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Open Access Publications from the University of California

UCB Moorea Class: Biology and Geomorphology of Tropical Islands is an intensive field course (13 units), taught every Fall semester by UC Berkeley. A highly selective group of 20-22 undergraduate students spend a month on campus in Berkeley for lectures and labs five days a week, then go to the Richard Gump Biological Station on the island of Moorea in French Polynesia for nine weeks to carry out an intensive research project and to do some general educational field trips and labs, supervised by a number of professors and graduate student instructors. They learn all the stages of scientific research from conception of a project to giving talks and and writing. These papers are the result of their research.

Cover page of Morphological and Chemical Differences Among Populations of Hibiscus Tiliaceus Along an Elevational Gradient in Moorea, French Polynesia

Morphological and Chemical Differences Among Populations of Hibiscus Tiliaceus Along an Elevational Gradient in Moorea, French Polynesia

(2006)

Environmental variables change over elevational gradients and can isolate plant populations. Three varieties of Hibiscus tiliaceus L. exist on an elevational gradient in Moorea, French Polynesia. These variety’s morphological and chemical characteristics are associated with the differences between their environments. Leaf and flower morphological data were collected and analyzed and found significant differences in petal width and length, anther count, burgundy center color, and leaf width and length between the varieties, particularly between the coastal and mountain types. The increased rainfall and lower temperatures of the high mountains lowered net primary production for the mountain variety as compared to the coastal and mid-mountain varieties. The mid-mountain variety was found to have greater competition for light than the other varieties. These can be linked to the significant size differences in leaves and inflorescence. Chemical differences were analyzed using anti-microbial and anti-cancer bioscreens. Significant differences were found in the anti-microbial bioscreen between the mid-mountain variety, which showed little activity, and both the coastal and mountain varieties. The anti-cancer screen showed increased activity from the coastal and mountain leaves. Chemical differences are influenced by increased insolation and chemical protection from microbes in wet conditions. Anthropological uses of the varieties are linked to the greater size of the coastal type. The plant populations studied are associated with the differences in their environments.

Cover page of Interspecific Insect Interactions and Mutualism on the Underside of Guava Psidium Guajava Leaves, Mo’orea, French Polynesia

Interspecific Insect Interactions and Mutualism on the Underside of Guava Psidium Guajava Leaves, Mo’orea, French Polynesia

(2006)

Environmental Science Policy and Management, University of California, Berkeley, California 94720 USA Abstract. Interspecific mutualisms between ant and scale insect species have been well documented as symbiotic relationships that merit resource acquisition in exchange for protection. In this study, insect removal experiments were preformed on the branches of Psidium guajava in order to measure the effects that insect populations have on one another. Five ant removal, five scale removal and five control trees were treated. Data was taken daily over the course of 18 days. Ant activity was measured using a one-minute, unidirectional, point count and the number of scales per branch was determined by photographing a sample of five leaves per branch. Wilcoxon rank-sum tests found that ant populations differ significantly to that of controls in the absence of scale insects. Scale insect populations were not significantly affected by the removal of ants. Observational ant behavior data was also collected that supports possible tending behavior.

Cover page of Distribution, Ecology, and Systematics of the Filmy Ferns (Hymenophyllaceae) of Moorea, French Polynesia

Distribution, Ecology, and Systematics of the Filmy Ferns (Hymenophyllaceae) of Moorea, French Polynesia

(2006)

Ferns present an interesting case in island biogeography because of their unusually high dispersal ability. A general survey of the filmy ferns (Hymenophyllaceae) of Moorea, French Polynesia was undertaken by observing distribution in the field, conducting tests of desiccation tolerance, and inferring a phylogeny based on morphological characters. A total of 12 filmy fern species (including three species previously unreported in the literature for Moorea) were found to occur in moist, wellcovered habitats throughout the island, with distinct sets of high elevation and low elevation species. Five species were included in an experiment to determine relative degree of desiccation tolerance; results indicate that terrestrial species have lower desiccation tolerance than epiphytic or epipetric species. In order to place the Moorea filmy ferns in the larger archipelago context, eight additional Society Island species were included in the phylogeny for a total of 20 taxa based on 21 morphological characters; interspecies relationships reflect the taxonomy of Hymenophyllaceae sensu lato. Filmy fern species are widely dispersed throughout the Society Islands, and there is no indication of an adaptive radiation on Moorea.

