1
|
Crossman CA, Hamilton PK, Brown MW, Conger LA, George RC, Jackson KA, Radvan SN, Frasier TR. Effects of inbreeding on reproductive success in endangered North Atlantic right whales. ROYAL SOCIETY OPEN SCIENCE 2024; 11:240490. [PMID: 39086821 PMCID: PMC11289666 DOI: 10.1098/rsos.240490] [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: 03/25/2024] [Accepted: 05/24/2024] [Indexed: 08/02/2024]
Abstract
Only approximately 356 North Atlantic right whales (Eubalaena glacialis) remain. With extremely low levels of genetic diversity, limited options for mates, and variation in reproductive success across females, there is concern regarding the potential for genetic limitations of population growth from inbreeding depression. In this study, we quantified reproductive success of female North Atlantic right whales with a modified de-lifing approach using reproductive history information collected over decades of field observations. We used double-digest restriction site-associated sequencing to sequence approximately 2% of the genome of 105 female North Atlantic right whales and combined genomic inbreeding estimates with individual fecundity values to assess evidence of inbreeding depression. Inbreeding depression could not explain the variance in reproductive success of females, however we present evidence that inbreeding depression may be affecting the viability of inbred fetuses-potentially lowering the reproductive success of the species as a whole. Combined, these results allay some concerns that genetic factors are impacting species survival as genetic diversity is being retained through selection against inbred fetuses. While still far fewer calves are being born each year than expected, the small role of genetics underlying variance in female fecundity suggests that variance may be explained by external factors that can potentially be mitigated through protection measures designed to reduce serious injury and mortality from human activities.
Collapse
Affiliation(s)
- Carla A. Crossman
- Biology Department, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3
| | - Philip K. Hamilton
- Anderson Cabot Center for Ocean Life, New England Aquarium, Central Wharf, Boston, Massachusetts, USA
| | - Moira W. Brown
- Canadian Whale Institute, Welshpool, New Brunswick, Canada
| | - Lisa A. Conger
- NOAA Fisheries, Northeast Fisheries Science Center, Woods Hole, MA, USA
| | - R. Clay George
- Georgia Department of Natural Resources, Wildlife Conservation Section, Brunswick, GA, USA
| | - Katharine A. Jackson
- Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Saint Petersburg, FL, USA
| | - Sonya N. Radvan
- Biology Department, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3
| | - Timothy R. Frasier
- Biology Department, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3
| |
Collapse
|
2
|
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.
Collapse
|
3
|
Wiedenfeld DA, Alberts AC, Angulo A, Bennett EL, Byers O, Contreras‐MacBeath T, Drummond G, da Fonseca GAB, Gascon C, Harrison I, Heard N, Hochkirch A, Konstant W, Langhammer PF, Langrand O, Launay F, Lebbin DJ, Lieberman S, Long B, Lu Z, Maunder M, Mittermeier RA, Molur S, Khalifa al Mubarak R, Parr MJ, Ratsimbazafy J, Rhodin AGJ, Rylands AB, Sanderson J, Sechrest W, Soorae P, Supriatna J, Upgren A, Vié J, Zhang L. Conservation resource allocation, small population resiliency, and the fallacy of conservation triage. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2021; 35:1388-1395. [PMID: 33484006 PMCID: PMC8518633 DOI: 10.1111/cobi.13696] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 01/09/2021] [Accepted: 01/16/2021] [Indexed: 05/30/2023]
Abstract
Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.
Collapse
Affiliation(s)
| | | | - Ariadne Angulo
- IUCN SSC Amphibian Specialist Group3701 Lake Shore Blvd. W, P.O. Box 48586TorontoONM8W 1P5Canada
| | | | - Onnie Byers
- IUCN SSC Conservation Planning Specialist Group12101 Johnny Cake Ridge RoadApple ValleyMN55124U.S.A.
| | - Topiltzin Contreras‐MacBeath
- Centro de Investigaciones BiológicasUniversidad Autónoma del Estado de MorelosAvenida Universidad 1001, Col. Chamilpa, CP 62209CuernavacaMorelosMexico
| | - Gláucia Drummond
- Fundação BiodiversitasAvenida Celso Porfírio Machado No. 1813, BelvedereBelo HorizonteMG30320–400Brazil
| | | | - Claude Gascon
- The Global Environment Facility1818 H Street NW Rm N8‐800WashingtonDC20433U.S.A.
