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  • Thumbnail for Evolution of Life History in Three High Elevation Puya (Bromeliaceae)
    Evolution of Life History in Three High Elevation Puya (Bromeliaceae) by Veldhuisen, Leah

    The Andes are known as a hotspot for biodiversity and high species endemism for both plants and animals. Two important tropical, high-elevation ecosystems in the Andes are the puna in Peru, Bolivia and Chile between 7° and 27° South, and the páramo in Colombia, Venezuela and Ecuador between 11° North and 8° South; both are found at elevations above 3500 meters. The genus Puya (Bromeliaceae) is found throughout the puna and the páramo, and is relatively under-studied. Life history of most Puya species is largely unknown, with the notable exception of entirely semelparous Puya raimondii, which flowers once right before dying and does not reproduce clonally. Other species in the genus do reproduce clonally to varying degrees; their life history strategies have not been defined. Decreased cloning ability in Puya may be evolving convergently as in other plant groups endemic to high-elevation, tropical ecosystems. We studied three species of Puya (P. raimondii, P. cryptantha and P. goudotiana) across the two ecosystems in Bolivia and Colombia, and collected data on threshold size at flowering and clonal reproduction. Data were also analyzed in conjunction with life history theory to hypothesize each species’ life history strategy. All three species were found to have a consistent and predictable minimum size at flowering, while P. cryptantha was found to also have a minimum size for clonal reproduction. No such evidence was found for P. goudotiana. Our data supported that P. raimondii is fully semelparous, and indicated that P. goudotiana and P. cryptantha may be semi-semelparous.

  • Thumbnail for Brood size dependent differences in prey delivery rates among Flammulated Owls (Psiloscops flammeolus)
    Brood size dependent differences in prey delivery rates among Flammulated Owls (Psiloscops flammeolus) by Grundy, Bryan David

    Optimal clutch size has been an important focus within evolutionary biology since David Lack’s innovative work in 1947. Prey abundance, typically thought to limit clutch size, may be especially limiting in raptors, since the females contribute minimally to prey provisioning. Studying species with significant energetic constraints may illuminate the relationship between energetics, parental division of labor and clutch size. Flammulated Owls (Psiloscops flammeolus) are a small raptor with prey that is small relative to their body size, further constraining flammulated owls energetically when compared to raptors with larger prey. I hypothesized that female flammulated owls with clutches of three will contribute more to prey deliveries than females with clutches of two, while male prey delivery rates will not vary with brood size. Prey delivery data from 115 flammulated owl nests in the Front Range of Colorado were recorded from 2004-2013. During the second half of the nestling period broods of three received more prey deliveries than broods of two (p < 0.05). Additionally, during the second half of the nestling period no significant difference was found between male and female prey delivery rates for broods of three (p > 0.05). However, among adults with broods of two, males provided significantly more prey than females (p < 0.05). Male prey delivery rate between brood sizes was not significantly different (p > 0.05). These results indicate that broods of three may require greater energy expenditure than broods of two from the female, but not the male parent. While these results pertain to a bird with a small inflexible clutch size, similar research on birds with larger more flexible clutch sizes may reveal how and if clutch size and parental division of labor have co-evolved within avian taxa.