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Lysiak NSJ, Ferguson SH, Hornby CA, Heide-Jørgensen MP, Matthews CJD. Prolonged baleen hormone cycles suggest atypical reproductive endocrinology of female bowhead whales. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230365. [PMID: 37501659 PMCID: PMC10369022 DOI: 10.1098/rsos.230365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 07/05/2023] [Indexed: 07/29/2023]
Abstract
Serial measurements of hormone concentrations along baleen plates allow for reconstructions of mysticete whale reproductive histories. We assessed gestation and calving interval in bowhead whales (Balaena mysticetus) by measuring progesterone, oestradiol, corticosterone and nitrogen stable isotope ratios (δ15N) along baleen of 10 females from the eastern Canada-west Greenland population. Three immature females (body size < 14.32 m) had uniformly low progesterone concentrations across their baleen, while seven mature females (body size ≥ 14.35 m) had repeated, sustained elevations of progesterone indicative of pregnancies. The mean duration of progesterone elevations (23.6 ± 1.50 months) was considerably longer than the approximately 14 month gestation previously estimated for this species. We consider several possible explanations for this observation, including delayed implantation or sequential ovulations prior to gestation, strategies that would allow females to maximize their fitness in variable Arctic conditions, as well as suggest modified criteria defining gestation as a shorter component of the entire progesterone peak. Calving intervals varied within and among individuals (mean = 3.7 years; range = range 2.8-5.7 years), providing population-specific reproductive estimates for growth models used in bowhead whale management and conservation.
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Affiliation(s)
- N. S. J. Lysiak
- Biology Department, Suffolk University, Boston, 02108, MA, USA
| | - S. H. Ferguson
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6
| | - C. A. Hornby
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6
| | | | - C. J. D. Matthews
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6
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2
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Kappeler PM, Benhaiem S, Fichtel C, Fromhage L, Höner OP, Jennions MD, Kaiser S, Krüger O, Schneider JM, Tuni C, van Schaik J, Goymann W. Sex roles and sex ratios in animals. Biol Rev Camb Philos Soc 2023; 98:462-480. [PMID: 36307924 DOI: 10.1111/brv.12915] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 10/12/2022] [Accepted: 10/14/2022] [Indexed: 11/29/2022]
Abstract
In species with separate sexes, females and males often differ in their morphology, physiology and behaviour. Such sex-specific traits are functionally linked to variation in reproductive competition, mate choice and parental care, which have all been linked to sex roles. At the 150th anniversary of Darwin's theory on sexual selection, the question of why patterns of sex roles vary within and across species remains a key topic in behavioural and evolutionary ecology. New theoretical, experimental and comparative evidence suggests that variation in the adult sex ratio (ASR) is a key driver of variation in sex roles. Here, we first define and discuss the historical emergence of the sex role concept, including recent criticisms and rebuttals. Second, we review the various sex ratios with a focus on ASR, and explore its theoretical links to sex roles. Third, we explore the causes, and especially the consequences, of biased ASRs, focusing on the results of correlational and experimental studies of the effect of ASR variation on mate choice, sexual conflict, parental care and mating systems, social behaviour, hormone physiology and fitness. We present evidence that animals in diverse societies are sensitive to variation in local ASR, even on short timescales, and propose explanations for conflicting results. We conclude with an overview of open questions in this field integrating demography, life history and behaviour.
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Affiliation(s)
- Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center - Leibniz Institute of Primatology, Kellnerweg 4, 37077, Göttingen, Germany
- Department of Sociobiology/Anthropology, University of Göttingen, Kellnerweg 6, 37077, Göttingen, Germany
| | - Sarah Benhaiem
- Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, D-10315, Berlin, Germany
| | - Claudia Fichtel
- Behavioral Ecology and Sociobiology Unit, German Primate Center - Leibniz Institute of Primatology, Kellnerweg 4, 37077, Göttingen, Germany
| | - Lutz Fromhage
- Department of Biological and Environmental Science, Ambiotica, University of Jyväskylä, PO Box 35, 40014, Jyväskylä, Finland
| | - Oliver P Höner
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, D-10315, Berlin, Germany
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, ANU College of Science, The Australian National University, RN Robertson Building, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149, Münster, Germany
| | - Oliver Krüger
- Department of Animal Behavior, Bielefeld University, Morgenbreede 45, 33615, Bielefeld, Germany
| | - Jutta M Schneider
- Department of Biology, Institute of Zoology, Universität Hamburg, Martin-Luther-King Platz 3, 20146, Hamburg, Germany
| | - Cristina Tuni
- Department of Biology II, Ludwig Maximilians University of Munich, Großhaderner Str 2, 82152, Planegg-Martinsried, Germany
| | - Jaap van Schaik
- Applied Zoology and Nature Conservation, University of Greifswald, Loitzer Str. 26, 17489, Greifswald, Germany
| | - Wolfgang Goymann
- Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, Eberhard-Gwinner-Str. 6a, D-82319, Seewiesen, Germany
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3
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Hunt KE, Buck CL, Ferguson SH, Fernández Ajo A, Heide-Jørgensen MP, Matthews CJD. Male Bowhead Whale Reproductive Histories Inferred from Baleen Testosterone and Stable Isotopes. Integr Org Biol 2022; 4:obac014. [PMID: 35617113 PMCID: PMC9125798 DOI: 10.1093/iob/obac014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Synopsis
Male mammals of seasonally reproducing species typically have annual testosterone (T) cycles, with T usually peaking during the breeding season, but occurrence of such cycles in male mysticete whales has been difficult to confirm. Baleen, a keratinized filter-feeding apparatus of mysticetes, incorporates hormones as it grows, such that a single baleen plate can record years of endocrine history with sufficient temporal resolution to discern seasonal patterns. We analyzed patterns of T every 2 cm across the full length of baleen plates from nine male bowhead whales (Balaena mysticetus) to investigate occurrence and regularity of T cycles and potential inferences about timing of breeding season, sexual maturation, and reproductive senescence. Baleen specimens ranged from 181–330 cm in length, representing an estimated 11 years (smallest whale) to 22 years (largest whale) of continuous baleen growth, as indicated by annual cycles in stable isotopes. All baleen specimens contained regularly spaced areas of high T content (T peaks) confirmed by time series analysis to be cyclic, with periods matching annual stable isotope cycles of the same individuals. In 8 of the 9 whales, T peaks preceded putative summer isotope peaks by a mean of 2.8 months, suggesting a mating season in late winter / early spring. The only exception to this pattern was the smallest and youngest male, which had T peaks synchronous with isotope peaks. This smallest, youngest whale also did not have T peaks in the first half of the plate, suggesting initiation of T cycling during the period of baleen growth. Linear mixed effect models suggest that whale age influences T concentrations, with the two largest and oldest males exhibiting a dramatic decline in T peak concentration across the period of baleen growth. Overall, these patterns are consistent with onset of sexual maturity in younger males and possible reproductive senescence in older males. We conclude that adult male bowheads undergo annual T cycles, and that analyses of T in baleen may enable investigation of reproductive seasonality, timing of the breeding season, and life history of male whales.
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Affiliation(s)
- Kathleen E Hunt
- Smithsonian-Mason School of Conservation & Department of Biology, George Mason University, 1500 Remount Rd, Front Royal, VA 22630, USA
| | - C Loren Buck
- Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., Flagstaff, AZ 86011, USA
| | - Steven H Ferguson
- Fisheries and Oceans Canada, Arctic Aquatic Research Division, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada
| | - Alejandro Fernández Ajo
- Marine Mammal Institute, Fisheries and Wildlife Department, Oregon State University, Newport, OR 97365, USA
| | | | - Cory J D Matthews
- Fisheries and Oceans Canada, Arctic Aquatic Research Division, 501 University Crescent, Winnipeg, MB R3T 2N6, Canada
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Hamilton PK, Frasier BA, Conger LA, George RC, Jackson KA, Frasier TR. Genetic identifications challenge our assumptions of physical development and mother–calf associations and separation times: a case study of the North Atlantic right whale (Eubalaena glacialis). Mamm Biol 2022. [DOI: 10.1007/s42991-021-00177-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AbstractWhile photo-identification is an effective tool to monitor individuals in wild populations, it has limitations. Specifically, it cannot be applied to very young animals before their identifying features have stabilized or to dead, decomposed animals. These shortfalls leave gaps in our understanding of survival, parentage, age structure, physical development, and behavioral variability. Here we report on 13 case studies of North Atlantic right whale, Eubalaena glacialis, calves that required genetics to track their life history data. These case studies revealed unexpected variations in mother–calf associations and separation times, as well as calf physical development. Prior to this study, calves were assumed to have died if their mothers were always alone on the feeding ground in the calf’s birth year. Using genetics and photo-identification, four such calves were discovered to be alive; two of the four possibly weaned earlier than expected at 7.5–8.0 months. To put these early separations in context, photo-identification data were queried and revealed that mothers and calves are seen apart from each other on the feeding grounds in 10–40% of all spring/summer sightings; previously, there were no published data on how often pairs are seen apart in the calf’s birth year. Two dead whales initially logged as calves of the year were discovered to be juveniles, thus allowing skewed survival estimates for calves of the year to be corrected. Genetically sampling animals early in their lives before they disperse or separate from their mothers provides an important means of individual identification at a time when photo-identification is not reliable.
