Showing papers by "A. Townsend Peterson published in 2006"

Novel methods improve prediction of species' distributions from occurrence data

Abstract: Prediction of species' distributions is central to diverse applications in ecology, evolution and conservation science. There is increasing electronic access to vast sets of occurrence records in museums and herbaria, yet little effective guidance on how best to use this information in the context of numerous approaches for modelling distributions. To meet this need, we compared 16 modelling methods over 226 species from 6 regions of the world, creating the most comprehensive set of model comparisons to date. We used presence-only data to fit models, and independent presence-absence data to evaluate the predictions. Along with well-established modelling methods such as generalised additive models and GARP and BIOCLIM, we explored methods that either have been developed recently or have rarely been applied to modelling species' distributions. These include machine-learning methods and community models, both of which have features that may make them particularly well suited to noisy or sparse information, as is typical of species' occurrence data. Presence-only data were effective for modelling species' distributions for many species and regions. The novel methods consistently outperformed more established methods. The results of our analysis are promising for the use of data from museums and herbaria, especially as methods suited to the noise inherent in such data improve.

Predicting species distributions from small numbers of occurrence records: A test case using cryptic geckos in Madagascar

Abstract: Aim: Techniques that predict species potential distributions by combining observed occurrence records with environmental variables show much potential for application across a range of biogeographical analyses. Some of the most promising applications relate to species for which occurrence records are scarce, due to cryptic habits, locally restricted distributions or low sampling effort. However, the minimum sample sizes required to yield useful predictions remain difficult to determine. Here we developed and tested a novel jackknife validation approach to assess the ability to predict species occurrence when fewer than 25 occurrence records are available. Location: Madagascar. Methods: Models were developed and evaluated for 13 species of secretive leaf-tailed geckos (Uroplatus spp.) that are endemic to Madagascar, for which available sample sizes range from 4 to 23 occurrence localities (at 1 km2 grid resolution). Predictions were based on 20 environmental data layers and were generated using two modelling approaches: a method based on the principle of maximum entropy (Maxent) and a genetic algorithm (GARP). Results: We found high success rates and statistical significance in jackknife tests with sample sizes as low as five when the Maxent model was applied. Results for GARP at very low sample sizes (less than c. 10) were less good. When sample sizes were experimentally reduced for those species with the most records, variability among predictions using different combinations of localities demonstrated that models were greatly influenced by exactly which observations were included. Main conclusions: We emphasize that models developed using this approach with small sample sizes should be interpreted as identifying regions that have similar environmental conditions to where the species is known to occur, and not as predicting actual limits to the range of a species. The jackknife validation approach proposed here enables assessment of the predictive ability of models built using very small sample sizes, although use of this test with larger sample sizes may lead to overoptimistic estimates of predictive power. Our analyses demonstrate that geographical predictions developed from small numbers of occurrence records may be of great value, for example in targeting field surveys to accelerate the discovery of unknown populations and species. © 2007 The Authors.

Uses and requirements of ecological niche models and related distributional models

Abstract: Modeling approaches that relate known occurrences of species to landscape features to discover ecological properties and predict geographic occurrences have seen extensive recent application in ecology, systematics, and conservation. A key component in this process is estimation or characterization of species' distributions in ecological space, which can then be useful in understanding their potential distributions in geographic space. Hence, this process is often termed ecological niche modeling or (less boldly) species distribution modeling. Applications of this approach vary widely in their aims, products, and requirements; this variety is reviewed herein, examples are provided, and differences in data needs and possible interpretations are discussed.

Ecologic niche modeling and spatial patterns of disease transmission.

Abstract: Ecologic niche modeling (ENM) is a growing field with many potential applications to questions regarding the geography and ecology of disease transmission. Specifically, ENM has the potential to inform investigations concerned with the geography, or potential geography, of vectors, hosts, pathogens, or human cases, and it can achieve fine spatial resolution without the loss of information inherent in many other techniques. Potential applications and current frontiers and challenges are reviewed.

