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Patricia Mehlhop

Publications and source records attributed to Patricia Mehlhop.

4 recordsLinked to original sources
USGS2009

A rapid field techniques for preparing ant chromosomes for karyotypic analysis

This technique for chromosomal preparation of ant tissues for karyotypic analysis is advantageous under field conditions because it reduces processing time and can be used under humid conditions. The cerebral ganglia from prepupae or early pupae are incubated 20 minutes in a hypotonic citrate solution, minced in a fixative solution of 3:3:4 glacial acetic acid: absolute methanol: distilled HOH, rinsed in a fixative solution of 1:1 glacial acetic acid: methanol followed by Carnoy's fixative, then immediately flame dried. The resulting metaphase chromosomes are well spaced and usually show banding characteristics.

Stain Technology↗
USGS2008

Temporal patterns of seed use and availability in a guild of desert ants

1 Temporal patterns of seed use were studied from late winter to autumn in three species of seed-harvesting ants in the Sonoran Desert. Measures of effective foraging activity, dietary niche breadth and dietary niche overlaps were obtained each month and were tested for correlation with estimates of the available seed resource. 2 Seeds were the only numerically important type of food in the diets of all species. 3 The ants partitioned the resource according to both seed species and seed size, although there was considerable overlap. 4 Pheidole xerophila had the smallest forager body size and is a specialist on small seeds because it harvested them in greater proportion than their rank in the soils and expanded its diet to larger seeds only when the abundance of small seeds declined. 5 When the abundance of the small seeds of Bouteloua barbata decreased, the middle-sized ant, Veromessor pergandei , showed a decrease in foraging activity, increase in niche breadth, and a decrease in overlap with P.xerophila. 6 Seed size preferences of V.pergandei did not vary seasonally, except that during the month of highest seed abundance, V.pergandei showed no size preference. 7 Pogonomyrmex rugosus was the largest ant; it preferred larger seeds and was inactive when small seeds were most abundant. Seasonal foraging activity and niche parameters were random in relation to seed abundance. 8 We suggest that nocturnal foraging by P.rugosus during the summer months was a response to interference with diurnal foraging by either predation frorn horned lizards or competition from V.pergandei. 9 Seasonal abundance of small seeds explains most of the seasonal foraging patterns of P.xerophila and V.pergandei. The summertime abundance of larger seeds during years of adequate precipitation may account for the seasonal activity patterns of P.rugosus.

Ecological Entomology↗
USGS1998

Southwest

The southwestern region of the United States is a land of extremes and contrasts. Elevations vary from below sea level in the Imperial Valley of California to mountain peaks approaching 4,000 meters. Landscapes are striking and variable and include mountains, foothills, canyons, deserts, plains, and rivers. The area is arid or semiarid and, depending on the location, may have mild winters and summers, periods of bitter cold, or intervals of intense heat. Climate is inextricably tied to water and its availability. Historically, water varied from abundant to sparse over the span of a year, and adaptations of native plants and animals reflect those extremes. Annual precipitation, usually in the form of rain, varies from 30 to 40 millimeters in the low-elevation Sonoran Desert to more than 1,000 millimeters in the high mountains (Brown 1982a; Bahre and Shelton 1993). This variation in topography and climate has produced great floral and faunal diversity.

Book chapter↗