Sexual selection and sperm competition in the guppy ( Poecilia reticulata)

When differences among individuals in the ability to acquire mates result in evolutionary change, this is known as sexual selection. My goal was to investigate sexual selection on male traits in the guppy (Poecilia reticulata). I assessed reproductive skew and correlates of male reproductive success in a wild population and found that male reproductive success was strongly skewed and correlated with gonopodium length, but not with the relative area of coloured spots, body length, or sperm velocity. I then determined the role of sperm competition in shaping sperm form and function by comparing sperm traits across populations. I found that males in high predation populations, which presumably experience more intense sperm competition, had significantly faster sperm with longer midpieces than males in low predation populations, which experience less intense sperm competition. These results suggest that gonopodium length is a sexually selected trait and that sperm competition selects for sperm velocity

The role of the convoluted segment of the proximal tubule in the disposal of 131 I-insulin in the rat kidney

It is generally accepted that in the kidney insulin is metabolized in the proximal tubule, but whether in the convoluted segment, the straight segment, or both has not been established. By means of autoradiography counting of radioactivity, and interrupted flow techniques, the following observations have been made. 131 I-labelled porcine insulin is metabolized exclusively in the convoluted segment of the proximal tubule. Although the glomerular filtrate is the major source of insulin supply to the renal epithelia, the peritubular capillary plexuses provide as much as 30% or more of the total insulin delivered to the renal epithelia. The epithelium of the convoluted segment is capable of sequestering 131 I-insulin from the peritubular capillary plexuses, a phenomenon which has not been established previously.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49671/1/1001400205_ftp.pd

Grating Magneto-Optical Traps for Strontium

This thesis describes the construction of a new laboratory and a new apparatusfor ultracold strontium experiments. It also describes the the creation of the first strontium grating magneto-optical trap (MOT). The new strontium apparatus has been improved to provide high, and controllable atomic flux, high magnetic field coils, low vacuum pressure, plenty of optical access, and a streamlined computer control system. This flexible apparatus is designed to operate several potential experiments. Our work with strontium grating MOTs will help to enable the creation of compact, stable, and portable quantum devices that harness the unique capabilities of alkaline earth atoms. We present the construction of the grating MOT apparatus, the demonstration of the broad line strontium grating MOT, and the transfer to the narrow line grating MOT. In addition, we show the effectiveness of sawtooth wave adiabatic passage (SWAP) in the grating MOT geometry. Lastly, we present work from the previous apparatus, measuring the isotope shifts on the clock and intercombination transitions in strontium

Geographic variation in sperm traits reflects predation risk and natural rates of multiple paternity in the guppy

Guppies (Poecilia reticulata) are models for understanding the interplay between natural and sexual selection. In particular, predation has been implicated as a major force affecting female sexual preferences, male mating tactics and the level of sperm competition. When predation is high, females typically reduce their preferences for showy males and engage more in antipredator behaviours, whereas males exploit these changes by switching from sexual displays to forced matings. These patterns are thought to account for the relatively high levels of multiple paternity in high-predation populations compared to low-predation populations. Here, we assess the possible evolutionary consequences of these patterns by asking whether variation in sperm traits reflect differences in predation intensity among four pairs of Trinidadian populations: four that experience relatively low levels of predation from a gape-limited predator and four that experience relatively high levels of predation from a variety of piscivores. We found that males in high-predation populations had faster swimming sperm with longer midpieces compared to males in low-predation populations. However, we found no differences among males in high- and low-predation populations with respect to sperm number, sperm head length, flagellum length and total sperm length

A comparison of the hypoglycemic effect of insulin with systemic venous and portal venous administration

The hyperglycemic effect of insulin by prolonged intraportal and systemic infusion was measured in unanesthetized dogs with a modified portacaval transposition. There was no significant difference in response with the two routes of administration. The relation of these results to research directed to surgical therapy of diabetes is discussed. © 1963 W. B. Saunders Company

Sperm Swimming Velocity Predicts Competitive Fertilization Success in the Green Swordtail Xiphophorus helleri

Sperm competition is expected to favour the evolution of traits that influence the performance of sperm when they compete to fertilize a female's eggs. While there is considerable evidence that selection favours increases in sperm numbers, much less is known about how sperm quality contributes towards competitive fertilization success. Here, we determine whether variation in sperm quality influences competitive fertilization success in the green swordtail Xiphophorus helleri, a highly promiscuous livebearing fish. We use artificial insemination as a method of controlled sperm delivery and show that sperm swimming velocity is the primary determinant of fertilization success when ejaculates from two males compete to fertilize a female's eggs. By contrast, we found no evidence that sperm length had any effect on siring success. We also found no evidence that pre- and postcopulatory sexual traits were phenotypically integrated in this species, suggesting that the previous observation that reproductive skew favours males with high mating rates is unlikely to be due to any direct association between sperm quality and male sexual ornamentation

Excavation of Barrow III, Irton Moor, North Yorkshire.

YesIrton Moor was excavated by Derek Simpson in 1973 but remained unpublished at the time of his death in 2006. Material from the excavation including a skeletal report and some publication drawings were located in DDAS’s archives and brought back to Bradford for archiving. Sufficient work had been done by DDAS to bring the report to publication though clearly the archive had suffered over the years. Irton Moor represents a small structured round cairn of the Early Bronze Age producing evidence for long-term occupation of the site from the Early Neolithic though this occupation does not appear to have been continuous. The cairn was used for Food Vessel and Collared Urn-associated cremations