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62. Sperm competition within a dominance hierarchy: investment in social status vs. investment in ejaculates.

Author

Montrose, V. Tamara, Harris, W. Edwin, Moore, A. J., and Moore, P. J.

Subjects
*SPERM competition, *SOCIAL interaction, *A priori, *SOCIAL status, *COMPETITION (Biology), *SOCIAL dominance, *PHYSIOLOGICAL stress, *COCKROACHES, *MALE ejaculation, *EDUCATION, *PHYSIOLOGY
Abstract

There is increasing recognition that male–male competition can take many forms, but as yet the form is not predictable a priori. Many recent studies have focused attention on how males in disadvantaged mating roles compensate through sperm competition. However, mating systems in which subordinate males are reproductively suppressed, particularly through the stress of social interactions, may limit the ability of males to respond by increasing investment in sperm quality. We examined the interaction between social status and ejaculate tactics in Nauphoeta cinerea, a cockroach that has a mating system with well-characterized dominance hierarchies. Both social experience with other males and social status influenced aspects of ejaculates. The stress of social interactions reduced the size of the ejaculate and number of sperm inseminated. In ejaculates formed prior to social experience, however, males that go on to become dominant inseminated more sperm than males that go on to become subordinate, suggesting innate differences among males. Our results show that though selection for increased success in sperm competition for subordinate males in a hierarchy can occur, both the traits and the way in which the balance between pre- and post-copulatory strategies is negotiated will depend on specific details of the mating system. These details will include how the physiological effects of social interactions may limit selection through male–male competition. [ABSTRACT FROM AUTHOR]

Published
2008
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63. Estimating density of mountain hares using distance sampling: a comparison of daylight visual surveys, night-time thermal imaging and camera traps

Author

Bedson, Carlos P. E., Thomas, Lowri, Wheeler, Philip M., Reid, Neil, Harris, W. Edwin, Lloyd, Huw, Mallon, David, Preziosi, Richard, Bedson, Carlos P. E., Thomas, Lowri, Wheeler, Philip M., Reid, Neil, Harris, W. Edwin, Lloyd, Huw, Mallon, David, and Preziosi, Richard

Abstract

Surveying cryptic, nocturnal animals is logistically challenging. Consequently, density estimates may be imprecise and uncertain. Survey innovations mitigate ecological and observational difficulties contributing to estimation variance. Thus, comparisons of survey techniques are critical to evaluate estimates of abundance. We simultaneously compared three methods for observing mountain hare Lepus timidus using Distance sampling to estimate abundance. Daylight visual surveys achieved 41 detections, estimating density at 14.3 hares km–2 (95%CI 6.3–32.5) resulting in the lowest estimate and widest confidence interval. Night-time thermal imaging achieved 206 detections, estimating density at 12.1 hares km–2 (95%CI 7.6–19.4). Thermal imaging captured more observations at furthest distances, and detected larger group sizes. Camera traps achieved 3705 night-time detections, estimating density at 22.6 hares km–2 (95%CI 17.1–29.9). Between the methods, detections were spatially correlated, although the estimates of density varied. Our results suggest that daylight visual surveys tended to underestimate density, failing to reflect nocturnal activity. Thermal imaging captured nocturnal activity, providing a higher detection rate, but required fine weather. Camera traps captured nocturnal activity, and operated 24/7 throughout harsh weather, but needed careful consideration of empirical assumptions. We discuss the merits and limitations of each method with respect to the estimation of population density in the field.

64. Estimating density of mountain hares using distance sampling: a comparison of daylight visual surveys, night-time thermal imaging and camera traps

Author

Bedson, Carlos P. E., Thomas, Lowri, Wheeler, Philip M., Reid, Neil, Harris, W. Edwin, Lloyd, Huw, Mallon, David, Preziosi, Richard, Bedson, Carlos P. E., Thomas, Lowri, Wheeler, Philip M., Reid, Neil, Harris, W. Edwin, Lloyd, Huw, Mallon, David, and Preziosi, Richard

Abstract

Surveying cryptic, nocturnal animals is logistically challenging. Consequently, density estimates may be imprecise and uncertain. Survey innovations mitigate ecological and observational difficulties contributing to estimation variance. Thus, comparisons of survey techniques are critical to evaluate estimates of abundance. We simultaneously compared three methods for observing mountain hare Lepus timidus using Distance sampling to estimate abundance. Daylight visual surveys achieved 41 detections, estimating density at 14.3 hares km–2 (95%CI 6.3–32.5) resulting in the lowest estimate and widest confidence interval. Night-time thermal imaging achieved 206 detections, estimating density at 12.1 hares km–2 (95%CI 7.6–19.4). Thermal imaging captured more observations at furthest distances, and detected larger group sizes. Camera traps achieved 3705 night-time detections, estimating density at 22.6 hares km–2 (95%CI 17.1–29.9). Between the methods, detections were spatially correlated, although the estimates of density varied. Our results suggest that daylight visual surveys tended to underestimate density, failing to reflect nocturnal activity. Thermal imaging captured nocturnal activity, providing a higher detection rate, but required fine weather. Camera traps captured nocturnal activity, and operated 24/7 throughout harsh weather, but needed careful consideration of empirical assumptions. We discuss the merits and limitations of each method with respect to the estimation of population density in the field.

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