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Zeng J, Li Y, Gong Y, Shi Y, Feng H, Song S. Variation in parental investment preferences for nestlings of the Gray-backed Shrike ( Lanius tephronotus) in alpine environments. Ecol Evol 2024; 14:e70267. [PMID: 39301298 PMCID: PMC11410560 DOI: 10.1002/ece3.70267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 08/03/2024] [Accepted: 08/23/2024] [Indexed: 09/22/2024] Open
Abstract
In the northeastern edge of the Qinghai-Tibet Plateau, the Gray-backed Shrike, a shrubland bird species of the plateau, confronts harsh living conditions. The impact of such an environment on their reproductive strategies has long intrigued us. This study reveals significant environmental effects on the investment of the Gray-backed Shrike during their nestling-rearing and egg-laying stages. (1) Based on measurements of 215 shrike eggs from 2017 to 2021, we found that under the cold alpine climate, Gray-backed Shrikes opt for a strategy of larger clutches and bigger eggs as average rainfall decreases. Concurrently, parents display a decreasing hatching order strategy, resulting in significant weight differences among newly hatched nestlings. (2) Marginal and core offspring exhibited no significant differences in fledging conditions. Core offspring generally have a slightly larger physique than marginal ones. However, marginal offspring exhibit the highest growth rate, with similar survival rates across different offspring categories. Parental rearing adopts a nest survival strategy. (3) The food provisioning rate by parents correlates strongly with the number of nestlings, the age of the nestling, and the nest's sex ratio. Differences exist between female and male provisioning rates based on begging intensity and average temperature; higher average temperatures lead to more food, with males providing more food. (4) Factors like nest sex ratio, offspring category, nestling age, and nestling sex influence the feeding preferences of parents. When overall nestling ratios skew towards either male or female, parental feeding preferences align with the actual nest sex ratio. Male and female parental feeding preferences differ based on average temperature and nestling sex. Males consistently exhibit a stronger preference for feeding male nestlings, regardless of the nest's sex ratio. In contrast, females don't show a clear preference, leading to differences in survival rates for different nestling sex under male feeding preferences.
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Affiliation(s)
- Jinyuan Zeng
- School of Life Sciences Lanzhou University Lanzhou Gansu Province China
| | - Yueqi Li
- School of Life Sciences Lanzhou University Lanzhou Gansu Province China
| | - Yuhan Gong
- School of Life Sciences Lanzhou University Lanzhou Gansu Province China
| | - Yurou Shi
- School of Life Sciences Lanzhou University Lanzhou Gansu Province China
| | - Hongyuan Feng
- Gansu Qilian Mountain National Nature Reserve Management Center Zhangye City Gansu Province China
| | - Sen Song
- School of Life Sciences Lanzhou University Lanzhou Gansu Province China
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Tooth A, Morosinotto C, Karell P. Sex allocation is color morph-specific and associated with fledging condition in a wild bird. Behav Ecol 2024; 35:arae039. [PMID: 38818250 PMCID: PMC11138213 DOI: 10.1093/beheco/arae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 04/03/2024] [Accepted: 05/14/2024] [Indexed: 06/01/2024] Open
Abstract
Melanin-based color polymorphism is predicted to evolve and maintain through differential fitness of morphs in different environments, and several empirical studies indicate that life history strategies, physiology, and behavior vary among color morphs. Sex allocation theory predicts that parents should adjust their sex allocation based on differential costs of raising sons and daughters, and therefore, color morphs are expected to modify their brood sex ratio decisions. In color polymorphic tawny owls (Strix aluco), the pheomelanistic brown morph is associated with higher energy requirements, faster growth, and higher parental effort than the gray morph. As hypothesized, we find that brown tawny owl mothers produced more daughters in early broods and more males in late broods, whereas gray mothers did the opposite. At fledging, daughters of early broods and of brown mothers were heavier than those of late broods or gray mothers. Hence, larger and more costly daughters appeared to benefit more than males from being born to brown mothers early in the season. Brown mothers breeding later in the season produced more cheap sons, while gray mothers face fewer challenges under limited resources and favor daughters. These findings suggest that environmental conditions influence brood sex allocation strategies of genetically determined color morphs differently.