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Crowe LM, Brown MW, Corkeron PJ, Hamilton PK, Ramp C, Ratelle S, Vanderlaan ASM, Cole TVN. In plane sight: a mark-recapture analysis of North Atlantic right whales in the Gulf of St. Lawrence. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01156] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
North Atlantic right whales Eubalaena glacialis are most commonly observed along the eastern seaboard of North America; however, their distribution and occupancy patterns have become less predictable in the last decade. This study explored the individual right whales captured photographically from both dedicated and opportunistic sources from 2015 to 2019 in the Gulf of St. Lawrence (GSL), an area previously understudied for right whale presence. A total of 187 individuals, including reproductive females, were identified from all sources over this period. In years when more substantial survey effort occurred (2017-2019), similar numbers of individuals were sighted (mean = 133, SD = 1.5), and dedicated mark-recapture aerial surveys were highly effective at capturing almost all of the whales estimated in the region (2019: N = 137, 95% CI = 135-147). A high rate of inter-annual return was observed between all 5 study years, with 95% of the animals seen in 2019 sighted previously. Capture rates indicated potential residencies as long as 5 mo, and observed behaviors included feeding and socializing. Individuals were observed in the northern and southern GSL, regions divided by a major shipping corridor. Analyses suggest that individuals mostly moved less than 9.1 km d-1, although rates of up to 79.8 km d-1 were also calculated. The GSL is currently an important habitat for 40% of this Critically Endangered species, which underscores how crucial protection measures are in this area.
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Affiliation(s)
- LM Crowe
- Integrated Statistics Under Contract to the Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
| | - MW Brown
- Canadian Whale Institute, Welshpool, New Brunswick, Canada, E5E 1B6
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - PJ Corkeron
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - PK Hamilton
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - C Ramp
- Mingan Island Cetacean Study, St. Lambert, Québec, Canada, J4P 1T3
- Sea Mammal Research Unit, University of St. Andrews, St. Andrews, Fife KY16 8LB, UK
| | - S Ratelle
- Gulf Fisheries Center, Department of Fisheries and Oceans, Moncton, New Brunswick, Canada, E1C 9B6
| | - ASM Vanderlaan
- Bedford Institute of Oceanography, Department of Fisheries and Oceans, Dartmouth, Nova Scotia, Canada, B2Y 4A2
| | - TVN Cole
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
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6
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Quintana-Rizzo E, Leiter S, Cole TVN, Hagbloom MN, Knowlton AR, Nagelkirk P, O’Brien O, Khan CB, Henry AG, Duley PA, Crowe LM, Mayo CA, Kraus SD. Residency, demographics, and movement patterns of North Atlantic right whales Eubalaena glacialis in an offshore wind energy development area in southern New England, USA. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01137] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Offshore wind energy development is growing quickly around the world. In southern New England, USA, one of the largest commercial offshore wind energy farms in the USA will be established in the waters off Massachusetts and Rhode Island, an area used by the Critically Endangered North Atlantic right whale Eubalaena glacialis. Prior to 2011, little was known about the use of this area by right whales. We examined aerial survey data collected between 2011-2015 and 2017-2019 to quantify right whale distribution, residency, demography, and movements in the region. Right whale occurrence increased during the study period. Since 2017, whales have been sighted in the area nearly every month, with peak sighting rates between late winter and spring. Model outputs suggest that 23% of the species’ population is present from December through May, and the mean residence time has tripled to an average of 13 d during these months. Age and sex ratios of the individuals present in the area are similar to those of the species as a whole, with adult males the most common demographic group. Movement models showed that southern New England is an important destination for right whales, including conceptive and reproductive females, and qualitative observations included animals feeding and socializing. Implementing mitigation procedures in coordination with these findings will be crucial in lessening the potential impacts on right whales from construction noise, increased vessel traffic, and habitat disruption in this region.
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Affiliation(s)
- E Quintana-Rizzo
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
- Simmons University, Boston, MA 02115, USA
| | - S Leiter
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - TVN Cole
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
| | - MN Hagbloom
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - AR Knowlton
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - P Nagelkirk
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - O O’Brien
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - CB Khan
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
| | - AG Henry
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
| | - PA Duley
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
| | - LM Crowe
- Integrated Statistics, under contract to the Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA 02543, USA
| | - CA Mayo
- Center for Coastal Studies, Provincetown, MA 02657, USA
| | - SD Kraus
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
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7
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Safari I, Goymann W. The evolution of reversed sex roles and classical polyandry: Insights from coucals and other animals. Ethology 2020. [DOI: 10.1111/eth.13095] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Ignas Safari
- Max‐Planck‐Institut für Ornithologie, Abteilung für Verhaltensneurobiologie Seewiesen Germany
- Coucal Project Chimala Tanzania
- Department of Biology University of Dodoma Dodoma Tanzania
