ASSESSING THE RELATIVE INFLUENCES OF ABIOTIC AND BIOTIC FACTORS ON A SPECIES’ DISTRIBUTION USING PSEUDO-ABSENCE AND FUNCTIONAL TRAIT DATA: A CASE STUDY WITH THE AMERICAN EEL (Anguilla rostrata)

Species’ distributions are influenced by abiotic and biotic factors but direct comparison of their relative importance is difficult, particularly when working with complex, multi-species datasets. Here, we present a flexible method to compare abiotic and biotic influences at common scales. First, data representing abiotic and biotic factors are collected using a combination of geographic information system, remotely sensed, and species’ functional trait data. Next, the relative influences of each predictor variable on the occurrence of a focal species are compared. Specifically, ‘sample’ data from sites of known occurrence are compared with ‘background’ data (i.e. pseudo-absence data collected at sites where occurrence is unknown, combined with sample data). Predictor variables that may have the strongest influence on the focal species are identified as those where sample data are clearly distinct from the corresponding background distribution. To demonstrate the method, effects of hydrology, physical habitat, and co-occurring fish functional traits are assessed relative to the contemporary (1950 – 1990) distribution of the American Eel (Anguilla rostrata) in six Mid-Atlantic (USA) rivers. We find that Eel distribution has likely been influenced by the functional characteristics of co-occurring fishes and by local dam density, but not by other physical habitat or hydrologic factors

Population structure of Lower Nubia in the Mesolithic-Christian groups

For almost 100 years, population structure in Nubians has been speculated upon. Initially, most scholars contended that Nubian biological evolution was the product of biological diffusion, or extraregional gene flow, from the different populations they came into contact with. In 1968, Adams put forth a new way to look at the archaeological record. He argued that the archaeological record was reflective of an in situ change, where Nubians evolved culturally without influences from other populations. Later, Carlson and Van Gerven (1979) hypothesized that the same forces that formed the archaeological record were also operating biologically. Since Adams and Carlson and Van Gerven suggested an alternative way to look at Nubian cultural and biological evolution, most research (with the exception of DNA studies) have concurred with their conclusions. The body of research into Nubian biological evolution is vast and incorporates DNA, craniometrics, dental metrics, and dental nonmetrics.However, very little work has been done with cranial discrete traits. In this dissertation, seven questions and their corollaries of Nubian population structure will be examined utilizing cranial discrete traits. Population genetics statistics for quantitative traits have become popular in craniometric data studies. Because of their effectiveness in deciphering subtle aspects of population structure, this dissertation will adapt the continuous population genetics statistics for use with categorical or discrete data. The results of the inquiry into Nubian population structure depict a complex pattern of biological evolution that suggests in situ evolution did not operate alone. Rather, sometimes in situ evolution occurred, while other times biological diffusion influenced their evolution. These interesting results mainly support the DNA evidence, which found evidence of multiple migrations across Nubia (Fox 1997; Krings et al. 1999).Sample size may have affected these results, as several of the samples numbered less than 30. However, small samples should not be ignored because they can contribute much information about past populations. Furthermore, this dissertation successfully modified and applied population genetics statistics to categorical data and can serve as a stepping stone for more sophisticated techniques to be applied to the methodology employed within

Do nuclear DNA and dental nonmetric data produce similar reconstructions of regional population history? An example from modern coastal Kenya

This study investigates whether variants in dental morphology and nuclear DNA provide similar patterns of intergroup affinity among regional populations using biological distance (biodistance) estimates. Many biodistance studies of archaeological populations use skeletal variants in lieu of ancient DNA, based on the widely accepted assumption of a strong correlation between phenetic- and genetic-based affinities. Within studies of dental morphology, this assumption has been well supported by research on a global scale but remains unconfirmed at a more geographically restricted scale. Paired genetic (42 microsatellite loci) and dental (nine crown morphology traits) data were collected from 295 individuals among four contemporary Kenyan populations, two of which are known ethnically as “Swahili” and two as “Taita;” all have welldocumented population histories. The results indicate that biodistances based on genetic data are correlated with those obtained from dental morphology. Specifically, both distance matrices indicate that the closest affinities are between population samples within each ethnic group. Both also identify greater divergence among samples from the different ethnic groups. However, for this particular study the genetic data may provide finer resolution at detecting overall among-population relationships

