1
|
Pavlik M, Williams TD, Green DJ. Female Songbirds Can Initiate the Transition from a Migratory to a Reproductive Physiology during Spring Migration. Physiol Biochem Zool 2021; 94:188-198. [PMID: 33852373 DOI: 10.1086/714218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractThe high energetic costs of both migration and reproduction and the physiological changes to support these costs suggest that these life-history stages should be compartmentalized with little overlap between stages. In contrast, previous studies have shown that male birds can initiate reproductive development during migration before arrival on the breeding grounds with increases in plasma testosterone levels and testis size. However, sex differences in seasonal gonadal function are now recognized as profound, and few studies to date have shown that females can initiate the costly, but critical, estrogen-dependent final stages of gonadal maturation and changes in liver function (yolk precursor synthesis, vitellogenesis) while on migration. Here, we show that female yellow warblers (Setophaga petechia) arrive on the breeding grounds with elevated plasma triglyceride levels compared with males. Some females had plasma triglyceride levels of 5-7 mmol L-1, suggesting that they arrived in a relatively advanced stage of yolk precursor production. Furthermore, we show that females that arrived with higher plasma triglyceride levels took less time to initiate their first clutch. Adaptive plasticity in the timing of the transition from a migratory to a reproductive physiology might help migrant birds buffer against a mismatch between timing of arrival and conditions on the breeding grounds and allow them to advance timing of breeding to maximize breeding productivity.
Collapse
|
2
|
Needham KB, Bergeon Burns C, Graham JL, Bauer CM, Kittilson JD, Ketterson ED, Hahn T, Greives TJ. Changes in processes downstream of the hypothalamus are associated with seasonal follicle development in a songbird, the dark-eyed junco (Junco hyemalis). Gen Comp Endocrinol 2019; 270:103-112. [PMID: 30339809 DOI: 10.1016/j.ygcen.2018.10.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 10/04/2018] [Accepted: 10/15/2018] [Indexed: 02/07/2023]
Abstract
Mechanisms related to seasonal reproductive timing in vertebrates have received far more study in males than in females, despite the fact that female timing decisions dictate when rearing of offspring will occur. Production and release of gonadotropin-releasing hormone (GnRH) by the hypothalamus stimulates the pituitary to secrete gonadotropins, initiating the beginning stages of gonadal recrudescence and production of the sex steroids, testosterone and estradiol, which are necessary to prime the liver for secretion of yolk precursors in breeding female birds. While stimulation by the hypothalamus can occur during the pre-breeding period, egg development itself is likely regulated downstream of the hypothalamus. We used GnRH challenges to examine variation in breeding-stage-specific patterns of pituitary and ovarian responsiveness in free-living female dark-eyed juncos (Junco hyemalis) and also examined the ovary and liver for variation in mRNA expression of candidate genes. Baseline LH levels increased during the transition from pre-breeding to egg-development, however no significant difference was observed in post-GnRH injection levels for LH or sex steroids (testosterone and estradiol). Interestingly, a stage by time-point interaction was observed, with post-GnRH LH levels increasing over baseline during the pre-breeding stage, but not during the egg-development stage. We observed a decrease in liver mRNA expression of estradiol receptor-alpha, and glucocorticoid and mineralocorticoid receptors and a decrease in glucocorticoid receptor expression levels in the ovary. A decline in FSH receptor expression across stages was also observed in the ovary. Combined, our data suggest seasonal variation in female's sensitivity to signals of HPG activity and energetic or stress signals. These data provide additional insight into the physiological mechanisms regulating onset of clutch initiation.
