Research
Communication signals are often complex suites of cues that may include any combination of visual, acoustical, tactical, electrical and/or chemical stimuli, varying in relative importance to receiver decisions. In general, the structure of such signals is primarily influenced by two non-mutually exclusive factors; information content and signal efficiency. Hypotheses of signal evolution based upon information content emphasize the aspects of signal structure upon which receiver decisions are made. For example, in the context of female choice, a single male visual trait might contain information about the species, sex, reproductive status and quality of the sender. However, interpretation of the information contained in a signal is dependent on the efficiency with which it is detected by the receiver, which in turn is influenced by the structure of the receiver’s sensory system and environmental parameters affecting signal transmission. Hypotheses of signal evolution based on efficiency thus highlight the importance of ecological transmission properties and receiver sensory perception on shaping signal form. My research examines the intimate relationship between signal structure and information content to determine how communication systems evolve, and how information in encoded in specific signals.
Evolution of communication systems
Signal variation and lability in multivariate receiver responses:
reproductive isolation and genetic introgression
In most sexually reproducing species with active mate choice, signaling and receiver systems are highly complex entities; male cues are often hierarchical in nature, consisting of a variety of traits for female assessment within each sensory modality (e.g. visual signals such as size, behaviour, colour), each one of which may in turn be composed of several different elements (e.g. the hue, chroma, intensity or pattern of colour). In addition, both within and among populations, females can vary in their response to both single male traits and multi-component signals in complicated ways. Between populations, geographic variation in trait-preference complexes can result in a variety of mate choice scenarios ranging from partial, or asymmetric, to complete positive assortative mating. For example, if interpopulation divergence in female preferences closely tracks divergence in male traits, then genetically co-varying signal-preference complexes can lead to behavioural isolation and, ultimately, speciation. However, reproductive isolation between groups may be constrained if mean female preference values and male signals fail to co-evolve in concert, the specific outcome of which will depend on the strength and form of the trait-preference relationship. My research examines the general mechanisms by which the shape and form of multiple, hierarchically arranged, within-population female preferences functions, combined with divergence in male traits, influence both intraspecific and interspecific reproductive dynamics.
Figure: An example of geographic variability in both male and female nuptial color patterns in two populations of Brook stickleback (Culaea inconstans).
A. B.
Figure A: Asymmetric reproductive isolation in two populations of brook stickleback. Bars represent the mean strength of preference for local males (q2+ se).
Figure B: Partial regression plots demonstrating conserved, significant directional relationships for a continuous male trait (courtship intensity) and female preference strength in two populations of brook stickleback.
Anthropogenetic evolution: selection, phenotypic change and reproductive dynamics within and between species
I am interested in the ecological mechanisms and evolutionary outcomes of human-mediated environmental change on natural populations and communities. Human induced environmental change can alter intraspecific and interspecific reproductive dynamics with significant implications for phenotypic evolution and species biodiversity. For example, habitat disturbance leading to spatial and/or temporal overlap in resource distributions or breeding time may bring ecologically segregated species into secondary contact and promote genomic introgression. Alternatively, environmentally induced alterations in the expression, transmission or reception of signals used in mate choice may increase the probability of hybridization between sympatric species by altering properties of mate recognition and discrimination. To date, my research has examined (1) the role of sexual selection in biological invasions involving hybridization and, (2) the ecological and evolutionary effects of endocrine disrupting chemicals (EDCs) and other land-use activities on sexually selected traits and species recognition.
I study how complex communication systems evolve and how they influence the formation and collapse of species boundaries.