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Affiliation(s)
- Amandine Tooth
- Department of Biology, Lund University, Sölvegatan 37 (Ecology Building), SE-223 62 Lund, Sweden
| | - Chiara Morosinotto
- Department of Biology, Lund University, Sölvegatan 37 (Ecology Building), SE-223 62 Lund, Sweden
- Bioeconomy Research Team, Novia University of Applied Sciences, Raseborgsvägen 9, FI-10600 Raseborg, Finland
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
- National Biodiversity Future Center (NBFC), Piazza Marina 61, I-90133 Palermo, Italy
| | - Patrik Karell
- Department of Biology, Lund University, Sölvegatan 37 (Ecology Building), SE-223 62 Lund, Sweden
- Bioeconomy Research Team, Novia University of Applied Sciences, Raseborgsvägen 9, FI-10600 Raseborg, Finland
- Evolutionary Biology Center, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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Fuentes E, Moreau J, Millet M, Bretagnolle V, Monceau K. Organic farming reduces pesticide load in a bird of prey. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 930:172778. [PMID: 38670354 DOI: 10.1016/j.scitotenv.2024.172778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/10/2024] [Accepted: 04/23/2024] [Indexed: 04/28/2024]
Abstract
Human activities have led to the contamination of all environmental compartments worldwide, including bird species. In birds, both the environment and maternal transfer lead to high inter-brood variability in contamination levels of pollutants, whereas intra-brood variability is generally low. However, most existing studies focused on heavy metals or persistent compounds and none, to our knowledge, addressed the variability in contamination levels of multiple pesticides and the factors influencing it. In this study, the number of pesticides detected (of 104 compounds searched) and the sum of their concentrations in the blood of 55 Montagu's harrier (Circus pygargus) nestlings from 22 nests sampled in 2021 were used as metrics of contamination levels. We investigated the effect of organic farming at the size of male's home range (i.e., 14 km2) and chicks' sex and hatching order on contamination levels. We did not find a difference between inter-brood and intra-brood variability in pesticide contamination levels, suggesting a different exposure of siblings through food items. While chicks' sex or rank did not affect their contamination level, we found that the percentage of organic farming around the nests significantly decreased the number of pesticides detected, although it did not decrease the total concentrations. This finding highlights the potential role of organic farming in reducing the exposure of birds to a pesticide cocktail.
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Affiliation(s)
- Elva Fuentes
- UMR 7372, Centre d'Études Biologiques de Chizé, La Rochelle Université & CNRS, 79360 Villiers en Bois, France.
| | - Jérôme Moreau
- UMR 7372, Centre d'Études Biologiques de Chizé, La Rochelle Université & CNRS, 79360 Villiers en Bois, France; UMR CNRS 6282 Biogéosciences, Équipe Écologie Évolutive, Université de Bourgogne, 21000 Dijon, France
| | - Maurice Millet
- Université de Strasbourg, CNRS-UMR 7515, ICPEES, 67087 Strasbourg cedex 2, France
| | - Vincent Bretagnolle
- UMR 7372, Centre d'Études Biologiques de Chizé, La Rochelle Université & CNRS, 79360 Villiers en Bois, France; LTSER "Zone Atelier Plaine & Val de Sèvre", CNRS, 79360 Villiers-en-Bois, France
| | - Karine Monceau
- UMR 7372, Centre d'Études Biologiques de Chizé, La Rochelle Université & CNRS, 79360 Villiers en Bois, France
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Gómez‐López G, Sanz‐Aguilar A, Carrete M, Arrondo E, Benítez JR, Ceballos O, Cortés‐Avizanda A, de Pablo F, Donázar JA, Frías Ó, Gangoso L, García‐Alfonso M, González JL, Grande JM, Serrano D, Tella JL, Blanco G. Insularity determines nestling sex ratio variation in Egyptian vulture populations. Ecol Evol 2023; 13:e10371. [PMID: 37529590 PMCID: PMC10385291 DOI: 10.1002/ece3.10371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 07/04/2023] [Accepted: 07/11/2023] [Indexed: 08/03/2023] Open
Abstract
Variation in offspring sex ratio, particularly in birds, has been frequently studied over the last century, although seldom using long-term monitoring data. In raptors, the cost of raising males and females is not equal, and several variables have been found to have significant effects on sex ratio, including food availability, parental age, and hatching order. Sex ratio differences between island populations and their mainland counterparts have been poorly documented, despite broad scientific literature on the island syndrome reporting substantial differences in population demography and ecology. Here, we assessed individual and environmental factors potentially affecting the secondary sex ratio of the long-lived Egyptian vulture Neophron percnopterus. We used data collected from Spanish mainland and island populations over a ca. 30-year period (1995-2021) to assess the effects of insularity, parental age, breeding phenology, brood size, hatching order, type of breeding unit (pairs vs. trios), and spatial and temporal variability on offspring sex ratio. No sex bias was found at the population level, but two opposite trends were observed between mainland and island populations consistent with the island syndrome. Offspring sex ratio was nonsignificantly female-biased in mainland Spain (0.47, n = 1112) but significantly male-biased in the Canary Islands (0.55, n = 499), where a male-biased mortality among immatures could be compensating for offspring biases and maintaining a paired adult sex ratio. Temporal and spatial variation in food availability might also have some influence on sex ratio, although the difficulties in quantifying them preclude us from determining the magnitude of such influence. This study shows that insularity influences the offspring sex ratio of the Egyptian vulture through several processes that can affect island and mainland populations differentially. Our research contributes to improving our understanding of sex allocation theory by investigating whether sex ratio deviations from parity are possible as a response to changing environments comprised by multiple and complexly interrelated factors.
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Affiliation(s)
- Guillermo Gómez‐López
- Department of Evolutionary Ecology, National Museum of Natural SciencesSpanish National Research CouncilMadridSpain
- Department of Biodiversity, Ecology and Evolution, Faculty of BiologyComplutense University of MadridMadridSpain
| | - Ana Sanz‐Aguilar
- Animal Demography and Ecology GroupInstitut Mediterrani d'Estudis Avançats, Spanish National Research CouncilMallorcaSpain
- Applied Zoology and Conservation GroupUniversitat de les Illes BalearsPalmaSpain
| | - Martina Carrete
- Department of Physical, Chemical and Natural SystemsPablo de Olavide UniversitySevillaSpain
| | - Eneko Arrondo
- Department of ZoologyUniversity of GranadaGranadaSpain
- Department of Applied BiologyMiguel Hernández UniversityElcheSpain
| | - José Ramón Benítez
- Department of BiodiversityAgencia de Medioambiente y Agua, Junta de AndalucíaSevillaSpain
| | | | - Ainara Cortés‐Avizanda
- Department of Plant Biology and EcologyUniversity of SevilleSevillaSpain
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - Félix de Pablo
- Department of Environment and Biosphere ReserveConsell Insular de Menorca, PlazaMaóSpain
| | - José Antonio Donázar
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - Óscar Frías
- Department of Physical, Chemical and Natural SystemsPablo de Olavide UniversitySevillaSpain
| | - Laura Gangoso
- Department of Biodiversity, Ecology and Evolution, Faculty of BiologyComplutense University of MadridMadridSpain
| | - Marina García‐Alfonso
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - José Luis González
- Department of Evolutionary Ecology, National Museum of Natural SciencesSpanish National Research CouncilMadridSpain
| | | | - David Serrano
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - José Luis Tella
- Department of Conservation BiologyDoñana Biological Station, Spanish National Research CouncilSevillaSpain
| | - Guillermo Blanco
- Department of Evolutionary Ecology, National Museum of Natural SciencesSpanish National Research CouncilMadridSpain