Invasive potential of common carp (*Cyprinus carpio*) and Nile tilapia (*Oreochromis niloticus*) in American freshwater systems

Abstract: Nonnative fish introductions disrupt ecosystem processes and can drive native species to local extinction. Two of the most widespread, introduced species are the common carp (Cyprinus carpio) from Eurasia and the Nile tilapia (Oreochromis niloticus) from Africa. In North and South America, these introductions stem from aquaculture facilities, as well as historical introductions for recreational angling. An emergent field of ecological niche modeling provides robust predictions of the geographic potential of alien species to better understand their capacity to become established at broad scales. We used this modeling approach to produce spatially explicit predictions of the invasive potential of common carp and Nile tilapia in the Americas. Model predictions were tested using occurrence data for established populations in their native area and in the Americas. Results indicated that predictive power of niche mod- els was high. Distributional potential of common carp in the Americas covers most temperate regions and high moun- tain tropical aquatic systems, whereas that of Nile tilapia is focused in the tropics and coast areas. The consequences of the potential establishment of these exotic species can be profound on native aquatic faunas, particularly on highly diverse regions such as the Amazon Basin and central Mexico. Resume : Les introductions de poissons non indigenes perturbent les processus ecosystemiques et peuvent causer l'extinction locale d'especes indigenes. Deux des especes les plus generalement introduites sont la carpe commune (Cyprinus carpio) d'Eurasie et le tilapia du Nil (Oreochromis niloticus) d'Afrique. En Amerique du Nord et du Sud, ces introductions proviennent des etablissements d'aquaculture, ainsi que des empoissonnements passes pour la peche sportive. Un domaine en emergence de la modelisation des niches ecologiques permet de faire des predictions robustes sur le potentiel geographique d'especes exotiques et ainsi de comprendre leur capacite a s'etablir sur de larges espaces geographiques. Cette approche de modelisation nous a permis de faire des predictions explicites du point de vue spatial concernant le potentiel d'invasion de la carpe commune et du tilapia du Nil dans les Ameriques. Nous avons teste les predictions du modele a l'aide de donnees de presence de populations etablies dans leur aire d'origine et dans les Ameriques. Les resultats montrent que le pouvoir predictif des modeles de niches sont eleves. Le potentiel de reparti- tion geographique de la carpe commune dans les Ameriques englobe la plupart des regions temperees et les ecosyste- mes aquatiques tropicaux de haute montagne; en revanche, le tilapia du Nil se concentre surtout dans les tropiques et les regions cotieres. L'etablissement potentiel des ces especes exotiques peut avoir de graves consequences sur les fau- nes aquatiques indigenes, particulierement dans les regions de forte diversite, telles que le bassin de l'Amazone et le centre du Mexique.

Geographic potential for outbreaks of marburg hemorrhagic fever

Abstract: Marburg virus represents one of the least well-known of the hemorrhagic fever-causing viruses worldwide; in particular, its geographic potential in Africa remains quite mysterious. Ecologic niche modeling was used to explore the geographic and ecologic potential of Marburg virus in Africa. Model results permitted a reinterpretation of the geographic point of infection in the initiation of the 1975 cases in Zimbabwe, and also anticipated the potential for cases in Angola, where a large outbreak recently (2004-2005) occurred. The geographic potential for additional outbreaks is outlined, including in several countries in which the virus is not known. Overall, results demonstrate that ecologic niche modeling can be a powerful tool in understanding geographic distributions of species and other biologic phenomena such as zoonotic disease transmission from natural reservoir populations.

Ecological niche modelling and prioritizing areas for species reintroductions

Abstract: Species reintroduction programmes, in prior- itizing areas for reintroductions, have traditionally used tools that include measures of habitat suitability and evaluations of area requirements for viable populations. Here we add two tools to this approach: evaluation of ecological requirements of species and evaluation of future suitability for species facing changing climates. We demonstrate this approach with two species for which reintroduction programmes are in the planning stages in Mexico: California condor Gymnogyps califor- nianus and Mexican wolf Canis lupus baileyi. For the condor, we identify three areas clustered in the Sierra San Pedro Martir, Baja California; for the wolf, we identify a string of suitable sites along the Sierra Madre Occidental of western Mexico. We discuss the limita- tions of this approach, identifying ways in which the models illustrated could be made more realistic and directly useful to reintroduction programmes.

