The 97th annual meeting of the Ecological Society of America begins Sunday in Portland. These meetings are truly enormous, and given the great amount of ecological research, past and present, on anoles, it’s surprising that there are not more anole talks scheduled. Nonetheless, there are three, and they look to be good ones. On Tuesday, Sean Giery will talk about studies on the ecosystem role of anoles in Miami. Basically, by examining stomach contents and measuring stable isotopes, he determined the extent to which terrestrial resources enter arboreal ecosystems. For A. equestris and A. distichus, the route is terrestrial insects walking up trees and being eaten, whereas for A. sagrei, it results from foraging on the ground. Also on Tuesday, Jason Kolbe talks on an experimental study of founder events in the Bahamas. We’ve already reported on this study, but Jason will be providing at least a few snippets of new data from this year’s field season. Finally, on Thursday, Kerrie Anne Lloyd will talk about a study looking at predation rates by domestic cats in Georgia, as determined by placing Kitty Cams on housecats. Turns out that a favorite prey item is, alas, green anoles.
Check out the abstracts for these talks below the fold, and if any AA readers attend the talks, please file a report.PS 41-221 – Cross-habitat trophic coupling by arboreal predators: Allochthonous inputs follow diverse routes between food webs
Tuesday, August 7, 2012
Exhibit Hall DE, Oregon Convention Center
Sean T. Giery , Biological Sciences, Florida International University, North Miami, FL
Nathan P. Lemoine , Biological Sciences, Florida International University, North Miami, FL
Caroline M. Hammerschlag-Peyer , Biological Sciences, Florida International University, North Miami, FL
Robin Abbey-Lee , Biological Sciences, Florida International University, North Miami, FL
Craig A. Layman , Biological Sciences, Florida International University, North Miami, FL
Two prominent areas of food web research include the effect of species diversity on food web function, and allochthonous resource flux in spatially coupling food webs. Yet, few studies have examined how species diversity might affect food web coupling. For example, species-specific traits such as diet breadth and habitat use could generate considerable variation in the magnitude and routing of allochthonous inputs. With this in mind, we provide an empirically derived, community-wide illustration of allochthonous flux between two adjacent food webs. More specifically, we investigated the differential routing of allochthonous flow between an arboreal and terrestrial habitat in which the dominant consumers were three species of arboreal lizard (knight anole, Anolis equestris; brown anole A. sagrei; and bark anole, A. distichus). Our goal was to identify interspecific variation in the magnitude of cross-habitat coupling and illustrate the different routes that carbon follows between these two habitats. Because the dominant vegetation in each habitat differed isotopically due to distinct photosynthetic pathways (arboreal = C3; terrestrial = C4), the contribution of each habitat was traced using stable isotopes. These data were combined with Anolis stomach contents and prey isotopes to infer differential routing of carbon among and within habitat-specific food webs.
Our results show that each Anolis species differed in habitat use and diet and that all species incorporated carbon from terrestrial and arboreal habitats. However, the proportion of terrestrially derived carbon differed considerably among species with the highest observed in knight anoles, followed by brown and bark anoles (0.38, 0.33, and 0.23, respectively). More importantly, prey isotopes, stomach contents and habitat use data showed that the routing of allochthonous input into the arboreal habitat differed for each species. Specifically, prey movement (ants and grasshoppers) into the arboreal habitat from the terrestrial habitat mediated coupling in knight and bark anoles, while foraging in the terrestrial habitat contributed to cross-habitat coupling in brown anoles. Because Anolis species occupy distinct habitats, and exhibit different diets, the routes that allochthonous inputs follow into the arboreal habitat varies for each species. Given the various routes of allochthonous inputs elucidated in our study, we suggest that cross-habitat flux can be mediated by species-specific traits, therefore indicating an important role for consumer diversity in allochthonous resource flux.
