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Hossain M, Pal S, Kumar Tiwari P, Pal N. Bifurcations, chaos, and multistability in a nonautonomous predator-prey model with fear. CHAOS (WOODBURY, N.Y.) 2021; 31:123134. [PMID: 34972329 DOI: 10.1063/5.0067046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Classical predator-prey models usually emphasize direct predation as the primary means of interaction between predators and prey. However, several field studies and experiments suggest that the mere presence of predators nearby can reduce prey density by forcing them to adopt costly defensive strategies. Adoption of such kind would cause a substantial change in prey demography. The present paper investigates a predator-prey model in which the predator's consumption rate (described by a functional response) is affected by both prey and predator densities. Perceived fear of predators leads to a drop in prey's birth rate. We also consider both constant and time-varying (seasonal) forms of prey's birth rate and investigate the model system's respective autonomous and nonautonomous implementations. Our analytical studies include finding conditions for the local stability of equilibrium points, the existence, direction of Hopf bifurcation, etc. Numerical illustrations include bifurcation diagrams assisted by phase portraits, construction of isospike and Lyapunov exponent diagrams in bi-parametric space that reveal the rich and complex dynamics embedded in the system. We observe different organized periodic structures within the chaotic regime, multistability between multiple pairs of coexisting attractors with intriguing basins of attractions. Our results show that even relatively slight changes in system parameters, perturbations, or environmental fluctuations may have drastic consequences on population oscillations. Our observations indicate that the fear effect alters the system dynamics significantly and drives an otherwise irregular system toward regularity.
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Affiliation(s)
- Mainul Hossain
- Department of Mathematics, Visva-Bharati, Santiniketan 731235, India
| | - Saheb Pal
- Department of Mathematics, Visva-Bharati, Santiniketan 731235, India
| | - Pankaj Kumar Tiwari
- Department of Basic Science and Humanities, Indian Institute of Information Technology, Bhagalpur 813210, India
| | - Nikhil Pal
- Department of Mathematics, Visva-Bharati, Santiniketan 731235, India
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2
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Hill SD, Pawley MDM, Bishop CD. Annual variation in bird numbers across Kaipatiki, Auckland. NEW ZEALAND JOURNAL OF ZOOLOGY 2020. [DOI: 10.1080/03014223.2020.1833948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Samuel D. Hill
- Research, Investigations and Monitoring Unit, Auckland Council, Auckland, New Zealand
| | - Matthew D. M. Pawley
- School of Natural and Computational Sciences, Massey University, Auckland, New Zealand
| | - Craig D. Bishop
- School of Science, Auckland University of Technology, Auckland, New Zealand
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3
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Yarra AN, Magoulick DD. Effect of Stream Permanence on Predation Risk of Lotic Crayfish by Riparian Predators. SOUTHEAST NAT 2020. [DOI: 10.1656/058.019.0407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Allyson N. Yarra
- Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701
| | - Daniel D. Magoulick
- US Geological Survey, Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University Arkansas, Fayetteville, AR 72701
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4
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Wegge P, Rolstad J. Climate change and bird reproduction: warmer springs benefit breeding success in boreal forest grouse. Proc Biol Sci 2018; 284:rspb.2017.1528. [PMID: 29118133 PMCID: PMC5698643 DOI: 10.1098/rspb.2017.1528] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 10/09/2017] [Indexed: 11/12/2022] Open
Abstract
Global warming is predicted to adversely affect the reproduction of birds, especially in northern latitudes. A recent study in Finland inferred that declining populations of black grouse, Tetrao tetrix, could be attributed to advancement of the time of mating and chicks hatching too early—supporting the mismatch hypothesis. Here, we examine the breeding success of sympatric capercaillie, T. urogallus, and black grouse over a 38-year period in southeast Norway. Breeding season temperatures increased, being most pronounced in April. Although the onset of spring advanced nearly three weeks, the peak of mating advanced only 4–5 days. In contrast to the result of the Finnish study, breeding success increased markedly in both species (capercaillie: 62%, black grouse: 38%). Both brood frequency and brood size increased during the study period, but significantly so only for brood frequency in capercaillie. Whereas the frequency of capercaillie broods was positively affected by rising temperatures, especially during the pre-hatching period, this was not the case in black grouse. Brood size, on the other hand, increased with increasing post-hatching temperatures in both species. Contrary to the prediction that global warming will adversely affect reproduction in boreal forest grouse, our study shows that breeding success was enhanced in warmer springs.