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5
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Sawada A, Iwasaki T, Akatani K, Takagi M. Mate choice for body size leads to size assortative mating in the Ryukyu Scops Owl Otus elegans. Ecol Evol 2022; 12:e9578. [PMID: 36523518 PMCID: PMC9745103 DOI: 10.1002/ece3.9578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/16/2022] [Accepted: 11/18/2022] [Indexed: 12/15/2022] Open
Abstract
Understanding evolutionary phenomena that involve size assortative mating requires elucidating the generating mechanisms on which assortment is based. Although various mechanisms have been suggested, their relative importance may differ across taxonomic groups. Males selecting for large, fecund females combined with the dominance of large males in the competition for females has been suggested as a major mechanism in specific groups. However, raptors do not appear to conform to this, because the selection for smallness among males (assumed in a theory of reversed sexual size dimorphism) and the selection for largeness among males (assumed in the theory of size assortative mating) are in opposite directions. We studied the assortative mating during a long-term study of the Ryukyu Scops Owls Otus elegans interpositus. Significant assortative mating was found for culmen length (from the base to the tip of the bill) and wing length (from the bend of the wing to the tip of the longest primary). Statistical control of the spatial and temporal accessibility of potential mates did not affect the assortment. Males with short wings had slightly higher fitness components than those with long wings, and females settling early tended to have small wings. Considering that early-settling females can preferentially choose their mates, these results suggest that smaller females have an advantage when choosing smaller males with good reproductive performance. Improved flying and hunting ability of smaller individuals may be the background of choosing smaller individuals. We propose that, not passive process like similarity between individuals and their potential mates, but active mate choice for small individuals is an explanation for the assortative mating in this owl.
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Affiliation(s)
- Akira Sawada
- Biodiversity DivisionNational Institute for Environmental StudiesTsukubaJapan
| | - Tetsuya Iwasaki
- Department of Biology and Geosciences, Graduate School of ScienceOsaka City UniversityOsakaJapan
| | - Kana Akatani
- Department of Biology and Geosciences, Graduate School of ScienceOsaka City UniversityOsakaJapan
| | - Masaoki Takagi
- Department of Natural History Science, Graduate School of ScienceHokkaido UniversitySapporoJapan
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6
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Kouba M, Bartoš L, Bartošová J, Hongisto K, Korpimäki E. Long-term trends in the body condition of parents and offspring of Tengmalm's owls under fluctuating food conditions and climate change. Sci Rep 2021; 11:18893. [PMID: 34556766 PMCID: PMC8460639 DOI: 10.1038/s41598-021-98447-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 09/08/2021] [Indexed: 11/23/2022] Open
Abstract
Physical condition is important for the ability to resist various parasites and diseases as well as in escaping predators thus contributing to reproductive success, over-winter survival and possible declines in wildlife populations. However, in-depth research on trends in body condition is rare because decades-long datasets are not available for a majority of species. We analysed the long-term dataset of offspring covering 34 years, male parents (40 years) and female parents (42 years) to find out whether the decline of Tengmalm's owl population in western Finland is attributable to either decreased adult and/or juvenile body condition in interaction with changing weather conditions and density estimates of main foods. We found that body condition of parent owl males and females declined throughout the 40-year study period whereas the body condition of owlets at the fledging stage very slightly increased. The body condition of parent owls increased with augmenting depth of snow cover in late winter (January to March), and that of offspring improved with increasing precipitation in late spring (May to June). We conclude that the decreasing trend of body condition of parent owl males and females is important factor probably inducing reduced adult survival and reduced reproduction success thus contributing to the long-term decline of the Tengmalm's owl study population. The very slightly increasing trend of body condition of offspring is obviously not able to compensate the overall decline of Tengmalm's owl population, because the number of offspring in turn simultaneously decreased considerably in the long-term. The ongoing climate change appeared to work in opposite ways in this case because declining depth of snow cover will make the situation worse but increased precipitation will improve. We suggest that the main reasons for long-term decline of body condition of parent owls are interactive or additive effects of reduced food resources and increased overall predation risk due to habitat degradation (loss and fragmentation of mature and old-growth forests due to clear-felling) subsequently leading to decline of Tengmalm's owl study population.
