Marvalee H. Wake - US grants

This project investigates the morphology and evolutionary relationships of the members of the third order of the Amphibia--the Gymnophiona. Descriptive, morphometric, developmental, and functional morphological data on bones, muscles, nerves, skin structures, and other anatomical components will be gathered to better understand the biology of this relatively rare tropical group. This will provide data so that more robust analyses of the evolutionary relationships of the species, genera, and families of the group, and their relationship to other vertebrates, can be made; the study may provide new insight into pattern and process of evolution.

Investigation of the biology of a lineage of amphibians, the Order Gymnophiona or caecilians, will provide information important to understanding 1) their structure and function, 2) their relationships to each other, to other amphibians, and to other vertebrates, and 3) patterns of evolution and adaptation in animals that have modified bodies, and patterns of evolution in general. The study will integrate developmental, functional, and structural biology in a multi-disciplinary approach using a diversity of research techniques. These tropical amphibians live in habitats that are fast disappearing, so their study will provide information on their ecological relationships and especially their contribution to the biodiversity of the world.

This proposal provides a plan for enhancing the scientific skills of middle school and secondary school teachers by combining field research experiences for teachers with a collaborative, professionally-guided approach to the development, evaluation, and assessment of curriculum based on the teachers' own research experience. Eighty teachers will participate in project activities. The curriculum will stress scientific process skills, participatory learning, classroom research activities, and an interdisciplinary approach to scientific issues. Cost sharing is equivalent to 27% of the NSF award.

9527681 Wake A general hypothesis in evolutionary biology is that modification of a developmental pattern may be correlated with a change in reproductive mode. Analysis of development of the skeleton, and some elements of the muscular and nervous systems, in a monophyletic lineage, the amphibian Order Gymnophiona, will test the general hypothesis of correlation of reproductive and developmental patterns. Development in three focal species representing three families will be analyzed. One species represents a basal family with an oviparous, free-living larval life history, the other two are viviparous (live-bearing with maternal nutrition). One viviparous species is terrestrial, the other fossorial, and their developmental patterns and, consequently, adult morphologies differ significantly. Consequently, interactions of phylogenetic history, life history, habitat, development and function can be approached and analyzed. Comparative development of the skull will be examined to ascertain the basis of homology of structural elements, and the degree to which modification of development is correlated with the factors mentioned above. The microstructure of tooth development will be examined to understand the development and evolution of the unique fetal dentition of viviparous forms. The development of the vertebrae will be studied to test the hypothesis that resegmentation is a fundamental property of development, and to determine the process by which it occurs. The development of specific neural and muscular elements associated with the skeletal ontogeny, such as the jaw musculature and the hypoglossal nerve, will be studied. A diversity of techniques will be employed: immunohistochemistry, scanning and transmission electron microscopy, clearing and staining, and others. A program t o breed caecilians in captivity will be established in order to: (1) provide means of examining the diversity of reproductive modes in the lineage; (2) provide embryos at crucial developmental stages for study; and (3) assure the maintenance of species threatened in their natural habitats. This is an integrative study that should lead to significant advancement in the search to understand the relationship between reproduction, development and evolution

Wake 9700914 Ecomorphology is a sub-discipline that has emerged from interest in the relationship between organismal morphology and natural history. Morphology includes both structure and function. Relating variation at these levels to variation in whole-organism performance can help to reveal causality between morphology and performance. This, combined with demonstration of the importance of performance measures in organismal ecoloey or behavior, makes ecomorphological inference more robust. This is a proposal to study the feeding ecomorphology of the monophyletic lizard family Crotaphytidae. Crotaphytids show trends in feeding apparatus structure, feeding behavior, and dietary ecology. Bite force is an important performance variable influencing feeding behavior and dietary ecology. Structural and functional analyses of the feeding apparatus of three crotaphytid taxa will be used to construct computer models. These models will generate predictions of bite force that will be tested by bite-force measurement. Simulated structural and functional perturbations of the models will help to identify causality between structural and functional variation and biteforce variation. Identification of such causality links studies of morphology to ecology and behavior and, ultimately, facilitates rigorous evaluation of ecomorphological evolution.

Viviparity-live-bearing modes of reproduction, rather than egg-laying-has evolved independently in lineages of many animals. It therefore is a consequence of convergent evolution, with the same feature occurring in taxa that do not share a common ancestor that bears the trait (homoplasy). Viviparity in amphibians has many different expressions of these independent evolutions including retention of the internally fertilized ova in the oviducts with our without maternal nutrition after yolk is resorbed, intraoviductal cannibalism, retention of externally fertilized ova in the skin of the mother's back, and others.
This research program will investigate the mechanisms by which viviparity has arisen by comparing 1) features of parental ovaries, oviducts, and skin with those of related species that are egg-layers to elucidate the effects of 'pregnancy' maintenance; 2) patterns of development of embryos of taxa with different modes of viviparity and with related egg-laying species; 3) modes of retention of the developing embryos, including the hormonal substrate as measured morphologically; 4) modes of nutrition of the developing young; 5) the features of metamorphosis of the young of viviparous species as compared with those of related egg-layers; and 6) length of 'pregnancy' and the environmental and physiological cues for birth. The study will be one of the first to consider mechanisms by which homoplasy has evolved, rather than simply documenting instances of such patterns of evolution.

