Tag: Panel B: “Vertebrate Expression”

Prey detection and feeding success of the comb jelly Mnemiopsis leidyi on the copepod Acartia tonsa in still and turbulent waters

Presenter: Clare Chisholm (Environmental Science)

Mentor: Kelly Sutherland

Oral Presentation

Panel B: “Vertebrate Expression” Walnut Room

Concurrent Session 3: 1:45-3:00pm

Facilitator: Chris Moe

The comb jelly or ctenophore, Mnemiopsis leidyi, is a voracious predator in both its native and non-native habitats. Though M. leidyi inhabits coastal waters that are frequently turbulent, previous feeding studies have been conducted in still water tanks. This study aimed to research their feeding behaviors in turbulent waters, which is more representative of their natural environment. Interactions between the free-swimming ctenophores and copepod prey (Acartia tonsa) were observed and recorded (n = 73) in a laboratory turbulence tank. Turbulence was created using submersible speakers, and the interactions were recorded using a video camera. Capture efficiency denoted interactions containing direct contact between copepods and M. leidyi that led to eventual capture, frequently after multiple interspecies contacts. Overall copepod capture efficiency was similar in still (48%) and turbulent (43%) water, as were the overall prey retention rates for each (still = 26%; turbulent = 20%). However, M. leidyi exhibited anticipatory responses, defined as altering the position of feeding structures, nearly twice as often in still (41%) waters than in turbulent (20%) waters. The hydromechanical “noise” produced by background turbulence may inhibit the capacity of the ctenophore to detect and respond to fluid motions produced by its prey.

Opposing Roles of Wnt and BMP signaling in Zebrafish caudal fin regeneration

Presenter: Alan Gomez (Biology)

Mentor: Kryn Stankunas

Oral Presentation

Panel B: “Vertebrate Expression” Walnut Room

Concurrent Session 3: 1:45-3:00pm

Facilitator: Chris Moe

Zebrafish and many other vertebrates possess an incredible ability to regenerate damaged or amputated body parts including the retina, spinal chord, fins and limbs. The zebrafish caudal fin is a widely studied system because of its simple anatomy, accessibility, and robust ability to completely and consistently regenerate after amputation in under two weeks. Regeneration of the zebrafish caudal fin is dependent upon the formation of a proliferating mass of cells that grow at the amputation site called the blastema. The cells that line the bone rays in the mature zebrafish contribute to the blastema along with other cell types and are responsible for rebuilding the lost bone. These osteoblasts become activated after a fin injury through dramatic changes in their genetic program. Two signaling pathways called Wnt and BMP are particularly important for inducing these genetic changes and for organizing the spatial localization of osteoblasts in the blastema. BMP and Wnt are proteins that cause changes in gene expression programs of the cells that they physically interact with at the cell surface. Proper expression of Wnt and BMP in the blastema is essential for regeneration to occur. By examining the genes activated by Wnt and BMP during regeneration we have concluded that the gene expression programs activated by BMP work to counteract those of Wnt signaling. Investigating this feedback between BMP and Wnt has helped to characterize the specific roles that these signaling pathways play during the process of bone regeneration.

The Flexibility of Gestural Communication in Bornean Orangutans (Pongo pygmaeus) in Kalimantan Tengah

Presenter: Cudmore (Anthropology)

Mentor: Kirstin Sterner

Oral Presentation

Panel B: “Vertebrate Expression” Walnut Room

Concurrent Session 3: 1:45-3:00pm

Facilitator: Chris Moe

Great ape communication research attempts to reveal the cognitive abilities of our closest living relatives and to inform our understanding of the evolution of human language. Although great ape gestural communication has been well documented, relatively few studies are specific to the orangutan. The aim of this study was to determine if rehabilitant orangutans (Pongo pygmaeus) at the Orangutan Care Center and Quarantine (Pasir Panjang, Indonesian Borneo) use distinct gestures toward other orangutans versus toward humans. Because orangutans are tree-living species whose arms are typically not free to gesture, we predicted that orangutan gestures are adapted to employ the whole body. Using 59 sub-adults in 18 different home enclosures, we examined gestural types and frequencies in comparisons of orangutan-orangutan and orangutan-human communication. Orangutan-human trials were run with both the experimenter facing and non-facing to further measure gestural flexibility. Our results show that 92% of orangutan-human gestures were made with the limbs, while the majority (46%) of orangutan- orangutan gestures were facial. When the human experimenter was facing, 76% of gestures were visual, while when non-facing, only 7% were visual. Our results suggest that limb gesturing toward the experimenter may be partly due to rehabilitant orangutans learning that caretakers respond more readily to anthropocentric gestures, like arm/hand pointing. Our findings demonstrate that these orangutans use gestures flexibly.

Hidden Information in the Fossil Record: Using Discriminant Analysis on Isolated Postcrania

Presenter: Brianna McHorse (Biology)

Mentor: Samantha Hopkins

Oral Presentation

Panel B: “Vertebrate Expression” Walnut Room

Concurrent Session 3: 1:45-3:00pm

Facilitator: Chris Moe

Postcrania (non-skull or teeth bones) are often preserved in the fossil record but, unless found with teeth or skulls, are rarely identified beyond the family level. As a result, they offer a potentially untapped resource for studies of extinct diversity. Discriminant statistical analyses of linear measurements on these postcranial bones show remarkably high identification success rates for many mammal types, including antilocaprids (pronghorn), camelids (camels and llamas), and equids (horses). The approach we use is ideal, as it captures more subtle bone-shape variation than examining scatterplots of measurements but is more straightforward than three-dimensional morphometric methods. Further, applying Bayesian methods to the established discriminant analysis can allow integration of multiple skeletal elements, e.g., phalanges (fingers), astragali (ankles), and metapodials (hand and foot bones). We test this new method on a known, artificially created assemblage of modern cervid (deer), camelid, and antilocaprid postcranial bones. In a mixed training set of four bone types, we achieved identification success rates ranging from 87.5% to 100%. Our method is simple but has the potential to quickly and significantly improve knowledge of the hoofed mammal ecology at several postcrania-rich fossil sites. We focus on hoofed mammals, but the method should transfer well to other mammalian groups, shedding light on hidden diversity and improving any studies that rely on identification.