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Affiliation(s)
- Per Wegge
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, PO Box 5003 NMBU, 1432, Ås, Norway
| | - Jørund Rolstad
- Department of Forest Genetics and Biodiversity, Norwegian Institute of Bioeconomy Research, PO Box 115, 1431, Ås, Norway
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5
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Englert Duursma D, Gallagher RV, Griffith SC. Effects of El Niño Southern Oscillation on avian breeding phenology. DIVERS DISTRIB 2018. [DOI: 10.1111/ddi.12750] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
| | | | - Simon C. Griffith
- Department of Biological Sciences Macquarie University North Ryde NSW Australia
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6
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Abstract
Although reproductive strategies can be influenced by a variety of intrinsic and extrinsic factors, life history theory provides a rigorous framework for explaining variation in reproductive effort. The terminal investment hypothesis proposes that a decreased expectation of future reproduction (as might arise from a mortality threat) should precipitate increased investment in current reproduction. Terminal investment has been widely studied, and a variety of intrinsic and extrinsic cues that elicit such a response have been identified across an array of taxa. Although terminal investment is often treated as a static strategy, the level at which a cue of decreased future reproduction is sufficient to trigger increased current reproductive effort (i.e., the terminal investment threshold) may depend on context, including the internal state of the organism or its current external environment, independent of the cue that triggers a shift in reproductive investment. Here, we review empirical studies that address the terminal investment hypothesis, exploring both the intrinsic and extrinsic factors that mediate its expression. Based on these studies, we propose a novel framework within which to view the strategy of terminal investment, incorporating factors that influence an individual's residual reproductive value beyond a terminal investment trigger - the dynamic terminal investment threshold.
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Stevenson TJ, Bernard DJ, McCarthy MM, Ball GF. Photoperiod-dependent regulation of gonadotropin-releasing hormone 1 messenger ribonucleic acid levels in the songbird brain. Gen Comp Endocrinol 2013; 190:81-7. [PMID: 23660447 PMCID: PMC3742601 DOI: 10.1016/j.ygcen.2013.04.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 12/19/2022]
Abstract
Annual changes in day length induce marked changes in reproductive function in temperate zone vertebrates. In many avian species, in contrast to other seasonally breeding animals, plasticity in hypothalamic gonadotropin-releasing hormone - 1 (GnRH1) expression rather than (or in addition to) release governs changes in pituitary-gonadal activity. Investigations of the cellular and molecular mechanisms that govern GnRH1 plasticity were previously hindered by a collective inability of scientists in the field to characterize the gnrh1 cDNA in songbirds. We finally overcame this roadblock after data from the zebra finch (Taeniopygia guttata) genome project enabled us to rapidly clone the gnrh1 cDNA from hypothalamic RNA of zebra finches and European starlings (Sturnus vulgaris). Here, we review the original data that identified GnRH1 protein plasticity in the songbird brain and discuss earlier failed attempts to clone gnrh1 in these animals. Then, we present recent efforts, including our own, that successfully characterized gnrh1 in zebra finch and starling, and demonstrated dynamic regulation of gnrh1 mRNA expression, particularly in sub-populations of preoptic area neurons, in the latter. Overall, this paper highlights GnRH1 plasticity in the avian brain, and weaves into the narrative the previously untold story of the challenges to sequencing gnrh1 in songbirds.
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Affiliation(s)
- Tyler J Stevenson
- Institute for Mind and Biology, University of Chicago, Chicago, IL, USA.