Pleistocene fragmentation of Amazon species' ranges

Abstract: Historical patterns of connection and isolation of the impressive biological diversity of the Amazon Basin have been the subject of extensive debate, based on evidence drawn from distributional patterns of endemic species, vegetation histories from palynological studies, and geological studies. We develop species-specific ecological niche models based on current occurrence patterns of 17 species of birds and woody plants, which we project onto modelled Pleistocene (Last Glacial Maximum) climatic patterns to reconstruct past potential distributions of each species. Forest species’ distributions showed fragmentation at Last Glacial Maximum and these fragments were coincident spatially, whereas savanna species showed no clear trends. Our results suggest that past climate changes fragmented forest species’ ranges within a matrix of uncertain composition.

Global invasive potential of 10 parasitic witchweeds and related Orobanchaceae.

Abstract: The plant family Orobanchaceae includes many parasitic weeds that are also impressive invaders and aggressive crop pests with several specialized features (e.g. microscopic seeds, parasitic habits). Although they have provoked several large-scale eradication and control efforts, no global evaluation of their invasive potential is as yet available. We use tools from ecological niche modeling in combination with occurrence records from herbarium specimens to evaluate the global invasive potential of each of 10 species in this assemblage, representing several of the worst global invaders. The invasive potential of these species is considerable, with all tropical and subtropical countries, and most temperate countries, vulnerable to invasions by one or more of them.

Niche differentiation and fine-scale projections for argentine ants based on remotely sensed data

Abstract: Modeling ecological niches of species is a promising approach for predicting the geographic potential of invasive species in new environments. Argentine ants (Linepithema humile) rank among the most successful invasive species: native to South America, they have invaded broad areas worldwide. Despite their widespread success, little is known about what makes an area susceptible—or not—to invasion. Here, we use a genetic algorithm approach to ecological niche modeling based on high-resolution remote-sensing data to examine the roles of niche similarity and difference in predicting invasions by this species. Our comparisons support a picture of general conservatism of the species' ecological characteristics, in spite of distinct geographic and community contexts.

Climate change effects on Neotropical manakin diversity based on ecological niche modeling

Abstract: ABSTRACT Assessing the nature and magnitude of potentialeffects of climate change on populations isimportant to anticipating effects on speciesdiversity for conservation planning. We usedecological niche modeling to predict present andfuture distributions of 49 species of manakins(Pipridae) and allies. Predictions forpresent-day distributions were highly coincidentwith independent test data, suggesting goodpredictive ability. Assuming no dispersal,projections of potential distributions underfour scenarios of climate change predicted that20% of manakin species would likely goextinct from their current ranges, and thatdistributions would in general be reduced andfragmented, regardless of the area ofpresent-day potential distribution or rarity.Predicted changes in potential distributions,spatial configuration of suitable habitats, andgeographic position of species ranges were moredramatic for species inhabiting flatlands thanfor montane species. These results are anexample of how ecological niche mo...

Global invasive potential of the house crow Corvus splendens based on ecological niche modelling

Abstract: Summaries of recent rapid range expansions shown by the house crow Corvus splendens have provided insights into the global nature of this invasion process, but its long-term potential has not yet been evaluated. To explore the potential dimensions of this geographic expansion, we used ecological niche modeling based on known occurrences of the species on its native distributional area, in the context of GIS data sets describing climatic variables, topographic information, and human presence. Our models provided predictions of areas already invaded that were statistically significantly more coincident than expected under random (null) models. The predicted potential range of the species includes areas already affected, as well as potentially suitable areas in Central America, the Caribbean, equatorial and West Africa, and mainland and insular Southeast Asia, not yet colonized.

Taxonomy is important in conservation: a preliminary reassessment of Philippine species-level bird taxonomy

Abstract: Alpha taxonomy involves delineation of the basic unit of biology: the species. The concepts by which we define species, however, have been controversial, with several alternatives competing at present, some creating fewer and some more species units, depending on interpretation of species limits. Although it is tempting to assume that species concepts would have little interaction with the geographic foci of species richness and endemism — and some have so argued — this assumption does not withstand careful analysis. In this paper, I develop a first-pass assessment of Philippine bird taxonomy under an alternative species concept, and compare the results with the traditional biological species concept lists. Differences between the two lists were dramatic, but not just in numbers of species; rather, new, previously unrecognized or previously underappreciated foci of endemism were noted. A thorough understanding of the taxonomic basis of species lists is therefore critical to conservation planning.