| | - Ian Harrison
- Conservation InternationalArlingtonVA22202U.S.A.
| | - Nicolas Heard
- Mohamed bin Zayed Species Conservation FundP.O. Box 13112Abu DhabiUAE
| | - Axel Hochkirch
- Department of Biogeography and IUCN SSC Invertebrate Conservation CommitteeTrier UniversityTrier54286Germany
| | - William Konstant
- Margot Marsh Biodiversity Foundation403 Poplar RoadFlourtownPA19031U.S.A.
| | | | | | - Frederic Launay
- Mohamed bin Zayed Species Conservation FundP.O. Box 13112Abu DhabiUAE
- PantheraNew YorkNY10018U.S.A.
| | | | - Susan Lieberman
- Wildlife Conservation Society2300 Southern Blvd.BronxNY10460U.S.A.
| | - Barney Long
- Global Wildlife ConservationAustinTX78704U.S.A.
| | - Zhi Lu
- Center for Nature and Society, School of Life SciencesPeking UniversityBeijing100871China
| | - Michael Maunder
- Center for Ecology and ConservationUniversity of ExeterPenryn CampusCornwallTR10 9FEU.K.
| | | | - Sanjay Molur
- Zoo Outreach Organization12 Thiruvannamalai Nagar, Saravanampatti – Kalapatti Road, SaravanampattiCoimbatoreTamil Nadu641 035India
| | - Razan Khalifa al Mubarak
- Mohamed bin Zayed Species Conservation FundP.O. Box 13112Abu DhabiUAE
- Environment Agency ‐ Abu DhabiP.O. Box 45553Abu DhabiUAE
| | | | - Jonah Ratsimbazafy
- Groupe d'Etude et de Recherche sur les Primates de MadagascarAntananarivoMadagascar
| | | | | | | | | | - Pritpal Soorae
- Environment Agency ‐ Abu DhabiP.O. Box 45553Abu DhabiUAE
| | - Jatna Supriatna
- Department of BiologyFMIPA, University of IndonesiaDepok16421Indonesia
| | - Amy Upgren
- American Bird ConservancyThe PlainsVA20198U.S.A.
| | | | - Li Zhang
- Key Laboratory for Biodiversity Science and Ecological Engineering, Ministry of EducationInstitute of EcologyBeijing Normal UniversityBeijing100875China
| |
Collapse
|
4
|
Grueber CE, Farquharson KA, Wright BR, Wallis GP, Hogg CJ, Belov K. First evidence of deviation from Mendelian proportions in a conservation programme. Mol Ecol 2021; 30:3703-3715. [PMID: 34051005 DOI: 10.1111/mec.16004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/05/2021] [Indexed: 11/29/2022]
Abstract
Classic Mendelian inheritance is the bedrock of population genetics and underpins pedigree-based management of animal populations. However, assumptions of Mendelian inheritance might not be upheld in conservation breeding programmes if early viability selection occurs, even when efforts are made to equalise genetic contributions of breeders. To test this possibility, we investigated deviations from Mendelian proportions in a captive metapopulation of the endangered Tasmanian devil. This marsupial population is ideal for addressing evolutionary questions in conservation due to its large size, range of enclosure types (varying in environmental conditions), good genomic resources (which aid interpretation), and the species' biology. Devil mothers give birth to more offspring than they can nurse in the pouch, providing the potential for intense viability selection amongst embryos. We used data from 140 known sire-dam-offspring triads to isolate within-family selection from population-level mechanisms (such as mate choice or inbreeding), and compared observed offspring genotypes at 123 targeted SNPs to neutral (i.e., Mendelian) expectations. We found lower offspring heterozygosity than expected, and subtle patterns that varied across a gradient of management intensity from zoo-like enclosures to semi-wild environments for some loci. Meiotic drive or maternal-foetal incompatibilities are consistent with our results, although we cannot statistically confirm these mechanisms. We found some evidence that maternal genotype affects annual litter size, suggesting that family-level patterns are driven by differential offspring mortality before birth or during early development. Our results show that deviations from Mendelian inheritance can occur in conservation programmes, despite best-practice management to prevent selection.