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Saino N, Romano M, Caprioli M, Fasola M, Lardelli R, Micheloni P, Scandolara C, Rubolini D, Gianfranceschi L. Timing of molt of barn swallows is delayed in a rare Clock genotype. PeerJ 2013; 1:e17. [PMID: 23638351 PMCID: PMC3629011 DOI: 10.7717/peerj.17] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 01/04/2013] [Indexed: 11/20/2022] Open
Abstract
Photoperiodic responses are major factors entraining circannual life-cycles, functioning to adaptively synchronize annual routines to seasonal fluctuations in ecological conditions. Photoperiodism in physiology and behaviour is enforced by genes, including the vertebrate Clock orthologues, which are associated, for example, with phenology of migration in fish and breeding in birds. However, the role of Clock in photoperiodic plumage molt processes is unknown. We analyzed variation in molt schedules in relation to Clock genotype, using the long-distance migratory barn swallow (Hirundo rustica) as a model and by identifying males and females using molecular sexing techniques. Consistently with previous studies, we found one very common (Q7) and two rare (Q6, Q8) variants of a functionally significant Clock polyglutamine repeat. Molt schedules of primary wing feathers of swallows during their wintering period in Nigeria differed among Clock genotypes: rare (1.1%) Q7/Q8 heterozygotes had significantly delayed molt compared to the other genotypes. Molt schedules did not differ between males and females, and no differential association between molt and Clock in relation to sex emerged. The same rare Clock genotype that exhibited delayed breeding in Europe was here found to delay molt in Africa. Though based on a limited number of Q7/Q8 individuals from an otherwise very large sample, these novel results suggest that Clock is involved in the photoperiodic control of both molt and breeding, potentially also via reciprocal carry-over effects. If confirmed in species with higher Clock polymorphism, present results may have far-reaching consequences for the study of photoperiodic control of molt and expression of annual routines.
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Affiliation(s)
- Nicola Saino
- Department of Biosciences , University of Milan , Milan , Italy
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9
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Gunn M, Champion Z, Casey M, Teal P, Casey P. Testicular and spermatozoan parameters in the pukeko (Porphyrio porphyrio melanotus). Anim Reprod Sci 2008; 109:330-42. [DOI: 10.1016/j.anireprosci.2007.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Revised: 11/04/2007] [Accepted: 11/13/2007] [Indexed: 10/22/2022]
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10
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Schoech SJ, Hahn TP. RETRACTED ARTICLE: Latitude affects degree of advancement in laying by birds in response to food supplementation: a meta-analysis. Oecologia 2008; 157:369-76. [PMID: 18604561 DOI: 10.1007/s00442-008-1091-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 06/04/2008] [Indexed: 02/05/2023]
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11
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Hau M, Gill SA, Goymann W. Tropical field endocrinology: ecology and evolution of testosterone concentrations in male birds. Gen Comp Endocrinol 2008; 157:241-8. [PMID: 18571172 DOI: 10.1016/j.ygcen.2008.05.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 05/06/2008] [Accepted: 05/20/2008] [Indexed: 10/22/2022]
Abstract
Comparative research on natural populations of vertebrates, in particular avian species, has been instrumental in documenting the existence of interspecific variation in the hormonal regulation of behavior. Studies on tropical birds, which tend to experience ecological conditions that diverge from those of higher latitude birds, have been invaluable in showcasing such variation. Here we review recent advances in tropical avian field endocrinology, focusing on male circulating testosterone concentrations during the breeding season. We summarize the evidence for a decrease in male circulating testosterone concentrations from high towards low latitudes. We revisit both established and recently proposed ecological hypotheses that attempt to explain the existence of this pattern, as well as the variation in testosterone concentrations and dynamics within tropical populations of birds. We highlight additional social and life history variables that may need to be considered if we aim at gaining an integrated understanding of the ultimate factors that influence the relationship between hormonal signals and behavioral traits in natural populations. Understanding the ecological factors that influence circulating hormone concentrations will be an important first step in our understanding of the evolutionary processes that are at the basis of variations in hormone-behavior connections. Such findings should be supplemented by studies on functional aspects of the testosterone signal at the organismal and cellular level.
