Gerstner Scholar Profiles

2015-2017

Dr. James Herrera

Herrera

Research Focus – For my postdoctoral fellowship, I am expanding my prior studies of diversification to investigate the mode and tempo of primate evolution. I am investigating how diversification has varied with biogeography, time, paleoenvironments and community composition for all primates across the globe and in deep time.

The first step is to infer a combined phylogeny for all primates, including both extinct and living taxa. I am gathering published and new morphological data for living and fossil primates from museum collections, including the extraordinary collections at the AMNH. I will combine these with molecular data available for almost all living species and several subfossil species. I then will apply a total evidence dating approach that determines the inferred speciation and extinction rates of the tree based on the fossils included in the analyses.

The second step is to compare speciation and extinction dynamics inferred from the phylogeny of only living species to those inferred from fossils. Estimates of speciation and extinction have been made from phylogenies of only living species, but the validity of these methods is contentious. I will compare the diversification dynamics estimated from different methods and test the most likely processes explaining diversification dynamics in deep time over the 65 million year history of Primates. I will quantify how species diversity varies across the evolutionary tree and test if age, diversification rate, biogeography and intrinsic traits explain the variation in observed species diversity.

My research also investigates the biogeography and community ecology in Madagascar by expanding from my previous studies of lemurs to include more taxonomic groups, including bats, carnivores, tenrecs, birds, amphibians, reptiles, fishes, and plants. I am seeking collaborations with specialists in these other groups to test if the patterns observed for lemurs hold for other groups as well. Finally, I am collaborating with other researchers to quantify the habitat loss around the measured communities to assess their threat status.

Biography -James Herrera received his Bachelors in Arts degree in 2009 from the University of Miami (FL) in Anthropology. He then earned his Master of Arts degree in 2011 from Stony Brook University (NY) in Anthropology and received his Ph.D. in 2015 from the Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University (NY).


Dr. Brendan Reid

BR_AMNH_websitepic

Research Focus – My research interests lie in understanding and conserving turtle diversity.  Turtles represent both an enormously charismatic and highly threatened group of reptiles, with approximately two-thirds of all turtle species considered to be at risk of extinction.  They are morphologically and biogeographically extremely distinctive.  While many other taxonomic groups are at their most diverse in the tropics, turtles instead exhibit their highest levels of species diversity in subtropical areas.  In fact, the United States is home to more turtle species than any other nation, and the southeastern US is considered to be a global hotspot of turtle diversity.  A better understanding of the processes responsible for creating and maintaining turtle diversity will help us understand how this diversity has survived in the face of shifting climates and habitats over the past several million years and how turtles may fare in the future.

Several roadblocks, however, still exist to understanding turtle diversity.  Reproductive barriers among turtle taxa develop slowly, and ancient introgression as well as contemporary gene flow can obscure our understanding of past and ongoing speciation processes.  Turtle DNA in general evolves relatively slowly compared to other vertebrate groups, and some recently-diverged turtle groups that exhibit a great deal of morphological diversity (such as the American map turtles) are still highly similar or identical for many traditional molecular markers used in evolutionary studies.

For my research at the AMNH, I will generate genomic single nucleotide polymorphism (SNP) data for an array of turtle species, focusing on pond turtles (family Emydidae) and mud turtles (family Kinosternidae) in North America.  These data will be used to refine our understanding of recent evolution in these groups as well as to test hypotheses generated from paleophylogeographic species distribution models (which use present-day ranges, past climate reconstructions, and phylogenetic relationships to project species’ distributions into the past and to infer changes in distribution over time).  By explicitly incorporating genetic data into range modeling, I intend to improve our understanding of how species’ ranges change over time, discriminate the effects of different potential drivers of species distributions (including climatic tolerances, local adaptation, and competitive interactions), and develop more accurate methods for predicting future changes in species ranges and the distribution of biodiversity.

Biography - Brendan Reid received his Masters degree in Conservation Biology from Columbia University in 2009.  His Masters thesis project on genetic barcoding of turtles developed from a research internship at the AMNH, where he worked extensively with Museum research associates Dr. Eugenia Naro-Maciel and Dr. Minh Le.  He has continued to work on various research topics (ranging from the genetic structure of spiny lobsters and New Guinea snapping turtles to the historical demography of green sea turtles) with AMNH scientists and other collaborators in the years since.  For his Ph.D., Brendan studied under Dr. Zach Peery at the University of Wisconsin-Madison, where he investigated the ecology and conservation status of three wetland turtle species (including the endangered Blanding’s turtle) in the Midwest using demographic and landscape genetic approaches, obtaining his doctorate in 2015.


