Search Results

This chapter examines the implications of climate change for population dynamics and stability. Population dynamics, or the variation in abundance of a population through time, can be decomposed into two components: density-dependent and density-independent processes. Density-dependent processes are those involving competitive interactions among members of the same species within the same population that influence survival and reproduction. Density-independent processes are those that do not involve interactions with other members of the same species in the same population but rather owe to external factors such as environmental variation. It is this latter set of processes that has relevance to climate change, though density dependence certainly has a role to play in the response of populations to climate change.

The field of evolutionary ecology has long been interested in the design and diversity of social learning heuristics, simple strategies that animals use to extract useful information from their social environment. This chapter reviews a slice of this literature, as well as explicitly analyze the evolution of social learning heuristics. The chapter outlines a family of social learning heuristics and analyze their evolutionary performance under two broadly different kinds of environmental variation. As each social learning heuristic also shapes a social environment as individuals use it, the chapter considers the population feedbacks of each heuristic as well. The analyses in this chapter are both ecological and game theoretic. This chapter's analyses are also explicitly evolutionary—heuristics succeed or fail depending upon long-term survival and reproduction in a population, not atomistic one-shot payoffs. As a result, some of the conclusions reflect an evolutionary rationality. For example, heuristics that randomize their behavior can succeed where those that are consistent fail. Overall, however, the approach the chapter reviews here supports the general conclusion that social learning heuristics are likely to be multiple and subtly adapted to different physical, statistical, and social environments.

This chapter discusses the relationships between environmental variation and interpopulational differences in body size of two desert lizards: chuckwallas (Sauromalus obesus) and desert iguanas (Dipsosaurus dorsalis). It discusses how environmental conditions influence body size as a life history trait and explains the differences in geographic pattern of body size variation between these two species.

Reciprocal transplant experiments in general, and those involving serpentine systems in particular, are important tools for understanding plant adaptation to heterogeneous environments. This chapter discusses several important factors that should be considered when designing reciprocal transplant or common garden experiments. It stresses that proper replication of such experiments across multiple sites, using experimental lineages (potentially including recombinant lines) in combination with detailed edaphic measurements and/or manipulations, can help us learn about the specific traits which may be under diversifying selection across soil types, and the axes of environmental variation that are most critical to that diversification.

This chapter discusses the extensive spatio-temporal environmental variation that parents and offspring are likely to experience during dispersal, making its costs and benefits more likely to be distinct across generations. The process of dispersal is costly, and it is often more advantageous for individuals to remain in their natal population. Variation in habitat quality, however, can sometimes more than compensate for the cost of dispersal — especially in cases where individuals escape a habitat of declining quality. This chapter explores the conditions that might favour both constancy and context-dependency in dispersal phenotypes across generations for species that experience spatio-temporally varying habitat. The focus here is on spatio-temporally varying environments, since theoretical models suggest that environmental variation is the most common evolutionary cause of dispersal and because spatial and temporal environmental variation is ubiquitous in natural systems.

This chapter consolidates the conclusions arrived at through the studies and cases tackled throughout the book. Insect environmental physiology is seen to have an extraordinarily bright and interesting future, one that could provide a key interface between genetics and molecular biology, and even the evolution of life. The chapter outlines a series of major problems and questions in insect biology that deserve attention if this field is to move forward, among which is how climate change will inevitably affect and cause major changes in the environments of insects. How will such changes affect the insects in terms of their growth, abundance, behaviour, and other aspects of their lives? Another area that deserves attention is the lifecycle approach. How do the different stages of insect growth and maturity respond to environmental variation? These and much more issues are discussed in the chapter in order to provide a brief outlook on the field in general and how it can further progress.

Vector-borne viruses (arboviruses) are emerging threats to both human and animal health. The global expansion of dengue virus, West Nile virus, chikungunya, and most recently Zika virus are prominent examples of how quickly mosquito-transmitted viruses can emerge and spread. We currently lack high quality data from a diversity of mosquito-arbovirus systems on the specific mosquito and viral traits that drive disease transmission. Further, the factors that contribute to variation in these traits and disease transmission remain largely unidentified. In this chapter, we outline and explore the following: 1. the specific mechanisms governing the outcome of vector-virus interactions 2. how genetic variation across mosquito populations and viral strains, as well as environmental variation in abiotic and biotic factors shape the mosquito-virus interaction and 3. the implications of these interactions for understanding and predicting arbovirus transmission, as well as for control of mosquito species that transmit human pathogens.

This chapter describes the geologic, geographic, and ecological context of the location of Luquillo Mountains, particularly the factors affecting the response mechanisms of terrestrial and aquatic ecosystems to disturbance. It describes the existing conditions of the physical environment, chemical environment, and the biota of the Luquillo Mountains as they respond to disturbances. It then merges the decade-long research about the Mountains with the other tropical ecosystems around the globe.

The most extreme forms of migratory variation are polymorphisms (genetic variation) and polyphenisms (environmental variation). They are particularly prevalent in insects in which they take a variety of forms including winglessness, wing length, flight muscles, and even traits involving song (crickets) or trophic apparatus (true bugs). There are trade-offs between energetic investment in wings, flight muscle, and reproductive capacity or behavior. These are influenced by hormone titers and their timing. Comparisons at hierarchical taxonomic levels consistently suggest that pterygomorphisms are associated with degrees of habitat permanence, with winglessness more likely in long-lasting, unvarying habitats. Polyphenisms especially are also found in the seeds of plants, with partitioning between those germinating near the parent and those with modifications for long-distance transport by wind or animals.

This chapter argues for two crucial ideas. First, over deep history and at different times and places, humans have experienced very different physical, biological, economic and social environments. Even as foragers, our ancestors experienced different worlds, but over the last 10,000 years change has become more frequent and intense. As a consequence, human adaptive response to the many environments with which we have coped cannot solely or primarily be based on innate, genetically programmed capacities. Social learning is the engine of human adaptability. Second, while defenders of the social intelligence hypothesis are right to emphasise the cognitive challenges posed by human social environments, they have typically over-rated the importance of deception and manipulation, and under-rated the cognitive challenge of coordination. Humans evolved as technically skilled, ecologically informed, cooperative foragers, and that was a cognitively demanding lifeway, especially given the dynamism of human environments.

This chapter summarizes and expands on the previous attempts at modelling condition-dependent dispersal. Whether competitively strong or weak individuals should disperse becomes the focal question here. It is initially assumed that competitive ability varies due to some environmental variation that the organism cannot control, but it can adapt its dispersal strategy to the environment and to its own body condition. On the other hand, it is also assumed that parents have a variable amount of resources that they can allocate to produce few strong or many weak offspring along the offspring size-number trade-off. This chapter treats two families of models to address how the evolutionarily stable dispersal strategy depends on body condition and how offspring size co-evolves with dispersal.