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12
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Hahn TP, MacDougall-Shackleton SA. Adaptive specialization, conditional plasticity and phylogenetic history in the reproductive cue response systems of birds. Philos Trans R Soc Lond B Biol Sci 2008; 363:267-86. [PMID: 17686737 PMCID: PMC2606750 DOI: 10.1098/rstb.2007.2139] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Appropriately timed integration of breeding into avian annual cycles is critical to both reproductive success and survival. The mechanisms by which birds regulate timing of breeding depend on environmental cue response systems that regulate both when birds do and do not breed. Despite there being multiple possible explanations for birds' abilities to time breeding appropriately in different environments, and for the distribution of different cue response system characteristics among taxa, many studies infer that adaptive specialization of cue response systems has occurred without explicitly considering the alternatives. In this paper, we make explicit three hypotheses concerning the timing of reproduction and distribution of cue response characteristics among taxa: adaptive specialization; conditional plasticity; and phylogenetic history. We emphasize in particular that although conditional plasticity built into avian cue response systems (e.g. differing rates of gonadal development and differing latencies until onset of photorefractoriness) may lead to maladaptive annual cycles in some novel circumstances, this plasticity also can lead to what appear to be adaptively specialized cue response systems if not viewed in a comparative context. We use a comparative approach to account for the distribution of one important feature of avian reproductive cue response systems, photorefractoriness. Analysis of the distribution within songbirds of one criterion for absolute photorefractoriness, the spontaneous regression of the gonads without any decline in photoperiod, reveals that a failure to display this trait probably represents an adaptive specialization to facilitate a flexible reproductive schedule. More finely resolved analysis of both criteria for absolute photorefractoriness (the second being total lack of a reproductive response even to constant light after gonadal regression has occurred) within the cardueline finches not only provides further confirmation of this interpretation, but also indicates that these two criteria for photorefractoriness can be, and have been, uncoupled in some taxa. We suggest that careful comparative studies at different phylogenetic scales will be extremely valuable for distinguishing between adaptive specialization and non-adaptive explanations, such as phylogenetic history as explanations of cue response traits in particular taxa. We also suggest that particular focus on taxa in which individuals may breed on very different photoperiods (latitudes or times of year) in different years should be particularly valuable in identifying the range of environmental conditions across which conditionally plastic cue responses can be adaptive.
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Affiliation(s)
- Thomas P Hahn
- Section of Neurobiology, Physiology and Behavior, University of California Davis, Davis, CA 95616, USA.
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13
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Baraldi-Artoni SM, Bottino F, Oliveira D, Sobue Franzo V, Amoroso L, Orsi AM, Cruz C. Morphometric study of Rynchotus rufescens testis throughout the year. BRAZ J BIOL 2007; 67:363-7. [PMID: 17876449 DOI: 10.1590/s1519-69842007000200024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Accepted: 10/04/2005] [Indexed: 11/22/2022] Open
Abstract
The research aimed to study the morphologic variation of the testis, seeking to promote the selection and genetic control of those that present appreciable spermatic production throughout the year. Testis morphology of the Rynchotus rufescens partridge was investigated, analyzing the testis weight, the seminiferous tubules diameter, the thickness of the seminiferous epithelium, the amount of meiotic figures and the thickness of the tunica albuginea. Sixty male partridges were used, divided in 12 groups, and one group per month had the testis collected for the histological routine and the sections were stained using the Hematoxilin-Eosin technique. For the histological sections analysis, morphometric measures were taken, with the aid of an Image Analyzer and the resulting data were submitted to analysis of variance and to Tukey's test. Based on the histological modifications of the seminiferous epithelium and the morphometric analysis, the partridge testis morphology could be divided in four successive phases throughout the year. The reproductive phase occurred in the spring, characterized by the complete spermatogenesis process. The regression phase occurred in the summer, with the involution of the seminiferous epithelium. The rest phase took place in the fall, with spermatogonias presence and some spermatocytes beginning the meiosis. The phase of recrudescence occurred in the winter, with the recovery of the seminiferous epithelium and absence of spermatozoa. In conclusion, the characteristics analyzed revealed a variation over the year, with greater production of spermatozoa in the spring and less in the winter.
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Affiliation(s)
- S M Baraldi-Artoni
- Departamento de Morfologia e Fisiologia Animal, de Ciencias Agrárias e Veterinárias, Universidade Estadual Paulista, 14884-900, Jaboticabal, SP, Brazil.
