And Sustained Metabolism In Flight‐Trained European Starlings, Wales A. Carter, Kristen J. Demoranville, Barbara J. Pierce, Scott R. Mcwilliams Feb 2020

The Effects Of Dietary Linoleic Acid And Hydrophilic Antioxidants On Basal, Peak, And Sustained Metabolism In Flight‐Trained European Starlings, Wales A. Carter, Kristen J. Demoranville, Barbara J. Pierce, Scott R. Mcwilliams

Biology Faculty Publications

Dietary micronutrients have the ability to strongly influence animal physiology and ecology. For songbirds, dietary polyunsaturated fatty acids (PUFAs) and antioxidants are hypothesized to be particularly important micronutrients because of their influence on an individual's capacity for aerobic metabolism and recovery from extended bouts of exercise. However, the influence of specific fatty acids and hydrophilic antioxidants on whole‐animal performance remains largely untested. We used diet manipulations to directly test the effects of dietary PUFA, specifically linoleic acid (18:2n6), and anthocyanins, a hydrophilic antioxidant, on basal metabolic rate (BMR), peak metabolic rate (PMR), and rates of fat catabolism, lean catabolism, and …


Dietary Antioxidants Attenuate The Endocrine Stress Response During Long-Duration Flight Of A Migratory Bird, Stefania Casagrande, Kristen J. Demoranville, Lisa Trost, Barbara J. Pierce, Amadeusz Bryła, Maciej Dzialo, Edyta T. Sadowska, Ulf Bauchinger, Scott R. Mcwilliams Jan 2020

Dietary Antioxidants Attenuate The Endocrine Stress Response During Long-Duration Flight Of A Migratory Bird, Stefania Casagrande, Kristen J. Demoranville, Lisa Trost, Barbara J. Pierce, Amadeusz Bryła, Maciej Dzialo, Edyta T. Sadowska, Ulf Bauchinger, Scott R. Mcwilliams

Biology Faculty Publications

Glucocorticoids (GCs) are metabolic hormones that promote catabolic processes, which release stored energy and support high metabolic demands such as during prolonged flights of migrating birds. Dietary antioxidants (e.g. anthocyanins) support metabolism by quenching excess reactive oxygen species produced during aerobic metabolism and also by activating specific metabolic pathways. For example, similar to GCs’ function, anthocyanins promote the release of stored energy, although the extent of complementarity between GCs and dietary antioxidants is not well known. If anthocyanins complement GCs functions, birds consuming anthocyanin-rich food can be expected to limit the secretion of GCs when coping with a metabolically challenging …


The Fat Of The Matter: How Dietary Fatty Acids Can Affect Exercise Performance, Barbara J. Pierce, Scott R. Mcwilliams Nov 2014

The Fat Of The Matter: How Dietary Fatty Acids Can Affect Exercise Performance, Barbara J. Pierce, Scott R. Mcwilliams

Biology Faculty Publications

Fatty-acid composition of fat stores affects exercise performance in a variety of vertebrates although few such studies focus on flying vertebrates such as migratory birds, which are exceptional exercisers. We first discuss the natural variation in quality of fat available in natural foods eaten by migratory birds and their behavioral preferences for specific fatty acids in these foods. We then outline three proposed hypotheses for how dietary fatty acids can affect exercise performance, and some of the evidence to date that pertains to these hypotheses with special emphasis on the exercise performance of migratory birds. In theory, selectively feeding on …


A Comparison Of Prairie Vole Audible And Ultrasonic Pup Calls And Attraction To Them By Adults Of Each Sex, Thomas A. Terleph Jan 2011

A Comparison Of Prairie Vole Audible And Ultrasonic Pup Calls And Attraction To Them By Adults Of Each Sex, Thomas A. Terleph

Biology Faculty Publications

Rodent pups of many species emit both ultrasonic vocalizations (USVs) and calls spanning into a lower frequency range, audible to humans (AUDs), yet there has been little systematic comparison of these different call types, or analyses of how they might differ in signal function. Here the spectral and temporal characteristics of USV and AUD pup calls are described for the prairie vole (Microtus ochrogaster), a model used in studies of monogamous mating and biparental care, and a species with an unusually large functional and anatomical representation of auditory cortex. Findings provide a detailed description of each call type, …


Estimation Of Short-Term Tag-Induced Mortality In Horseshoe Crabs Limulus Polyphemus, Jennifer Mattei, Mark Beekey, H. R. Potter, C. S. Bond, Alyssa Woronik, J. A. Roberts, K. A. Smith Jan 2011

Estimation Of Short-Term Tag-Induced Mortality In Horseshoe Crabs Limulus Polyphemus, Jennifer Mattei, Mark Beekey, H. R. Potter, C. S. Bond, Alyssa Woronik, J. A. Roberts, K. A. Smith

Biology Faculty Publications

Horseshoe crabs Limulus Polyphemus range along the East Coast of the United States and over 150,000 of them have been marked with U.S. Fish and Wildlife Service disk tags. It has been assumed that the tags do not harm the animals and are similar to common epibionts often found on the shells of the horseshoe crabs. We investigated whether newlv tagged adult female horseshoe crabs would exhibit higher short-term mortality rates than untagged adult females. All crabs were collected from a beach in Connecticut and then were transported to a laboratory for the experiment. Tagging involved drilling a small hole …


Bilateral Multi-Electrode Neurophysiological Recordings Coupled To Local Pharmacology In Awake Songbirds, Liisa A. Tremere, Thomas A. Terleph, Jin Kwon Jeong, Raphael Pinaud Feb 2010

Bilateral Multi-Electrode Neurophysiological Recordings Coupled To Local Pharmacology In Awake Songbirds, Liisa A. Tremere, Thomas A. Terleph, Jin Kwon Jeong, Raphael Pinaud

Biology Faculty Publications

Here we describe a protocol for bilateral multielectrode neurophysiological recordings during intracerebral pharmacological manipulations in awake songbirds. This protocol encompasses fitting adult animals with head-posts and recording chambers, and acclimating them to periods of restraint. The adaptation period is followed by bilateral penetrations of multiple electrodes to obtain acute, sensory-driven neurophysiological responses before versus during the application of pharmacological agents of interest. These local manipulations are achieved by simultaneous and restricted drug infusions carried out independently for each hemisphere. We have used this protocol to elucidate how neurotransmitter and neuroendocrine systems shape the auditory and perceptual processing of natural, learned …


Horseshoe Crab Spawning Survey Protocol, Jennifer Mattei Jan 2009

Horseshoe Crab Spawning Survey Protocol, Jennifer Mattei

Biology Faculty Publications

The protocol lists supplies and clothing needed for the survey, as well as which data is to be collected and when and how it should be entered for the census of horseshoe crabs on the Recapture Data Sheet for 2009. Adopted from Cape Cod and Delaware Bay survey protocols.


Response Properties Of The Auditory Telencephalon In Songbirds Change With Recent Experience And Season, Thomas A. Terleph, Kai Lu, David S. Vicario Aug 2008

Response Properties Of The Auditory Telencephalon In Songbirds Change With Recent Experience And Season, Thomas A. Terleph, Kai Lu, David S. Vicario

Biology Faculty Publications

The caudomedial nidopallium (NCM) is a telencephalic auditory area that is selectively activated by conspecific vocalizations in zebra finches and canaries. We recently demonstrated that temporal and spectral dynamics of auditory tuning in NCM differ between these species [1]. In order to determine whether these differences reflect recent experience, we exposed separate groups of each species and sex to different housing conditions. Adult birds were housed either in an aviary with conspecifics (NORM), with heterospecifics (canary subjects in a zebra finch aviary, and vice versa: (CROSS)), or in isolation (ISO) for 9 days prior to testing. We then recorded extracellular …


A Songbird Forebrain Area Potentially Involved In Auditory Discrimination And Memory Formation, Raphael Pinaud, Thomas A. Terleph Mar 2008

A Songbird Forebrain Area Potentially Involved In Auditory Discrimination And Memory Formation, Raphael Pinaud, Thomas A. Terleph

Biology Faculty Publications

Songbirds rely on auditory processing of natural communication signals for a number of social behaviors, including mate selection, individual recognition and the rare behavior of vocal learning - the ability to learn vocalizations through imitation of an adult model, rather than by instinct. Like mammals, songbirds possess a set of interconnected ascending and descending auditory brain pathways that process acoustic information and that are presumably involved in the perceptual processing of vocal communication signals. Most auditory areas studied to date are located in the caudomedial forebrain of the songbird and include the thalamo-recipient field L (subfields L1, L2 and L3), …


Neural Correlates Of Auditory Processing, Learning And Memory Formation In Songbirds, Raphael Pinaud, Thomas A. Terleph, Ryan D. Wynne, Liisa A. Tremere Feb 2008

Neural Correlates Of Auditory Processing, Learning And Memory Formation In Songbirds, Raphael Pinaud, Thomas A. Terleph, Ryan D. Wynne, Liisa A. Tremere

Biology Faculty Publications

Songbirds have emerged as powerful experimental models for the study of auditory processing of complex natural communication signals. Intact hearing is necessary for several behaviors in developing and adult animals including vocal learning, territorial defense, mate selection and individual recognition. These behaviors are thought to require the processing, discrimination and memorization of songs. Although much is known about the brain circuits that participate in sensorimotor (auditory-vocal) integration, especially the “songcontrol” system, less is known about the anatomical and functional organization of central auditory pathways. Here we discuss findings associated with a telencephalic auditory area known as the caudomedial nidopallium (NCM). …


Fruit Quality And Consumption By Songbirds During Autumn Migration, Susan B. Smith, Kathleen H. Mcpherson, Jeffrey M. Backer, Barbara J. Pierce, David W. Podlesak, Scott R. Mcwilliams Sep 2007

Fruit Quality And Consumption By Songbirds During Autumn Migration, Susan B. Smith, Kathleen H. Mcpherson, Jeffrey M. Backer, Barbara J. Pierce, David W. Podlesak, Scott R. Mcwilliams

Biology Faculty Publications

Seasonal fruits are an important food resource for small songbirds during autumn migration in southern New England. Therefore, conservation and management of important stopover sites used by migrating birds requires knowledge about nutritional requirements of songbirds and nutritional composition of commonly consumed fruits. We measured nutrient composition and energy density of nine common fruits on Block Island, Rhode Island, and conducted a field experiment to estimate consumption rates of three of these fruits by birds during autumn migration. Most common fruits on Block Island contained primarily carbohydrates (41.3–91.2% dry weight), and little protein (2.6–8.6%) and fat (0.9–3.7%), although three contained …


Eleutherodactylus Ridens (Pygmy Rainfrog) Predation, Tobias Eisenberg, Twan Leenders Sep 2007

Eleutherodactylus Ridens (Pygmy Rainfrog) Predation, Tobias Eisenberg, Twan Leenders

Biology Faculty Publications

Workers of the large ponerine ant Paraponera clavata typically forage on small to medium-sized arthropods or collect pieces of plants or nectar but have been suspected of predating small vertebrates.


New Distribution Records For Amphibians And Reptiles In Connecticut, With Notes On The Status Of An Introduced Species, Gregory J. Watkins-Colwell, Twan Leenders, Brian T. Roach, Daniel J. Drew, Gregg Dancho, Jeanne Yuckienuz Oct 2006

New Distribution Records For Amphibians And Reptiles In Connecticut, With Notes On The Status Of An Introduced Species, Gregory J. Watkins-Colwell, Twan Leenders, Brian T. Roach, Daniel J. Drew, Gregg Dancho, Jeanne Yuckienuz

Biology Faculty Publications

Recent field work and a review of catalogued specimens in the herpetology collections at the Yale Peabody has yielded 170 new town records for amphibians and reptiles in Connecticut. These are reported here, along with observations on the status of the red-ear slider (Trachemys scripta) in Connecticut.


A Switch From Polyandry To Serial Monogamy: Results From A Three Year Tagging Study Of Horseshoe Crabs In Long Island Sound, Jennifer Mattei Ph.D., Paul Goodell, Christine Depierro, Meghann Burke Jan 2006

A Switch From Polyandry To Serial Monogamy: Results From A Three Year Tagging Study Of Horseshoe Crabs In Long Island Sound, Jennifer Mattei Ph.D., Paul Goodell, Christine Depierro, Meghann Burke

Biology Faculty Publications

Part of an ongoing population study of the North American Horseshoe Crab, Limulus polyphemus, in Long Island Sound was completed during the 2003 – 2005 spawning seasons at Milford Point, in Milford, CT. Horseshoe crabs range more widely throughout Long Island Sound than expected and exhibit weak site fidelity. Animals originally tagged in Milford were found as far west as Stamford and as far east as Clinton, CT. during the 3 year study. Out of 522 female horseshoe crabs tagged in 2004 only 4 came back to spawn again at Milford Pt. in 2005. The sex ratios of tagged and …


Seasonal Changes In Composition Of Lipid Stores In Migratory Birds: Causes And Consequences, Barbara J. Pierce, Scott R. Mcwilliams May 2005

Seasonal Changes In Composition Of Lipid Stores In Migratory Birds: Causes And Consequences, Barbara J. Pierce, Scott R. Mcwilliams

Biology Faculty Publications

It is well established that birds use fat stores to primarily fuel migration; however, few studies have focused on the causes and consequences of observed seasonal changes in fatty acid composition of fat stores in birds. We propose and test two hypotheses that address the causes of these seasonal changes in composition of fat stores: (1) diet composition determines fatty acid composition of fat stores, and (2) birds selectively metabolize and store certain fatty acids during migration in lieu of changing their diet. When we offered Red-eyed Vireos (Vireo olivaceous) choices between diets that differed only in fatty acid composition, …


Effect Of Dietary Fatty Acid Composition On Depot Fat And Exercise Performance In A Migrating Songbird, The Red-Eyed Vireo, Barbara J. Pierce, Scott R. Mcwilliams, Timothy P. O'Connor, Allen R. Place, Christopher G. Guglielmo Jan 2005

Effect Of Dietary Fatty Acid Composition On Depot Fat And Exercise Performance In A Migrating Songbird, The Red-Eyed Vireo, Barbara J. Pierce, Scott R. Mcwilliams, Timothy P. O'Connor, Allen R. Place, Christopher G. Guglielmo

Biology Faculty Publications

Most migrating birds accumulate lipid stores as their primary source of energy for fueling long distance flights. Lipid stores of birds during migration are composed of mostly unsaturated fatty acids; whether such a fatty acid composition enhances exercise performance of birds is unknown. We tested this hypothesis by measuring metabolic rate at rest and during intense exercise in two groups of red-eyed vireos, a long-distance migratory passerine, fed either a diet containing 82% unsaturated fat (82%U), or one containing 58% unsaturated fat (58%U). Vireos fed the 82%U diet had fat stores containing (77%) unsaturated fatty acids, whereas vireos fed the …


Apparent Sibling Rivalry In The Freshwater Clam Sphaerium Striatinum, Mark Beekey, Ronald H. Karlson Nov 2004

Apparent Sibling Rivalry In The Freshwater Clam Sphaerium Striatinum, Mark Beekey, Ronald H. Karlson

Biology Faculty Publications

In Sphaerium striatinum, a freshwater brooding bivalve, up to 97.5% of offspring that adults initially produce fail to reach independence. Marsupial sacs, specialized extensions of gill filaments that act as nurseries, initially contain multiple offspring in various sizes and stages of development. However, by the time offspring reach later stages of development, marsupial sacs typically contain only one offspring. Brood mortality is hypothesized to be the result of competition among embryos for nutrients and/or space. Sphaeriid eggs do not contain enough yolk for offspring to complete development. Adults supply additional nutrients required to reach independence. Brood capacity is limited by …