Collapse
Affiliation(s)
- Catherine E Grueber
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia.,San Diego Zoo Global, San Diego, CA, USA
| | - Katherine A Farquharson
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Belinda R Wright
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Graham P Wallis
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Carolyn J Hogg
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Katherine Belov
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| |
Collapse
|
5
|
Graham KM, Burgess EA, Rolland RM. Stress and reproductive events detected in North Atlantic right whale blubber using a simplified hormone extraction protocol. CONSERVATION PHYSIOLOGY 2021; 9:coaa133. [PMID: 33489237 PMCID: PMC7808127 DOI: 10.1093/conphys/coaa133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 10/16/2020] [Accepted: 12/14/2020] [Indexed: 06/12/2023]
Abstract
As studies quantifying steroid hormones in marine mammal blubber progress, methodological refinements may improve the utility and consistency of blubber hormone measurements. This study advances blubber extraction methodologies by testing a simplified extraction protocol that reduces time and complexity compared to a protocol widely used in cetacean blubber studies. Using blubber samples archived from remote biopsy (n = 21 live whales) and necropsy collection (n = 7 dead whales) of North Atlantic right whales (NARW; Eubalaena glacialis) of known life history states, we performed analytical and biological validations to assess the feasibility of measuring reproductive (testosterone, progesterone) and glucocorticoid (cortisol) hormones in blubber via enzyme immunoassay following the simplified extraction. Analytical validations (parallelism, accuracy, extraction efficiency, repeatability) showed the simplified extraction produced similar results to the extended protocol, offering a more efficient and consistent technique. In live, apparently healthy whales, blubber testosterone concentrations (mean ± SE) were significantly higher in males (2.02 ± 0.36 ng/g) compared to females (0.81 ± 0.15 ng/g). Blubber progesterone was highest in a confirmed pregnant female (60.3 ng/g), which was 12-fold greater than the mean concentration of non-pregnant females (4.56 ± 0.88 ng/g). Blubber cortisol concentrations in whales that died from anthropogenic causes averaged 5.31 ± 2.28 ng/g, whereas most live, healthy whales had cortisol values below 1 ng/g. Among living whales, a whale actively entangled in fishing gear had the highest blubber cortisol measurement (3.51 ng/g), exhibiting levels similar to whales that died from acute entanglement (2.88 ± 0.42 ng/g). Overall, the highest blubber cortisol concentration (18.0 ng/g) was measured in a dead whale with a severe chronic entanglement, approximately 30-fold greater than mean blubber cortisol of apparently healthy whales (0.58 ± 0.11 ng/g). The methodological approach presented here provides a reference for researchers interested in an alternative, streamlined technique for hormone extraction of cetacean blubber and contributes to the diverse tool set for stress and reproductive assessments of endangered NARWs.
Collapse
Affiliation(s)
- Katherine M Graham
- Anderson Cabot Center for Ocean Life at the New England Aquarium, Central Wharf, Boston, MA 02110, USA
| | - Elizabeth A Burgess
- Anderson Cabot Center for Ocean Life at the New England Aquarium, Central Wharf, Boston, MA 02110, USA
| | - Rosalind M Rolland
- Anderson Cabot Center for Ocean Life at the New England Aquarium, Central Wharf, Boston, MA 02110, USA
| |
Collapse
|
6
|
Sharp SM, McLellan WA, Rotstein DS, Costidis AM, Barco SG, Durham K, Pitchford TD, Jackson KA, Daoust PY, Wimmer T, Couture EL, Bourque L, Frasier T, Frasier B, Fauquier D, Rowles TK, Hamilton PK, Pettis H, Moore MJ. Gross and histopathologic diagnoses from North Atlantic right whale Eubalaena glacialis mortalities between 2003 and 2018. DISEASES OF AQUATIC ORGANISMS 2019; 135:1-31. [PMID: 31219432 DOI: 10.3354/dao03376] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Seventy mortalities of North Atlantic right whales Eubalaena glacialis (NARW) were documented between 2003 and 2018 from Florida, USA, to the Gulf of St. Lawrence, Canada. These included 29 adults, 14 juveniles, 10 calves, and 17 of unknown age class. Females represented 65.5% (19/29) of known-sex adults. Fourteen cases had photos only; 56 carcasses received external examinations, 44 of which were also necropsied. Cause of death was determined in 43 cases, of which 38 (88.4%) were due to anthropogenic trauma: 22 (57.9%) from entanglement, and 16 (42.1%) from vessel strike. Gross and histopathologic lesions associated with entanglement were often severe and included deep lacerations caused by constricting line wraps around the flippers, flukes, and head/mouth; baleen plate mutilation; chronic extensive bone lesions from impinging line, and traumatic scoliosis resulting in compromised mobility in a calf. Chronically entangled whales were often in poor body condition and had increased cyamid burden, reflecting compromised health. Vessel strike blunt force injuries included skull and vertebral fractures, blubber and muscle contusions, and large blood clots. Propeller-induced wounds often caused extensive damage to blubber, muscle, viscera, and bone. Overall prevalence of NARW entanglement mortalities increased from 21% (1970-2002) to 51% during this study period. This demonstrates that despite mitigation efforts, entanglements and vessel strikes continue to inflict profound physical trauma and suffering on individual NARWs. These cumulative mortalities are also unsustainable at the population level, so urgent and aggressive intervention is needed to end anthropogenic mortality in this critically endangered species.
