An official website of the United States government
Synopsis Context-dependent allocation of resources drives trade-offs among fitness-related traits and other phenotypes to which those traits are linked. In addition, the amount and type of acquired resources can also affect the phenotypes of other organisms through indirect genetic effects, as exemplified by the maternal provisioning of offspring. Despite a large literature on maternal effects, we lack a comprehensive understanding of the extent to which mothers might affect the phenotypes of their offspring, as well as the various mechanisms by which they do so, particularly with regard to many functional traits that are key determinants of survival and reproduction. Our goals in this paper are to review the various approaches to measuring and understanding maternal effects and to highlight some promising avenues for integration of maternal effects with some other key areas of evolutionary ecology. We focus especially on nutritional geometry; maternal age; and traits proximate to fitness such as whole-organism performance. Finally, we discuss the logistic and practical limits of quantifying these effects in many animal systems and emphasize the value of integrative approaches in understanding the mechanisms underlying maternal influence on offspring phenotypes.
more »
« less
Nesting in Anolis Lizards: An Understudied Topic in a Well-Studied Clade
Maternal nesting behavior in oviparous species strongly influences the environmental conditions their embryos experience during development. In turn, these early-life conditions have consequences for offspring phenotypes and many fitness components across an individual’s lifespan. Thus, identifying the evolutionary and ecological causes and effects of nesting behavior is a key goal of behavioral ecology. Studies of reptiles have contributed greatly to our understanding of how nesting behavior shapes offspring phenotypes. While some taxonomic groups have been used extensively to provide insights into this important area of biology, many groups remain poorly studied. For example, the squamate genus Anolis has served as a model to study behavior, ecology, and evolution, but research focused on Anolis nesting behavior and developmental plasticity is comparatively scarce. This dearth of empirical research may be attributed to logistical challenges (e.g., difficulty locating nests), biological factors (e.g., their single-egg clutches may hinder some experimental designs), and a historical focus on males in Anolis research. Although there is a gap in the literature concerning Anolis nesting behavior, interest in nesting ecology and developmental plasticity in this group has grown in recent years. In this paper, we (1) review existing studies of anole nesting ecology and developmental plasticity; (2) highlight areas of anole nesting ecology that are currently understudied and discuss how research in these areas can contribute to broader topics (e.g., maternal effects and global change biology); and (3) provide guidelines for studying anole nesting in the field. Overall, this review provides a foundation for establishing anoles as models to study nesting ecology and developmental plasticity.
more »
« less
- PAR ID:
- 10392193
- Date Published:
- Journal Name:
- Frontiers in Ecology and Evolution
- Volume:
- 10
- ISSN:
- 2296-701X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
With decades of intensive study, Anolis lizards have emerged as a biological model system. We review how new research on anoles has advanced our understanding of ecology and evolution, challenging long-standing paradigms and opening new areas of inquiry. Recent anole research reveals how changes in behavior can restructure ecological communities and can both stimulate and stymie evolution, sometimes simultaneously. Likewise, investigation of anoles as spatial or phylogenetic evolutionary experiments has documented evolutionary repeatability across spatiotemporal scales, while also illuminating its limits. Current research places anoles as an emerging model for Anthropocene biology, with recent work illustrating how species respond as humans reconfigure natural habitats, alter the climate, and create novel environments and communities through urbanization and species introduction. Combined with ongoing methodological developments in genomics, phylogenetics, and ecology, the growing foundational knowledge of Anolis positions them as a powerful model system in ecology and evolution for years to come. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 54 is November 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.more » « less
-
Understanding the relationship between the environment parents experience during reproduction and the environment embryos experience in the nest is essential for determining the intergenerational responses of populations to novel environmental conditions. Thermal stress has become commonplace for organisms inhabiting areas affected by rising temperatures. Exposure to body temperatures that approach, but do not exceed, upper thermal limits often induces adverse effects in organisms, but the propensity for these temperatures to have intergenerational consequences has not been explored in depth. Here, we quantified the effects of thermal stress on the reproductive physiology and development of brown anoles (Anolis sagrei) when thermal stress is experienced by mothers and by eggs during incubation.Mothers exposed to thermal stress produced smaller eggs and smaller offspring with reduced growth rates, while egg stress reduced developmental time and offspring mass. Hatchling survival and growth were negatively affected by thermal stress experienced by mothers but not by thermal stress experienced as eggs. We found mixed evidence for an additive effect of thermal stress on offspring; rather, thermal stress had specific (and most often negative) effects on different components of offspring phenotypes and fitness proxies when experienced either by mothers or by eggs. Stressful body temperatures therefore can function in a similar manner to other types of maternal effects in reptiles; however, this maternal effect has predominantly negative consequences on offspring.more » « less
-
ABSTRACT As a response to environmental cues, maternal glucocorticoids (GCs) may trigger adaptive developmental plasticity in the physiology and behavior of offspring. In North American red squirrels (Tamiasciurus hudsonicus), mothers exhibit increased GCs when conspecific density is elevated, and selection favors more aggressive and perhaps more active mothers under these conditions. We tested the hypothesis that elevated maternal GCs cause shifts in offspring behavior that may prepare them for high-density conditions. We experimentally elevated maternal GCs during gestation or early lactation. We measured two behavioral traits (activity and aggression) in weaned offspring using standardized behavioral assays. Because maternal GCs may influence offspring hypothalamic–pituitary–adrenal (HPA) axis dynamics, which may in turn affect behavior, we also measured the impact of our treatments on offspring HPA axis dynamics (adrenal reactivity and negative feedback), and the association between offspring HPA axis dynamics and behavior. Increased maternal GCs during lactation, but not gestation, slightly elevated activity levels in offspring. Offspring aggression and adrenal reactivity did not differ between treatment groups. Male, but not female, offspring from mothers treated with GCs during pregnancy exhibited stronger negative feedback compared with those from control mothers, but there were no differences in negative feedback between lactation treatment groups. Offspring with higher adrenal reactivity from mothers treated during pregnancy (both controls and GC-treated) exhibited lower aggression and activity. These results suggest that maternal GCs during gestation or early lactation alone may not be a sufficient cue to produce substantial changes in behavioral and physiological stress responses in offspring in natural populations.more » « less
-
Abstract Vertebrate embryos require access to water; however, many species nest in terrestrial habitats that vary considerably in moisture content. Oviparous, non‐avian reptiles have served as models to understand how environmental factors, like moisture availability, influence development because eggs are often exposed to prevailing environments in the absence of parental care. Though much research demonstrates the importance of water absorption by eggs, many ecological factors that influence moisture availability in natural nests have received little attention. For example, the type of substrate in which nests are constructed is understudied. We experimentally incubated eggs of the brown anole lizard (Anolis sagrei) in 2 naturally occurring nest substrates that were treated with varying amounts of water to determine how natural substrates influence development at different moisture concentrations. One substrate consisted of sand and crushed seashells and the other was mostly organic material (i.e. decayed plant material). Both are common nesting substrates at our field site. When controlling for water uptake by eggs, we found that egg survival and hatchling phenotypes were similar between substrates; however, embryos developed more quickly in the sand/shell substrate than the organic substrate, indicating substrate‐specific effects on embryo physiology. These results demonstrate that different natural substrates can result in similar developmental outcomes if the water available to eggs is comparable; however, some aspects of development, like developmental rate, are affected by the type of substrate, independent of water availability. Further study is required to determine how natural substrates influence embryo physiology independent of water content.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fevo.2022.821115
