Making the best of a bad job? Chick mortality and flexible female brood care in Snowy Plovers

Kupán, Krisztina; Székely, Tamás; Cruz‐López, Medardo; Seymour, Keeley; Kuepper, Clemens

doi:10.1101/2019.12.19.880856

Cited by 3 publications

(7 citation statements)

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“…At the end of the season, late nesting females are under a tight schedule for producing sequential clutches rapidly before impending high tides and precipitation flood the breeding grounds (Plaschke et al, 2019). Notably, chick survival is especially high at the beginning of the season when resources are plentiful (Cruz-López et al, 2017;Kupán et al, 2019), which would support the notion that monogamous females breeding in the middle of the season may account for resource constraints by producing larger eggs to enhance chick survival.…”

Section: Discussion (1375 Words)mentioning

confidence: 88%

“…Here, we investigate age-dependent egg size variation using a 14-year longitudinal mark-recapture dataset of snowy plovers (Charadrius nivosus) breeding at Bahía de Ceuta -a wild sub-tropical population in western Mexico. The snowy plover is a long-lived shorebird (Colwell et al, 2017) exhibiting a rare breeding behaviour characterized by sex-role reversal including facultative sequential polyandry (Eberhart-Phillips et al, 2017;Kupán et al, 2019). The prominent variation of reproductive investment within the same sex provides a highly suitable study system to investigate how senescence and mating strategy shape female reproductive output in a species with non-conventional sex roles.…”

Section: Impact Summary (297 Words)mentioning

confidence: 99%

“…In the rare circumstance when we were unable to identify parents before hatching, we attempted capturing parents whilst they tended chicks. As snowy plovers only show a small degree of sexual dimorphism (Küpper et al, 2009), we determined sex of all captured plovers in the field through a combination of plumage characteristics (Argüelles-Ticó et al, 2016), time of capture, and other behavioural cues (e.g., sexspecific brood care; Kupán et al, 2019). Furthermore, we confirmed sex molecularly from DNA extracted from blood samples through PCR amplification of Z and W specific DNA regions with two sex-typing markers: P2/P8 and Calex-31 (Griffiths et al, 1998;Küpper et al, 2007;Dos Remedios et al, 2010).…”

Section: Data Collectionmentioning

confidence: 99%

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Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers

Eberhart‐Hertel¹,

Rodrigues²,

Krietsch³

et al. 2020

Preprint

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Identifying age-dependent trade-offs between reproductive effort and survival in wild organisms is central for understanding the evolutionary mechanisms of senescence. According to the disposable soma theory, early-life energy investments in reproduction compromise late-life investments in somatic maintenance – leading to senescence. Once thought to only be detectable in captive populations, senescence has recently been documented by several longitudinal studies of wild organisms. However, some reproductive traits that are used to quantify senescence may also be shaped by other age-dependent processes such as mating tactics. For instance, polygamy, which is often positively associated with age, may lead to reduced gamete size due to trade-offs between gamete quantity and quality. Here we investigate how mating behaviour and senescence are associated with reproductive trade-offs of female snowy plovers (Charadrius nivosus). Snowy plovers are long-lived shorebirds (longevity record: 19 years) that produce several nests each year, with females either being polyandrous and sequentially changing partners between breeding attempts or remaining monogamous between attempts. We examined how age, seasonality, and mating tactics affect within-female variation in egg volume using repeated measures collected over a 14-year period. Our results provide clear evidence for senescence in snowy plover females starting at three years of age. Furthermore, females laid smaller eggs in years when they were polyandrous compared to years when they were monogamous, with early- and late-season clutches having the smallest eggs. We suggest that individual female reproductive performance is regulated by flexible mating tactics and age- and season-dependent effects. Our findings highlight the existence of multiple trade-offs for female reproductive investments that likely shape individual variation in lifetime reproductive success. We encourage future research investigating reproductive senescence of wild populations to incorporate age-dependent reproductive investments in light of mating system dynamics.Impact SummaryWhy do organisms senesce at older ages? Life-history theory predicts that early life investments in reproduction compromise future investment opportunities for somatic repair, which leads to senescence. Earlier works assumed that senescence was only observable in captive populations due to the high degree of extrinsic mortality experienced by wild organisms. However, with the expansion of longitudinal studies collecting repeated measures from wild individuals, recent works have identified key insights into the selective processes driving patterns of senescence in nature. Here, we use a 14-year longitudinal mark-recapture dataset of snowy plovers (Charadrius nivosus) breeding in a wild subtropical population in western Mexico to investigate age-dependent trade-offs between female reproductive effort and performance. The snowy plover is a long-lived shorebird characterized by a flexible polyandrous mating system. This rare breeding behaviour represents a unique background for investigating senescence in light of between and within-individual variation in reproductive investment. Our study focused on age-dependent dynamics of egg volume – a convenient measure of a female’s intrinsic reproductive investment, particularly in birds with precocial chicks. We explored age-related correlates of within-female egg volume dynamics while controlling for among-female variation and the confounding effect of trait-dependent (dis)appearance of young (or old) females in the population. Our results show that egg volume expresses an early-life increase followed by a late-life decrease, indicative of reproductive senescence. Furthermore, females tended to lay smaller eggs in years during which they were polyandrous than in years when they were monogamous. Notably, polyandry was not associated with age. As expected, egg volume was highly repeatable within females and clutches. We conclude that age-dependent reproductive effort is an important component driving between- and within-individual variation in reproductive performance of facultatively polygamous species. We encourage future works studying reproductive senescence of wild populations to incorporate age-dependent reproductive investment and mating tactics.

