Using Marine Snails to Teach Biogeography and Macroevolution: The Role of Larvae and Dispersal Ability in the Evolution and Persistence of Species

While some marine animals are capable of traveling great distances, many have limited mobility as adults and spend the majority of their lifetimes in a small geographical area or may even be cemented to a single place. While it might be expected that species with limited mobility would have small geographic distributions, some nevertheless occur over very large areas. This is the case for some marine snails (gastropods). A key factor that impacts the geographic distribution of marine snails is the type of larvae they have during the phase of their life history that follows hatching from an egg. Because adult snails do not typically travel vast distances, the mobility of the larval stage determines the species’ ability to reach new territories. Some larvae are capable of long-distance travel, while others are not. An important component of the process of speciation involves geographic isolation, so the type of larvae a snail species possesses impacts the likelihood that it will become geographically isolated and give rise to a new species. Larval form also affects how long snail species will persist on geological timescales before going extinct, as well as rates of speciation. This paper briefly reviews the evolutionary consequences of different types of larval development in marine gastropods (especially cone snails, which are one of the most diverse groups of marine animals), particularly in determining the dispersal ability and geographic ranges of individual species, the amount of genetic exchange among populations within species, and the duration of species through time. The goal of this short review is to provide context and examples for classroom discussions of the connections between biogeography and macroevolution. Furthermore, a classroom activity is presented that involves students’ using information about snail life history and biogeography to develop research plans (and predicted results) that could be utilized to test (i.e., support or reject) several macroevolutionary hypotheses

GEOSPATIAL ANALYSIS OF PEDIATRIC TUBERCULOSIS IN BOHOL, PHILIPPINES: DISEASE CLUSTERS AND ACCESS TO CARE

Worldwide, children represent approximately 10% of global tuberculosis (TB) cases. We recently reported a high tuberculin skin test (TST)-positive prevalence (355/5,476; weighted prevalence=6.4%) among children (\u3c15 years) throughout the island of Bohol, Philippines, with some geographically isolated communities having prevalence as high as 29%. In this study, we conducted a secondary geospatial and hot-spot analysis of this household-based cluster survey to assess the association between access to care (distance to a health care facility) and TST-positive prevalence. Our analysis indicated that villages with high TST-positive prevalence (≥10%) were significantly further from Provincial Health Office based in the capital city of Tagbilaran in time-distance (p=0.0001, r=0.2387) and kilometers (p=0.0011, r=0.3170). Similarly, prevalence was positively correlated with distance to the municipal Rural Health Unit (RHU), where most receive their medical care, in time-distance (p=0.0055; r=0.0415); however, the association was not significant in kilometers (p=0.3315; r=0.0715). Distance to health care facilities could represent an obstacle to access to care, thereby limiting diagnosis and treatment and resulting in increased risk of transmission to others in the community. Health care outreach in geographically isolated areas is critical to treatment and control of efforts for pediatric TB

Salt marsh harvest mouse abundance and site use in a managed marsh

The salt marsh harvest mouse (Reithrodontomys raviventris) is a federal and California listed endangered mammal endemic to the San Francisco Bay. The objectives of this research were to determine habitat use of endangered salt marsh harvest mice in a managed marsh in Fremont California, and to evaluate whether managed flooding of the marsh provides favorable habitat conditions for the mice. In addition, this research explores the effectiveness of using mark-recapture model selection analysis to estimate capture probability, survival, and population growth rate for salt marsh harvest mice. Mice were captured for four nights per month between May and August, 2008. Thirty-six unique salt marsh harvest mice were captured for a catch per 100 nights of trap effort of 1.9. The sex ratio of male to female mice was skewed towards males with a sex of 2.3:1. Salt marsh harvest mice were distributed randomly throughout the marsh and no relationships were found between mice distribution and pickleweed salinity, pickleweed height, distance to levees, distance to dry or filled water bodies, percent cover of vegetation, or sympatric rodents. The findings of this study indicate that catch-per-trap-effort, the current standard method to estimate salt marsh harvest mice populations, may not be accurate. The results of this study can be used by managers of salt marsh harvest mice habitat to manage and estimate mouse populations

A Case Study of Pedestrian Environments Around Tamien Station in San Jose, California: An Analysis of Existing Conditions and Recommendations to Improve Pedestrian Access and Promote Walking Around Tamien Station

The objective of this research is to understand how the analysis of design elements can foster design recommendations for the transformation of the pedestrian environment around the Tamien Station area. This was done by conducting a street segment audit for twenty-five selected streets around the one-half mile walking distance of Tamien Station providing recommendations based on audit findings and urban design analysis