Dr. Nelson Salinas

Salinas

Research Focus – I am trained as a botanist and have worked on Neotropical plant diversity over the last 15 years. Most of my previous research has been devoted to either floristics of the NW Amazon flora, or systematics of Neotropical plant groups, including blueberries (family Ericaceae), bromeliads (Bromeliaceae), and spiral gingers (Costaceae). More recently, I have become interested in biogeography, particularly in the estimation of ancestral ranges of tropical taxa, such as Ericaceae, and improving the delimitation of their geographical areas of endemism.

 As a Gerstner Scholar, I am continuing my research on biogeography from a bioinformatics perspective. My current project aims to assess the adequacy of statistical models to describe patterns of geographic distributions of a variety of organisms. Attaining such a widely-applicable class of models will allow biogeographers to advance new tools for analysis, helping to incorporate uncertainty of geographical distribution data into historical range reconstructions and to implement more elaborate hypothesis testing procedures. As a first approximation to these models, I am beginning by developing an algorithm to infer areas of endemism, that is, geographic regions to which two or more taxa are likely to be restricted. This new algorithm will be tested against both simulated and empirical data, and implemented as a Python program that will be available to other researchers.

The empirical part of my Gerstner Scholar project includes biogeographic analyses of Neotropical blueberries (Ericaceae: Vaccinieae). These plants are ecologically important elements of the montane flora across Latin America, where they are usually found in well-preserved rain forests. Most species are epiphytic shrubs, which have bright, colorful flowers that are often pollinated by hummingbirds. Their diversity (around 600 species) and multiplicity of distribution patterns (from narrow endemics to widespread taxa) make them an excellent group to examine the efficacy of different methods to uncover areas of endemism.

Biography - Nelson Salinas received his B.Sc. in 2004 from the Universidad Nacional de Colombia, and his Ph.D. in 2015 in Biology from the City University of New York, in collaboration with the New York Botanical Garden. His doctoral research was focused on the taxonomy, phylogenetics, and biogeography of Neotropical blueberries.


2014-2016

Dr. Abigail Curtis

Curtis

Research Focus – I am studying the role of paranasal sinuses in the evolution of morphological disparity and species diversity in bats using microCT scans. Paranasal sinuses are air-filled cavities in the bones surrounding the nasal chamber in mammals that appear to opportunistically develop in space where bone is mechanically unnecessary. Sinuses functionally decouple the inner and outer tables of the bones they pneumatize, which may allow external skull shape to be more easily modified without affecting the morphology of more functionally constrained regions, such as the nasal chamber and braincase. Thus, paranasal sinuses may facilitate evolution of skull size and shape disparity. Bats are an excellent framework in which to test this hypothesis because they represent over one fifth of living mammals species, and show remarkable disparity in skull size and shape. Clades of bats that show the greatest species diversity also show some of the greatest morphological disparity, and the literature suggests that some species with highly derived morphologies also have unusual sinus morphologies that have yet to be described. My work will provide the first quantitative data on bat paranasal sinuses, and will generate a large collection of CT scans from AMNH specimens. This research will aid our understanding of how mammal skulls evolve to meet the demands of differing diets, and may reveal factors that facilitate evolution of cranial shape disparity and allow species to adopt novel ecologies.

Biography - Abigail Curtis received her Ph.D. in Biology at UCLA in 2014, and was advised by Dr. Blaire Van Valkenburgh. She earned her B.S. in Biological Sciences from SUNY at Albany in 2008. Her interest in anatomy and functional morphology was sparked during her time as a mammalogy research and collections intern at the New York State Museum during her junior and senior years of college. This experience also gave her an appreciation for museums as an invaluable resource to the scientific community as well as the public.


Dr. Steven Davis

Davis

Research Focus - My research centers in weevil (Curculionoidea) systematics, exploring the morphology, patterning, and evolutionary development of these remarkably diverse and curious beetles. My research centers in weevil (Curculionoidea) systematics, exploring the morphology, patterning, and evolutionary development of these remarkably diverse and curious beetles. While my interests are strongly nested within comparative morphology and weevil systematics, I desire to employ a broad range of tools in evolutionary biology to better understand the taxonomy, classification, and evolution of one of the largest radiations in the tree of life.

Emanating from these interests, I have been integrating techniques of evo-devo and developmental biology to better understand the genetic basis of morphological structure and evolution. I began by exploring the development and patterning of the weevil rostrum, a feature of this group which is believed to represent a key evolutionary innovation permitting them to undergo a spectacular radiation.

