scholarly journals Estimating egg mass–body mass relationships in birds

The Auk ◽  
2020 ◽  
Vol 137 (3) ◽  
Author(s):  
John T Rotenberry ◽  
Priya Balasubramaniam

Abstract The mass of a bird’s egg is a critical attribute of the species’ life history and represents a fundamental component of reproductive effort. Indeed, the tradeoff between the number of eggs in a clutch and clutch mass lies at the heart of understanding how environmental attributes such as nest predation or adult mortality influence reproductive investment. However, egg masses have not been reported for the majority of avian species. We capitalized on the strong allometric relationship between avian body mass and egg mass to produce egg mass estimates for over 5,500 species previously lacking such information. These estimates are accompanied by measures of the robustness of the regressions used to produce them (e.g., sample size, root mean square error [RMSE] of estimation, coefficient of determination, and degree of extrapolation), thus allowing independent evaluation of the suitability of any estimate to address a particular research question relating to avian life history. Most estimates (~5,000) were based on family-level egg mass–body mass regressions, with the remainder derived from other relationships such as ordinal regressions. We compared estimating regressions based on adult vs. female body masses and, after finding little difference between the 2, based our final estimates on adult masses as those were more numerous in the literature. What small differences between adult- and female-based regressions that did occur were not related to sexual size dimorphism across families. These new estimates, coupled with ~5,000 egg masses reported in the literature, provide a foundation of over 10,000 species for wider investigations assessing variation in reproductive effort in birds over a broad array of ecological and evolutionary contexts.

2018 ◽  
pp. 68-97
Author(s):  
Douglas S. Glazier

In this chapter, I show how clutch mass, offspring (egg) mass, and clutch size relate to body mass among species of branchiopod, maxillipod, and malacostracan crustaceans, as well as how these important life history traits vary among major taxa and environments independently of body size. Clutch mass relates strongly and nearly isometrically to body mass, probably because of physical volumetric constraints. By contrast, egg mass and clutch size relate more weakly and curvilinearly to body mass and vary in inverse proportion to one another, thus indicating a fundamental trade-off, which occurs within many crustacean taxa as well. In general, offspring (egg) size and number and their relationships to body mass appear to be more ecologically sensitive and evolutionarily malleable than clutch mass. The body mass scaling relationships of egg mass and clutch size show much more taxonomic and ecological variation (log-log scaling slopes varying from near 0 to almost 1 among major taxa) than do those for clutch mass, a pattern also observed in other animal taxa. The curvilinear body mass scaling relationships of egg mass and number also suggest a significant, size-related shift in how natural selection affects offspring versus maternal fitness. As body size increases, selection apparently predominantly favors increases in offspring size and fitness up to an asymptote, beyond which increases in offspring number and thus maternal fitness are preferentially favored. Crustaceans not only offer excellent opportunities for furthering our general understanding of life history evolution, but also their ecological and economic importance warrants further study of the various factors affecting their reproductive success.


Behaviour ◽  
2003 ◽  
Vol 140 (7) ◽  
pp. 935-945 ◽  
Author(s):  
Katsuya Ichinose ◽  
Masahisa Tochihara

AbstractWe hypothesized that apple snails would change life-history traits in the presence of common carp to reduce or avoid predation risk. Carp of about 150 mm body length were released in small plots set in a rice field in southern Japan at 0, 0.2, or 0.6 carp/m2. Egg-mass size, proportion of hatched eggs, and duration of hatching of the snail were measured once or twice a week from July to September. Snails collected in traps were used to estimate both snail density by the Jolly-Seber mark-recapture method and distribution of shell lengths in each plot. The weight of the snail was regressed on a size-weight equation, and the snail biomass was determined by multiplying the estimated density and the regressed weight. The reproductive effort of the snails was calculated as the number of eggs divided by the biomass of adult females. The egg mass size and reproductive effort were significantly increased in the presence of carp. These increases were considered as life-history changes of apple snails in the presence of a predator.


2005 ◽  
Vol 62 (8) ◽  
pp. 1720-1732 ◽  
Author(s):  
Erin S Dunlop ◽  
Judi A Orendorff ◽  
Brian J Shuter ◽  
F Helen Rodd ◽  
Mark S Ridgway

We examine the degree and causes of divergence in growth and reproduction in two populations of smallmouth bass (Micropterus dolomieu) introduced a century ago. Despite a common source, the Provoking Lake population now has a higher population density and slower growing individuals than the Opeongo Lake population. Using this system, we test the predictions of life history theory that delayed maturation and reduced reproductive investment are expected in high density populations with slow individual growth rates. Observations on both populations run directly counter to the aforementioned expectations. Instead, Provoking males have smaller sizes and younger ages at nesting and higher gonad masses than Opeongo males; Provoking females have smaller sizes at maturity, larger egg sizes, and higher ovarian dry masses than Opeongo females. Temperature, food availability, diet ontogeny, young-of-the-year mortality, and adult mortality were examined as plausible contributors to the divergence. Results suggest that low food availability, likely caused or mediated by intraspecific competition for prey, and lack of large prey in the diet are contributing to the slow growth, increased reproductive investment, and higher mortality following reproduction in Provoking. This study provides insight into the processes that produce rapid divergence of life history in a species exhibiting parental care.