| | - Wolfgang Goymann
- Max‐Planck‐Institut für Ornithologie, Abteilung für Verhaltensneurobiologie Seewiesen Germany
- Coucal Project Chimala Tanzania
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8
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Martien KK, Taylor BL, Chivers SJ, Mahaffy SD, Gorgone AM, Baird RW. Fidelity to natal social groups and mating within and between social groups in an endangered false killer whale population. ENDANGER SPECIES RES 2019. [DOI: 10.3354/esr00995] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Betty EL, Stockin KA, Smith ANH, Bollard B, Orams MB, Murphy S. Sexual maturation in male long-finned pilot whales (Globicephala melas edwardii): defining indicators of sexual maturity. J Mammal 2019. [DOI: 10.1093/jmammal/gyz086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Male reproductive biology is described for the Southern Hemisphere long-finned pilot whale (Globicephala melas edwardii), a subspecies that regularly mass strands along the New Zealand coastline. Ten mass stranding events sampled over a 7-year period enabled assessments of key life history parameters. Sexual maturation in immature, maturing, and mature males was assessed using morphological data and histological examination of testicular tissue. Variation was observed in the age (11–15 years) and length (450–490 cm) at which individuals attained sexual maturity. Using Bayesian cumulative logit regression models, we estimated the average age and length at the attainment of sexual maturity to be 13.5 years and 472 cm, respectively. Combined testes weight, combined testes length, an index of testicular development (combined testes weight/combined testes length), and mean seminiferous tubule diameter were all good indicators of sexual maturity status. Combined testes length was the best nonhistological indicator, and all testicular measures were found to be better indicators of sexual maturation for G. m. edwardii than age or total body length. Sexual maturity was attained before physical maturity (> 40 years and 570 cm), and at a younger age and smaller body length than previously reported for Globicephala melas melas in the North Atlantic. Given the ease of collection, minimal processing, and applicability to suboptimal material collected from stranding events, future studies should assess the value of testicular size as an indicator of sexual maturity in pilot whales and other cetacean species. Estimates of the average age and length at sexual maturity for G. m. edwardii provided in this study may be used to inform population models required for conservation management of the subspecies, which is subject to high levels of stranding-related mortality.
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Affiliation(s)
- Emma L Betty
- School of Natural and Computational Sciences, College of Sciences, Massey University, Auckland, New Zealand
- School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - Karen A Stockin
- School of Natural and Computational Sciences, College of Sciences, Massey University, Auckland, New Zealand
| | - Adam N H Smith
- School of Natural and Computational Sciences, College of Sciences, Massey University, Auckland, New Zealand
| | - Barbara Bollard
- School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - Mark B Orams
- School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
- Sustainability Research Centre, University of the Sunshine Coast, Queensland, Australia
| | - Sinéad Murphy
- Marine and Freshwater Research Centre, Department of Natural Sciences, School of Science and Computing, Galway-Mayo Institute of Technology, Galway, Ireland
- Institute of Zoology, Zoological Society of London, London, United Kingdom
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10
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Hunt KE, Lysiak NSJ, Matthews CJD, Lowe C, Fernández Ajó A, Dillon D, Willing C, Heide-Jørgensen MP, Ferguson SH, Moore MJ, Buck CL. Multi-year patterns in testosterone, cortisol and corticosterone in baleen from adult males of three whale species. CONSERVATION PHYSIOLOGY 2018; 6:coy049. [PMID: 30254748 PMCID: PMC6148970 DOI: 10.1093/conphys/coy049] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 08/05/2018] [Accepted: 09/01/2018] [Indexed: 05/03/2023]
Abstract
Male baleen whales have long been suspected to have annual cycles in testosterone, but due to difficulty in collecting endocrine samples, little direct evidence exists to confirm this hypothesis. Potential influences of stress or adrenal stress hormones (cortisol, corticosterone) on male reproduction have also been difficult to study. Baleen has recently been shown to accumulate steroid hormones during growth, such that a single baleen plate contains a continuous, multi-year retrospective record of the whale's endocrine history. As a preliminary investigation into potential testosterone cyclicity in male whales and influences of stress, we determined patterns in immunoreactive testosterone, two glucocorticoids (cortisol and corticosterone), and stable-isotope (SI) ratios, across the full length of baleen plates from a bowhead whale (Balaena mysticetus), a North Atlantic right whale (Eubalaena glacialis) and a blue whale (Balaenoptera musculus), all adult males. Baleen was subsampled at 2 cm (bowhead, right) or 1 cm (blue) intervals and hormones were extracted from baleen powder with methanol, followed by quantification of all three hormones using enzyme immunoassays validated for baleen extract of these species. Baleen of all three males contained regularly spaced peaks in testosterone content, with number and spacing of testosterone peaks corresponding well to SI data and to species-specific estimates of annual baleen growth rate. Cortisol and corticosterone exhibited some peaks that co-occurred with testosterone peaks, while other glucocorticoid peaks occurred independent of testosterone peaks. The right whale had unusually high glucocorticoids during a period with a known entanglement in fishing gear and a possible disease episode; in the subsequent year, testosterone was unusually low. Further study of baleen testosterone patterns in male whales could help clarify conservation- and management-related questions such as age of sexual maturity, location and season of breeding, and the potential effect of anthropogenic and natural stressors on male testosterone cycles.