Collapse
Affiliation(s)
- Katie B Needham
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA; Environmental and Conservation Sciences Program, North Dakota State University, Fargo, ND, USA
| | | | - Jessica L Graham
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA; Environmental and Conservation Sciences Program, North Dakota State University, Fargo, ND, USA
| | - Carolyn M Bauer
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA; Department of Biology, Adelphi University, Garden City, NY, USA
| | - Jeffrey D Kittilson
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | | | - Thomas Hahn
- College of Biological Sciences, UC Davis, Davis, CA, USA
| | - Timothy J Greives
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA; Environmental and Conservation Sciences Program, North Dakota State University, Fargo, ND, USA
| |
Collapse
|
3
|
González-Medina E, Castillo-Guerrero JA, Herzka SZ, Fernández G. High quality diet improves lipid metabolic profile and breeding performance in the blue-footed booby, a long-lived seabird. PLoS One 2018; 13:e0193136. [PMID: 29462199 PMCID: PMC5819808 DOI: 10.1371/journal.pone.0193136] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 02/05/2018] [Indexed: 11/19/2022] Open
Abstract
Understanding the role of diet in the physiological condition of adults during reproduction and hence its effect on reproductive performance is fundamental to understand reproductive strategies in long-lived animals. In birds, little is known about the influence of the quality of food consumed at the beginning of the reproductive period and its short-term effects on reproductive performance. To assess the role of diet in the physiological condition of female blue-footed booby, Sula nebouxii (BFBO), during reproduction we evaluated whether individual differences in diet (assessed by using δ13C and δ15N values of whole blood from female birds and muscle tissue of the principal prey species) prior to egg laying and during incubation influenced their lipid metabolic profile (measured as triglyceride levels and C:N ratio) and their reproductive performance (defined by laying date, clutch size and hatching success). Females with higher δ15N values in their blood during the courtship and incubation periods had a higher lipid metabolic profile, earlier laying date, greater clutch size (2-3 eggs) and higher hatching success. Females that laid earlier and more eggs (2-3 eggs) consumed more Pacific anchoveta (Cetengraulis mysticetus) and Pacific thread herring (Opisthonema libertate) than did other females. These two prey species also had high amounts of lipids (C:N ratio) and caloric content (Kcal/g fresh weight). The quality of food consumed by females at the beginning of reproduction affected their physiological condition, as well as their short-term reproductive performance. Our work emphasizes the importance of determining the influence of food quality during reproduction to understand the reproductive decisions and consequences in long-lived animals.
Collapse
Affiliation(s)
- Erick González-Medina
- Posgrado de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Ciudad Universitaria, México D.F., Mexico
- * E-mail: (GF); (EGM)
| | - José Alfredo Castillo-Guerrero
- CONACYT- –Universidad de Guadalajara, Departamento de Estudios para el Desarrollo Sustentable de la Zona Costera, Centro Universitario de la Costa Sur, San Patricio– Melaque, Municipio de Cihuatlán, Jalisco, Mexico
| | - Sharon Zinah Herzka
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Baja California, Mexico
| | - Guillermo Fernández
- Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Mazatlán, Mexico
- * E-mail: (GF); (EGM)
| |
Collapse
|
4
|
Low breeding propensity and wide-ranging movements by marbled murrelets in Washington. J Wildl Manage 2016. [DOI: 10.1002/jwmg.21192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
5
|
Price ER. The physiology of lipid storage and use in reptiles. Biol Rev Camb Philos Soc 2016; 92:1406-1426. [PMID: 27348513 DOI: 10.1111/brv.12288] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/10/2016] [Accepted: 05/16/2016] [Indexed: 12/26/2022]
Abstract
Lipid metabolism is central to understanding whole-animal energetics. Reptiles store most excess energy in lipid form, mobilise those lipids when needed to meet energetic demands, and invest lipids in eggs to provide the primary source of energy to developing embryos. Here, I review the mechanisms by which non-avian reptiles store, transport, and use lipids. Many aspects of lipid absorption, transport, and storage appear to be similar to birds, including the hepatic synthesis of lipids from glucose substrates, the transport of triglycerides in lipoproteins, and the storage of lipids in adipose tissue, although adipose tissue in non-avian reptiles is usually concentrated in abdominal fat bodies or the tail. Seasonal changes in fat stores suggest that lipid storage is primarily for reproduction in most species, rather than for maintenance during aphagic periods. The effects of fasting on plasma lipid metabolites can differ from mammals and birds due to the ability of non-avian reptiles to reduce their metabolism drastically during extended fasts. The effect of fasting on levels of plasma ketones is species specific: β-hydroxybutyrate concentration may rise or fall during fasting. I also describe the process by which the bulk of lipids are deposited into oocytes during vitellogenesis. Although this process is sometimes ascribed to vitellogenin-based transport in reptiles, the majority of lipid deposition occurs via triglycerides packaged in very-low-density lipoproteins (VLDLs), based on physiological, histological, biochemical, comparative, and genomic evidence. I also discuss the evidence for non-avian reptiles using 'yolk-targeted' VLDLs during vitellogenesis. The major physiological states - feeding, fasting, and vitellogenesis - have different effects on plasma lipid metabolites, and I discuss the possibilities and potential problems of using plasma metabolites to diagnose feeding condition in non-avian reptiles.