Cover page of Habitat and Bleaching in the Foraminiferan Peneroplis Pertusus

Habitat and Bleaching in the Foraminiferan Peneroplis Pertusus

(2006)

The effects of human activities on the earth’s environment have gained increasing attention in recent years. With coral reefs declining worldwide, efficient tools for assessing reef health are more important than ever. The species of larger foraminifera known as Peneroplis pertusus share key characteristics with reef building corals. By examining the populations’ natural distribution along with the abiotic factors affecting bleaching, a better understanding of reef systems as a whole is achieved. In this study, P. pertusus was collected from ten different sites on a fringing reef in Moorea, French Polynesia. Collected from coral rubble at one, two, and three meters depths, they were analyzed for abundance, size, and extent of bleaching. Light experiments were used in the laboratory to determine response to increased solar radiation. One-way statistical analysis, along with the Wilcoxon test found no strong correlation between depth and percent bleaching. A difference between individual size and percent bleaching was found and a natural population dynamics are presumed to occur n Moorea. Light experiments found increased bleaching in P. pertusus showing increased solar radiation to be a factor in bleaching.

Cover page of Function, Design, Scaling, and Sexual Differences of Dimorphic Chelae in the Land Crab, Cardisoma Carnifex

Function, Design, Scaling, and Sexual Differences of Dimorphic Chelae in the Land Crab, Cardisoma Carnifex

(2006)

Crab chelae are a model system for studying the relationship between the biomechanics of an organism’s structure and its ecolgical role. This study investigated how chelae dimorphism may correlate with specialization in function in the land crab Cardisoma carnifx (Herbst 1791). This was achieved by comparing field observations of preferential claw usage during diurnal activities to a mechanical model drived from anatomical claw measurements, claw closing effort of captured specimens, and calculations of expected closing force. Behavior, mechanical scaling, and effort were also compared between males and females. Foraging, eating, and lead claw entering burrow showed significant differences in claw use frequency. It was also found that the major and minor claws scaled differently with respect to carapace length, with the major claw displaying positively allometric scaling and the minor claw displaying near-isometric scaling. Measurement of claw closing effort with respect to claw length showed high correlation in male minor and female major claws. In males, expected force measurements showed a greater rate of growth in the minor claw than in the major claw with respect to claw lengh, but in females, expected force in the major claw exhibited a greater rate of growth. A possible explanation for the differences in design between sexes may be that there are functional differences between male nd female chelae, such as the primary use of male minor claw and female major claw in gripping objects when stressed.

Cover page of Distribution and Dispersal of the South Pacifc Tree, Fagraea Berteriana (Loganiaceae)

Distribution and Dispersal of the South Pacifc Tree, Fagraea Berteriana (Loganiaceae)

(2006)

Tahitian legend states Fagraea berteriana is a gift of repentance from the god, Tane. The scientific community knows little more about this tree than its inter-island distribution in the South Pacific. I surveyed the island of Moorea to map an intra-island distribution of F. berteriana and quantify environmental characteristics surrounding the tree’s growth. I tested dispersal hypotheses by collecting bird observations and conducting seed germination experiments that included a numer of seed scarification treatments. The tree occurred in densities ranging from 44 to 244 trees/hectare and at elevations spanning from approximately 300 to 900 m. Density differed with significance between two sites, Tohiea and the Cross Island Trail. Tree density increased with greater elevations and more southerly aspects. Ninety-five percent of the trees sampled grew on slopes greater than 80%. There was no correlation between tree density and slope or between density and tree height. Tree density did not significantly differ between three substrate types: rock, rocky soil, and soil. I observed Silvereyes and Red-vented bulbuls consuming F. berteriana fruits and germination from seeds, although at a less than 1% rate. The germination success and bird observations served as a preliminary investigation of the dispersal of F. berteriana and fostered ideas concerning worthwhile future directions of study.