Adaptive content mapping for internet navigation

The Internet as the biggest human library ever assembled keeps on growing. Although all kinds of information carriers (e.g. audio/video/hybrid file formats) are available, text based documents dominate. It is estimated that about 80% of all information worldwide stored electronically exists in (or can be converted into) text form. More and more, all kinds of documents are generated by means of a text processing system and are therefore available electronically. Nowadays, many printed journals are also published online and may even discontinue to appear in print form tomorrow. This development has many convincing advantages: the documents are both available faster (cf. prepress services) and cheaper, they can be searched more easily, the physical storage only needs a fraction of the space previously necessary and the medium will not age. For most people, fast and easy access is the most interesting feature of the new age; computer-aided search for specific documents or Web pages becomes the basic tool for information-oriented work. But this tool has problems. The current keyword based search machines available on the Internet are not really appropriate for such a task; either there are (way) too many documents matching the specified keywords are presented or none at all. The problem lies in the fact that it is often very difficult to choose appropriate terms describing the desired topic in the first place. This contribution discusses the current state-of-the-art techniques in content-based searching (along with common visualization/browsing approaches) and proposes a particular adaptive solution for intuitive Internet document navigation, which not only enables the user to provide full texts instead of manually selected keywords (if available), but also allows him/her to explore the whole database

A geometric morphometric analysis of contemporary Hispanic populations from Mexico and Colombia

In contexts such as natural disasters, humanitarian efforts, and other forensic investigations, the timely and accurate development of the biological profile (sex, age, ancestry, and stature of skeletonized remains) is vital to the identification of decedents. At present, the term “Hispanic” is a socio-linguistic classifier that includes all persons of South or Central American, Mexican, Cuban, Puerto Rican, or other Latino and Spanish-speaking persons into a single category; the term is also the current designator used by forensic anthropologists—in ancestry estimation—to identify anyone from a Latin American country. From a biological standpoint, the term is ineffective in describing these individuals because the human biological variation within and among different Hispanic populations cannot be encompassed by a single category. With regards to the development of the biological profile, ancestry estimations for these individuals are tenuous at best. This is due to the poor nature of the single reference sample used to create the current methods in ancestry and sex estimation—a common trend in forensic anthropology. The untested assumption that all Hispanic individuals are skeletally homogenous results in haphazard identifications and hinders effective forensic investigation. The primary objective of this research is to examine geometric morphometric variability in 547 documented individuals from three contemporaneous Latin American groups represented by Colombian, Mexican, and Migrant (U.S./Mexico border crossers) samples in order to ascertain whether it is possible to distinguish specific Hispanic populations. Using geometric morphometric (GM) analyses, the effects of shape-related variation independent of size can be implemented to isolate where on the cranium differences between groups are expressed. The results suggest that GM-derived population-specific criteria for Hispanic individuals possess the discriminatory power that is necessary towards improving the underdeveloped methods of identification for diverse Hispanic individuals living in the U.S. and abroad. Canonical variate analyses of the three samples separates the groups distinctly along both axes (CV1 and CV2). The morphological differences are predominantly seen in cranial height and sagittal vault shape, with Colombians having taller cranial vaults than the Mexican samples. The final results of this study demonstrate the utility that GM approaches have in forensic anthropology with respect to ancestry estimation and can be used to update various techniques required to develop the biological profile. Without constantly updating, refining, and re-validating the techniques, forensic anthropologists fail to provide the caliber of service required to approach the various forensic contexts

Nonparametric Feature Extraction from Dendrograms

We propose feature extraction from dendrograms in a nonparametric way. The Minimax distance measures correspond to building a dendrogram with single linkage criterion, with defining specific forms of a level function and a distance function over that. Therefore, we extend this method to arbitrary dendrograms. We develop a generalized framework wherein different distance measures can be inferred from different types of dendrograms, level functions and distance functions. Via an appropriate embedding, we compute a vector-based representation of the inferred distances, in order to enable many numerical machine learning algorithms to employ such distances. Then, to address the model selection problem, we study the aggregation of different dendrogram-based distances respectively in solution space and in representation space in the spirit of deep representations. In the first approach, for example for the clustering problem, we build a graph with positive and negative edge weights according to the consistency of the clustering labels of different objects among different solutions, in the context of ensemble methods. Then, we use an efficient variant of correlation clustering to produce the final clusters. In the second approach, we investigate the sequential combination of different distances and features sequentially in the spirit of multi-layered architectures to obtain the final features. Finally, we demonstrate the effectiveness of our approach via several numerical studies