Collapse
Affiliation(s)
- Edwin R Price
- Department of Biological Sciences, Developmental Integrative Biology Research Group, University of North Texas, Denton, TX, 76203, U.S.A
| |
Collapse
|
6
|
Watts HE, Edley B, Hahn TP. A potential mate influences reproductive development in female, but not male, pine siskins. Horm Behav 2016; 80:39-46. [PMID: 26836771 PMCID: PMC4818704 DOI: 10.1016/j.yhbeh.2016.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 12/29/2015] [Accepted: 01/29/2016] [Indexed: 10/22/2022]
Abstract
The role of photoperiod in avian reproductive timing has been well studied, and we are increasingly recognizing the roles of other environmental cues such as social cues. However, few studies have evaluated the extent to which males and females of the same species respond similarly to the same type of cue. Moreover, previous studies have rarely examined how variation in the quality or nature of a given social cue might modulate its effect. Here, we examine the sensitivity of male and female pine siskins (Spinus pinus) to a potential mate as a stimulatory cue for gonadal recrudescence, and we investigate whether variation in the relationship between a bird and its potential mate modulates the effect of that potential mate. Birds were initially housed without opposite sex birds on a 12L:12D photoperiod with ad libitum food. After gonadal recrudescence had begun males and females were randomly paired with an opposite sex bird or housed alone. An additional group of males was paired with estradiol-implanted females. In males, these social treatments had no effect on testis length, cloacal protuberance length, luteinizing hormone (LH) levels, or testosterone levels. In females, presence of a potential mate had a significant and positive effect on ovary score, defeathering of the brood patch, and LH levels. Among paired birds, the degree of affiliation within a pair corresponded to the extent of reproductive development in females, but not males. Thus, reproductive timing in females appears to be sensitive to both the presence of a potential mate and her relationship with him.
Collapse
Affiliation(s)
- Heather E Watts
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, USA.
| | - Bruce Edley
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, USA
| | - Thomas P Hahn
- Department of Neurobiology, Physiology & Behavior, University of California, Davis 95616, USA
| |
Collapse
|
7
|
Overjordet IB, Kongsrud MB, Gabrielsen GW, Berg T, Ruus A, Evenset A, Borgå K, Christensen G, Jenssen BM. Toxic and essential elements changed in black-legged kittiwakes (Rissa tridactyla) during their stay in an Arctic breeding area. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 502:548-556. [PMID: 25300019 DOI: 10.1016/j.scitotenv.2014.09.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 09/17/2014] [Accepted: 09/18/2014] [Indexed: 06/04/2023]
Abstract
Seasonal fluctuations in mercury (Hg), cadmium (Cd), zinc (Zn), copper (Cu) and selenium (Se) concentrations were studied in black-legged kittiwakes (Rissa tridactyla) from Kongsfjorden, Svalbard (79°57'N, 12°12'E). Element concentrations were determined in muscle and liver tissue in kittiwakes collected in May, July and October 2007. Stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) were analysed in muscle tissue to calculate trophic position (TP) and examine the possible influence of carbon source on element accumulation. Metallothionein (MT) concentrations in liver, as well as Hg and Cd concentration in size-fractionated liver supernatant were determined to evaluate the association between elements and MT. Mercury concentrations declined from May through July to October in both tissues, while concentrations of Cd were similar in May and July and lower in October. A decline in TP between May and July, indicating a shift from fish-based diet towards an invertebrate-based diet explains the declining Hg concentration. The low Hg and Cd concentrations in October may be a result of an increased elimination, probably related to moulting. Selenium decreased in the same manner as Hg in liver and muscle, possibly related to the formation of Se-Hg complexes. Zinc and Cu did not fluctuate in muscle tissue, whereas hepatic Zn concentrations where highest in May. Hepatic Zn concentrations were higher in females compared to males in May, possibly related to egg production. Hepatic MT concentrations were lower in October compared to July, following the same trend as Hg and Cd. Cadmium was predominantly bound to the MT fraction of proteins in liver tissue, whereas Hg was associated with the larger proteins, indicating that MT was not sequestering Hg in the kittiwakes.
Collapse
Affiliation(s)
- Ida Beathe Overjordet
- Norwegian University of Science and Technology (NTNU), Department of Biology, N-7491 Trondheim, Norway.
| | - Magnus Brunvoll Kongsrud
- Norwegian University of Science and Technology (NTNU), Department of Biology, N-7491 Trondheim, Norway
| | | | - Torunn Berg
- NTNU, Department of Chemistry, N-7491 Trondheim, Norway
| | - Anders Ruus
- Norwegian Institute for Water Research (NIVA), N-0349 Oslo, Norway
| | - Anita Evenset
- Akvaplan-niva, Fram Centre, N-9296 Tromsø, Norway; Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Norway
| | - Katrine Borgå
- Norwegian Institute for Water Research (NIVA), N-0349 Oslo, Norway; Department of Biosciences, University of Oslo, Norway
| | | | - Bjørn Munro Jenssen
- Norwegian University of Science and Technology (NTNU), Department of Biology, N-7491 Trondheim, Norway
| |
Collapse
|
8
|
Hennin HL, Legagneux P, Bêty J, Williams TD, Gilchrist HG, Baker TM, Love OP. Pre-breeding energetic management in a mixed-strategy breeder. Oecologia 2014; 177:235-43. [PMID: 25411112 DOI: 10.1007/s00442-014-3145-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 11/07/2014] [Indexed: 11/26/2022]
Abstract
Integrative biologists have long appreciated that the effective acquisition and management of energy prior to breeding should strongly influence fitness-related reproductive decisions (timing of breeding and reproductive investment). However, because of the difficulty in capturing pre-breeding individuals, and the tendency towards abandonment of reproduction after capture, we know little about the underlying mechanisms of these life-history decisions. Over 10 years, we captured free-living, arctic-breeding common eiders (Somateria mollissima) up to 3 weeks before investment in reproduction. We examined and characterized physiological parameters predicted to influence energetic management by sampling baseline plasma glucocorticoids (i.e., corticosterone), very-low-density lipoprotein (VLDL), and vitellogenin (VTG) for their respective roles in mediating energetic balance, rate of condition gain (physiological fattening rate) and reproductive investment. Baseline corticosterone increased significantly from arrival to the initiation of reproductive investment (period of rapid follicular growth; RFG), and showed a positive relationship with body mass, indicating that this hormone may stimulate foraging behaviour to facilitate both fat deposition and investment in egg production. In support of this, we found that VLDL increased throughout the pre-breeding period, peaking as predicted during RFG. Female eiders exhibited unprecedentedly high levels of VTG well before their theoretical RFG period, a potential strategy for pre-emptively depositing available protein stores into follicles while females are simultaneously fattening. This study provides some of the first data examining the temporal dynamics and interaction of the energetic mechanisms thought to be at the heart of individual variation in reproductive decisions and success in many vertebrate species.
Collapse
Affiliation(s)
- Holly L Hennin
- Department of Biological Sciences, University of Windsor, Windsor, ON, N9B 3P4, Canada,
| | | | | | | | | | | | | |
Collapse
|
9
|
Labrada-Martagón V, Zenteno-Savín T, Mangel M. Linking physiological approaches to marine vertebrate conservation: using sex steroid hormone determinations in demographic assessments. CONSERVATION PHYSIOLOGY 2014; 2:cot035. [PMID: 27293619 PMCID: PMC4732477 DOI: 10.1093/conphys/cot035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 11/20/2013] [Accepted: 12/01/2013] [Indexed: 05/26/2023]
Abstract
Sex, age and sexual maturation are key biological parameters for aspects of life history and are fundamental information for assessing demographic changes and the reproductive viability and performance of natural populations under exploitation pressures or in response to environmental influences. Much of the information available on the reproductive condition, length at sexual maturity and sex determinations of endangered species has been derived from direct examination of the gonads in dead animals, either intentionally or incidentally caught, or from stranded individuals. However, morphological data, when used alone, do not provide accurate demographic information in sexually monomorphic marine vertebrate species (e.g. sharks, sea turtles, seabirds and cetaceans). Hormone determination is an accurate and non-destructive method that provides indirect information about sex, reproductive condition and sexual maturity of free-ranging individuals. Correlations between sex steroid concentrations and biochemical parameters, gonadal development and state, reproductive behaviour and secondary external features have been already demonstrated in many species. Different non-lethal approaches (e.g. surgical and mark-recapture procedures), with intrinsic advantages and disadvantages when applied on free-ranging organisms, have been proposed to asses sex, growth and reproductive condition. Hormone determination from blood samples will generate valuable additional demographic information needed for stock assessment and biological conservation.
Collapse
Affiliation(s)
- Vanessa Labrada-Martagón
- Center for Stock Assessment Research, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
- Programa de Planeación Ambiental y Conservación, Centro de Investigaciones Biológicas del Noroeste, S.C., La Paz, Baja California Sur, México C.P. 23096
| | - Tania Zenteno-Savín
- Programa de Planeación Ambiental y Conservación, Centro de Investigaciones Biológicas del Noroeste, S.C., La Paz, Baja California Sur, México C.P. 23096
| | - Marc Mangel
- Center for Stock Assessment Research, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
- Department of Biology, University of Bergen, Bergen 5020, Norway
| |
Collapse
|
10
|
Plumel MI, Wasselin T, Plot V, Strub JM, Van Dorsselaer A, Carapito C, Georges JY, Bertile F. Mass spectrometry-based sequencing and SRM-based quantitation of two novel vitellogenin isoforms in the leatherback sea turtle (Dermochelys coriacea). J Proteome Res 2013; 12:4122-35. [PMID: 23837631 DOI: 10.1021/pr400444m] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
No biomarker has yet been discovered to identify the reproductive status of the endangered leatherback sea turtle (Dermochelys coriacea). Although vitellogenin (VTG) could be used for this, its sequence is not known in D. coriacea and no quantitative assay has been carried out in this species to date. Using de novo sequencing-based proteomics, we unambiguously characterized sequences of two different VTG isoforms that we named Dc-VTG1 and Dc-VTG2. To our knowledge, this is the first clear evidence of different VTG isoforms and the structural characterization of derived yolk proteins in reptiles. This work illustrates how massive de novo sequencing can characterize novel sequences when working on "exotic" nonmodel species in which even nucleotide sequences are not available. We developed assays for absolute quantitation of these two isoforms using selected reaction monitoring (SRM) mass spectrometry, thus providing the first SRM assays developed specifically for a nonsequenced species. Plasma levels of Dc-VTG1 and Dc-VTG2 decreased as the nesting season proceeded, and were closely related to the increased levels of reproductive effort. The SRM assays developed here therefore provide an original and efficient approach for the reliable monitoring of reproduction cycles not only in D. coriacea, but potentially in other turtle species.
Collapse
Affiliation(s)
- Marine I Plumel
- Département Sciences Analytiques, Université de Strasbourg, IPHC, 25 rue Becquerel, 67087 Strasbourg, France
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Eng ML, Elliott JE, Letcher RJ, Williams TD. Individual variation in body burden, lipid status, and reproductive investment is related to maternal transfer of a brominated diphenyl ether (BDE-99) to eggs in the zebra finch. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:345-352. [PMID: 23071079 DOI: 10.1002/etc.2033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/14/2012] [Accepted: 09/05/2012] [Indexed: 06/01/2023]
Abstract
Avian eggs are exposed to hydrophobic contaminants through maternal transfer. How maternal transfer of contaminants within a species is influenced by individual variation in characteristics such as body burden, yolk precursor levels, or reproductive investment is not understood. The authors investigated sources of variation in the maternal transfer of 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) in zebra finches (Taeniopygia guttata). The authors dosed adult female zebra finches with levels of BDE-99 relevant to exposure in wild birds (0, 33.7 or 173.8 ng/g body wt/d) for three weeks prior to pairing. Maternal BDE-99 and very-low-density lipoprotein (VLDL) in plasma were measured during egg formation and at clutch completion, and BDE-99 was measured in the corresponding egg. The lipid-normalized egg-to-maternal tissue BDE-99 relationship decreased with increasing maternal burden. Individual variation in maternal VLDL was related to BDE-99 transfer to the eggs when BDE-99 was at background levels in control birds, but not when BDE-99 was elevated in dosed birds. The decrease in maternal plasma BDE-99 over the laying period was only significant (p < 0.05) in the high-dose birds. Finally, the decrease in BDE-99 in maternal plasma during egg-laying was significantly positively correlated with clutch mass in the high-dose group. These results suggest that the relationship between maternal and egg contaminant levels can be highly variable. This has significant implications for using eggs as indicators of adult or environmental concentrations.
Collapse
Affiliation(s)
- Margaret L Eng
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
| | | | | | | |
Collapse
|
12
|
Currylow AF, Tift MS, Meyer JL, Crocker DE, Williams RN. Seasonal variations in plasma vitellogenin and sex steroids in male and female Eastern Box Turtles, Terrapene carolina carolina. Gen Comp Endocrinol 2013; 180:48-55. [PMID: 23174697 DOI: 10.1016/j.ygcen.2012.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 11/08/2012] [Accepted: 11/09/2012] [Indexed: 11/29/2022]
Abstract
The Eastern Box Turtle (Terrapene carolina carolina) is a widespread species that has recently experienced precipitous declines throughout its range. Although many studies have documented aspects of reproduction in box turtles, reproductive physiology of free-ranging animals is unknown and can be crucial in this species' recovery. Over a two-year period, we measured reproductive parameters, (vitellogenin [Vtg], estradiol-17β [E2], and total testosterone [TT]), in plasma of 116 free-ranging Eastern Box Turtles across their active season. We found similar seasonal variations of Vtg and E2 within females. Mid-season, females showed a sharp peak in E2 that correlates with the putative beginning of the ovarian cycle. Individual females lacking these expected peaks of both Vtg and E2 suggest that some female T. c. carolina may not reproduce annually. Females typically expressed undetectable levels of TT, yet there was a small peak in TT early in the active season. Male Eastern Box Turtles exhibited a dual peak in TT. Elevated TT in males was significantly associated with observed sexual behaviors and smaller home ranges. Body condition had no effect on the concentration of TT or E2 in either sex. This is the first study to (1) document Vtg and sex steroid hormones in free-ranging animals of this genus, and (2) relate those metrics to individuals, the population, the purported annual cycle, and to other chelonian species.
