http://academic.oup.com/auk/article-pdf/102/3/661/30080634/auk0661.pdf

Scaling: why is animal size so important?

SYNOPSIS. Maternal effects comprise a class of phenotypic effects that parents have on phenotypes of their offspring that are unrelated to the offspring's own genotype. Although biologists have known about the importance of these effects for decades, maternal effects have only recently been studied widely by evolutionary ecologists. Moreover, the impact of maternal effects on the rate and direction of evolution of other components of the phenotype has only recently been fully elucidated by theoretical genetic models. This paper provides a brief overview of maternal effects research, focusing on research conducted in animal systems. First, I review and summarize definitions and theoretical treatments of maternal effects. Then I survey the diversity of maternal effects and some of the kinds of ecological and evolutionary impacts that maternal effects have been shown to have on offspring performance. Third, I discuss some of the ecological and evolutionary implications of maternal effects in ecological research. In this context, it is argued that the kinds of maternal effects that have been studied, and some of the potential implications of maternal effects that have not been explored are both artifacts of research effort. Hence, I identify several fruitful areas for future maternal effects research. Lastly, I describe the necessity of explicitly incorporating maternal effects in ecological research, whether or not the researcher is focusing on them as the topic of the research.

Maternal effects in animal ecology

Measuring Behaviour: An Introductory Guide, Paul Martin, Patrick Bateson. University of Cambridge Press, Cambridge (1986), x, +200. Price £20.00 (hardback), £6.95 (paperback)

The Birds of the Western Palearctic

The avian W chromosome shares many features with the mammalian Y chromosome: it is small, mostly heterochromatic, and filled with large repetitive arrays. No gene so far been assigned to the W chromosome in any bird species and, as a practical consequence, a general tag for avian gender identification on the molecular level is lacking. Here I describe the isolation of a chicken homologue to the mouse chromo-helicase-DNA binding (CHD) gene which encodes a protein involved in global regulation of transcriptional activation on the chromatin level. The avian CHD gene exists in two genomic copies, one of which termed CHD-W) was located on the W chromosome in all non-ratio species investigated. The gene displays extreme levels of sequence conservation since chicken CHD-W and mouse CHD are 82.9% and 95.6% identical at the nucleotide and amino acid level respectively. Molecular sexing can be accomplished in probably all non-ratite birds by hybridizing Southern blots with CHD probes, PCR-based gender identification is also demonstrated. A general system for avian sexing should facilitate many studies of behaviour, evolutionary ecology, genetics, and evolution.

https://www.jstor.org/stable/pdfplus/50650.pdf

First Gene on the Avian W Chromosome (CHD) Provides a Tag for Universal Sexing of Non-Ratite Birds

This book reviews comprehensively incubation effects on embryonic development in birds and reptiles and presents the first ever synthesis of data from these two vertebrate classes. The book is in three parts. The first deals with the structure, shape and function of eggs. The second examines the effects of the four main parameters on the process of incubation: temperature, water relations, respiratory gas exchange, and turning. The third section deals with early embryonic development and the methods used to investigate and manipulate the embryo. Further chapters deal with aestivation, megapodes and oviparity. International experts in each field have contributed to this extensively referenced volume and it will be of great interest not only to research biologists, but also to bird and reptile breeders, whether in commercial organisations or in zoos.

Egg Incubation: Its Effects on Embryonic Development in Birds and Reptiles

All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract a mate, nests contain eggs and/or offspring, thereby suggesting a direct trade-off between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birds' nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birds' nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.1054

The design and function of birds' nests

Aim The laying of eggs and the building of a nest structure to accommodate them are two of the defining characteristics of members of the class Aves. Nest structures vary considerably across avian taxa and for many species the design of the completed nest can have important consequences for both parents and their offspring. While nest characteristics are expected to vary adaptively in response to environmental conditions, large-scale spatial variation in nest characteristics has been largely overlooked. Here, we examined the effects of latitudinal variation in spring temperatures on nest characteristics, including insulatory properties, and reproductive success of blue tits, Cyanistes caeruleus, and great tits, Parus major. 

Location Great Britain. 

Methods Nests and reproductive data were collected from seven study sites, spread over five degrees of latitude. Then, the nest insulatory properties were determined before the nests were separated into either nest base material or cup lining material. 

Results As spring temperatures increased with decreasing latitude, the mass of the nest base material did not vary in either species, whilst the mass of the cup lining material and nest insulatory properties decreased in both species. This suggests that in response to increasing temperatures the breeding female reduces the mass of the cup lining material thereby maintaining an appropriate microclimate for incubating and brooding. The mean laying dates of both species advanced with decreasing latitude and increasing spring temperatures, although reproductive success did not vary. 

Main conclusions This is the first study to demonstrate that birds are systematically adjusting their nest structure in response to variation in ambient temperatures across large spatial scales. Therefore, nest composition reliably indicates environmental conditions and we suggest that studies of nest structure may be sentinels for the early signs of rapid climate change.

Latitudinal variation in blue tit and great tit nest characteristics indicates environmental adjustment

Capsule For nest construction by Blue Tits, but not Great Tits, first‐egg date (FED) and air temperature significantly affected the mass of the nest as a whole and some of its component parts. Aims To test the hypothesis that use of nest materials is influenced by prevailing climatic conditions during nest construction. Methods Nests used in the study were built by Blue Tits Cyanistes caeruleus and Great Tits Parus major in nestboxes at a site in Lincolnshire, England during the 2008 and 2009 breeding seasons. Nests were dissected into their component parts and then weighed. Results Stepwise discriminant analysis showed that the masses of grasses, feathers and bark were significantly affected by species (all higher in Blue Tits) and year significantly affected the mass of wool and dust in the nests. anova showed that total mass of the nest was not significantly affected by year of construction or species. By contrast, species, but not year, did significantly influence the masses of animal‐ and plant‐deriv...

First‐egg date and air temperature affect nest construction in Blue Tits Cyanistes caeruleus, but not in Great Tits Parus major

A sexually mature individual of Darwinopterus preserved together with an egg from the Jurassic of China provides direct evidence of gender in pterosaurs and insights into the reproductive biology of these extinct fliers. This new find and several other examples of Darwinopterus demonstrate that males of this pterosaur had a relatively small pelvis and a large cranial crest, whereas females had a relatively large pelvis and no crest. The ratio of egg mass to adult mass is relatively low, as in extant reptiles, and is comparable to values for squamates. A parchment-like eggshell points to burial and significant uptake of water after oviposition. This evidence for low parental investment contradicts the widespread assumption that reproduction in pterosaurs was like that of birds and shows that it was essentially like that of reptiles.

https://science.sciencemag.org/content/sci/331/6015/321.full.pdf

D. Charles Deeming

Papers

Egg Incubation: Its Effects on Embryonic Development in Birds and Reptiles

The design and function of birds' nests

Latitudinal variation in blue tit and great tit nest characteristics indicates environmental adjustment

First‐egg date and air temperature affect nest construction in Blue Tits Cyanistes caeruleus, but not in Great Tits Parus major

An egg-adult association, gender, and reproduction in pterosaurs.