Collapse
Affiliation(s)
- S M Sharp
- International Fund for Animal Welfare, Yarmouth Port, MA 02675, USA Addresses for other authors are given in the supplements at www.int-res.com/articles/suppl/d135p001_supp.pdf
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Springate L, Frasier TR. Gamete compatibility genes in mammals: candidates, applications and a potential path forward. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170577. [PMID: 28878999 PMCID: PMC5579115 DOI: 10.1098/rsos.170577] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/31/2017] [Indexed: 06/01/2023]
Abstract
Fertilization represents a critical stage in biology, where successful alleles of a previous generation are shuffled into new arrangements and subjected to the forces of selection in the next generation. Although much research has been conducted on how variation in morphological and behavioural traits lead to variation in fertilization patterns, surprisingly little is known about fertilization at a molecular level, and specifically about how genes expressed on the sperm and egg themselves influence fertilization patterns. In mammals, several genes have been identified whose products are expressed on either the sperm or the egg, and which influence the fertilization process, but the specific mechanisms are not yet known. Additionally, in 2014 an interacting pair of proteins was identified: 'Izumo' on the sperm, and 'Juno' on the egg. With the identification of these genes comes the first opportunity to understand the molecular aspects of fertilization in mammals, and to identify how the genetic characteristics of these genes influence fertilization patterns. Here, we review recent progress in our understanding of fertilization and gamete compatibility in mammals, which should provide a helpful guide to researchers interested in untangling the molecular mechanisms of fertilization and the resulting impacts on population biology and evolutionary processes.
Collapse
|
8
|
Murphy S, Barber JL, Learmonth JA, Read FL, Deaville R, Perkins MW, Brownlow A, Davison N, Penrose R, Pierce GJ, Law RJ, Jepson PD. Reproductive Failure in UK Harbour Porpoises Phocoena phocoena: Legacy of Pollutant Exposure? PLoS One 2015. [PMID: 26200456 PMCID: PMC4511585 DOI: 10.1371/journal.pone.0131085] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Reproductive failure in mammals due to exposure to polychlorinated biphenyls (PCBs) can occur either through endocrine disrupting effects or via immunosuppression and increased disease risk. To investigate further, full necropsies and determination of summed 25 polychlorinated biphenyls congeners (∑PCBs lipid weight) in blubber were undertaken on 329 UK-stranded female harbour porpoises (1990-2012). In sexually mature females, 25/127 (19.7%) showed direct evidence of reproductive failure (foetal death, aborting, dystocia or stillbirth). A further 21/127 (16.5%) had infections of the reproductive tract or tumours of reproductive tract tissues that could contribute to reproductive failure. Resting mature females (non-lactating or non-pregnant) had significantly higher mean ∑PCBs (18.5 mg/kg) than both lactating (7.5 mg/kg) and pregnant females (6 mg/kg), though not significantly different to sexually immature females (14.0 mg/kg). Using multinomial logistic regression models ΣPCBs was found to be a significant predictor of mature female reproductive status, adjusting for the effects of confounding variables. Resting females were more likely to have a higher PCB burden. Health status (proxied by "trauma" or "infectious disease" causes of death) was also a significant predictor, with lactating females (i.e. who successfully reproduced) more likely to be in good health status compared to other individuals. Based on contaminant profiles (>11 mg/kg lipid), at least 29/60 (48%) of resting females had not offloaded their pollutant burden via gestation and primarily lactation. Where data were available, these non-offloading females were previously gravid, which suggests foetal or newborn mortality. Furthermore, a lower pregnancy rate of 50% was estimated for "healthy" females that died of traumatic causes of death, compared to other populations. Whether or not PCBs are part of an underlying mechanism, we used individual PCB burdens to show further evidence of reproductive failure in the North-east Atlantic harbour porpoise population, results that should inform conservation management.