Collapse
Affiliation(s)
- Andrea F Currylow
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA.
| | | | | | | | | |
Collapse
|
13
|
Furlonger A, Huynh L, Luloff T, Schmidt K, MacDougall-Shackleton S. Effects of supplementation with preferred foods on the reproductive axis of American Goldfinches (Spinus tristis). CAN J ZOOL 2012. [DOI: 10.1139/z11-127] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Numerous field studies indicate that food supplementation of birds can advance laying date. In addition, laboratory studies, though less common, suggest that altering the amount of food, the predictability of food, or food type can affect reproductive physiology. American Goldfinches ( Spinus tristis , formerly Carduelis tristis (L., 1758)) breed in late summer when thistle (Cynareae) seeds become abundant, suggesting that specific food types may affect their reproductive physiology. We tested whether supplementation with preferred seeds would affect reproductive physiology of male and female American Goldfinches. Birds were photostimulated and fed a standard pellet diet, or supplemented with a variety of preferred seeds. Supplemented females developed larger ovarian follicles. Supplemented males had higher levels of plasma testosterone, but only if they were also housed with a female. These results suggest that preferred seed types can act as a supplementary cue in this species, and fine-tune photoperiod-driven changes in reproductive physiology.
Collapse
Affiliation(s)
- A.A. Furlonger
- Department of Biology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5B7, Canada
| | - L. Huynh
- Department of Biology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5B7, Canada
| | - T.W. Luloff
- Department of Biology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5B7, Canada
| | - K.L. Schmidt
- Department of Biology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5B7, Canada
| | - S.A. MacDougall-Shackleton
- Department of Psychology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5C2, Canada
| |
Collapse
|
14
|
Crossin GT, Trathan PN, Phillips RA, Dawson A, Le Bouard F, Williams TD. A carryover effect of migration underlies individual variation in reproductive readiness and extreme egg size dimorphism in macaroni penguins. Am Nat 2010; 176:357-66. [PMID: 20636133 DOI: 10.1086/655223] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Where life-history stages overlap, there is the potential for physiological conflicts that might be important in mediating carryover effects. However, our knowledge of the specific physiological mechanisms underlying carryover effects remains rudimentary, and specific examples remain rare. Here we show that female macaroni penguins (Eudyptes chrysolophus) initiate vitellogenesis and yolk formation while at sea during return migrations to breeding colonies; yolk formation takes approximately 16 days, but females lay only 7-14 days after their return. Once on land, Eudyptes penguins show a unique reproductive pattern of extreme egg size dimorphism in which the smaller, first-laid A-egg is 55%-75% of the size of the larger B-egg. We show that the degree of egg size dimorphism is inversely correlated with time between arrival and laying; that is, females that begin reproductive development well in advance of their return produce more dimorphic eggs. Furthermore, late-arriving females that produce the most dimorphic eggs have lower plasma levels of the yolk precursor vitellogenin on arrival; that is, they show lower reproductive "readiness." These data support the hypothesis that extreme egg size dimorphism in Eudyptes penguins is due to a physiological constraint imposed by a migratory carryover effect and argue against small A-eggs having a specific, adaptive function.
Collapse
Affiliation(s)
- Glenn T Crossin
- Centre for Ecology and Hydrology, Natural Environment Research Council, Penicuik, Midlothian, Scotland, United Kingdom.