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Affiliation(s)
- Marek Kouba
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland.
- Department of Ethology and Companion Animal Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic.
| | - Luděk Bartoš
- Department of Ethology and Companion Animal Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic
- Department of Ethology, Institute of Animal Science, Prague, Czech Republic
| | - Jitka Bartošová
- Department of Ethology and Companion Animal Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic
- Department of Ethology, Institute of Animal Science, Prague, Czech Republic
| | | | - Erkki Korpimäki
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland
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7
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Roos S, Campbell ST, Hartley G, Shore RF, Walker LA, Wilson JD. Annual abundance of common Kestrels (Falco tinnunculus) is negatively associated with second generation anticoagulant rodenticides. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:560-574. [PMID: 33770305 PMCID: PMC8060177 DOI: 10.1007/s10646-021-02374-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/19/2021] [Indexed: 05/15/2023]
Abstract
Rats and mice can damage food and agricultural products as well as transmit diseases, thereby requiring control of their numbers. Application of Second Generation Anticoagulant Rodenticides (SGARs) often reduces rodent numbers locally. However, predators eating rodents, including non-target species, that have consumed SGARs may be secondarily exposed and potentially lethally poisoned. Here we study whether SGARs may have contributed to the widespread population declines of a rodent-eating raptor, the Common Kestrel (Falco tinnunculus) in the UK. We show that 161 (66.8%) of the 241 Kestrels submitted for ecotoxicology tests between 1997 and 2012 had detectable levels of at least one SGAR in their livers. Adult Kestrels had significantly higher prevalence of SGARs than juveniles, suggesting accumulation of SGARs through time. The prevalence and concentrations of individual SGARs in Kestrels were significantly higher in England than in Scotland. SGAR prevalence in Kestrels were positively associated with some land cover types, primarily arable cereals and broad-leaved woodland, and negatively associated with mainly mean elevation, probably reflecting variation in SGAR usage across land cover types. By using volunteer-collected data on national Kestrel abundance 1997-2012, we show that there is a negative correlation between the Kestrel population index in a specific year and the concentration of bromadialone as well as the total SGAR concentration in the same year. Although correlative, this is the first study to provide evidence for a potential population-limiting effect of SGARs on a raptor.
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Affiliation(s)
- Staffan Roos
- RSPB Centre for Conservation Science, 2 Lochside View, EH12 9DH, Edinburgh, UK.
- Swedish Species Information Centre, Swedish University of Agricultural Sciences, Box 7007, 750 07, Uppsala, Sweden.