Cover page of Christmas Colors : Colormorph Distribution of Spirobranchus Giganteus Pallas 1766 on Moorea, French Polynesia

Christmas Colors : Colormorph Distribution of Spirobranchus Giganteus Pallas 1766 on Moorea, French Polynesia

(2006)

Spirobranchus giganteus Pallas 1766 is an obligate associate of coral. This study focused on the distribution of five branchial crown colormorphs (Blue, Brown, Marigold, Purple, and White) on eight coral species (Acropora I, Acropora II, Porites I, Porites II, Porites III, Porites IV, Porites V, Porites VI) by quadrat sampling method. White was the most abundant colormorph, representing 24.0% of the total. Blue was the least abundant colormorph at 9.5% of the total. There were no significant differences in Shannon-Weiner Diversity Index (H’) of colormorphs between coral species. Also, relative colormorph abundance did not differ significantly between coral species or between the Front and Back positions. Only Blue and Marigold differed significantly in relative abundance between Top, Midde, and Bottom positions. Findings support a colormorph distribution of colormorphs. There are two possible explanations: 1) mortality and selection effects on distribution and 2) phenotypic plasticity, a combination of genetic and environmental factors contributing to the occurrence of certain phenotypes.

Cover page of Feeding Preference of the Cushion Star, Culcita Novaeguineae in Mo’orea

Feeding Preference of the Cushion Star, Culcita Novaeguineae in Mo’orea

(2006)

Previous studies of the feeding biology of Culcita novaeguineae Muller & Troschel in Hawai’i have shown that the cushion star prefers to prey on coral species of the genus Pocillopora over the genus Porites. Distribution and feeding biology studies of C. novaeguineae in Cook’s Bay on the island of Mo’orea, French Polynesia have shown that it habitats near Porites spp. coral in areas where Porites spp. coral is sparse, and prefers to prey on Acropora spp. coral. The purpose of this study was to further examine coral prey preference of C. novaeguineae in Mo’orea, using specimens from four areas on the island for better representation of its feeding ecology on Mo’orea, French Polynesia. My studies showed that C. novaeguineae in Mo’orea prefers Acropora spp. and Pocillopora spp., over Porites spp. (p=0.0046), and showed no preference for Acropora spp., over Pocillopora spp.. The study further determined that C. novaeguineae primarily feeds nocturnally, and moves persistently in search for food. As a coral predator, C. novaeguineae can affect abundance of certain coral species, and change the overall reef ecology in Mo’orea.

Cover page of Predator Defense Mechanisms in Shallow Water Sea Cucumbers (Holothuroidea)

Predator Defense Mechanisms in Shallow Water Sea Cucumbers (Holothuroidea)

(2006)

The various predator defense mechanisms possessed by shallow water sea cucumbers were surveyed in twelve different species and morphs. While many defense mechanisms such as the presence of Cuverian tubules, toxic secretions, and unpalatability have been identified in holothurians, I hypothesized that the possession of these traits as well as the degree to which they are utilized varies from species to species. The observed defense mechanisms were compared against a previously-derived phylogeny of the sea cucumbers of Moorea. Furthermore, I hypothesized that while the presence of such structures is most likely a result of the species’ placement on a phylogenetic tree, the degree to which they utilize such structures and their physical behavior are influenced by their individual ecologies. The presence of a red liquid secretion was restricted to individuals of the genus Holothuria (Linnaeus 1767) however not all members of the genus exhibited this trait. With the exception of H. leucospilota, which possessed both Cuverian tubules and a red secretion, Cuverian tubules were observed in members of the genus Bohadschia (Ostergren 1896). In accordance with the hypothesis, both the phylogenetics and individual ecology appear to influence predator defense mechanisms. However, even closely related species of similar ecology may differ considerably.

Cover page of Resource Partitioning By Wintering Shorebirds : A Behavioral Comparison of Two Species in a Tropical Estuary

Resource Partitioning By Wintering Shorebirds : A Behavioral Comparison of Two Species in a Tropical Estuary

(2006)

Shorebirds often feed in multispecies groups that display interesting niche dynamics. On Moorea, French Polynesia, the Wandering Tattler (Tringa incana) and Pacific Golden Plover (Pluvialis fulva) are the dominant shorebird species during the northern winter. These species’ feeding behavior was observed at the Temae estuary on the northeast side of the island. Relative abundance of the two species was determined using transect counts at the estuary and an adjacent beach. T. incana displayed more striking and sprinting behavior, while P. fulva displayed more picking and walking behavior. T. incana also consumed more crabs than P. fulva. The two species existed in relatively equal abundance in the estuary; T. incana was more common on the beach. Though these data suggest some differences in feeding niche, a great deal of overlap was observed. The degree of niche partitioning appears to be greater in this study than in similar studies conducted on these species’ breeding grounds.