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14
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Satterlee DG, Cole CA, Castille SA. Cloacal Gland and Gonadal Photoresponsiveness in Male Japanese Quail Selected for Divergent Plasma Corticosterone Response to Brief Restraint. Poult Sci 2006; 85:1072-80. [PMID: 16776477 DOI: 10.1093/ps/85.6.1072] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Corticosterone is linked to testicular depression, and in Coturnix, a relatively photorefractory species, day length and androgen dependency in cloacal gland development and foam production are evident. Furthermore, male quail selected for reduced (low stress, LS) rather than exaggerated (high stress, HS) plasma corticosterone stress response show more photo-induced reproductive development, greater resistance to reproductive declines induced by exposure to very short days, and a quicker recovery to a higher reproductive level upon return to long days. To determine whether a milder reduction in day length would also influence stress line reproductive photoresponsiveness, and perhaps photorefractoriness, males grown on 16 h of light were given 13 h of light for 4 wk followed by a return to long days for 12 wk. Cloacal gland measurements were made following the initial stimulatory photoperiod and weekly thereafter during the 2 light treatments. Plasma testosterone was determined initially, after 4 wk of light reduction, and at the end of the study, along with BW, testes weight (TWT), and TWT relative to BW. Cloacal gland volume (CVOL) was greater in LS than HS males grown on long days. Whereas exposure to 13 h of light reduced CVOL in both lines, line differences (LS > HS) persisted during the first 3 wk of light reduction. Moreover, by 2 wk of rephotostimulation, and weekly thereafter, line differences (LS > HS) in CVOL reemerged. Cloacal gland foam production and the proportion of individuals that produced cloacal gland foam responses reflected changes in CVOL. The BW did not differ by line, yet LS males had a higher TWT and TWT relative to BW than HS ones. All individuals, however, exhibited relative photorefractory responses. Whereas none of the LS males completely resisted reproductive regression induced by a 3 h light reduction, LS males showed other reproductive benefits upon mild photocastration and subsequent rephotostimulation (e.g., greater resistance to CVOL and cloacal gland foam production losses during a mild light crash and quicker restoration to full reproductive potential upon relighting).
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Affiliation(s)
- D G Satterlee
- Applied Animal Biotechnology Laboratories, Department of Animal Sciences, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Louisiana State University, Baton Rouge 70803, USA.
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15
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Jensen T, Durrant B. Assessment of reproductive status and ovulation in female brown kiwi (Apteryx mantelli) using fecal steroids and ovarian follicle size. Zoo Biol 2006. [DOI: 10.1002/zoo.20074] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Goodson JL, Saldanha CJ, Hahn TP, Soma KK. Recent advances in behavioral neuroendocrinology: insights from studies on birds. Horm Behav 2005; 48:461-73. [PMID: 15896792 PMCID: PMC2570788 DOI: 10.1016/j.yhbeh.2005.04.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 04/05/2005] [Accepted: 04/07/2005] [Indexed: 01/16/2023]
Abstract
Ever since investigations in the field of behavioral endocrinology were hatched with experiments on roosters, birds have provided original insights into issues of fundamental importance for all vertebrate groups. Here we focus on more recent advances that continue this tradition, including (1) environmental regulation of neuroendocrine and behavioral systems, (2) steroidogenic enzyme functions that are related to intracrine processes and de novo production of neurosteroids, and (3) hormonal regulation of neuroplasticity. We also review recent findings on the anatomical and functional organization of steroid-sensitive circuits in the basal forebrain and midbrain. A burgeoning body of data now demonstrates that these circuits comprise an evolutionarily conserved network, thus numerous novel insights obtained from birds can be used (in a relatively straightforward manner) to generate predictions for other taxa as well. We close by using birdsong as an example that links these areas together, thereby highlighting the exceptional opportunities that birds offer for integrative studies of behavioral neuroendocrinology and behavioral biology in general.
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Affiliation(s)
- James L Goodson
- Psychology Department, University of California, 5212 McGill Hall, San Diego, La Jolla, CA 92093-0109, USA.