| | - Steve T Campbell
- Science and Advice for Scottish Agriculture (SASA), Scottish Government, Roddinglaw Road, Edinburgh, EH12 9FJ, UK
| | - Gill Hartley
- Science and Advice for Scottish Agriculture (SASA), Scottish Government, Roddinglaw Road, Edinburgh, EH12 9FJ, UK
| | - Richard F Shore
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP, UK
| | - Lee A Walker
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP, UK
| | - Jeremy D Wilson
- RSPB Centre for Conservation Science, 2 Lochside View, EH12 9DH, Edinburgh, UK
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8
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Brood sex ratio modulates the effects of extra food on parental effort and sibling competition in a sexually dimorphic raptor. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-02970-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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9
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Merkling T, Hatch SA, Leclaire S, Danchin E, Blanchard P. Offspring sex-ratio and environmental conditions in a seabird with sex-specific rearing costs: a long-term experimental approach. Evol Ecol 2019. [DOI: 10.1007/s10682-019-09983-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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10
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Sumasgutner P, Tate GJ, Koeslag A, Amar A. Family morph matters: factors determining survival and recruitment in a long-lived polymorphic raptor. J Anim Ecol 2016; 85:1043-55. [PMID: 26990283 DOI: 10.1111/1365-2656.12518] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 03/04/2016] [Indexed: 01/02/2023]
Abstract
From an evolutionary perspective, recruitment into the breeding population represents one of the most important life-history stages and ultimately determines the effective population size. In order to contribute to the next generation, offspring must survive to sexual maturity, secure a territory and find a mate. In this study, we explore factors influencing both offspring survival and their subsequent recruitment into the local breeding population in a long-lived urban raptor, the black sparrowhawk (Accipiter melanoleucus). Adult black sparrowhawks show discrete colour polymorphism (dark and light morphs), and in South Africa, morphs are distributed clinally with the highest proportion of dark morphs (c.75%) present in our study population on the Cape Peninsula. Parental morph was associated with both survival and recruitment. For survival, parental morph combination was important - with young produced by pairs of contrasting morphs having higher survival rates than young fledged from like-pairs. The association between recruitment and morph was more complex; with an interaction between male morph and breeding time, whereby recruitment of offspring from dark morph fathers was more likely when fledging earlier in the season. The opposite relationship was found for light morph fathers, with their offspring more likely to be recruited if fledged later in the season. This interaction may be due to differential morph-specific hunting success of fathers (males contribute most food provisioning), linked to background matching and crypsis in different weather conditions. Dark morph males may hunt more successfully in rainier and cloudier conditions, which occur more frequently earlier in the breeding season, and light morph males may be more successful later on, when weather conditions become increasingly brighter and drier. Our results reveal a complex situation whereby the family morph combination influences survival, and the father morphs specifically recruitment, revealing morph-specific benefits dependent on the timing of breeding. These empirical data are among the first to support the idea that differential fitness consequence of morph combination may explain balanced polymorphism in a vertebrate population.
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Affiliation(s)
- Petra Sumasgutner
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa.,Centre for Statistics in Ecology, Environment and Conservation, University of Cape Town, Cape Town, South Africa
| | - Gareth J Tate
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa
| | - Ann Koeslag
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa
| | - Arjun Amar
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa
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11
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Merkling T, Welcker J, Hewison AM, Hatch SA, Kitaysky AS, Speakman JR, Danchin E, Blanchard P. Identifying the selective pressures underlying offspring sex-ratio adjustments: a case study in a wild seabird. Behav Ecol 2015. [DOI: 10.1093/beheco/arv032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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12
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Bowers EK, Thompson CF, Sakaluk SK. Persistent sex-by-environment effects on offspring fitness and sex-ratio adjustment in a wild bird population. J Anim Ecol 2015; 84:473-86. [PMID: 25266087 PMCID: PMC4377307 DOI: 10.1111/1365-2656.12294] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 09/23/2014] [Indexed: 12/19/2022]
Abstract
A major component of sex-allocation theory, the Trivers-Willard model (TWM), posits that sons and daughters are differentially affected by variation in the rearing environment. In many species, the amount of parental care received is expected to have differing effects on the fitness of males and females. When this occurs, the TWM predicts that selection should favour adjustment of the offspring sex ratio in relation to the expected fitness return from offspring. However, evidence for sex-by-environment effects is mixed, and little is known about the adaptive significance of producing either sex. Here, we test whether offspring sex ratios vary according to predictions of the TWM in the house wren (Troglodytes aedon, Vieillot). We also test the assumption of a sex-by-environment effect on offspring using two experiments, one in which we manipulated age differences among nestlings within broods, and another in which we held nestling age constant but manipulated brood size. As predicted, females with high investment ability overproduced sons relative to those with lower ability. Males were also overproduced early within breeding seasons. In our experiments, the body mass of sons was more strongly affected by the sibling-competitive environment and resource availability than that of daughters: males grew heavier than females when reared in good conditions but were lighter than females when in poor conditions. Parents rearing broods with 1:1 sex ratios were more productive than parents rearing broods biased more strongly towards sons or daughters, suggesting that selection favours the production of mixed-sex broods. However, differences in the condition of offspring as neonates persisted to adulthood, and their reproductive success as adults varied with the body mass of sons, but not daughters, prior to independence from parental care. Thus, selection should favour slight but predictable variations in the sex ratio in relation to the quality of offspring that parents are able to produce. Offspring sex interacts with the neonatal environment to influence offspring fitness, thus favouring sex-ratio adjustment by parents. However, increased sensitivity of males to environmental conditions, such as sibling rivalry and resource availability, reduces the fitness returns from highly male-biased broods.