| | | | | | | | | | | |
Collapse
|
15
|
Caro SP, Charmantier A, Lambrechts MM, Blondel J, Balthazart J, Williams TD. Local adaptation of timing of reproduction: females are in the driver's seat. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2008.01486.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
16
|
Gorman KB, Esler D, Walzem RL, Williams TD. Plasma yolk precursor dynamics during egg production by female greater scaup (Aythya marila): Characterization and indices of reproductive state. Physiol Biochem Zool 2009; 82:372-81. [PMID: 19117471 DOI: 10.1086/589726] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We characterized dynamics of the plasma yolk precursors vitellogenin (VTG), very-low-density lipoprotein (total VLDL-TG), and VLDL particle size distribution during egg production by female greater scaup (order: Anseriformes, Aythya marila). We also evaluated VTG and total VLDL-TG as physiological indices of reproductive state. Mean (+/-1 SE) plasma concentrations of VTG and total VLDL-TG for females with nondeveloped ovaries were 0.58 +/- 0.05 microg Zn mL(-1) and 3.75 +/- 0.29 mmol TG L(-1), respectively. Yolk precursor concentrations increased rapidly to maximum levels in association with small increases in ovary mass during rapid follicle growth. Mean concentrations of VTG and total VLDL-TG for females with a full ovarian follicle hierarchy were 3.38 +/- 0.40 microg Zn mL(-1) and 7.31 +/- 2.56 mmol TG L(-1), respectively. Concentrations of VTG and total VLDL remained elevated throughout the laying cycle and decreased markedly by 3 d into incubation. Individual reproductive state (non-egg producing vs. egg producing) was more accurately identified by plasma profiles of VTG (90%) than by those of total VLDL-TG (74%). Greater scaup VLDL particle sizes during egg production were within the range for predicted yolk-targeted VLDL size (25-44 nm). We conclude that plasma profiles of VTG and total VLDL-TG can be used as nonlethal, physiological indices of reproductive state in greater scaup and should be of great utility to a variety of evolutionary, ecological, and applied conservation studies of reproduction in waterfowl.
Collapse
Affiliation(s)
- Kristen B Gorman
- Centre for Wildlife Ecology, Simon Fraser University, Burnaby, British Columbia, Canada.
| | | | | | | |
Collapse
|
17
|
|
18
|
Challenger WO, Williams TD, Christians JK, Vézina F. Follicular development and plasma yolk precursor dynamics through the laying cycle in the European starling (Sturnus vulgaris). Physiol Biochem Zool 2001; 74:356-65. [PMID: 11331507 DOI: 10.1086/320427] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2000] [Indexed: 11/04/2022]
Abstract
We investigated the quantitative matching of plasma yolk precursor supply (the plasma pool) to follicle demand during yolk formation in European starlings (Sturnus vulgaris). Plasma concentrations of the two yolk precursors, vitellogenin (VTG) and very low density lipoprotein (VLDL), were only elevated coincident with rapid yolk development (RYD) and matched variation in total yolky follicle mass. VTG and VLDL were low (<0.4 microg/mL and <4.2 mg/mL, respectively) in nonbreeders and prebreeders with no yolky follicles, and at clutch completion. They increased to 4.02 microg/mL and 19.4 mg/mL in birds with a full follicle hierarchy (F1-F4), and concentrations then remained high and actually increased up to the point where only a single, yolky (F1) follicle remained. However, there was some evidence for mismatching of supply and demand: (a) precursor concentrations increased throughout the laying cycle even though the number of developing follicles decreased. We suggest that this is because of a requirement to maintain a large precursor pool to maintain high uptake rates; and (b) in birds with a full follicle hierarchy, precursor concentrations were negatively correlated with total follicle mass. This suggests that high uptake rates in large follicles can actually deplete circulating precursor concentrations. Plasma concentrations of both yolk precursors increased rapidly in the early morning with (predicted) time after ovulation, consistent with a lack of fine control of precursor concentrations. However, mean plasma VTG concentrations did not differ between morning or evening samples. In contrast, plasma VLDL concentrations were lower in the morning (16.8 mg/mL) than in the evening (22.9 mg/mL). Although there is marked individual variation in plasma VTG and VLDL (four- to eightfold), both precursors were repeatable in the short term (24 h), and plasma VTG was repeatable over a 14-d interval between successive breeding attempts.
Collapse
Affiliation(s)
- W O Challenger
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | | | | | | |
Collapse
|