Diet Quality And Food Limitation Affect The Dynamics Of Body Composition And Digestive Organs In A Migratory Songbird (Zonotrichia Albicollis), Barbara J. Pierce, Scott R. Mcwilliams Jan 2004

Diet Quality And Food Limitation Affect The Dynamics Of Body Composition And Digestive Organs In A Migratory Songbird (Zonotrichia Albicollis), Barbara J. Pierce, Scott R. Mcwilliams

Biology Faculty Publications

Migrating songbirds interrupt their feeding to fly between stopover sites that may vary appreciably in diet quality. We studied the effects of fasting and food restriction on body composition and digestive organs in a migratory songbird and how these effects interacted with diet quality to influence the rate of recovery of nutrient reserves. Food limitation caused whitethroated sparrows to reduce both lean and fat reserves, with about 20% of the decline in lean mass represented by a decline in stomach, small intestine, and liver. During refeeding on diets similar in nutrient composition to either grain or fruit, foodlimited grain-fed birds …


The Effect Of Size-Limited Brood Capacity On Brood Size In A Freshwater Bivalve, Mark Beekey Jan 2004

The Effect Of Size-Limited Brood Capacity On Brood Size In A Freshwater Bivalve, Mark Beekey

Biology Faculty Publications

Size limited brood capacity is common among species with hard exoskeletons or shells. In these species, brood size is limited by the physical capacity to hold offspring. Here we present evidence that brood size is limited by physical constraints in Sphaerium striatinum , a small brooding bivalve. Sphaerium striatinum is a sequential brooder and produces offspring throughout the year. Offspring are brooded in marsupial sacs located on the inner demibranch. In an unconstrained brooder one would predict that brood size would increase as a function of adult length cubed, a volumetric relationship. In S. striatinum, brood size increases as less …


Effects Of Social Interaction On The Electric Organ Discharge In A Mormyrid Fish, Gnathonemus Petersii (Mormyridae, Teleostei), Thomas A. Terleph, Peter Moller Jan 2003

Effects Of Social Interaction On The Electric Organ Discharge In A Mormyrid Fish, Gnathonemus Petersii (Mormyridae, Teleostei), Thomas A. Terleph, Peter Moller

Biology Faculty Publications

African weakly discharging electric fish (Mormyridae) use their self-generated electric signals and electroreceptive abilities for orientation and communication in the context of courtship and territorial interactions. This paper documents socially mediated changes in the electric organ discharge (EOD) of subadult Gnathonemus petersii under non-breeding environmental conditions. Increases in EOD duration and changes in the relative phase amplitudes occurred in dominant fish during same-sex (male–male, female–female) and opposite-sex interactions. Similar changes were also observed in fish that were restricted in their physical interactions, suggesting that direct contact is not necessary to induce dominance-typical EOD waveforms. The possible communicative functions of these …


Parental Care In Sphaerium Striatinum Lamarck: Evidence For Retention Of Competent Offspring, Mark Beekey, Ronald H. Karlson, Alyse R. Greenberg Oct 2000

Parental Care In Sphaerium Striatinum Lamarck: Evidence For Retention Of Competent Offspring, Mark Beekey, Ronald H. Karlson, Alyse R. Greenberg

Biology Faculty Publications

The timing of offspring release is a fundamental turning point in the life history of any organism. It represents the end to many of the most costly forms of parental care (e.g., provisioning of nutrients for developing eggs and zygotes) and the beginning of an independent life for the offspring. Generally temporal variation in this event is attributed to a variety of physiological and evolutionary trade-offs. Here we examine the retention of offspring in the freshwater clam Sphaerium striatinum Lamarck. Brooded offspring are typically not released into the environment until they are 4.0 mm shell length (SL). We provide evidence …