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Affiliation(s)
- Kathleen E Hunt
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
| | - Nadine S J Lysiak
- Biology Department, University of Massachusetts Boston, Boston, MA, USA
| | - Cory J D Matthews
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada
| | - Carley Lowe
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
| | - Alejandro Fernández Ajó
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
| | - Danielle Dillon
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
| | - Cornelia Willing
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
| | | | - Steven H Ferguson
- Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada
| | - Michael J Moore
- Marine Mammal Center, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - C Loren Buck
- Department of Biological Sciences, Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
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11
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Root-Gutteridge H, Cusano DA, Shiu Y, Nowacek DP, Van Parijs SM, Parks SE. A lifetime of changing calls: North Atlantic right whales, Eubalaena glacialis, refine call production as they age. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2017.12.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Green ML, Herzing DL, Baldwin JD. Molecular assessment of mating strategies in a population of Atlantic spotted dolphins. PLoS One 2015; 10:e0118227. [PMID: 25692972 PMCID: PMC4334488 DOI: 10.1371/journal.pone.0118227] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 01/09/2015] [Indexed: 11/19/2022] Open
Abstract
Similar to other small cetacean species, Atlantic spotted dolphins (Stenella frontalis) have been the object of concentrated behavioral study. Although mating and courtship behaviors occur often and the social structure of the population is well-studied, the genetic mating system of the species is unknown. To assess the genetic mating system, we genotyped females and their progeny at ten microsatellite loci. Genotype analysis provided estimates of the minimum number of male sires necessary to account for the allelic diversity observed among the progeny. Using the estimates of male sires, we determined whether females mated with the same or different males during independent estrus events. Using Gerud2.0, a minimum of two males was necessary to account for the genetic variation seen among progeny arrays of all tested females. ML-Relate assigned the most likely relationship between offspring pairs; half or full sibling. Relationship analysis supported the conservative male estimates of Gerud2.0 but in some cases, half or full sibling relationships between offspring could not be fully resolved. Integrating the results from Gerud2.0, ML-Relate with previous observational and paternity data, we constructed two-, three-, and four-male pedigree models for each genotyped female. Because increased genetic diversity of offspring may explain multi-male mating, we assessed the internal genetic relatedness of each offspring's genotype to determine whether parent pairs of offspring were closely related. We found varying levels of internal relatedness ranging from unrelated to closely related (range -0.136-0.321). Because there are several hypothesized explanations for multi-male mating, we assessed our data to determine the most plausible explanation for multi-male mating in our study system. Our study indicated females may benefit from mating with multiple males by passing genes for long-term viability to their young.
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Affiliation(s)
- Michelle L. Green
- Department of Biology, Florida Atlantic University, 3200 College Avenue, Davie, Florida, 33314, United States of America
| | - Denise L. Herzing
- Wild Dolphin Project, P.O. Box 8436, Jupiter, Florida, 33468, United States of America
- Department of Biology, Department of Psychology, Florida Atlantic University, 777 Glades Road, Boca Raton, Florida, 33431, United States of America
| | - John D. Baldwin
- Department of Biology, Florida Atlantic University, 3200 College Avenue, Davie, Florida, 33314, United States of America
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13
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Dines JP, Otárola-Castillo E, Ralph P, Alas J, Daley T, Smith AD, Dean MD. Sexual selection targets cetacean pelvic bones. Evolution 2014; 68:3296-306. [PMID: 25186496 DOI: 10.1111/evo.12516] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 08/07/2014] [Indexed: 02/07/2023]
Abstract
Male genitalia evolve rapidly, probably as a result of sexual selection. Whether this pattern extends to the internal infrastructure that influences genital movements remains unknown. Cetaceans (whales and dolphins) offer a unique opportunity to test this hypothesis: since evolving from land-dwelling ancestors, they lost external hind limbs and evolved a highly reduced pelvis that seems to serve no other function except to anchor muscles that maneuver the penis. Here, we create a novel morphometric pipeline to analyze the size and shape evolution of pelvic bones from 130 individuals (29 species) in the context of inferred mating system. We present two main findings: (1) males from species with relatively intense sexual selection (inferred by relative testes size) tend to evolve larger penises and pelvic bones compared to their body length, and (2) pelvic bone shape has diverged more in species pairs that have diverged in inferred mating system. Neither pattern was observed in the anterior-most pair of vertebral ribs, which served as a negative control. This study provides evidence that sexual selection can affect internal anatomy that controls male genitalia. These important functions may explain why cetacean pelvic bones have not been lost through evolutionary time.