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17
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BEEBE K, BENTLEY GE, HAU M. A seasonally breeding tropical bird lacks absolute photorefractoriness in the wild, despite high photoperiodic sensitivity. Funct Ecol 2005. [DOI: 10.1111/j.1365-2435.2005.00994.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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18
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Pereyra ME, Sharbaugh SM, Hahn TP. Interspecific variation in photo-induced GnRH plasticity among nomadic cardueline finches. BRAIN, BEHAVIOR AND EVOLUTION 2005; 66:35-49. [PMID: 15821347 DOI: 10.1159/000085046] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Accepted: 01/05/2005] [Indexed: 11/19/2022]
Abstract
Changes in response to photoperiod are of fundamental importance to seasonal cycles in avian reproductive development. In this study we present data on photo-induced changes in gonadotropin-releasing hormone (GnRH) immunoreactivity associated with the development of photorefractoriness in males of 3 closely related species of cardueline finch: common redpoll (Carduelis flammea), pine siskin (C. pinus) and white-winged crossbill (Loxia leucoptera). All are nomadic, mid- to high-latitude breeders with varying levels of reproductive flexibility: redpolls are typically seasonal, pine siskins more flexibly seasonal and white-winged crossbills temporally opportunistic. Males were exposed to either long (20L:4D) or short days (5L:19D), beginning in January, and GnRH was assessed via immunocytochemistry 4.5 months later. Plasma LH, testis size, and molt score were also measured. Significant reductions in the number of irGnRH cells detected, cross-sectional cell area and optical density of these cells occurred in both redpolls and siskins on long, as compared with short, days. These decreases in irGnRH, coupled with spontaneous testicular regression and onset of molt were consistent with the development of absolute photorefractoriness on constant long days. In contrast, the tendency for numbers of GnRH immunopositive cells and mean measures of GnRH immunoreactivity (cell area, optical density and axonal fiber density) to decrease were much more moderate in white-winged crossbills held on long versus short days. Although none of the four measures of GnRH immunoreactivity differed significantly between treatments in crossbills, significant shifts in the frequency distribution of irGnRH neurons to include greater numbers of less immunoreactive cells suggested that antigenic GnRH content was reduced in many cells. These photo-induced shifts in optical densities of GnRH cells in long-day, as compared with short-day crossbills followed, to a lesser extent, the pattern in pine siskins and common redpolls. For all three species, patterns of decrease in GnRH immunoreactivity, gonadal regression and molt suggest that some form of refractoriness to photostimulation develops on constant long days. However, more moderate tendencies for GnRH immunoreactivity to decrease in white-winged crossbills, coupled with limited gonadal regression and molt on long days suggest that absolute photorefractoriness might develop more slowly in this taxon than in others, or alternatively, a condition arises that is more similar to relative photorefractoriness. These data indicate that relatively small differences in the response of the neuroendocrine system to stimulatory cues such as day length may lead to remarkably different capabilities for reproductive flexibility even within a closely related family of birds.
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Affiliation(s)
- Maria Elena Pereyra
- Section of Neurobiology, Physiology and Behavior, University of California, Davis, Calif. 95616-8761, USA.