Native-range ecology and invasive potential of Cricetomys in North America.

Abstract: African giant pouched rats (Cricetomys) are native to tropical Africa, where they range from Senegal and Gambia east across West Africa and the Congo Basin to the Indian Ocean coast of East Africa. Ecological niche models show that Cricetomys species differ in their invasive potential. Although neither of the presently recognized Cricetomys species appears to have genuinely broad distributional potential in North America, models predict that C. emini would have extremely restricted distributional potential, whereas C. gambianus would have a broader potential across the southeastern United States.

Application of molecular clocks in ornithology revisited

Abstract: Molecular clocks have seen many applications in ornithology, but many applications are uncritical. In this commentary, I point out logical inconsistencies in many uses of clocks in avian molecular systematics. I call for greater rigor in application of molecular clocks – clocks should only be used when clocklike behavior has been tested and confirmed, and when appropriate calibrations are available. Authors and reviewers should insist on such rigor to assure that systematics is indeed scientific, and not just storytelling.

Hundred-year changes in the avifauna of the Valley of Mexico, Distrito Federal, Mexico

Abstract: Resumen en: Species lists were compiled for the Valley of Mexico from the nineteenth century and from 1950-present. Of a total of 401 species, 228 were documented t...

Vegetation-index models predict areas vulnerable to purple loosestrife (lythrum salicaria) invasion in kansas

Abstract: Purple loosestrife (Lythrum salicaria) constitutes an invasive species detrimental to wetland habitats in North America. To estimate areas vulnerable to it in Kansas, we modeled the potential geographic distribution of the species by using current records in the state, remotely sensed vegetation- index data from the Moderate Resolution Imaging Spectrometer (MODIS), and the Genetic Algorithm for Rule-Set Prediction (GARP). Models built using only localities from northeastern Kansas (the origin of invasion within the state) consistently predicted test localities in other parts of the state with negligible omission. An additional analysis using records from all counties where the species is known showed a similar prediction. All models indicated suitable conditions for purple loosestrife in much of eastern and central Kansas, as well as in riverine and irrigated areas in the western part of the state. The approach presented here might prove useful for assessing the regional colonization potential of other newly detected invasive species before other studies can be undertaken.

Predicting invasive potential of smooth crotalaria (Crotalaria pallida) in Brazilian national parks based on African records

Abstract: Alien weed species rank among the most important threats to conservation of biodiversity, making understanding the extent to which protected natural areas are vulnerable to invasion by weeds pivotal in long-term maintenance and conservation of biodiversity. We investigated the potential geographic range of the invasive paleotropical weed, smooth crotalaria, in protected natural areas across Brazil. The ecological niche dimensions of smooth crotalaria in Africa (its putative original distribution) were modeled using a genetic algorithm. Models for the native range and their projections to South America showed good predictive ability when challenged with independent occurrence data. All Brazilian protected natural areas were predicted as highly vulnerable to invasion by this species. However, smooth crotalaria appears more likely to occur in open (savanna-like vegetation, such as cerrado and pantanal) and highly fragmented (Atlantic forest) areas than in extensive closed forests (Amazon). Managemen...

Consistency of Taxonomic Treatments: A Response to Remsen (2005)

Abstract: This is the publisher's version, also available electronically from http://www.bioone.org/doi/abs/10.1642/0004-8038%282006%29123%5B885%3ACOTTAR%5D2.0.CO%3B2.

Potential geographic distribution of the Bugun Liocichla Liocichla bugunorum, a poorly-known species from north-eastern India

Abstract: Peterson, A. T. & Pape , M. 2006. Potential geographic distribution of the Bugun Liocichla Liocichla bugunorum, a poorly-known species from north-eastern India. Indian Birds 2 (6): 146–149. A. Townsend Peterson, Natural History Museum & Biodiversity Research Center, The University of Kansas, Lawrence, Kansas 66045, U.S.A. Email: town@ku.edu. Monica Papeo, Natural History Museum & Biodiversity Research Center, The University of Kansas, Lawrence, Kansas 66045, U.S.A.