Drury, J. P. | bioRxiv Science

bioRxiv2019

Multiple routes to interspecific territoriality in sister species of North American perching birds

Behavioral interference between species can influence a wide range of ecological and evolutionary processes. Here we test foundational hypotheses regarding the origins and maintenance of interspecific territoriality, and evaluate the role of interspecific territoriality and hybridization in shaping species distributions and transitions from parapatry to sympatry in sister species of North American perching birds (Passeriformes). We found that interspecific territoriality is pervasive among sympatric sister species pairs, and that interspecifically territorial species pairs have diverged more recently than sympatric non-interspecifically territorial pairs. None of the foundational hypotheses alone explain the observed patterns of interspecific territoriality, but our results support the idea that some cases of interspecific territoriality arise from misdirected intraspecific aggression while others are evolved responses to resource competition. The combination of interspecific territoriality and hybridization appears to be an unstable state associated with parapatry, while species that are interspecifically territorial and do not hybridize are able to achieve extensive fine- and coarse-scale breeding range overlap. In sum, these results suggest that interspecific territoriality has multiple origins and that interspecific territoriality and hybridization together can have striking impacts on species ranges.

evolutionary biology↗

bioRxiv2018

Continent-scale phenotype mapping using photographs from citizen scientists

Field investigations of phenotypic variation in free-living organisms are often limited in scope owing to time and funding constraints. By collaborating with online communities of amateur naturalists, investigators can greatly increase the amount and diversity of phenotypic data in their analyses while simultaneously engaging with a public audience. Here, we present a method for quantifying phenotypes of individual organisms in citizen scientists photographs. We then show that our protocol for measuring wing phenotypes from photographs yields accurate measurements in two species of Calopterygid damselflies. Next, we show that, while most observations of our target species were made by members of the large and established community of amateur naturalists at iNaturalist.org, our efforts to increase recruitment through various outreach initiatives were successful. Finally, we present results from two case studies: (1) an analysis of wing pigmentation in male smoky rubyspots (Hetaerina titia) showing previously undocumented geographical variation in a seasonal polyphenism, and (2) an analysis of variation in the relative size of the wing spots of male banded demoiselles (Calopteryx splendens) in Great Britain questioning previously documented evidence for character displacement. Our results demonstrate that our protocol can be used to create high quality phenotypic datasets using citizen scientists photographs, and, when combined with metadata (e.g., date and location), can greatly broaden the scope of studies of geographical and temporal variation in phenotypes. Our analyses of the recruitment and engagement process also demonstrate that collaborating with an online community of amateur naturalists can be a powerful way to conduct hypothesis-driven research aiming to elucidate the processes that impact trait evolution at landscape scales.

evolutionary biology↗