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19
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Harper GA. Heavy rimu (Dacrydium cupressinum) mast seeding and rat (Rattusspp.) population eruptions on Stewart Island/Rakiura. NEW ZEALAND JOURNAL OF ZOOLOGY 2005. [DOI: 10.1080/03014223.2005.9518408] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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20
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Hau M, Wikelski M, Gwinner H, Gwinner E. Timing of reproduction in a Darwin's finch: temporal opportunism under spatial constraints. OIKOS 2004. [DOI: 10.1111/j.0030-1299.2004.13206.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Hahn TP, Pereyra ME, Sharbaugh SM, Bentley GE. Physiological responses to photoperiod in three cardueline finch species. Gen Comp Endocrinol 2004; 137:99-108. [PMID: 15094340 DOI: 10.1016/j.ygcen.2004.02.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Revised: 02/23/2004] [Accepted: 02/24/2004] [Indexed: 11/25/2022]
Abstract
Cardueline finches (canaries, goldfinches, and rosefinches, etc.) vary widely in the degree to which their natural reproductive schedules track seasonal changes in photoperiod. In this study, we tested for photo-induction of reproductive development and photorefractoriness in males of three cardueline finch species: pine siskins (Carduelis pinus), common redpolls (Carduelis flammea), and white-winged crossbills (Loxia leucoptera). Exposure to long days (20L:4D) in winter induced gonadal growth and elevation of circulating luteinizing hormone (LH) in all three species. After 4.5 months on constant long days, gonadal regression was complete in redpolls and siskins, but only partial in crossbills. Feather molt was most advanced in redpolls, slightly less advanced in siskins, and least advanced in crossbills. These results indicate that the reproductive systems of all three species were stimulated by long days, but that the crossbills, which are temporal opportunists, either did not become absolutely photorefractory, or developed refractoriness more slowly than did the other two species. Reproductive development of controls held for 4.5 months on constant short days (5L:19D) was negligible in redpolls and crossbills, but substantial in siskins, suggesting that of the three species, pine siskins may be the least dependent on long days for reproductive development. Changes in fat deposition and body mass also differed among species. Short day redpolls tended to be fatter and heavier than long day redpolls, and long day crossbills tended to be fatter and heavier than short day crossbills. Body mass and fat depot of siskins remained high irrespective of photoperiod. These results illustrate substantial variation among these close relatives, and are consistent with the idea that differences in apparent reproductive flexibility among cardueline taxa relate to interspecific differences in responsiveness to environmental cues, not simply to differences in the environments experienced. This kind of information is critical to an understanding of the mechanistic bases of natural variation in reproductive schedules, and of how different species may be affected by modifications to the environment.
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Affiliation(s)
- Thomas P Hahn
- Center for Animal Behavior and Section of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616-8761, USA.
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González-Solı́s J. Regulation of incubation shifts near hatching by giant petrels: a timed mechanism, embryonic signalling or food availability? Anim Behav 2004. [DOI: 10.1016/j.anbehav.2003.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Coppack TIMOTHY, Pulido FRANCISCO. Photoperiodic Response and the Adaptability of Avian Life Cycles to Environmental Change. ADV ECOL RES 2004. [DOI: 10.1016/s0065-2504(04)35007-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Sharp PJ, Blache D. A neuroendocrine model for prolactin as the key mediator of seasonal breeding in birds under long- and short-day photoperiods. Can J Physiol Pharmacol 2003; 81:350-8. [PMID: 12769227 DOI: 10.1139/y03-025] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Seasonal breeding is associated with sequential increases in plasma luteinizing hormone (LH) and prolactin in the short-day breeding emu, and in long-day breeding birds that terminate breeding by the development of reproductive photorefractoriness. A model of the avian neuroendocrine photoperiodic reproductive response is proposed, incorporating a role for prolactin, to account for neuroendocrine mechanisms controlling both long- and short-day breeding. The breeding season terminates after circulating concentrations of prolactin increase above a critical threshold to depress gonadotropin releasing hormone (GnRH) neuronal and gonadotrope (LH) activity. Subsequently, photorefractoriness develops for prolactin secretion and for LH secretion, independently of high plasma prolactin. The breeding season in the emu is advanced compared with long-day breeders, because after photorefractiness for both LH and prolactin secretion is dissipated, plasma concentrations of both hormones increase to maximum values while days are still short.
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Affiliation(s)
- Peter J Sharp
- Division of Integrative Biology, Roslin Institute, Roslin, Midlothian EH25 9PS, Scotland, UK.