Current and future work includes understanding the specific functions of these genes, their expression patterns, and determine the utility of such developmental data in a comparative phylogenetic context, using RNA interference (RNAi) and in situ hybridization. While it is a primary goal to understand how the rostrum forms (i.e., how the head elongates), throughout the weevil superfamily, this structure (defined as an extension of various head segments and bearing the mouthparts at the apex) has also magnificently diversified into countless forms and demonstrates amazing modifications traversing the different weevil lineages. The rice weevil, Sitophilus oryzae, has been the main experimental candidate for this research, though other weevil taxa which transcend the range of rostral diversity, are significant to agriculture and forestry, and can be reared in the laboratory, are being utilized for comparison, including Dendroctonus ponderosae (Mountain Pine Beetle), Diaprepes abbreviatus (Citrus Root Weevil), Hypothenemus hampei (Coffee Berry Borer), and Curculio spp. (Acorn Weevils).

Weevils, however, are not the only beetles (nor insects) to possess a rostrum. Other insect groups, such as Diptera (flies), Lepidoptera (moths and butterflies), Hemiptera (true bugs), and Siphonaptera (fleas), possess structures that resemble a rostrum, though these structures are formed through elongation of different mouthparts. Of the insect groups that bear a true rostrum, including various lineages within Coleoptera (beetles), Hymenoptera (bees and wasps), and Mecoptera (scorpionflies), weevils have maximized the diversity in rostral forms. As a comparison to weevil rostrum formation and patterning, rostrum development in lineages within Lycidae (Net-winged beetles) and Mecoptera also is being investigated.

New insect systems in developmental biology are being developed through such developmental research, in which the relationships between morphological change and structural genes responsible for phenotypic change are examined. These results will also have remarkable influence in understanding homology statements in phylogenetics, can be used in phylogenetic reconstruction, and can allow for rigorous interpretation of character and developmental evolution across groups. Examination of rostrum formation in other beetle families and insect orders will address a key question in evolutionary developmental biology concerning the degree of novelty of evolutionary innovations and convergence of morphological features.

Biography - Steve Davis received his B.S. in entomology from the University of Maryland, College Park, in 2005, completing his undergraduate thesis with Dr. Charles Mitter (UMCP) and Dr. Patricia Gentili-Poole (Smithsonian, USNM) on carpenter moth (Cossidae) systematics; thesis entitled " A revision of the Cossulinae of Costa Rica and cladistic analysis of the world species (Lepidoptera: Cossidae)." He went on to complete his M.A. in entomology from the University of Kansas in 2008, studying weevil systematics with Dr. Michael Engel, the thesis entitled " Morphology and phylogeny of the weevil subfamily Baridinae (Coleoptera: Curculionidae)." He then continued on at Univ. of Kansas with Dr. Engel to receive his Ph.D. in 2014 studying weevil systematics, morphology, and evolutionary developmental biology.


Dr. Christopher Martinez

Martinez

Research Focus – I am broadly interested in the evolution of form and function and enjoy applying morphological analyses in different systems. During my Ph.D. I assessed the diversity of pectoral fin shape in batoids and also linked sexual dimorphism in skate fins to the development of their reproductive organs. Currently, my research as a Gerstner Scholar is focused on understanding modes of oral jaw diversification in teleost fishes. I am primarily working on two of the lesser-known cichlid subfamilies, Etroplinae and Ptychochrominae. Etroplinae includes two genera, Etroplus of India/Sri Lanka and Paretroplus, whose species are endemic to Madagascar. Ptychochrominae consists of five genera that are also endemic to Madagascar. Variation in overall body form and jaw morphology is larger in the ptychochromines, although etropline cichlids also display interesting morphological patterns that appear to be habitat specific.

I am using geometric morphometrics to quantify and compare morphological diversity of body shape and internal structure of oral jaws between the two cichlid subfamilies. In addition, I am evaluating jaw variation in terms of a four-bar linkage system, which has been used as a model for jaw mechanics in a number of fish groups. As an essential component of this research, we are currently updating the phylogenetic relationships of Malagasy and South Asian cichlids in order to estimate ancestral states of jaw form and their corresponding functional properties. This information will be used in a modeling framework that is designed to simulate hypothetical morphological pathways that represent transitions between functional states of ancestors to that of their descendants. Due to the complex nature of the form-function relationship in four-bar linkages, we expect starting ancestral morphologies to be a vital determinant of the ability and ease by which a species may respond to selection for new functional states. This research will give us valuable context with which to understand current jaw diversity and will also provide a framework to pursue a number of questions. For instance, among species whose jaws are suited to a diet of snails (durophagy), which is most likely to evolve the ability to capture mobile prey (e.g. piscivory)?

Biography – Christopher Martinez received his B.Sc. from the University of California, Santa Barbara in 2006 where he researched a mutualistic relationship between corals and amphipods. He completed his Ph.D. at Stony Brook University in 2014, with his dissertation research concerning the morphological diversity of batoid fishes (i.e. skates and rays) and also spatial modeling of marine communities.