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Affiliation(s)
- James P Dines
- Mammalogy, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California, 90007; Integrative and Evolutionary Biology, University of Southern California, Los Angeles, California, 90089
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Gillett RM, Murray BW, White BN. Characterization of class I- and class II-like major histocompatibility complex loci in pedigrees of North Atlantic right whales. J Hered 2013; 105:188-202. [PMID: 24381183 DOI: 10.1093/jhered/est095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
North Atlantic right whales have one of the lowest levels of genetic variation at minisatellite loci, microsatellite loci, and mitochondrial control region haplotypes among mammals. Here, adaptive variation at the peptide binding region of class I and class II DRB-like genes of the major histocompatibility complex was assessed. Amplification of a duplicated region in 222 individuals revealed at least 11 class II alleles. Six alleles were assigned to the locus Eugl-DRB1 and 5 alleles were assigned to the locus Eugl-DRB2 by assessing segregation patterns of alleles from 81 parent/offspring pedigrees. Pedigree analysis indicated that these alleles segregated into 12 distinct haplotypes. Genotyping a smaller subset of unrelated individuals (n = 5 and 10, respectively) using different primer sets revealed at least 2 class II pseudogenes (with ≥ 4 alleles) and at least 3 class I loci (with ≥ 6 alleles). Class II sequences were significantly different from neutrality at peptide binding sites suggesting loci may be under the influence of balancing selection. Trans-species sharing of alleles was apparent for class I and class II sequences. Characterization of class II loci represents the first step in determining the relationship between major histocompatibility complex variability and factors affecting health and reproduction in this species.
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Affiliation(s)
- Roxanne M Gillett
- the Natural Resources DNA Profiling and Forensic Centre, Department of Biology, Trent University, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada
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15
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Frasier TR, Gillett RM, Hamilton PK, Brown MW, Kraus SD, White BN. Postcopulatory selection for dissimilar gametes maintains heterozygosity in the endangered North Atlantic right whale. Ecol Evol 2013; 3:3483-94. [PMID: 24223284 PMCID: PMC3797493 DOI: 10.1002/ece3.738] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 11/09/2022] Open
Abstract
Although small populations are expected to lose genetic diversity through genetic drift and inbreeding, a number of mechanisms exist that could minimize this genetic decline. Examples include mate choice for unrelated mates and fertilization patterns biased toward genetically dissimilar gametes. Both processes have been widely documented, but the long-term implications have received little attention. Here, we combined over 25 years of field data with high-resolution genetic data to assess the long-term impacts of biased fertilization patterns in the endangered North Atlantic right whale. Offspring have higher levels of microsatellite heterozygosity than expected from this gene pool (effect size = 0.326, P < 0.011). This pattern is not due to precopulatory mate choice for genetically dissimilar mates (P < 0.600), but instead results from postcopulatory selection for gametes that are genetically dissimilar (effect size = 0.37, P < 0.003). The long-term implication is that heterozygosity has slowly increased in calves born throughout the study period, as opposed to the slight decline that was expected. Therefore, this mechanism represents a natural means through which small populations can mitigate the loss of genetic diversity over time.
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Affiliation(s)
- T R Frasier
- Department of Biology and Forensic Sciences Program, Saint Mary's University 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
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Cole TVN, Hamilton P, Henry AG, Duley P, Pace RM, White BN, Frasier T. Evidence of a North Atlantic right whale Eubalaena glacialis mating ground. ENDANGER SPECIES RES 2013. [DOI: 10.3354/esr00507] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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17
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CARROLL EMMAL, CHILDERHOUSE SIMONJ, CHRISTIE MARK, LAVERY SHANE, PATENAUDE NATHALIE, ALEXANDER ALANA, CONSTANTINE ROCHELLE, STEEL DEBBIE, BOREN LAURA, SCOTT BAKER C. Paternity assignment and demographic closure in the New Zealand southern right whale. Mol Ecol 2012; 21:3960-73. [DOI: 10.1111/j.1365-294x.2012.05676.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Garg KM, Chattopadhyay B, Doss D PS, A K VK, Kandula S, Ramakrishnan U. Promiscuous mating in the harem-roosting fruit bat, Cynopterus sphinx. Mol Ecol 2012; 21:4093-105. [PMID: 22725709 DOI: 10.1111/j.1365-294x.2012.05665.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Observations on mating behaviours and strategies guide our understanding of mating systems and variance in reproductive success. However, the presence of cryptic strategies often results in situations where social mating system is not reflective of genetic mating system. We present such a study of the genetic mating system of a harem-forming bat Cynopterus sphinx where harems may not be true indicators of male reproductive success. This temporal study using data from six seasons on paternity reveals that social harem assemblages do not play a role in the mating system, and variance in male reproductive success is lower than expected assuming polygynous mating. Further, simulations reveal that the genetic mating system is statistically indistinguishable from promiscuity. Our results are in contrast to an earlier study that demonstrated high variance in male reproductive success. Although an outcome of behavioural mating patterns, standardized variance in male reproductive success (I(m)) affects the opportunity for sexual selection. To gain a better understanding of the evolutionary implications of promiscuity for mammals in general, we compared our estimates of I(m) and total opportunity for sexual selection (I(m) /I(f), where I(f) is standardized variance in female reproductive success) with those of other known promiscuous species. We observed a broad range of I(m) /I(f) values across known promiscuous species, indicating our poor understanding of the evolutionary implications of promiscuous mating.
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Affiliation(s)
- Kritika M Garg
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 56065, India.
