Citation:

Jaeger, J R., B. R. Riddle, AND D F. Bradford. CRYPTIC NEOGENE VICARIANCE AND QUATERNARY DISPERSAL OF THE RED-SPOTTED TOAD (BUFO PUNCTATUS) INSIGHTS ON THE EVOLUTION OF NORTH AMERICAN WARM DESERT BIOTAS. MOLECULAR ECOLOGY. Blackwell Publishing, Malden, MA, 14:3033-3048, (2005).

Impact/Purpose:

The primary objectives of this research are to:

Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;

Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;

Develop and validate multivariate models based on quantification studies;

Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;

Complete an initial draft (potentially web based) of a national landscape condition assessment.

This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.

Description:

We define the geographic distributions of embedded evolutionary mitochondrial DNA (mtDNA) lineages (clades) within a broadly distributed, arid- dwelling toad, Bufo punctatus, and evaluate these patterns as they relate to hypothesized vicariant events leading to the formation of biotas associated with the major warm desert regions of western North America. To complement deeper scale phylogenetic analyses, we nested parsimony-based haplotype networks within the major identified evolutionary lineages and applied nested clade analysis (NCA) to further elucidate and evaluate more recent phylogeographic patterns potentially associated with Quaternary (Pleistocene-Holocene) vicariance and dispersal. We assessed mtDNA variation among 187 samples from 80 sites located throughout most of the species range. Phylogenetic analyses provided strong support for three monophyletic clades within B. punctatus. Sequence divergences among these major clades were almost identical, and phylogenetic analyses revealed no support for any particular branching order among the clades. The observed divergence levels and congruence with postulated events in earth history implicate a Late Neogene (Late Miocene-Pliocene) time-frame for the separation of the major mtDNA lineages.
The geographic distributions of haplotypes within the three major clades showed little overlap and corresponded to the general boundaries of the Peninsular Desert, and two continental desert clades, Eastern (Chihuahuan Desert-Colorado Plateau) and Western (Mojave-Sonoran deserts), geographically separated along the Rocky Mountains and the Sierra Madre Occidental (roughly the continental divide). Evaluation of nucleotide and haplotype diversity and interpretations from NCA revealed that Eastern clade populations on the Colorado Plateau are a result of recent range expansion, most likely post-Pleistocene, from populations in the Chihuahuan Desert. The Western clade appears to have maintained some populations within the Mojave Desert during recent Pleistocene times. We identified two locations where the major continental clades are in current contact and speculate as to why the observed deep phylogeographic structure has not been eroded during the multiple previous interglacials during the Pleistocenerecent range expansion, most likely post-Pleistocene, from populations in the Chihuahuan Desert. The Western clade appears to have maintained some populations within the Mojave Desert during recent Pleistocene times. We identified two locations where the major continental clades are in current contact and speculate as to why the observed deep phylogeographic structure has not been eroded during the multiple previous interglacials during the Pleistocene.

Record Details: