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HISTORICAL PATTERNS OF HABITAT CHANGES AND GENETIC DIVERGENCE IN THE DESERT AND SHORT HORNED LIZARDS
Jones, K. B. HISTORICAL PATTERNS OF HABITAT CHANGES AND GENETIC DIVERGENCE IN THE DESERT AND SHORT HORNED LIZARDS. Presented at Annual Horne Lizard Conservation Society Symposium, Portal, AZ, October 20-21, 2000.
Historical environmental change is thought to have played an important role in the diversification of the biota of western North America. Many patterns of diversification have been associated with glacial-interglacial cycles of the latest Pleistocene. To evaluate the relative influence of old and recent historical environmental change on lineage diversification, mitochondrial DNA of the short-horned lizard (Phrynosoma douglasi) and the desert homed lizard (Phrynosoma platyrhinos) were analyzed. Both species are widespread and have relatively old histories in western North America. The short-horned and desert homed lizards demonstrated multiple scales of lineage diversification representing responses to relatively old and recent historical environmental change. Deep levels of divergence in short-homed lizards were structured geographically among Kuchler Physiographic regions and were temporally concordant with the late Tertiary uplift of the western North American cordillera. The desert homed lizard demonstrated a deep divergence between the southern Sonoran Desert and the remainder of the species' range. The depth of lineage diversity in both lizards was concordant with a model of habitat change during the last glacial maximum. Regions that maintained large patches of suitable habitat during the last glacial maximum had deep levels of divergence whereas regions that lost large areas of suitable habitat had shallow levels of within-region divergence. The phylogeographic patterns of the two species, and results of simulated habitat change, do not support a model of mass habitat shift to the south in response to glaciation. Rather, results of this study suggest that suitable habitats and populations persisted in many areas within the current ranges of both species ranges during the last glacial maximum, although the distribution of the desert homed lizard was more limited.
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.
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LAB
ENVIRONMENTAL SCIENCES DIVISION
LANDSCAPE ECOLOGY BRANCH