2019 ◽  
Author(s):  
Cecina Babich Morrow ◽  
S. K. Morgan Ernest ◽  
Andrew J. Kerkhoff

AbstractLife history traits represent organism’s strategies to navigate the fitness trade-offs between survival and reproduction. Eric Charnov developed three dimensionless metrics to quantify fundamental life history trade-offs. Lifetime reproductive effort (LRE), relative reproductive lifespan (RRL), and relative offspring size (ROS), together with body mass, can be used classify life history strategies across the four major classes of tetrapods: amphibians, reptiles, mammals, and birds. First, we investigate how the metrics have evolved in concert with body mass. In most cases, we find evidence for correlated evolution between body mass and the three metrics. Finally, we compare life history strategies across the four classes of tetrapods and find that LRE, RRL, and ROS delineate a space in which the major tetrapod clades occupy mostly unique subspaces. These distinct combinations of life history strategies provide us with a framework to understand the impact of major evolutionary transitions in energetics, physiology, and ecology.


2020 ◽  
Vol 223 (16) ◽  
pp. jeb226563
Author(s):  
Riccardo Ton ◽  
Thomas E. Martin

ABSTRACTMetabolism is thought to mediate the connection between environmental selection pressures and a broad array of life history tradeoffs, but tests are needed. High juvenile predation correlates with fast growth, which may be achieved via fast juvenile metabolism. Fast offspring metabolism and growth can create physiological costs later in life that should be minimized in species with low adult mortality. Yet, relationships between juvenile metabolism and mortality at offspring versus adult stages are unexplored. We found that post-natal metabolism was positively correlated with adult mortality but not nest predation rates among 43 songbird species on three continents. Nest predation, but not adult mortality, explained additional variation in growth rates beyond metabolism. Our results suggest that metabolism may not be the mechanism underlying the relationships between growth and mortality at different life stages.


2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Cecina Babich Morrow ◽  
S. K. Morgan Ernest ◽  
Andrew J. Kerkhoff

Life-history traits represent organisms' strategies to navigate the fitness trade-offs between survival and reproduction. Eric Charnov developed three dimensionless metrics to quantify fundamental life-history trade-offs. Lifetime reproductive effort (LRE), relative reproductive lifespan (RRL) and relative offspring size (ROS), together with body mass can be used to classify life-history strategies across the four major classes of tetrapods: amphibians, reptiles, mammals and birds. First, we investigate how the metrics have evolved in concert with body mass within tetrapod lineages. In most cases, we find evidence for correlated evolution among body mass and the three dimensionless metrics. Second, we compare life-history strategies across the four classes of tetrapods and find that LRE, RRL and ROS delineate a space in which the major tetrapod classes occupy mostly unique subspaces. These distinct combinations of life-history strategies provide us with a framework to understand the impact of major evolutionary transitions in energetics, physiology and ecology.


2021 ◽  
Author(s):  
Jean‐Louis Hemptinne ◽  
Emilie Lecompte ◽  
Arnaud Sentis ◽  
Anthony F. G. Dixon ◽  
Alexandra Magro

Author(s):  
Jean-Louis Hemptinne ◽  
Emilie Lecompte ◽  
Arnaud Sentis ◽  
Anthony Dixon ◽  
Alexandra Magro

1. The balance between risk and benefit of exploiting resources drives life history evolution. Predators are naturally recognized as major drivers of the life history evolution of their prey. The concept of an evolutionary arms race posits that prey also influence the life history evolution of their predators. There is far more evidence on the role of predators than of prey. 2. The goal of this study was to investigate the role of prey in life history evolution of predators using ladybird beetle predators either of aphids or coccids. These particular organisms were chosen because literature shows that the pace of life of aphids is faster than that of coccids and this difference is reflected in the life histories of the ladybirds that specialize on feeding on aphids or coccids. 3. Thirty-four species of ladybird predators of aphids and eight of coccids belonging to five different tribes were collected and reared in the laboratory. The females were weighed as well as their eggs, and their reproductive investment calculated as the number of ovarioles multiplied by the average mass of an egg. Phylogenetic relatedness was controlled for in the statistical analyses. 4. Controlling for female mass revealed that ladybird predators of aphids lay bigger eggs and have a higher reproductive investment than ladybird predators of coccids. These differences are not influenced by phylogenetic relatedness but only by the type of prey. We suggest that ladybird predators of coccids lay smaller eggs because neonate larvae do not have to search, catch and subdue prey, and that they have a smaller reproductive investment because they need to allocate more resources to locate prey. 5. Recognizing the influence of prey on the life history evolution of predators is important for understanding food web dynamics.


2020 ◽  
Vol 129 (4) ◽  
pp. 875-887
Author(s):  
Rebecca J Lakin ◽  
Paul M Barrett ◽  
Colin Stevenson ◽  
Robert J Thomas ◽  
Matthew A Wills

Abstract Relationships between distribution patterns and body size have been documented in many endothermic taxa. However, the evidence for these trends in ectotherms generally is equivocal, and there have been no studies of effects in crocodylians specifically. Here, we examine the relationship between latitudinal distribution and body mass in 20 extant species of crocodylians, as well as the relationships between seven important reproductive variables. Using phylogenetically independent contrasts to inform generalized linear models, we provide the first evidence of a latitudinal effect on adult female body mass in crocodylians. In addition, we explore the relationships between reproductive variables including egg mass, hatchling mass and clutch size. We report no correlation between egg mass and clutch size, upholding previously reported within-species trends. We also find no evidence of a correlation between measures of latitudinal range and incubation temperature, contrasting with the trends found in turtles.


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