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Section: Discussion (1375 Words)mentioning

confidence: 88%

Section: Impact Summary (297 Words)mentioning

confidence: 99%

Section: Data Collectionmentioning

confidence: 99%

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Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers

Eberhart‐Hertel¹,

Rodrigues²,

Krietsch³

et al. 2020

Preprint

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Section: Background and Summarymentioning

confidence: 99%

CeutaOPEN, individual-based field observations of breeding snowy plovers Charadrius nivosus

et al. 2020

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Shorebirds (part of the order Charadriiformes) have a global distribution and exhibit remarkable variation in ecological and behavioural traits that are pertinent to many core questions in the fields of evolutionary ecology and conservation biology. Shorebirds are also relatively convenient to study in the wild as they are ground nesting and often occupy open habitats that are tractable to monitor. Here we present a database documenting the reproductive ecology of 1,647 individually marked snowy plovers (Charadrius nivosus) monitored between 2006 and 2016 at Bahía de Ceuta (23°54N, 106°57W)-an important breeding site in northwestern Mexico. the database encompasses various morphological, behavioural, and fitness-related traits of males and females along with spatial and temporal population dynamics. This open resource will serve as an important data repository for addressing overarching questions in avian ecology and wetland conservation during an era of big data and global collaborative science.

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“…1). Previously, we have used subsets of these data to report on a wide variety of topics in organismal biology, including sex ratio variation 12 , population viability 13 , courtship behaviour 14 , incubation behaviour 15 , parental care 16 , ontogeny 17 , chronobiology 18 , camouflage mechanisms 19 , offspring desertion 20 and mating system dynamics 21 . The motivation for making our database open is to provide evolutionary ecologists with an accessible resource that will serve as an important repository for addressing overarching questions in organismal biology and conservation.…”

Section: Background and Summarymentioning

confidence: 99%

CeutaOPEN: Individual-based field observations of breeding snowy ploversCharadrius nivosus

Eberhart-Phillips

Cruz‐López

Lozano-Angulo

et al. 2019

Preprint

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Shorebirds (partim members of order Charadriiformes) have a global distribution and exhibit remarkable variation in ecological and behavioural traits that are pertinent to many core questions in the fields of evolutionary ecology and conservation biology. Shorebirds are also relatively convenient to study in the wild as they are ground nesting and often occupy open habitats that are tractable to monitor. Here we present a database documenting the reproductive ecology of 1,600 individually marked snowy plovers (Charadrius nivosus) monitored between 2006 and 2016 at Bahía de Ceuta (23°54 N, 106°57 W) – an important breeding site in north-western Mexico. The database encompasses various morphological, behavioural, and fitness-related traits of males and females along with spatial and temporal population dynamics. This open resource will serve as an important data repository for addressing overarching questions in avian ecology and wetland conservation during an era of big data and global collaborative science.

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Making the best of a bad job? Chick mortality and flexible female brood care in Snowy Plovers

Cited by 3 publications

References 83 publications

Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers

Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers

CeutaOPEN, individual-based field observations of breeding snowy plovers Charadrius nivosus

CeutaOPEN: Individual-based field observations of breeding snowy ploversCharadrius nivosus

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