OOS 15-3 – Interacting evolutionary mechanisms during island introductions in brown anole lizards
Tuesday, August 7, 2012: 2:10 PM
A106, Oregon Convention Center
Jason Kolbe , Biological Sciences, University of Rhode Island, Kingston, RI
Manuel Leal , Biology, Duke University, Durham, NC
Thomas W. Schoener , Evolution and Ecology, University of California, Davis, Davis, CA
David A. Spiller , Evolution and Ecology, University of California, Davis, Davis, CA
Jonathan Losos, Organismal and Evolutionary Biology, Harvard University, Cambridge, MA
Founding events are a necessary component of both natural colonization and human-mediated introductions; yet, they are rarely observed in nature, thus the evolutionary significance of these events is difficult to evaluate. Whether random processes such as founder events contribute substantially to patterns of evolutionary divergence is controversial. We conducted an experiment in nature to determine the respective contributions of founder effects and natural selection to evolutionary divergence among lizard populations established on small islands in the Bahamas. We introduced opposite-sex pairs of brown anoles (Anolis sagrei) sampled from the same population on a large island to each of seven unoccupied islands. We characterized the vegetation (height and diameter) and repeatedly sampled lizards from the source population, from the seven experimental founder islands, and from 12 nearby reference islands. We took tissue samples for genetic analyses, measured body size and hindlimb length, and recorded perch use (height and diameter) throughout the experiment to track changes over time. We predicted that the founding events would generate genetic and morphological differences among the experimental islands due to random sampling of the source population. By contrast, the shift from the more forested habitat of the source area to the sparse, narrow-diameter vegetation on the small experimental islands should result in selection for shorter hindlimbs.
The founding events generated significant among-island genetic and morphological differences unrelated to environments on the experimental islands. This founder effect persisted throughout the course of the experiment despite all populations adapting in the predicted direction—shorter hindlimbs—in response to the narrower vegetation on the small islands. Thus both founder effects and natural selection jointly determine trait values in these populations over the first four years of the experiment. By measuring founder attributes at the start of the study and repeatedly sampling populations on the colonized islands, we were able to evaluate the relative contributions of founder effects, population bottlenecks, natural selection, and gene flow to the pattern of evolutionary divergence among these island populations. Persistence of the founder effect signal in this experiment suggests this evolutionary process may be more important than previously thought. Furthermore, the recent founding of populations via human-mediated introduction may increase the relative importance and detectability of founder effects in relation to other evolutionary mechanisms.
PS 84-205 – KittyCams: A new look at suburban free-roaming cat predation
Thursday, August 9, 2012
Exhibit Hall DE, Oregon Convention Center
Kerrie Anne T. Loyd , Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA
Sonia M. Hernandez , Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA
Kyler J. Abernathy , National Geographic Remote Imaging, Washington DC, DC
Barrett Foster , National Geographic Remote Imaging, Washington DC, DC
John P. Carroll , Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA
Michael J. Yabsley , Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA
Greg J. Marshall , National Geographic Remote Imaging, Washington DC, DC
Domestic cats (Felis catus) are extremely efficient and abundant non-native predators. The predation rate of the domestic cat remains a topic of considerable social and scientific debate and warrants attention using improved methodology. Previous predation studies relied on homeowner reports of wildlife take from prey returns to the household. We monitored the activities of 60 owned, free-roaming cats in suburban Athens, Georgia over a one year period (Nov. 2010- Oct. 2011) using KittyCam video cameras. KittyCams are animal-borne National Geographic “CritterCams” that allow recording of an animal-eye view without disrupting behavior. Cats were recruited through a survey about perceptions of domestic cats and free health screens and annual vaccinations were offered as an incentive for participation. Enrolled cats wore a video camera for 7-10 total days and all outdoor activity was recorded for analysis. Specific research goals related to predation included: 1) quantifying the frequency of cat interactions with native wildlife 2) identifying common prey species of suburban cats 3) examining predictors of outdoor behavior.
We collected an average of 37 hours of footage from each project cat. Preliminary results indicate that a minority of roaming cats (44%) hunt wildlife and that reptiles, mammals and invertebrates constitute the majority of suburban prey. Hunting cats captured an average of 2 items during seven days of roaming. Carolina Anoles (Anolis carolinensis) were the most common prey species and these new results suggest that additional research is needed regarding cat impact on suburban reptile populations. Eighty-five percent of wildlife captures were witnessed during the warm season (March-November in the southern US). Twenty-three percent of cat prey items were returned to households; 49% of items were left at the site of capture and 26% consumed. These results suggest that previous studies on pet cat depredation vastly underestimated capture rate. Cats roaming in rural areas were more likely to be hunters while cat age, sex, and time spent outside did not significantly influence hunting behavior. The KittyCams project aims to contribute reliable statistics and irrefutable images to the growing debate over free-roaming cats in the environment. Scientific manuscripts and educational materials for the general public are currently in preparation.