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Wright LI, Fuller WJ, Godley BJ, McGowan A, Tregenza T, Broderick AC. Reconstruction of paternal genotypes over multiple breeding seasons reveals male green turtles do not breed annually. Mol Ecol 2012; 21:3625-35. [PMID: 22591073 DOI: 10.1111/j.1365-294x.2012.05616.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
For species of conservation concern, knowledge of key life-history and demographic components, such as the number and sex ratio of breeding adults, is essential for accurate assessments of population viability. Species with temperature-dependent sex determination can produce heavily biased primary sex ratios, and there is concern that adult sex ratios may be similarly skewed or will become so as a result of climate warming. Prediction and mitigation of such impacts are difficult when life-history information is lacking. In marine turtles, owing to the difficultly in observing males at sea, the breeding interval of males is unknown. It has been suggested that male breeding periodicity may be shorter than that of females, which could help to compensate for generally female-biased sex ratios. Here we outline how the use of molecular-based paternity analysis has allowed us, for the first time, to assess the breeding interval of male marine turtles across multiple breeding seasons. In our study rookery of green turtles (Chelonia mydas), 97% of males were assigned offspring in only one breeding season within the 3-year study period, strongly suggesting that male breeding intervals are frequently longer than 1year at this site. Our results also reveal a sex ratio of breeding adults of at least 1.3 males to each female. This study illustrates the utility of molecular-based parentage inference using reconstruction of parental genotypes as a method for monitoring the number and sex ratio of breeders in species where direct observations or capture are difficult.
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Affiliation(s)
- Lucy I Wright
- Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
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Wiszniewski J, Corrigan S, Beheregaray LB, Möller LM. Male reproductive success increases with alliance size in Indo-Pacific bottlenose dolphins (Tursiops aduncus). J Anim Ecol 2011; 81:423-31. [PMID: 21981240 DOI: 10.1111/j.1365-2656.2011.01910.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Determining the extent of variation in male mating strategies and reproductive success is necessary to understand the fitness benefits of social and cooperative behaviour. 2. This study assesses the reproductive success of male Indo-Pacific bottlenose dolphins in a small embayment population where different behavioural strategies of males have previously been identified. Parentage for 44 sampled calves was examined using 23 microsatellite loci and one mitochondrial DNA marker. Our candidate parent pool of 70 males and 64 females contained individuals sampled from both the embayment and adjacent coastal populations. 3. A moderate level of polygyny was detected in our sample. We assigned paternity of 23 calves to 12 males at the strict 95% confidence level and an additional nine calves to two males at the 80% confidence level. The majority (92%) of successful males were identified as residents to the embayment, and 46% of offspring were located within the same social group or community as their father. 4. Our results suggest that the size of alliances was the best predictor of reproductive success for males in this population, while the strength of association among allied males, alliance stability and male ranging patterns had little influence. In line with predictions for male alliances formed between unrelated individuals, we found that reproductive skew within alliances was not large. 5. Together, our genetic and behavioural analyses demonstrate that alliance formation between male dolphins is a successful strategy to enhance reproductive output.
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Affiliation(s)
- Joanna Wiszniewski
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia.
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Ford MJ, Hanson MB, Hempelmann JA, Ayres KL, Emmons CK, Schorr GS, Baird RW, Balcomb KC, Wasser SK, Parsons KM, Balcomb-Bartok K. Inferred Paternity and Male Reproductive Success in a Killer Whale (Orcinus orca) Population. ACTA ACUST UNITED AC 2011; 102:537-53. [PMID: 21757487 DOI: 10.1093/jhered/esr067] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating ("resident") eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent results. The variance in male reproductive success was greater than expected by chance and similar to that of other aquatic mammals. Although the number of confirmed paternities was small, reproductive success appeared to increase with male age and size. We found no evidence that males from outside this small population sired any of the sampled individuals. In contrast to previous results in a different population, many offspring were the result of matings within the same "pod" (long-term social group). Despite this pattern of breeding within social groups, we found no evidence of offspring produced by matings between close relatives, and the average internal relatedness of individuals was significantly less than expected if mating were random. The population's estimated effective size was <30 or about 1/3 of the current census size. Patterns of allele frequency variation were consistent with a population bottleneck.
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Affiliation(s)
- Michael J Ford
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, Seattle, WA 98112, USA.
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Lotterhos KE. THE CONTEXT-DEPENDENT EFFECT OF MULTIPLE PATERNITY ON EFFECTIVE POPULATION SIZE. Evolution 2011; 65:1693-706. [DOI: 10.1111/j.1558-5646.2011.01249.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Green ML, Herzing DL, Baldwin JD. Reproductive success of male Atlantic spotted dolphins (Stenella frontalis) revealed by noninvasive genetic analysis of paternity. CAN J ZOOL 2011. [DOI: 10.1139/z10-111] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cetaceans are known to frequently engage in sexual behavior; however, the lack of male parental investment in offspring makes assessment of male reproductive success difficult. We assessed paternity in a small population (mean individuals sighted per year = 93) of Atlantic spotted dolphins ( Stenella frontalis (G. Cuvier, 1829)) utilizing noninvasively collected fecal material. Samples (n = 88) were collected from dolphins from four social clusters. Of the 29 offspring tested, 34.5% were assigned paternity, resulting in 10 paternities assigned to seven males. Our study indicates that achieving a certain age is a potential precursor for males to mate successfully, as 18 years was the youngest estimated age of a male at the time of calf conception. In all pairings but one, the males were older than the female (mean age difference = 7.7+ years). Successful males were from two of the four social clusters and males most often mated within their social group or with females from the next geographically closest group. The study combines genetic data with known maternal pedigree information and reveals patterns in the overall mating system in a cetacean species where reproductive success of males was previously unknown.