Dissertation Research: Comparative biomechanics of sand locomotion in lizards

Wyatt L. Korff
Marvalee H. Wake

University of California, Berkeley


Many animals spend their lives on fine wind-blown sand. Given this, it is surprising that so little is known about the elements of an animal's body form that may aid in locomotion over sand. Much like snowshoes aid humans moving on snow, previous investigations have suggested that lizards that possess toe fringes (sideways projecting elongate scales) are adapted to running on sand, but this hypothesis has yet to be rigorously tested. In this study, the investigators will study the rapid running of three closely related sand dwelling lizards: the Mojave fringe-toed lizard (Uma scorparia), and non-fringed California (Callisaurus draconoides draconoides) and fringed Mexican (Callisaurus draconoides crinitis) subpopulations of the zebra-tailed lizard. Two general questions will be addressed in this work: 1. do fringes on the toes of lizards help them run on sand? and 2. how does variation in foot shape affect the transmission of forces from the animal to the sandy substrate? This work approaches these questions by synthesizing the fields of organismal biology, evolutionary biology, mechanical engineering, and granular physics. The researchers will use video cameras capable of recording 1000 images per second (standard cameras record at 30 images per second) to slow down the movement of animals in their natural environments as they run on a number of different substrates. Information gathered will be used to construct a robotic appendage to which models representing the diversity of foot shapes found in many different species of lizards will be attached. By "playing back" the movement patterns recorded in the field on the robotically controlled feet, the investigators will be able to measure the forces generated by different foot shapes through substrates where the lizards live. From these studies, the effect of changes in foot shape in propelling the animals forward can be directly measured. This work is one of the first to investigate how animals run on different substrates, and whether there are particular foot shapes that may be more effective for rapid movements on sand.

0334939
Wake and Wake
A grant has been awarded to Drs. David Wake and Marvalee Wake at the University of California at Berkeley, as part of a four-institution collaboration, to study phylogenetic relationships of the living amphibians and their close fossil relatives. Living Amphibians are a prominent part of the Earth's vertebrate fauna and include three orders: the caecilians (Gymnophiona), salamanders (Caudata), and frogs and toads (Anura). Despite recent advances in discovering and describing their diversity, many critical questions in amphibian evolution remain unresolved and a fresh analysis of evolutionary relationships is needed to take new discoveries into account. Furthermore, the recent decline and apparent extinction of amphibians from many environments makes it urgent that we discover and classify the diversity present today. A team of seven investigators from diverse institutions (University of Texas at Austin, University of California at Berkeley, Harvard University, and the University of Kansas) and their colleagues will collaborate to resolve modern amphibian relationships. Field sampling in biodiversity hotspots will provide materials of new or previously unsampled lineages. Anatomical and morphological data from living and fossil forms will be combined with DNA sequences from a set of defined mitochondrial and nuclear genes for as many species as possible, and will be integrated with existing data sets. Analysis of these large data sets will be used to gain insight into such questions as repeated patterns of evolution, geographic patterns, and rates of evolution. Drs. Wake and Wake and their students and colleagues will focus on molecular and morphological studies of caecilians and salamanders, with targeted field work in South America and Africa, and will have special responsibility for the AmphibiaWeb component, as well as contributing to the overall integration of molecular and morphological datasets for phylogenetic analysis.
Understanding the evolutionary history of modern amphibians is critical for developing conservation strategies for amphibians as well as completing the vertebrate portion of the tree of life. The project will involve extensive student training and interaction with US and international colleagues. Communication with the public will utilize web resources, especially AmphibiaWeb, an existing site that will be expanded and further developed to provide information on all species of amphibians for professionals and the public at large. AmphibiaWeb will also provide training opportunities for students and senior professionals to enable them more effectively to communicate their findings.

Congresses of Vertebrate Morphology are held every three years in order to allow scientists who work on the morphology, sensu lato, of vertebrates to share research and learn techniques, while perhaps gaining new insight into their own systems. By bringing together leaders and innovators and students of complimentary subdisciplines, new syntheses and integration are likely to occur. Because of the participation of members of the Congress from many different countries, perspectives about research itself, and the styles of conduct of the scientific enterprise in different countries can be shared, increasing understanding of the global enterprise. The 9th Congress will be held in Latin America for the first time, and will facilitate greater participation of colleagues from that part of the world, and new international collaborations may well develop.

The Congress will involve established researchers as well as younger scholars. The plenary lectures and the symposia are structured so that a great diversity and broad scope of approaches, techniques, and taxa are considered. This will encourage exciting discussion, collaborations and syntheses, and integration of formerly separate subfields of biology and the physical sciences, as has occurred in previous such congresses with the initiation of 'evo-devo'. In addition we will provide to the membership a workshop that will introduce organismal biologists to 3-D x-ray techniques. Thus the Congress will have unique intellectual merit in providing excellent science to a wide range of biologists and facilitating extensive discussion among international scientists.
Reports on the Congress and research discussions will be posted on the ISVM website, which will be maintained long after the Congress ends in order to allow communication.

Broader impacts - In addition to the broader impacts outlined above relating to (1) integration and communication of research, (2) enhancement of research infrastructure through the encouragement of partnerships and collaborations, and (3) broad dissemination of research, we seek to broaden the participation colleagues from many countries whose participation has been limited at previous Congresses, and to encourage the involvement of young scholars from the US so that their understanding of international science is enhanced. We specifically encourage the participation of younger scholars, and of women, while welcoming an internationally and experientially diverse group of participants, which will expand the US science enterprise of the near future.