2006 Program Abstracts

 

A RE-EXAMINATION OF THE DECOUPLED JAW MECHANISM: FEEDING BEHAVIOR IN A GOBYCICHLID, ERETMODUS CYANOSTICTUS

Katie Colpitts, Matthew O’Neill, Alice Gibbs

 

Upper jaw (premaxilla) protrusion is thought to enhance feeding performance in zeleosts(bony fishes) by enabling more effective prey capture. In most fishes, premaxillary protrusion is coupled to lower jaw depression. Liem (1979) proposed that the goby cichlid, Eretmodus cyanostictus, uses a mechanism in which the premaxilla moves independently from the lower jaw, and instead is correlated with neurocranial rotation. We tested this hypothesis by comparing the goby cichlid to Archocentrus nigrofasciatus (convict cichlid), using high speed digital imaging, and dissection and manipulation. For the goby cichlid, we found no correlation between premaxillary protrusion and neurocranial rotation. However, our results did support Liem.s suggestion that in the goby cichlid premaxillary protrusionis decoupled from lower jaw depression. While this decoupled mechanism maycontribute to the diversity of the African cichlids, we note that South American cichlidswith a coupled mechanism of premaxillary protrusion display a similar level of diversity in feeding behaviors.

 Poster also presented at:

 Society for Integrative and Comparative Biology Annual Meeting January 3-7, 2007 Phoenix Convention Center, Phoenix, AZ.

  

AN ANALYSIS OF THE PUTATIVE HYBRID ORIGIN AND POSSIBLE PARENTAL SPECIES OF BRICKELLIA KNAPPIANA USING MORPHOMETRICS AND MOLECULAR GENETICS.

Barbara Simeles, Randall Scott, Tina Ayers

 One of the ca. 100 described species in the largest genus of the subtribe Alomiinae is Brickellia knappiana. Although it has been accepted by the California Native Plants Society as a rare plant, there is reason to believe that B. knappiana is simply a hybrid between two common Brickellia species that always occur in close proximity to it. This study uses morphometrics, chloroplast DNA (cpDNA) sequencing and amplified fragment length polymorphism (AFLP) analysis to determine the putative hybrid origin and possible parentage of B. knappiana. Morphometric analysis showed B. knappiana to be intermediate between B. longifolia and B. desertorum. The genetic analyses also supported the hybrid origin of B. knappiana via polymorphic markers (AFLP) and a characteristic indel in the cpDNA (DNA sequencing). Brickellia desertorum and B. longifolia appear to be the parental species of B. knappiana. Since AFLP data suggests that B. knappiana is not genetically distinct, it would seem that it is not a rare plant and that legal protection would be better provided to a more stable species.

 Poster also presented at:

 Society for Integrative and Comparative Biology Annual Meeting January 3-7, 2007 Phoenix Convention Center, Phoenix, AZ.

  

EVOLUTIONARY RELATIONSHIPS WITHIN PARACERCEIS, A SPHAEROMATID ISOPOD GENUS WITH INVASIVE POPULATIONS

Katherine Saunders and Stephen Shuster,

 The North American sphaeromatid genus, Paracerceis, includes 14 described species, whose evolutionary relationships are unknown. Paracerceis sculpta was first described from southern California, but also has populations in the Gulf of California, Mexico. The distribution of P. sculpta is now cosmopolitan, evidently due to its association with fouling communities and its ability to invade novel habitats. To examine evolutionary relationships within the genus, we used a 400 base pair sequence from the mitochondrial 16S ribosomal RNA gene. Our analysis included sequences from 3 Paracerceis species, as well as from 4other species belonging to 2 currently recognized sphaeromatid subfamilies, Dynameninaeand Sphaeromatinae. We compared the sequences obtained using maximum parsimony.  This approach showed Paracerceis to be a monophyletic group within the Dynameninae, with Paradella more distantly related to Paracerceis than was previously thought.  Understanding the evolutionary relationships among Paracerceis will provide information for future studies of invasive isopod populations as well as of the appearance and persistence of alternative mating strategies within this genus.

 Poster also presented at:

 Society for Integrative and Comparative Biology Annual Meeting January 3-7, 2007 Phoenix Convention Center, Phoenix, AZ.

  

GUNNISON'S PRAIRIE DOG ALARM CALLS IN RESPONSE TO TWO PREDATORS APPEARING SIMULTANEOUSLY

Lindsay Drayton, Kenneth Sterling, Constantine Slobodchikoff

Gunnison's prairie dogs (Cynomys gunnisoni) encode descriptive information in their alarm calls in response to a predator's species, individual identity, size, color, and behavior. In this study, we evaluated the situation where two predators appeared simultaneously in order to determine whether the prairie dogs would encode information about both predators into the alarm call. We first recorded alarm calls in response to two predators independently, a human and a domestic dog. We then recorded alarm calls in response to both the human and dog together in order to test the degree to which the prairie dogs were encoding information for each within one call. We analyzed the calls using discriminant function analysis on sixteen variables measured from sonograms. Results indicate that the alarm calls describing each predator in the independent treatments were significantly different and encoded specific characteristics for that predator. The alarm calls in response to the two predators together were significantly different from the calls for the two predators independently, but encoded more general characteristics, suggesting that the prairie dogs abstracted the essential characteristics of each predator and incorporated those into their calls.

 Poster also presented at:

 Society for Integrative and Comparative Biology Annual Meeting January 3-7, 2007 Phoenix Convention Center, Phoenix, AZ.

  

SYSTEMATICS OF LYSIPOMIA BASED ON CHLOROPLAST AND NUCLEAR SEQUENCE DATA

Donnelly A. West and Tina J. Ayers

The genus Lysipomia Kunth (Campanulaceae) is comprised of two subgenera and approximately forty species that grow exclusively in the Andes from 3000m to 5000m in elevation (Ayers 1999). Preliminary phylogenetic hypotheses based on nuclear ITS sequence data lacked information at the basal nodes (Fig 1). The atpB-rbcL spacer region in the chloroplast was sequenced for 12 species and then combined with the ITS data in order to clarify the phylogeny, test whether ancient hybridization was responsible for speciation, and firmly place one species (L. caespitosa) in a clade. The resulting phylogenetic tree (Fig 2) supports the original ITS phylogeny. There was no evidence to support the hybridization-speciation hypothesis since the atpB sequence data was congruent with the original ITS data. The combined analysis also allowed the unequivocal placement of L. caespitosa in the L. biliniata-cylindrocarpa clade. The atpB data was also used to distinguish a cryptic, undescribed species that had been included in the data set as L. sparrei (Fig 3).