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Affiliation(s)
- Michelle L. Green
- Department of Biology, Florida Atlantic University, 3200 College Avenue, Davie, FL 33314, USA
- Wild Dolphin Project, P.O. Box 8436, Jupiter, FL 33468, USA
- Department of Biology, Department of Psychology, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - Denise L. Herzing
- Department of Biology, Florida Atlantic University, 3200 College Avenue, Davie, FL 33314, USA
- Wild Dolphin Project, P.O. Box 8436, Jupiter, FL 33468, USA
- Department of Biology, Department of Psychology, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - John D. Baldwin
- Department of Biology, Florida Atlantic University, 3200 College Avenue, Davie, FL 33314, USA
- Wild Dolphin Project, P.O. Box 8436, Jupiter, FL 33468, USA
- Department of Biology, Department of Psychology, Florida Atlantic University, Boca Raton, FL 33431, USA
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Amaral AR, Möller LM, Beheregaray LB, Coelho MM. Evolution of 2 reproductive proteins, ZP3 and PKDREJ, in cetaceans. ACTA ACUST UNITED AC 2011; 102:275-82. [PMID: 21273216 DOI: 10.1093/jhered/esq131] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The rapid evolution of proteins involved in reproduction has been documented in several animal taxa. This is thought to be the result of forces involved in sexual selection and is expected to be particularly strong in promiscuous mating systems. In this study, a range of cetacean species were used to analyze the patterns of evolution in 2 reproductive proteins involved in fertilization: the zona pellucida 3 (ZP3), present in the egg coat, and PKDREJ, localized in the sperm head. We targeted exons 6 and 7 of ZP3 and a part of the REJ domain in PKDREJ for a total of 958 bp in 18 species. We found very low levels of amino acid sequence divergence in both proteins, a very weak signal of positive selection in ZP3 and no signal in PKDREJ. These results were consistent with previous reports of a slow rate of molecular evolution in cetaceans but unexpected due to the existence of promiscuous mating systems in these species. The results raise questions about the evolution of reproductive isolation and species recognition in whales and dolphins.
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Affiliation(s)
- Ana R Amaral
- Centro de Biologia Ambiental, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Lisbon, Portugal.
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McLeod BA, White BN. Tracking mtDNA Heteroplasmy through Multiple Generations in the North Atlantic Right Whale (Eubalaena glacialis). J Hered 2009; 101:235-9. [DOI: 10.1093/jhered/esp098] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Frasier TR, Hamilton PK, Brown MW, Kraus SD, White BN. Sources and Rates of Errors in Methods of Individual Identification for North Atlantic Right Whales. J Mammal 2009. [DOI: 10.1644/08-mamm-a-328.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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McLeod BA, Brown MW, Frasier TR, White BN. DNA profile of a sixteenth century western North Atlantic right whale (Eubalaena glacialis). CONSERV GENET 2009. [DOI: 10.1007/s10592-009-9811-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tatarenkov A, Healey CIM, Grether GF, Avise JC. Pronounced reproductive skew in a natural population of green swordtails, Xiphophorus helleri. Mol Ecol 2008; 17:4522-34. [PMID: 18986497 DOI: 10.1111/j.1365-294x.2008.03936.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
For many species in nature, a sire's progeny may be distributed among a few or many dams. This poses logistical challenges--typically much greater across males than across females--for assessing means and variances in mating success (number of mates) and reproductive success (number of progeny). Here we overcome these difficulties by exhaustively analyzing a population of green swordtail fish (Xiphophorus helleri) for genetic paternity (and maternity) using a suite of highly polymorphic microsatellite loci. Genetic analyses of 1476 progeny from 69 pregnant females and 158 candidate sires revealed pronounced skews in male reproductive success both within and among broods. These skews were statistically significant, greater than in females, and correlated in males but not in females with mating success. We also compare the standardized variances in swordtail reproductive success to the few such available estimates for other taxa, notably several mammal species with varied mating systems and degrees of sexual dimorphism. The comparison showed that the opportunity for selection on male X. helleri is among the highest yet reported in fishes, and it is intermediate compared to estimates available for mammals. This study is one of a few exhaustive genetic assessments of joint-sex parentage in a natural fish population, and results are relevant to the operation of sexual selection in this sexually dimorphic, high-fecundity species.
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Affiliation(s)
- Andrey Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
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