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Gartrell BD. Assessment of the Reproductive State in Male Swift Parrots (Lathamus discolor) by Testicular Aspiration and Cytology. J Avian Med Surg 2002. [DOI: 10.1647/1082-6742(2002)016[0211:aotrsi]2.0.co;2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Animals need to adjust reproductive decisions to environmental seasonality. In contrast to species from the well-studied temperate zones, little is known for tropical birds about the environmental cues that stimulate reproductive activity and the physiological mechanisms that regulate reproduction. I am investigating the environmental and endocrine mechanisms that underlie the timing of reproduction in spotted antbirds from the near-equatorial Panamanian rainforest and in small ground finches from the equatorial arid Galápagos islands. Spotted antbirds live in a fairly predictable seasonal environment and show regular changes in gonad sizes and some reproductive hormones. Despite the small annual variation in photoperiod close to the equator, these birds can measure slight photoperiodic increases and use it to initiate reproductive activity. Spotted antbirds also respond to seasonal changes in food availability, which allows them to flexibly adjust gonad growth to environmental conditions. Testosterone is involved in regulating song and aggressive behavior in these year-round territorial birds, although it can remain at low plasma levels throughout the year. In contrast, small ground finches exposed to a rather unpredictable climate on Galápagos appear to grow their gonads whenever heavy rains fall and have regressed gonads during other times of the year. The lack of a physiological preparation for the breeding season and their response to short-term cues related to rainfall indicate a striking flexibility in the regulation of breeding in small ground finches. I suggest that tropical birds can serve as model systems to study the physiological adaptations to different environments. Unraveling the neuroendocrine mechanisms behind the flexibility in reproductive timing will clarify whether differences found between temperate and tropical birds represent variations of the same basic mechanism or instead reflect a fundamental divergence in physiological control systems.
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Affiliation(s)
- M Hau
- Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA.
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Sudhakumari CC, Haldar C, Senthilkumaran B. Seasonal changes in adrenal and gonadal activity in the quail, Perdicula asiatica: involvement of the pineal gland. Comp Biochem Physiol B Biochem Mol Biol 2001; 128:793-804. [PMID: 11290461 DOI: 10.1016/s1096-4959(01)00302-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study assessed annual adrenal gland activity in the Indian tropical Jungle bush quail, Perdicula asiatica. We also elucidated the role of the annual variations in gonadal steroids and melatonin in the regulation of its activity. Increasing day length (photoperiod), ambient temperature and rainfall are positively correlated with adrenal and gonadal functions, and inversely related to pineal gland activity. Pineal, adrenal and gonadal weights showed cyclical patterns relative to environmental factors, which were also correlated with plasma melatonin, corticosterone and gonadal steroids, respectively. In both sexes of P. asiatica, pineal gland weight and/or plasma melatonin levels were inversely related to adrenal lipids, (e.g. phospholipids, free and esterified cholesterol) and plasma corticosterone levels. Melatonin levels also showed an inverse relationship with plasma testosterone and estradiol levels. These studies indicate that changes in environmental factors promote annual variations in adrenal and gonadal activity probably by modulating the pineal gland. Melatonin receptors have been localized in the pars tuberalis, adrenal gland and gonads of birds, the pineal gland may, therefore, mediate environmental stimuli indirectly and directly to down regulate adrenal and gonadal activity, which run in parallel in this species.
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Affiliation(s)
- C C Sudhakumari
- Department of Zoology, Banaras Hindu University, -221005, Varanasi, India.
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Keller PA, Elfick L, Garner J, Morgan J, McCluskey A. Corticotropin releasing hormone: therapeutic implications and medicinal chemistry developments. Bioorg Med Chem 2000; 8:1213-23. [PMID: 10896102 DOI: 10.1016/s0968-0896(00)00074-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Corticotropin releasing hormone (CRH, sometimes known as CRF) is an endogenous 41 amino acid peptide that has been implicated in the onset of pregnancy, the 'fight or flight' response, in addition to a large number of physiological disorders. Recently, medicinal chemists have developed a number of potent and selective compounds that show promise in a vast array of therapeutic uses. Herein we review the current status of research.
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Affiliation(s)
- P A Keller
- Department of Chemistry, The University of Wollongong, NSW, Australia.
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Hau M, Wikelski M, Wingfield JC. Visual and nutritional food cues fine-tune timing of reproduction in a neotropical rainforest bird. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/(sici)1097-010x(20000401)286:5<494::aid-jez7>3.0.co;2-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Cagnacci A, Volpe A. Influence of melatonin and photoperiod on animal and human reproduction. J Endocrinol Invest 1996; 19:382-411. [PMID: 8844459 DOI: 10.1007/bf03344974] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- A Cagnacci
- Istituto di Fisiopatologia della Riproduzione Umana, Universitá di Modena, Italy
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