Collapse
Affiliation(s)
- Sinéad Murphy
- Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom
| | - Jonathan L Barber
- Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, United Kingdom
| | | | - Fiona L Read
- Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire, United Kingdom
| | - Robert Deaville
- Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom
| | - Matthew W Perkins
- Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom
| | - Andrew Brownlow
- Scottish Marine Animal Stranding Scheme, SRUC Veterinary Services Drummondhill, Inverness, United Kingdom
| | - Nick Davison
- Scottish Marine Animal Stranding Scheme, SRUC Veterinary Services Drummondhill, Inverness, United Kingdom
| | - Rod Penrose
- Marine Environmental Monitoring, Penwalk, Llechryd, Cardigan, Ceredigion, United Kingdom
| | - Graham J Pierce
- Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire, United Kingdom
| | - Robin J Law
- Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom; Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, United Kingdom
| | - Paul D Jepson
- Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom
| |
Collapse
|
9
|
Mehlis M, Rahn AK, Bakker TCM. Sperm quality but not relatedness predicts sperm competition success in threespine sticklebacks (Gasterosteus aculeatus). BMC Evol Biol 2015; 15:74. [PMID: 25928309 PMCID: PMC4415302 DOI: 10.1186/s12862-015-0353-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 04/15/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mating between close relatives often leads to a reduction of an individual's fitness, due to an increased expression of deleterious alleles. Thus, in many animal taxa pre- as well as postcopulatory inbreeding avoidance mechanisms have evolved. An increased risk of inbreeding and hence a loss of genetic variation may occur during founder events as in most cases only few individuals establish a new population. The threespine stickleback (Gasterosteus aculeatus) is a small externally fertilizing fish species subject to strong sperm competition. Sticklebacks inhabit both marine and freshwater environments and anadromous populations have repeatedly established new genetically less diverse freshwater populations. Previous studies showed that anadromous sticklebacks strongly suffer from inbreeding depression and when given the choice females prefer to mate with unrelated males. RESULTS The present study aimed to address whether there exists a postcopulatory inbreeding avoidance mechanism solely based on sperm-egg interactions in sperm competition experiments. We used F1 individuals that originated either from a large, genetically heterogeneous anadromous population or from a small, genetically less diverse freshwater population. For each population, eggs of two different females were in vitro fertilized by the same two males' sperm in a paired study design. In the main experiment one male was the female's full-sib brother and in the control experiment all individuals were unrelated. The results revealed that fertilization success was independent of relatedness in both populations suggesting a general lack of a postcopulatory inbreeding avoidance mechanism. Instead, male quality (i.e. sperm morphology) predicted paternity success during competitive fertilization trials. CONCLUSION In sticklebacks, there is no evidence for postcopulatory inbreeding avoidance. Sperm morphology predicted paternity instead, thus sperm quality traits are under strong sexual selection, presumably driven by the high risk of sperm competition under natural conditions.
Collapse
Affiliation(s)
- Marion Mehlis
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, D-53121, Bonn, Germany.
| | - Anna K Rahn
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, D-53121, Bonn, Germany.
| | - Theo C M Bakker
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, D-53121, Bonn, Germany.
| |
Collapse
|
10
|
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.
Collapse
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
| | | | | | | | | | | | | |
Collapse
|
11
|
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.
Collapse
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
| | | | | |
Collapse
|