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Affiliation(s)
- E. Keith Bowers
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL 61790-4120 USA
| | - Charles F. Thompson
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL 61790-4120 USA
| | - Scott K. Sakaluk
- Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University, Normal, IL 61790-4120 USA
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13
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Offspring sex ratio varies with clutch size for female house wrens induced to lay supernumerary eggs. Behav Ecol 2013. [DOI: 10.1093/beheco/art100] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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14
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Merkling T, Leclaire S, Danchin E, Lhuillier E, Wagner RH, White J, Hatch SA, Blanchard P. Food availability and offspring sex in a monogamous seabird: insights from an experimental approach. Behav Ecol 2012. [DOI: 10.1093/beheco/ars023] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Nam KB, Meade J, Hatchwell BJ. Do parents and helpers adjust their provisioning effort in relation to nestling sex in a cooperatively breeding bird? Anim Behav 2011. [DOI: 10.1016/j.anbehav.2011.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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McDonald PG, Ewen JG, Wright J. Brood sex ratio does not affect helper effort in a cooperative bird, despite extreme sex-biased dispersal. Anim Behav 2010. [DOI: 10.1016/j.anbehav.2009.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Addison B, Kitaysky AS, Hipfner JM. Sex allocation in a monomorphic seabird with a single-egg clutch: test of the environment, mate quality, and female condition hypotheses. Behav Ecol Sociobiol 2008. [DOI: 10.1007/s00265-008-0643-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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MAGRATH MICHAELJL, VAN LIESHOUT EMILE, PEN IDO, VISSER GHENK, KOMDEUR JAN. Estimating expenditure on male and female offspring in a sexually size-dimorphic bird: a comparison of different methods. J Anim Ecol 2007; 76:1169-80. [DOI: 10.1111/j.1365-2656.2007.01292.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Townsend H, Maness T, Anderson D. Offspring growth and parental care in sexually dimorphic Nazca boobies (Sula granti). CAN J ZOOL 2007. [DOI: 10.1139/z07-047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A review of studies on nestling bird food requirements indicates that degree of sexual size dimorphism reliably predicts disparity in sex-specific food requirements, but that parents often fail to meet the excess requirement of the larger sex. We studied a population of Nazca boobies ( Sula granti Rothschild, 1902), a sexually dimorphic pelagic seabird, to determine whether parents provide more care to daughters, the larger sex. Daughters grew to a larger size than did sons during the nestling period, but did not reach the mean size of adult females, while sons exceeded the size of adult males. Estimates of parental effort exerted for sons versus daughters indicated similar levels of effort, and that females fledged in poorer condition than males did in the study year, one of intermediate breeding conditions. Results from another study conducted during better breeding conditions indicated little limitation on growth of either sex. Together, these studies are consistent with a ceiling on parental effort in a long-lived species that allows consistent self-maintenance for parents, but causes poor performance in the costlier sex under poor breeding conditions. Complementary studies of short-lived species are needed to evaluate our suggested linkage between parental effort, self-maintenance, and sexual size dimorphism.
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Affiliation(s)
- H.M. Townsend
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - T.J. Maness
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - D.J. Anderson
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
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